Lasofoxifene versus fulvestrant for ER+/HER2- metastatic breast cancer with an ESR1 mutation: results from the randomized, phase II ELAINE 1 trial

BACKGROUND

Acquired estrogen receptor alpha (ER/ESR1) mutations commonly cause endocrine resistance in ER+ metastatic breast cancer (mBC). Lasofoxifene, a novel selective ER modulator, stabilizes an antagonist conformation of wild-type and ESR1-mutated ER-ligand binding domains, and has antitumor activity in ESR1-mutated xenografts.

PATIENTS AND METHODS

In this open-label, randomized, phase II, multicenter, ELAINE 1 study (NCT03781063), we randomized women with ESR1-mutated, ER+/human epidermal growth factor receptor 2 negative (HER2-) mBC that had progressed on an aromatase inhibitor (AI) plus a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) to oral lasofoxifene 5 mg daily or IM fulvestrant 500 mg (days 1, 15, and 29, and then every 4 weeks) until disease progression/toxicity. The primary endpoint was progression-free survival (PFS); secondary endpoints were safety/tolerability.

RESULTS

A total of 103 patients received lasofoxifene (n = 52) or fulvestrant (n = 51). The most current efficacy analysis showed that lasofoxifene did not significantly prolong median PFS compared with fulvestrant: 24.2 weeks (∼5.6 months) versus 16.2 weeks (∼3.7 months; P = 0.138); hazard ratio 0.699 (95% confidence interval 0.434-1.125). However, PFS and other clinical endpoints numerically favored lasofoxifene: clinical benefit rate (36.5% versus 21.6%; P = 0.117), objective response rate [13.2% (including a complete response in one lasofoxifene-treated patient) versus 2.9%; P = 0.124], and 6-month (53.4% versus 37.9%) and 12-month (30.7% versus 14.1%) PFS rates. Most common treatment-emergent adverse events with lasofoxifene were nausea, fatigue, arthralgia, and hot flushes. One death occurred in the fulvestrant arm. Circulating tumor DNA ESR1 mutant allele fraction (MAF) decreased from baseline to week 8 in 82.9% of evaluable lasofoxifene-treated versus 61.5% of fulvestrant-treated patients.

CONCLUSIONS

Lasofoxifene demonstrated encouraging antitumor activity versus fulvestrant and was well tolerated in patients with ESR1-mutated, endocrine-resistant mBC following progression on AI plus CDK4/6i. Consistent with target engagement, lasofoxifene reduced ESR1 MAF, and to a greater extent than fulvestrant. Lasofoxifene may be a promising targeted treatment for patients with ESR1-mutated mBC and warrants further investigation.

High-dimensional immune cell profiling of cerebrospinal fluid from patients with metastatic breast cancer and leptomeningeal disease

Leptomeningeal disease (LMD) is a devastating complication of metastatic breast cancer (MBC). In this non-therapeutic study, we enrolled 12 patients with MBC and known or suspected LMD who were undergoing a lumbar puncture as part of clinical care and collected extra cerebrospinal fluid (CSF) and a paired blood sample from each patient at a single time point. Of the 12 patients, 7 patients are confirmed to have LMD based on positive cytology and/or convincing MRI imaging (LMD^pos), and 5 patients are deemed not to have LMD based on similar criteria (LMD^neg). Using high-dimensional, multiplexed flow cytometry, we profile and compare the CSF and peripheral blood mononuclear cell (PBMCs) immune populations between patients with LMD and those without. Patients with LMD observe a lower overall frequency of CD45⁺ cells (29.51% vs. 51.12%, p < 0.05), lower frequencies of CD8⁺ T cells (12.03% vs. 30.40%, p < 0.01), and higher frequency of T_regs than patients without LMD. Interestingly, the frequency of partially exhausted CD8⁺ T cells (CD38^hiTIM3^lo) is ~6.5-fold higher among patients with LMD vs. those without (2.99% vs. 0.44%, p < 0.05). Taken together, these data suggest that patients with LMD may have lower overall immune infiltrates than patients without LMD, suggesting a more permissive CSF immune microenvironment but a higher frequency of partially exhausted CD8⁺ T cells, which may offer an important therapeutic target.

Adjuvant Abemaciclib Combined with Endocrine Therapy for High Risk Early Breast Cancer: Safety and Patient-Reported Outcomes From the monarchE Study

BACKGROUND

In monarchE, abemaciclib plus endocrine therapy (ET) as adjuvant treatment of hormone receptor-positive, human epidermal growth factor 2-negative, high risk, early breast cancer demonstrated a clinically meaningful improvement in invasive disease-free survival versus ET alone. Detailed safety analyses conducted at a median follow-up of 27 months and key patient-reported outcomes (PRO) are presented.

PATIENTS AND METHODS

The safety population included all patients who received at least one dose of study treatment (n=5591). Safety analyses included incidence, management, and outcomes of common and clinically relevant adverse events (AEs). Patient-reported health-related quality-of-life, ET symptoms, fatigue, and side effect burden were assessed.

RESULTS

The addition of abemaciclib to ET resulted in higher incidence of Grade≥3 AEs (49.7% vs 16.3% with ET alone), predominantly laboratory cytopenias (e.g., neutropenia [19.6%]) without clinical complications. Abemaciclib-treated patients experienced more serious adverse events (SAEs; 13.3% vs 7.8%). Discontinuation of abemaciclib and/or ET due to AEs occurred in 18.5% of patients, mainly due to Grade1/2 AEs (66.8%). AEs were managed with comedications (e.g., antidiarrheals), abemaciclib dose holds (61.7%), and/or dose reductions (43.4%). Diarrhea was generally low grade (Grade1/2: 77%); Grade2/3 events were highest in the first month (20.5%), most short-lived (≤7 days) and did not recur. Venous thromboembolic events (VTE) were higher with abemaciclib+ET (2.5%) vs ET (0.6%); in the abemaciclib arm, increased VTE risk was observed with tamoxifen vs AIs (4.3% vs 1.8%). PROs were similar between arms, including being 'bothered by side effects of treatment', except for diarrhea. At ≥3 months, most patients reporting diarrhea reported "a little bit" or "somewhat".

CONCLUSION

In patients with high risk EBC, adjuvant abemaciclib+ET has an acceptable safety profile and tolerability is supported by PRO findings. Most AEs were reversible and manageable with comedications and/or dose modifications, consistent with the known abemaciclib toxicity profile.

Long-term efficacy and safety of addition of carboplatin with or without veliparib to standard neoadjuvant chemotherapy in triple-negative breast cancer: 4-year follow-up data from BrighTNess, a randomized phase 3 trial

BACKGROUND

Primary analyses of the phase 3 BrighTNess trial showed addition of carboplatin with/without veliparib to neoadjuvant chemotherapy significantly improved pathological complete response (pCR) rates with manageable acute toxicity in patients with triple-negative breast cancer (TNBC). Here, we report 4.5-year follow-up data from the trial.

DESIGN

Women with untreated stage II-III TNBC were randomized (2:1:1) to paclitaxel (weekly for 12 doses) plus either: (a) carboplatin (every 3 weeks for four cycles) plus veliparib (twice daily); (b) carboplatin plus veliparib placebo; or (c) carboplatin placebo plus veliparib placebo. All patients then received doxorubicin and cyclophosphamide (AC) every 2‒3 weeks for four cycles. The primary endpoint was pCR. Secondary endpoints included event-free survival (EFS), overall survival (OS), and safety. Since the co-primary endpoint of increased pCR with carboplatin plus veliparib with paclitaxel versus carboplatin with paclitaxel was not met, secondary analyses are descriptive.

RESULTS

Of 634 patients, 316 were randomized to carboplatin plus veliparib with paclitaxel, 160 to carboplatin with paclitaxel, and 158 to paclitaxel. With median follow-up of 4.5 years, the hazard ratio [HR] for EFS for carboplatin plus veliparib with paclitaxel versus paclitaxel was 0.63 (95% confidence interval [CI] 0.43‒0.92, P=0.02), but 1.12 (95% CI 0.72‒1.72, P=0.62) for carboplatin plus veliparib with paclitaxel versus carboplatin with paclitaxel. In post hoc analysis, HR for EFS was 0.57 (95% CI 0.36‒0.91, P=0.02) for carboplatin with paclitaxel versus paclitaxel. OS did not differ significantly between treatment arms, nor did rates of myelodysplastic syndromes, acute myeloid leukemia, or other secondary malignancies.

CONCLUSION

Improvement in pCR with addition of carboplatin was associated with long-term EFS benefit with a manageable safety profile, and without increasing the risk of second malignancies, while adding veliparib did not impact EFS. These findings support the addition of carboplatin to weekly paclitaxel followed by AC neoadjuvant chemotherapy for early stage TNBC.

Adjuvant abemaciclib combined with endocrine therapy for high-risk early breast cancer: updated efficacy and Ki-67 analysis from the monarchE study

BACKGROUND

Adjuvant abemaciclib combined with endocrine therapy (ET) previously demonstrated clinically meaningful improvement in invasive disease-free survival (IDFS) and distant relapse-free survival (DRFS) in hormone receptor-positive, human epidermal growth factor receptor 2-negative, node-positive, high-risk early breast cancer at the second interim analysis, however follow-up was limited. Here, we present results of the prespecified primary outcome analysis and an additional follow-up analysis.

PATIENTS AND METHODS

This global, phase III, open-label trial randomized (1 : 1) 5637 patients to adjuvant ET for ≥5 years ± abemaciclib for 2 years. Cohort 1 enrolled patients with ≥4 positive axillary lymph nodes (ALNs), or 1-3 positive ALNs and either grade 3 disease or tumor ≥5 cm. Cohort 2 enrolled patients with 1-3 positive ALNs and centrally determined high Ki-67 index (≥20%). The primary endpoint was IDFS in the intent-to-treat population (cohorts 1 and 2). Secondary endpoints were IDFS in patients with high Ki-67, DRFS, overall survival, and safety.

RESULTS

At the primary outcome analysis, with 19 months median follow-up time, abemaciclib + ET resulted in a 29% reduction in the risk of developing an IDFS event [hazard ratio (HR) = 0.71, 95% confidence interval (CI) 0.58-0.87; nominal P = 0.0009]. At the additional follow-up analysis, with 27 months median follow-up and 90% of patients off treatment, IDFS (HR = 0.70, 95% CI 0.59-0.82; nominal P < 0.0001) and DRFS (HR = 0.69, 95% CI 0.57-0.83; nominal P < 0.0001) benefit was maintained. The absolute improvements in 3-year IDFS and DRFS rates were 5.4% and 4.2%, respectively. Whereas Ki-67 index was prognostic, abemaciclib benefit was consistent regardless of Ki-67 index. Safety data were consistent with the known abemaciclib risk profile.

CONCLUSION

Abemaciclib + ET significantly improved IDFS in patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative, node-positive, high-risk early breast cancer, with an acceptable safety profile. Ki-67 index was prognostic, but abemaciclib benefit was observed regardless of Ki-67 index. Overall, the robust treatment benefit of abemaciclib extended beyond the 2-year treatment period.

Abstract PS13-11: Oral paclitaxel and encequidar (oPac+E) in the treatment of metastatic breast cancer (mBC): Management of gastrointestinal adverse events (GI AE). Study KX-ORAX-001

Background: There is a need for more effective and less toxic treatments for patients with mBC. Patients may prefer oral vs IV cytotoxic therapies to avoid frequent hospital visits. In addition, oral therapies allow frequent or metronomic dosing regimens which may alter the toxicity or activity profile of agents vs infrequent IV administration. oPac+E is oral paclitaxel combination with Encequidar, a specific, minimally absorbed, oral p-glycoprotein inhibitor that facilitates the absorption of oral paclitaxel. mBC patients who received oPac+E had significantly greater confirmed tumor response and longer survival with lower rates and severity of neuropathy but increased GI AE compared to IV paclitaxel (IVPac) (Study KX-ORAX-001 presented at SABCS, 2019, Abstract # GS6-01).

Methods: Study KX-ORAX-001 was a phase III, randomized, study in women with mBC for whom treatment with IVPac was recommended. Patients were randomized 2:1 to receive oPac+E or IVPac. Patients continued treatment until discontinuation due to progressive disease or toxicity. oPac 205 mg/m2 was given once daily for 3 days weekly. E 12.9 mg was given 1 hour before each dose of oPac. IVPac 175 mg/m2 was infused over 3 hours every 3 weeks. The primary endpoint was efficacy defined as tumor response confirmed by BICR at two consecutive evaluations. Key secondary endpoints included PFS, OS. Safety was monitored throughout the study.

Results: All IVPac patients received high-dose dexamethasone and antihistamine premedication, which have significant anti-emetic activity and may have received additional anti-emetic agents as needed. The protocol did not allow any prophylaxis for GI AE for oPac+E patients nor were they to receive predose corticosteroids, nor antihistamines.

The protocol was amended after approximately 30% of patients were enrolled to allow prophylactic anti-emetic medications for patients randomized to oPac+E. Patients were also given loperamide to take at home and were instructed to initiate loperamide with the onset of diarrhea. The rates of Grade ≥2, vomiting and diarrhea for patients treated with IVPac, the patients treated with oPac+E prior to after the amendment are summarized in the table below.

Prophylactic anti-emetic therapy and early use of loperamide markedly decreased the incidence of ≥Grade 2 vomiting and diarrhea although there was a greater incidence than IVPac.

The most frequently prescribed anti-emetic agents for oPac+E treated patients were ondansetron (54%), metoclopramide (21%), domperidone (4%) and aprepitant (3%). For patients randomized to IVPac, the most frequently prescribed agents were ondanesteron (59%), granisetron (24%), palenosetron (7%) and aprepitant (2%). Oral administration of the oral NK1 inhibitor aprepitant appeared to be associated with increased incidence of oral paclitaxel systemic toxicity, potentially due to inhibition of metabolism of oPac by cytochrome P450 3A4.

Conclusions: oPac+E was associated with greater efficacy in the treatment of mBC and lower rates and severity of peripheral neuropathy, but increased GI AE compared to IVPac 175mg/m2. GI AE in oPac+E treated patients can be managed by prophylactic use of anti-emetics, primarily 5-HT3 inhibitors and early intervention with the anti-diarrhea agent loperamide. The use of the oral NK1 inhibitor aprepitant in combination with oPac+E is not recommended.(NTC02594371)

IVPacoPac+E Pre-AmendmentoPac+E Post AmendmentGrade 2Grade 3Grade 4Grade 2Grade 3Grade 4Grade 2Grade 3Grade 4Vomiting4%1%0%24%7%0%7%4%0%Diarrhea7%1%0%27%9%0%16%3%0.5%

Citation Format: H S Rugo, G Umanzor, F J Barrios, R H Vasallo, M A Chivalan, S Bejarano, J R Ramirez, L Fein, R D Kowalyszyn, D L Cutler, D Kramer, J Goldfinch, H Wang, T Moore, R MF Kwan. Oral paclitaxel and encequidar (oPac+E) in the treatment of metastatic breast cancer (mBC): Management of gastrointestinal adverse events (GI AE). Study KX-ORAX-001 [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS13-11.

Abstract PS13-06: Lower rates of neuropathy with oral paclitaxel and encequidar (oPac+E) compared to IV paclitaxel (IVPac) in treatment of metastatic breast cancer (mBC): Study KX-ORAX-001

Background: Chemotherapy-induced peripheral neuropathy (CIPN) is a common dose-limiting toxicity associated with IVPac. Primarily sensory, CIPN is an often irreversible condition primarily affecting the hands and feet associated with pain, numbness, tingling, and sensitivity to cold and has a significant impact on quality of life and treatment tolerance. Risk of CIPN increases with age, dose intensity, cumulative dose, and preexisting conditions including diabetes.

Methods: Study KX-ORAX-001 was a phase III, randomized, international study in women with mBC for whom treatment with IVPac was recommended. Eligible patients were randomized 2:1 to receive oPac+E or IVPac. Patients continued treatment until discontinuation due to progressive disease or toxicity. oPac 205 mg/m2 was given once daily for 3 days weekly. E 12.9 mg was given 1 hour before each dose of oPac. IVPac 175 mg/m2 was infused over 3 hours every 3 weeks. The primary endpoint was efficacy defined as tumor response confirmed by BICR at two consecutive evaluations. Key secondary endpoints included PFS, OS. Safety was monitored throughout the study.

Results: A total of 402 mBC patients were enrolled, 265 randomized to oPac+E and 137 to IVPac (ITT population). 399 patients were treated and comprise the safety population. The confirmed response rate was significantly greater in the oPac+E group vs IVPac (35% vs 23%) for the ITT population. Median overall survival was (27.7 vs 16.7 months, ITT) at the time of the analysis. Long-term follow up for final determination of PFS and OS is ongoing.Incidence of neuropathy-related TEAEs were lower in patients receiving oPac+E vs IVPac: Overall (21% vs 64%; all grades), grade ≥3 (2% vs 15%). Cumulative risk for neuropathy with IVPac was &gt;50% by week 8 and was 83% at week 88. In contrast, the cumulative risk of neuropathy with oPac+E rose slowly and plateaued at 34% at week 88. Treatment discontinuations due to neuropathy occurred only in the IVPac arm (8%). Dose reductions due to neuropathy were reported in 8% of IVPac treated patients and in 2% of oPac+E treated patients. In agreement with the lower rates of peripheral neuropathy in patients treated with oPac+E, there was lower use of medications used for the treatment of neuropathic symptoms. Use of gabapentin or pregabalin was 12% for patients receiving oPac+E vs 40% for IVPac treated patients.

Conclusions: oPac+E was associated with greater efficacy in the treatment of patients with mBC and a lower incidence of neuropathy, slower onset and lesser severity of neuropathic events compared to IVPac 175mg/m2 administered every three weeks. Fewer patients receiving oPac+E required dose reduction due to neuropathy and no patients receiving oPac+E discontinued treatment due to neuropathy. Reduction in neuropathy may improve quality of life and allow longer administration of effective therapy while maintaining dose intensity.

Citation Format: H S Rugo, G Umanzor, F J Barrios, R H Vasallo, M A Chivalan, S Bejarano, J R Ramirez, L Fein, R D Kowalyszyn, D L Cutler, D Kramer, J Goldfinch, H Wang, T Moore, R MF Kwan. Lower rates of neuropathy with oral paclitaxel and encequidar (oPac+E) compared to IV paclitaxel (IVPac) in treatment of metastatic breast cancer (mBC): Study KX-ORAX-001 [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS13-06.

Alpelisib plus fulvestrant for PIK3CA-mutated, hormone receptor-positive, human epidermal growth factor receptor-2-negative advanced breast cancer: final overall survival results from SOLAR-1

BACKGROUND

Activation of the phosphatidylinositol-3-kinase (PI3K) pathway via PIK3CA mutations occurs in 28%-46% of hormone receptor-positive (HR+), human epidermal growth factor receptor-2-negative (HER2-) advanced breast cancers (ABCs) and is associated with poor prognosis. The SOLAR-1 trial showed that the addition of alpelisib to fulvestrant treatment provided statistically significant and clinically meaningful progression-free survival (PFS) benefit in PIK3CA-mutated, HR+, HER2- ABC.

PATIENTS AND METHODS

Men and postmenopausal women with HR+, HER2- ABC whose disease progressed on or after aromatase inhibitor (AI) were randomized 1 : 1 to receive alpelisib (300 mg/day) plus fulvestrant (500 mg every 28 days and once on day 15) or placebo plus fulvestrant. Overall survival (OS) in the PIK3CA-mutant cohort was evaluated by Kaplan-Meier methodology and a one-sided stratified log-rank test was carried out with an O'Brien-Fleming efficacy boundary of P ≤ 0.0161.

RESULTS

In the PIK3CA-mutated cohort (n = 341), median OS [95% confidence interval (CI)] was 39.3 months (34.1-44.9) for alpelisib-fulvestrant and 31.4 months (26.8-41.3) for placebo-fulvestrant [hazard ratio (HR) = 0.86 (95% CI, 0.64-1.15; P = 0.15)]. OS results did not cross the prespecified efficacy boundary. Median OS (95% CI) in patients with lung and/or liver metastases was 37.2 months (28.7-43.6) and 22.8 months (19.0-26.8) in the alpelisib-fulvestrant and placebo-fulvestrant arms, respectively [HR = 0.68 (0.46-1.00)]. Median times to chemotherapy (95% CI) for the alpelisib-fulvestrant and placebo-fulvestrant arms were 23.3 months (15.2-28.4) and 14.8 months (10.5-22.6), respectively [HR = 0.72 (0.54-0.95)]. No new safety signals were observed with longer follow-up.

CONCLUSIONS

Although the analysis did not cross the prespecified boundary for statistical significance, there was a 7.9-month numeric improvement in median OS when alpelisib was added to fulvestrant treatment of patients with PIK3CA-mutated, HR+, HER2- ABC. Overall, these results further support the statistically significant prolongation of PFS observed with alpelisib plus fulvestrant in this population, which has a poor prognosis due to a PIK3CA mutation. CLINICALTRIALS.

GOV ID

NCT02437318.

Talazoparib versus chemotherapy in patients with germline BRCA1/2-mutated HER2-negative advanced breast cancer: final overall survival results from the EMBRACA trial

BACKGROUND

In EMBRACA, talazoparib prolonged progression-free survival versus chemotherapy (hazard ratio [HR] 0.542 [95% confidence interval (CI) 0.413-0.711]; P < 0.0001) and improved patient-reported outcomes (PRO) in germline BRCA1/2 (gBRCA1/2)-mutated advanced breast cancer (ABC). We report final overall survival (OS).

PATIENTS AND METHODS

This randomized phase III trial enrolled patients with gBRCA1/2-mutated HER2-negative ABC. Patients received talazoparib or physician's choice of chemotherapy. OS was analyzed using stratified HR and log-rank test and prespecified rank-preserving structural failure time model to account for subsequent treatments.

RESULTS

A total of 431 patients were entered in a randomized study (287 talazoparib/144 chemotherapy) with 412 patients treated (286 talazoparib/126 chemotherapy). By 30 September 2019, 216 deaths (75.3%) occurred for talazoparib and 108 (75.0%) chemotherapy; median follow-up was 44.9 and 36.8 months, respectively. HR for OS with talazoparib versus chemotherapy was 0.848 (95% CI 0.670-1.073; P = 0.17); median (95% CI) 19.3 months (16.6-22.5 months) versus 19.5 months (17.4-22.4 months). Kaplan-Meier survival percentages (95% CI) for talazoparib versus chemotherapy: month 12, 71% (66% to 76%)/74% (66% to 81%); month 24, 42% (36% to 47%)/38% (30% to 47%); month 36, 27% (22% to 33%)/21% (14% to 29%). Most patients received subsequent treatments: for talazoparib and chemotherapy, 46.3%/41.7% received platinum and 4.5%/32.6% received a poly(ADP-ribose) polymerase (PARP) inhibitor, respectively. Adjusting for subsequent PARP and/or platinum use, HR for OS was 0.756 (95% bootstrap CI 0.503-1.029). Grade 3-4 adverse events occurred in 69.6% (talazoparib) and 64.3% (chemotherapy) patients, consistent with previous reports. Extended follow-up showed significant overall improvement and delay in time to definitive clinically meaningful deterioration in global health status/quality of life and breast symptoms favoring talazoparib versus chemotherapy (P < 0.01 for all), consistent with initial analyses.

CONCLUSIONS

In gBRCA1/2-mutated HER2-negative ABC, talazoparib did not significantly improve OS over chemotherapy; subsequent treatments may have impacted analysis. Safety was consistent with previous observations. PRO continued to favor talazoparib.

Improved tolerability of neratinib in patients with HER2-positive early-stage breast cancer: the CONTROL trial

BACKGROUND

Neratinib is an irreversible pan-HER tyrosine kinase inhibitor approved for extended adjuvant treatment in early-stage HER2-positive breast cancer based on the phase III ExteNET study. In that trial, in which no antidiarrheal prophylaxis was mandated, grade 3 diarrhea was observed in 40% of patients and 17% discontinued due to diarrhea. The international, open-label, sequential-cohort, phase II CONTROL study is investigating several strategies to improve tolerability.

PATIENTS AND METHODS

Patients who completed trastuzumab-based adjuvant therapy received neratinib 240 mg/day for 1 year plus loperamide prophylaxis (days 1-28 or 1-56). Sequential cohorts evaluated additional budesonide or colestipol prophylaxis (days 1-28) and neratinib dose escalation (DE; ongoing). The primary end point was the incidence of grade ≥3 diarrhea.

RESULTS

Final data for loperamide (L; n = 137), budesonide + loperamide (BL; n = 64), colestipol + loperamide (CL; n = 136), and colestipol + as-needed loperamide (CL-PRN; n = 104) cohorts, and interim data for DE (n = 60; completed ≥six cycles or discontinued; median duration 11 months) are available. No grade 4 diarrhea was observed. Grade 3 diarrhea rates were lower than ExteNET in all cohorts and lowest in DE (L 31%, BL 28%, CL 21%, CL-PRN 32%, DE 15%). Median number of grade 3 diarrhea episodes was one; median duration per grade 3 episode was 1.0-2.0 days across cohorts. Most grade 3 diarrhea and diarrhea-related discontinuations occurred in month 1. Diarrhea-related discontinuations were lowest in DE (L 20%, BL 8%, CL 4%, CL-PRN 8%, DE 3%). Decreases in health-related quality of life did not cross the clinically important threshold.

CONCLUSIONS

Neratinib tolerability was improved with preemptive prophylaxis or DE, which reduced the rate, severity, and duration of neratinib-associated grade ≥3 diarrhea compared with ExteNET. Lower diarrhea-related treatment discontinuations in multiple cohorts indicate that proactive management can allow patients to stay on neratinib for the recommended time period. CLINICALTRIALS.GOV: NCT02400476.

Time course and management of key adverse events during the randomized phase III SOLAR-1 study of PI3K inhibitor alpelisib plus fulvestrant in patients with HR-positive advanced breast cancer

BACKGROUND

Alpelisib (α-selective phosphatidylinositol 3-kinase inhibitor) plus fulvestrant is approved in multiple countries for men and postmenopausal women with PIK3CA-mutated, hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer following progression on or after endocrine therapy. A detailed understanding of alpelisib's safety profile should inform adverse event (AE) management and enhance patient care.

PATIENTS AND METHODS

AEs in the phase III SOLAR-1 trial were assessed in patients with and without PIK3CA mutations. The impact of protocol-specified AE-management recommendations was evaluated, including an amendment to optimize hyperglycemia and rash management.

RESULTS

Patients were randomly assigned to receive fulvestrant plus alpelisib (n = 284) or placebo (n = 287). The most common grade 3/4 AEs with alpelisib were hyperglycemia (grade 3, 32.7%; grade 4, 3.9%), rash (grade 3, 9.9%), and diarrhea (grade 3, 6.7%). Median time to onset of grade ≥3 toxicity was 15 days (hyperglycemia, based on fasting plasma glucose), 13 days (rash), and 139 days (diarrhea). Metformin alone or in combination with other antidiabetic agents was used by most patients (87.1%) with hyperglycemia. Preventive anti-rash medication resulted in lower incidence (any grade, 26.7% versus 64.1%) and severity of rash (grade 3, 11.6% versus 22.7%) versus no preventative medication. Discontinuations due to grade ≥3 AEs were lower following more-detailed AE management guidelines (7.9% versus 18.1% previously). Patients with PIK3CA mutations had a median alpelisib dose intensity of 248 mg/day. Median progression-free survival with alpelisib was 12.5 and 9.6 months for alpelisib dose intensities of ≥248 mg/day and <248 mg/day, respectively, compared with 5.8 months with placebo.

CONCLUSIONS

Hyperglycemia and rash occurred early during alpelisib treatment, while diarrhea occurred at a later time point. Early identification, prevention, and intervention, including concomitant medications and alpelisib dose modifications, resulted in less severe toxicities. Reductions in treatment discontinuations and improved progression-free survival at higher alpelisib dose intensities support the need for optimal AE management. CLINICALTRIALS.

GOV ID

NCT02437318.

Pembrolizumab monotherapy for previously treated metastatic triple-negative breast cancer: cohort A of the phase II KEYNOTE-086 study

BACKGROUND

Treatment options for previously treated metastatic triple-negative breast cancer (mTNBC) are limited. In cohort A of the phase II KEYNOTE-086 study, we evaluated pembrolizumab as second or later line of treatment for patients with mTNBC.

PATIENTS AND METHODS

Eligible patients had centrally confirmed mTNBC, ≥1 systemic therapy for metastatic disease, prior treatment with anthracycline and taxane in any disease setting, and progression on or after the most recent therapy. Patients received pembrolizumab 200 mg intravenously every 3 weeks for up to 2 years. Primary end points were objective response rate in the total and PD-L1-positive populations, and safety. Secondary end points included duration of response, disease control rate (percentage of patients with complete or partial response or stable disease for ≥24 weeks), progression-free survival, and overall survival.

RESULTS

All enrolled patients (N = 170) were women, 61.8% had PD-L1-positive tumors, and 43.5% had received ≥3 previous lines of therapy for metastatic disease. ORR (95% CI) was 5.3% (2.7-9.9) in the total and 5.7% (2.4-12.2) in the PD-L1-positive populations. Disease control rate (95% CI) was 7.6% (4.4-12.7) and 9.5% (5.1-16.8), respectively. Median duration of response was not reached in the total (range, 1.2+-21.5+) and in the PD-L1-positive (range, 6.3-21.5+) populations. Median PFS was 2.0 months (95% CI, 1.9-2.0), and the 6-month rate was 14.9%. Median OS was 9.0 months (95% CI, 7.6-11.2), and the 6-month rate was 69.1%. Treatment-related adverse events occurred in 103 (60.6%) patients, including 22 (12.9%) with grade 3 or 4 AEs. There were no deaths due to AEs.

CONCLUSIONS

Pembrolizumab monotherapy demonstrated durable antitumor activity in a subset of patients with previously treated mTNBC and had a manageable safety profile.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT02447003.

Impact of palbociclib plus letrozole on patient-reported health-related quality of life: results from the PALOMA-2 trial

Background

Patient-reported outcomes are integral in benefit-risk assessments of new treatment regimens. The PALOMA-2 study provides the largest body of evidence for patient-reported health-related quality of life (QOL) for patients with metastatic breast cancer (MBC) receiving first-line endocrine-based therapy (palbociclib plus letrozole and letrozole alone).

Patients and methods

Treatment-naïve postmenopausal women with estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2-) MBC were randomized 2 : 1 to palbociclib plus letrozole (n = 444) or placebo plus letrozole (n = 222). Patient-reported outcomes were assessed at baseline, day 1 of cycles 2 and 3, and day 1 of every other cycle from cycle 5 using the Functional Assessment of Cancer Therapy (FACT)-Breast and EuroQOL 5 dimensions (EQ-5D) questionnaires.

Results

As of 26 February 2016, the median duration of follow-up was 23 months. Baseline scores were comparable between the two treatment arms. No significant between-arm differences were observed in change from baseline in FACT-Breast Total, FACT-General Total, or EQ-5D scores. Significantly greater improvement in pain scores was observed in the palbociclib plus letrozole arm (-0.256 versus -0.098; P = 0.0183). In both arms, deterioration of FACT-Breast Total score was significantly delayed in patients without progression versus those with progression and patients with partial or complete response versus those without. No significant difference was observed in FACT-Breast and EQ-5D index scores in patients with and without neutropenia.

Conclusions

Overall, women with MBC receiving first-line endocrine therapy have a good QOL. The addition of palbociclib to letrozole maintains health-related QOL and improves pain scores in treatment-naïve postmenopausal patients with ER+/HER2- MBC compared with letrozole alone. Significantly greater delay in deterioration of health-related QOL was observed in patients without progression versus those who progressed and in patients with an objective response versus non-responders. ClinicalTrials.gov: NCT01740427 (https://clinicaltrials.gov/ct2/show/NCT01740427).

A phase II feasibility study of palbociclib in combination with adjuvant endocrine therapy for hormone receptor-positive invasive breast carcinoma

BACKGROUND

The CDK4/6 inhibitor palbociclib prolongs progression-free survival in hormone receptor-positive/HER2-negative (HR+/HER2-) metastatic breast cancer when combined with endocrine therapy. This phase II trial was designed to determine the feasibility of adjuvant palbociclib and endocrine therapy for early breast cancer.

PATIENTS AND METHODS

Eligible patients with HR+/HER2- stage II-III breast cancer received 2 years of palbociclib at 125 mg daily, 3 weeks on/1 week off, with endocrine therapy. The primary end point was discontinuation from palbociclib due to toxicity, non-adherence, or events related to tolerability. A discontinuation rate of 48% or higher would indicate the treatment duration of 2 years was not feasible, and was evaluated under a binomial test using a one-sided α = 0.025.

RESULTS

Overall, 162 patients initiated palbociclib; over half had stage III disease (52%) and most received prior chemotherapy (80%). A total of 102 patients (63%) completed 2 years of palbociclib; 50 patients discontinued early for protocol-related reasons (31%, 95% CI 24% to 39%, P = 0.001), and 10 discontinued due to protocol-unrelated reasons. The cumulative incidence of protocol-related discontinuation was 21% (95% CI 14% to 27%) at 12 months from start of treatment. Rates of palbociclib-related toxicity were congruent with the metastatic experience, and there were no cases of febrile neutropenia. Ninety-one patients (56%) required at least one dose reduction.

CONCLUSION

Adjuvant palbociclib is feasible in early breast cancer, with a high proportion of patients able to complete 2 years of therapy. The safety profile in the adjuvant setting mirrors that observed in metastatic disease, with approximately half of the patients requiring dose-modification. As extended duration adjuvant palbociclib appears feasible and tolerable for most patients, randomized phase III trials are evaluating clinical benefit in this population.

CLINICALTRIALS.GOV REGISTRATION

NCT02040857.

Palbociclib plus letrozole as first-line therapy in estrogen receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer with extended follow-up

PURPOSE

In the initial PALOMA-2 (NCT01740427) analysis with median follow-up of 23 months, palbociclib plus letrozole significantly prolonged progression-free survival (PFS) in women with estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC) [hazard ratio (HR) 0.58; P < 0.001]. Herein, we report results overall and by subgroups with extended follow-up.

METHODS

In this double-blind, phase 3 study, post-menopausal women with ER+/HER2- ABC who had not received prior systemic therapy for their advanced disease were randomized 2:1 to palbociclib-letrozole or placebo-letrozole. Endpoints include investigator-assessed PFS (primary), safety, and patient-reported outcomes (PROs).

RESULTS

After a median follow-up of approximately 38 months, median PFS was 27.6 months for palbociclib-letrozole (n = 444) and 14.5 months for placebo-letrozole (n = 222) (HR 0.563; 1-sided P < 0.0001). All subgroups benefited from palbociclib treatment. The improvement of PFS with palbociclib-letrozole was maintained in the next 2 subsequent lines of therapy and delayed the use of chemotherapy (40.4 vs. 29.9 months for palbociclib-letrozole vs. placebo-letrozole). Safety data were consistent with the known profile. Patients' quality of life was maintained.

CONCLUSIONS

With approximately 15 months of additional follow-up, palbociclib plus letrozole continued to demonstrate improved PFS compared with placebo plus letrozole in the overall population and across all patient subgroups, while the safety profile remained favorable and quality of life was maintained. These data confirm that palbociclib-letrozole should be considered the standard of care for first-line therapy in patients with ER+/HER2- ABC, including those with low disease burden or long disease-free interval. Sponsored by Pfizer; ClinicalTrials.gov: NCT01740427.

Abstract PD2-12: Palbociclib in combination with fulvestrant or tamoxifen as treatment for hormone receptor positive (HR+) metastatic breast cancer (MBC) with prior chemotherapy for advanced disease (TBCRC 035) A phase II study with pharmacodynamics markers

Background

Addition of the cyclin dependent kinase 4/6 inhibitor (CDK4/6i) palbociclib to endocrine therapy in the first and later line settings significantly improves progression free survival (PFS) in patients with HR+ MBC. The primary toxicity is neutropenia without an increase in febrile neutropenia. TBCRC035 explored rates of neutropenia in patients who had received prior chemotherapy for MBC with 2 dose levels of palbociclib, and correlated changes in retinoblastoma protein phosphorylation (pRB) and Ki67 expression in proliferating keratinocytes and tumor with response.

Methods

TBCRC035 is a 1:1 randomized multicenter phase II study evaluating palbociclib at either 125 or 100 mg in combination with physician choice fulvestrant or tamoxifen. Eligible patients (pts) with HR+ MBC had received &gt;1 but &lt;3 lines of chemotherapy for MBC, any number of prior hormone therapies, and were naïve to CDK4/6i. The primary endpoint was grade 3/4 neutropenia; secondary endpoints included response, safety/tolerability, inhibition of pRB and change in Ki67 in skin and tumor at day 14-21 of treatment compared to baseline. FFPE sections of skin punch and tumor biopsies obtained before and on treatment were stained using antibodies to Ki67, total RB, and phospho-RB-S780 using BOND polymer red detection. Stained slides were scanned into the Aperio image analysis platform; the percentage of marker positive cells and H-score was determined.

Results

70 pts were enrolled (fully accrued); 35 randomized to 100 vs 125 mg of palbociclib respectively; data for the last 3 pts on the 125 mg arm is pending. Grade 3/4 neutropenia was more common in the 125 mg vs the 100 mg arm (56 vs 34%); dose adjustments for adverse events (AEs) occurred in 47 vs 43%, 4 vs 0 pts discontinued treatment due to AEs. Grade 3 febrile neutropenia was rare (1 patient each arm). Median duration of treatment was 5.2 vs 7.2 months. Response data and correlation with changes in pRB and Ki67 expression in skin and tumor by treatment arm will be reported.

Conclusion

In pts with prior chemotherapy for HR+ MBC, treatment with 100 mg of palbociclib in patients is associated with a lower rate of &gt; grade 3 neutropenia compared to 125 mg. Correlation of response by dose with pRB and Ki67 has the potential to inform palbociclib dosing and reduce toxicity for pts with HR+ MBC.

Citation Format: Rugo HS, Mayer EL, Storniolo AM, Isaacs C, Mayer I, Stearns V, Nanda R, Nangia J, Wabl C, Deluca A, Kochupurakkal B, Wolff AC, Shapiro GI. Palbociclib in combination with fulvestrant or tamoxifen as treatment for hormone receptor positive (HR+) metastatic breast cancer (MBC) with prior chemotherapy for advanced disease (TBCRC 035) A phase II study with pharmacodynamics markers [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD2-12.

Abstract P2-14-01: The impact of local therapy on locoregional recurrence in women with high risk breast cancer in the neoadjuvant I-SPY2 TRIAL

Background: In women with breast cancer receiving neoadjuvant chemotherapy, residual cancer burden (RCB) predicts distant recurrence and survival. In those with high risk tumors, locoregional recurrence (LRR) remains a concern, and has been associated with type of local therapy received. We evaluated the impact of local therapy on LRR in the ISPY-2 TRIAL.

Methods: Data were analyzed in Stata 14.2, using Chi2 test, log rank test, and a Cox proportional hazards model. RCB was considered a categorical variable (0/1 versus 2/3), as described in prior publications. Breast surgery categories were lumpectomy +/- radiotherapy, or mastectomy +/- radiotherapy. Axillary surgery was defined as sentinel lymph node (SLN) surgery (≤6 nodes removed) or axillary dissection (&gt;6 nodes).

Results: Follow up data from the I-SPY2 TRIAL were available for 630 patients (median follow up 2.76 yrs, range 0.4-7.2). Type of local therapy was significantly associated with clinical stage at presentation, with stage III patients most frequently undergoing mastectomy + radiation (p&lt;0.001). Women with higher RCB were more likely to undergo mastectomy than those with lower RCB (61.3% vs 48.8% mastectomy rate, p=0.002), and more likely to receive adjuvant radiotherapy (62.0% vs 53.9%, p=0.048). There was no association between clinical stage, type of surgery, or radiotherapy and LRR (Table). Higher RCB was significantly associated with LRR, with 3 year locoregional recurrence free rate of 95.1% in RCB 0/1 versus 89.9% in RCB 2/3 (p=0.003).

In a Cox model adjusting for clinical stage, tumor subtype, surgical therapy, RCB status, nodal radiation, and age, significant predictors for LRR were tumor subtype and RCB status. Hazard ratio (HR) for LRR in those with RCB 0/1 was 0.39 compared to those with RCB 2/3 (95% CI 0.17-0.87, p=0.021). There was no difference in LRR between breast conservation and mastectomy; within the breast conservation group, those who had lumpectomy alone had higher hazard of LRR compared to those having lumpectomy + radiation (HR 3.1, 95% CI 1.1-9.2, p=0.043).

Conclusions: Extent of surgical therapy was not associated with local tumor control, regardless of advanced tumor stage at presentation. Rather, tumor biology and response to therapy were the best predictors of LRR. These data highlight the opportunity to minimize the morbidity of extensive surgical therapy for patients with excellent response to systemic therapy.

LRR rates by clinical features and treatment status FrequencyLRR RateP valueClinical Stage  0.5I240 (47.5%)5.8% II185 (36.6%)8.7% III80 (15.8%)6.3% Tumor Subtype  0.014ER+PR+Her2-161 (26.4%)3.1% ER+PR-Her2-56 (9.2%)3.6% Her2+176 (28.9%)6.3% Triple negative216 (35.5%)11.1% Local therapy  0.169Lumpectomy85 (13.5%)11.8% Lumpectomy with radiation198 (31.4%)5.6% Mastectomy173 (27.5%)5.2% Mastectomy with radiation174 (27.6%)8.6% Axillary surgery  0.23None5 (0.8%)20% SLN329 (52.2%)5.8% ALND296 (47%)8.5% Axillary radiation  0.535Yes42 (6.7%)9.5% No588 (93.3%)7.0% Axillary management  0.2No surgery or radiation5 (0.8%)20.0% SLN312 (50%)5.3% SLN+Axillary radiation17 (2.7%)8.3% ALND271 (43%)10.3% ALND+Axillary radiation25 (4%)5.4% RCB  0.0020/1293 (50.1%)3.8% 2/3292 (49.9%)10.3% 

Citation Format: Silverstein J, Suleiman L, Yau C, Price ER, Singhrao R, Yee D, DeMichele A, Isaacs C, Albain KS, Chien AJ, Forero-Torres A, Wallace AM, Pusztai L, Ellis ED, Elias AD, Lang JE, Lu J, Han HS, Clark AS, Korde L, Nanda R, Northfelt DW, Khan QJ, Viscusi RK, Euhus DM, Edmiston KK, Chui SY, Kemmer K, Wood WC, Park JW, Liu MC, Olopade O, Leyland-Jones B, Tripathy D, Moulder SL, Rugo HS, Schwab R, Lo S, Helsten T, Beckwith H, I-SPY 2 TRIAL Consortium, Berry DA, Asare SM, Esserman LJ, Boughey JC, Mukhtar RA. The impact of local therapy on locoregional recurrence in women with high risk breast cancer in the neoadjuvant I-SPY2 TRIAL [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-14-01.

Abstract P2-13-03: The impact of neratinib with or without anti-diarrheal prophylaxis on health-related quality of life in HER2+ early-stage breast cancer: Analyses from the ExteNET and CONTROL trials

Background: Neratinib is an irreversible pan-HER tyrosine kinase inhibitor. ExteNET, a randomized placebo-controlled phase III study, showed that neratinib given for 12 months after trastuzumab-based adjuvant therapy significantly improved 2-year (HR 0.67; 95% CI 0.50–0.91; p=0.0091) and 5-year (HR 0.73; 95% CI 0.57-0.92; p=0.008) iDFS in pts with early-stage HER2+ breast cancer. Anti-diarrheal prophylaxis was not mandated by protocol; grade 3/4 diarrhea occurred in 40% of pts with a median cumulative duration of 5 days. The phase II CONTROL study was initiated to investigate the effectiveness of various prophylactic regimens in the prevention of neratinib-associated diarrhea. Loperamide (L) alone or in combination with add-on agents targeting underlying inflammation [i.e. budesonide (BUD)] or bile acid malabsorption [i.e. colestipol (COL)] were tested. We report longitudinal HRQoL findings from both ExteNET and CONTROL.

Methods: Pts with early-stage HER2+ breast cancer who had received trastuzumab-based adjuvant therapy were eligible for both studies. In ExteNET, pts received neratinib or placebo for 12 months. In CONTROL, pts received neratinib for 13 x 28-day cycles combined with L, L + BUD or L + COL for 1 or 2 cycles (see table for schedules). HRQoL was assessed using Functional Assessment of Cancer Therapy–Breast (FACT-B), v4.0, at baseline, months 1, 3, 6, 9, 12 (ExteNET) or baseline, cycles 2, 4, 7, 10, 13 (CONTROL). Changes in scores from baseline were considered to be clinically meaningful if greater than the lowest estimate for an 'important difference' (ID) reported in the literature. Evaluable pts were required to have HRQoL assessments at baseline and at least 1 post-baseline. ClinicalTrials.gov: NCT00878709 (ExteNET); NCT02400476 (CONTROL).

Results: HRQoL findings are summarized in the table. Hospitalization rates due to diarrhea: 1.5% (neratinib + L), 0% (other cohorts) in CONTROL; and 1.4% (neratinib), 0.1% (placebo) in ExteNET.

  Mean change from baselineStudyCohort/GroupM1M3M6M9M12 FACT-B TOTAL (ID range: 7–8 points)CONTROLN + La,b (N=40)–3.8–4.5–1.5–2.5–3.3 N + L + BUDa,b,c (N=62)–6.0–4.9–1.6–3.6–4.5 N + L + COLa,b,d (N=125)–3.8–2.0–4.0–4.6–3.6 N + L prn + COLa,d (N=85)–1.8–1.54.0e––ExteNETN + L prna (N=1124)–4.6–3.4–3.5–3.3–3.7 P (N=1188)–1.7–3.5–2.9–2.9–2.8 FACT-B PWB (ID range: 2–3 points)CONTROLN + La,b (N=40)–4.0–2.3–1.9–2.4–2.3 N + L + BUDa,b,c (N=62)–3.2–2.1–1.4–1.7–1.7 N + L + COLa,b,d (N=125)–2.8–2.0–2.4–2.5–2.4 N + L prn + COLa,d (N=85)–2.8–1.80.0e––ExteNETN + L prna (N=1124)–2.9–1.9–1.7–1.6–1.5 P (N=1188)–0.6–0.8–0.7–0.6–0.4C, cycle; L, loperamide; M, month; N, neratinib; prn, as needed; PWB, physical well-being. CONTROL cut-off: 1 May 2018. aN 240 mg qd for 13 x 28d cycles or 12 months; bL 4 mg, then 4 mg tid d1-14, then 4 mg bid d15-28 or d15-56, then prn; cBUD 9 mg qd d1-28; dCOL 2 g qd d1-28; en=1.

Conclusions: Adjuvant neratinib with or without anti-diarrheal prophylaxis was associated with small decreases in HRQoL. With the exception of the FACT-B PWB subscale, HRQoL changes did not reach clinically meaningful thresholds. Follow-up in CONTROL is ongoing.

Citation Format: Delaloge S, Hurvitz S, Chan N, Bose R, Jankowitz RC, Thirlwell M, Láng I, ten Tije A, Trudeau M, Osborne CR, Shen Z-Z, Lalla D, Xu F, Hunt D, Olek E, Tripathy D, Rugo HS, Chien J, Chan A, Barcenas CH. The impact of neratinib with or without anti-diarrheal prophylaxis on health-related quality of life in HER2+ early-stage breast cancer: Analyses from the ExteNET and CONTROL trials [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-13-03.

Abstract P2-07-03: Refining neoadjuvant predictors of three year distant metastasis free survival: Integrating volume change as measured by MRI with residual cancer burden

Background: Patients achieving a pathologic complete response (pCR) following neoadjuvant therapy have significantly improved event-free survival relative to those who do not; and pCR is an FDA-accepted endpoint to support accelerated approval of novel agents/combinations in the neoadjuvant treatment of high risk early stage breast cancer. Previous studies have shown that recurrence risk increased with increasing burden of residual disease (as assessed by the RCB index). As well, these studies suggest that patients with minimum residual disease (RCB-I class) also have favorable outcomes (comparable to those achieving a pCR) within high risk tumor subtypes. In this study, we assess whether integrating RCB with MRI functional tumor volume (FTV), which in itself is prognostic, can improve prediction of distant recurrence free survival (DRFS); and identify a subset of patients with minimal residual disease with comparable DRFS as those who achieved a pCR. Imaging tools can then be used to identify the subset that will do well early and guide the timing of surgical therapy.

Method: We performed a pooled analysis of 596 patients from the I-SPY2 TRIAL with RCB, pre-surgical MRI FTV data and known follow-up (median 2.5 years). We first assessed whether FTV predicts residual disease (pCR or pCR/RCB-I) using ROC analysis. We applied a power transformation to normalize the pre-surgical FTV distribution; and assessed its association with DRFS using a bi-variate Cox proportional hazard model adjusting for HR/HER2 subtype. We also fitted a bivariate Cox model of RCB index adjusting for subtype; and assessed whether adding pre-surgical FTV to this model further improves association with DRFS using a likelihood ratio (LR) test. For the Cox modeling, penalized splines approximation of the transformed FTV and RCB index with 2 degrees of freedom was used to allow for non-linear effects of FTV and RCB on DRFS.

Result: Pre-surgical MRI FTV is significantly associated with DRFS (Wald p&lt;0.00001), and more effective at predicting pCR/RCB-I than predicting pCR alone (AUC: 0.72 vs. 0.65). Larger pre-surgical FTV remains associated with worse DRFS adjusting for subtype (Wald p &lt;0.00001). The RCB index is also significantly associated with DRFS adjusting for subtype (Wald p&lt;0.00001). Adding FTV to a model containing RCB and subtype further improves association with DRFS (LR p=0.0007). RCB-I patients have excellent DRFS (94% at 3 years compared to 95% in the pCR group). Efforts are underway to identify an optimal threshold for dichotomizing pre-surgical FTV and FTV change measures for use in combination with pCR/RCB-I class to generate integrated RCB (iRCB) groups as a composite predictor of DRFS.

Conclusion: Pre-surgical MRI FTV is effective at predicting minimal residual disease (RCB0/I) in the I-SPY 2 TRIAL. Despite the association between FTV and RCB, FTV appears to provide independent added prognostic value (to RCB and subtype), suggesting that integrating MRI volume measures and RCB into a composite predictor may improve DRFS prediction.

Citation Format: Hylton NM, Symmans WF, Yau C, Li W, Hatzis C, Isaacs C, Albain KS, Chen Y-Y, Krings G, Wei S, Harada S, Datnow B, Fadare O, Klein M, Pambuccian S, Chen B, Adamson K, Sams S, Mhawech-Fauceglia P, Magliocco A, Feldman M, Rendi M, Sattar H, Zeck J, Ocal I, Tawfik O, Grasso LeBeau L, Sahoo S, Vinh T, Yang S, Adams A, Chien AJ, Ferero-Torres A, Stringer-Reasor E, Wallace A, Boughey JC, Ellis ED, Elias AD, Lang JE, Lu J, Han HS, Clark AS, Korde L, Nanda R, Northfelt DW, Khan QJ, Viscusi RK, Euhus DM, Edmiston KK, Chui SY, Kemmer K, Wood WC, Park JW, Liu MC, Olopade O, Tripathy D, Moulder SL, Rugo HS, Schwab R, Lo S, Helsten T, Beckwith H, Haugen PK, van't Veer LJ, Perlmutter J, Melisko ME, Wilson A, Peterson G, Asare AL, Buxton MB, Paoloni M, Clennell JL, Hirst GL, Singhrao R, Steeg K, Matthews JB, Sanil A, Berry SM, Abe H, Wolverton D, Crane EP, Ward KA, Nelson M, Niell BL, Oh K, Brandt KR, Bang DH, Ojeda-Fournier H, Eghtedari M, Sheth PA, Bernreuter WK, Umphrey H, Rosen MA, Dogan B, Yang W, Joe B, I-SPY 2 TRIAL Consortium, Yee D, Pusztai L, DeMichele A, Asare SM, Berry DA, Esserman LJ. Refining neoadjuvant predictors of three year distant metastasis free survival: Integrating volume change as measured by MRI with residual cancer burden [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-07-03.

Abstract P2-13-01: Efficacy of neratinib in hormone receptor-positive patients who initiated treatment within 1 year of completing trastuzumab-based adjuvant therapy in HER2+ early-stage breast cancer: Subgroup analyses from the phase III ExteNET trial

Background: The international, randomized, placebo-controlled phase III ExteNET trial showed that 1 year (yr) of neratinib 240 mg/day after trastuzumab-based adjuvant therapy significantly improved invasive disease-free survival (iDFS) in 2840 patients with early-stage HER2+ breast cancer at 2 yr (hazard ratio 0.67; 95% CI 0.50–0.91; p=0.009) [Chan 2016] and 5 yr (hazard ratio 0.73; 95% CI 0.57-0.92; p=0.008) [Martin 2017]. A prespecified subgroup analysis by hormone receptor (HR) status suggested enhanced efficacy with neratinib in patients with HR+ (2-yr hazard ratio 0.51; 95% CI 0.33–0.77) vs. HR– tumors (2-yr hazard ratio 0.93; 95% CI 0.60–1.43). The efficacy of neratinib was also greater in patients who initiated treatment within 1 yr of prior trastuzumab compared with those who started neratinib later. The European Medicines Agency's Committee for Medicinal Products for Human Use recently recommended neratinib for use in patients with HR+ tumors who initiate treatment within 1 yr of completing trastuzumab-based adjuvant therapy. Subgroup analyses from ExteNET examining iDFS benefits in this patient population are presented here.

Methods: Patients with early-stage HER2+ breast cancer who completed trastuzumab-based (neo)adjuvant therapy were assigned to oral neratinib 240 mg/day or placebo for 1 yr. Randomization was stratified by HR status (determined locally before trial entry), nodal status, and trastuzumab regimen. Endocrine therapy was allowed in patients with HR+ disease. The primary endpoint, iDFS, was tested by 2-sided log-rank test and hazard ratios (95% CI) were estimated using Cox proportional hazards models. Kaplan-Meier methods were used to estimate iDFS rates. Secondary endpoints were DFS-DCIS, time to distant recurrence, distant DFS, and CNS recurrences. The primary analysis was conducted at 2 yr, and a sensitivity analysis conducted at 5 yr. Clinicaltrials.gov:NCT00878709.

Results: Of the 2840 patients (neratinib, n=1420; placebo, n=1420), 1631 (57%) had HR+ disease (neratinib, n=816; placebo, n=815). Most (93%) HR+ patients were receiving endocrine therapy at baseline. 1334 of 1631 (82%) patients with HR+ tumors were randomized to start neratinib within 1 yr of last trastuzumab dose (neratinib, n=670; placebo, n=664). iDFS benefits from neratinib in this population are shown in the table. Secondary endpoints were also improved with neratinib vs. placebo in this population. Safety data in this subset will be presented at the meeting.

Table. iDFS in patients with an interval between last trastuzumab dose and randomization of ≤1 yr

 HR+ population (N=1334)ITT population (N=2297)  Hazard ratiob  Hazard ratiob  Δ, %a(95% CI)P-valueΔ, %a(95% CI)P-value2-yr analysisc+4.50.490.002+2.90.630.006  (0.30–0.78)  (0.45–0.88) 5-yr analysisd+5.10.580.002+3.20.700.006  (0.41–0.82)  (0.54–0.90) aDifference in iDFS rates between neratinib vs. placebo; bNeratinib vs. placebo; cData cut-off: July 2014; dData cut-off: March 2017

Conclusions: Neratinib may have enhanced and sustained efficacy in patients with HR+ disease who initiate treatment within 1 yr of trastuzumab-based adjuvant therapy.

Citation Format: Gnant M, Martin M, Holmes F-A, Jackisch C, Chia SK, Iwata H, Moy B, Martinez N, Mansi J, Morales S, Ruiz-Borrego M, von Minckwitz G, Buyse M, Delaloge S, Bhandari M, Murias Rosales A, Galeano T, Fujita T, Luczak A, Barrios CH, Saura C, Rugo HS, Chien J, Johnston SR, Spencer M, Xu F, Barnett B, Chan A, Ejlertsen B. Efficacy of neratinib in hormone receptor-positive patients who initiated treatment within 1 year of completing trastuzumab-based adjuvant therapy in HER2+ early-stage breast cancer: Subgroup analyses from the phase III ExteNET trial [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-13-01.

Abstract P1-17-04: Long-term safety follow-up of patients with early stage breast cancer treated with scalp cooling on the Dignitana scalp cooling trial

Background

Scalp cooling has demonstrated efficacy in preventing hair loss in women with early stage breast cancer receiving neo/adjuvant chemotherapy. Data from 2 prospective trials (Rugo et al, and Nangia et al, JAMA 2017) led to FDA clearance of 2 automated scalp-cooling devices to prevent chemotherapy induced alopecia (CIA). Although scalp metastases from breast cancer are rare, historical concerns about scalp cooling included a theoretical increase in risk of recurrence in scalp due to reduced delivery of chemotherapy to the scalp.

Methods

We conducted a multicenter prospective trial evaluating the efficacy and safety of the DigniCap in women with stage I-II breast cancer receiving neo/adjuvant chemotherapy excluding sequential or combination anthracycline/taxanes with concurrent matched controls. The primary endpoint was unblinded patient self-assessment of 5 photographs using the Dean scale to estimate hair loss 4 weeks following the last dose of chemotherapy, with success defined as a Dean score of 0-2 (≤ 50% hair loss); additional endpoints included quality of life (QOL) and both short and long-term safety.

Results

106 patients using the scalp cooling device and 16 concurrent controls were enrolled. As previously reported, the use of scalp cooling was associated with less alopecia and improvement in several measures of QOL (Rugo et al, JAMA 2017). 91 patients have follow-up (FU) out to 3 years; 73 with estrogen receptor (ER) positive and 18 with ER negative disease. 5 DigniCap patients have developed recurrent breast cancer in breast (n=1), liver (n=1), bone, liver and breast (n=1), bone, liver, lung, and nodes (1), and bone, breast, GI tract and bladder (n=1). Of 12 control patients with available FU, 1 developed metastases to liver. 2 patients have died of metastatic disease, one in the DigniCap arm and one in the control arm. No new safety signals have been detected.

Conclusion

Scalp cooling using the DigniCap system in patients with early stage breast cancer receiving taxane based neo/adjuvant chemotherapy is safe and effective. No scalp metastases have been reported 3 years following completion of study treatment. 4 year FU data will be presented.

The study was funded by The Lazlo Tauber Family Foundation (UCSF), the Anne Moore Breast Cancer Research Fund (Weil Cornell), and the Friedman Family Foundation (Mount Sinai Beth Israel), as well as partially by Dignitana.

Citation Format: Rugo HS, Klein P, Melin SA, Hurvitz SA, Melisko ME, Moore A, D'Agostino, Jr. RB, Deluca A, Cigler T. Long-term safety follow-up of patients with early stage breast cancer treated with scalp cooling on the Dignitana scalp cooling trial [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-17-04.

Abstract OT3-04-04: A randomized phase II study of pembrolizumab in combination with carboplatin versus carboplatin alone in breast cancer patients with chest wall disease, with immunologic and genomic correlative studies

Background: Thirty percent of patients with breast cancer may experience chest wall recurrence, which is associated with a higher risk of developing distant metastases and a poor prognosis. Cancer cells may evade immune rejection through the programmed cell death 1 (PD-1) pathway. Pembrolizumab, an anti-PD-1 antibody, binds PD-1 and inhibits its interaction with the programmed death ligand 1 (PD-L1) to facilitate tumor immune rejection. We hypothesize that pembrolizumab may be an effective therapy in chest wall recurrence, given the inflammatory nature, and the high expression of PD-1 in tumors with lymphovascular invasion. Platinum agents may enhance anti-tumor immunity in a synergistic manner, and the combination of pembrolizumab and carboplatin has demonstrated efficacy in advanced lung cancer. In this study, the combination of pembrolizumab and carboplatin is being evaluated in breast cancer patients with chest wall disease.

Methods: This is a randomized phase II study of breast cancer patients with advanced, unresectable breast cancer involving the chest wall, being conducted through the Translational Breast Cancer Research Consortium (TBCRC). Patients may have hormone resistant disease (at least 2 prior lines of hormone therapy), triple negative breast cancer, or refractory HER2+ disease for enrollment. They may have other sites of distant metastases, have received any number of prior lines of therapy, have had prior surgery, but prior chest wall radiation is not necessary. Eighty-four patients at 7 TBCRC sites will be randomized 2:1 to treatment with pembrolizumab 200 mg IV and carboplatin AUC 5 IV every 3 weeks followed by pembrolizumab 200 mg IV alone every 3 weeks (Arm A, n=56) or carboplatin AUC 5 IV every 3 weeks (Arm B, n=28), with an option for patients in Arm B to cross-over to single agent pembrolizumab 200 mg IV every 3 weeks (arm Bx) on progression. Patients will undergo imaging with CT chest, abdomen, and pelvis at baseline and every 2 cycles of treatment for response evaluation. The primary endpoint is the disease control rate in the chest wall and distant sites at 18 weeks of treatment, and this study is powered to determine a 20% difference in disease control rates between arms A and B (hazard ratio of 0.52, α= 0.10, β= 0.20). After 18 patients are enrolled into Arm B, an interim analysis for futility will be conducted to enable early closure of that arm for lack of efficacy. Secondary endpoints in the study are toxicity, progression free survival, and response based on PD-L1 expression and irRECIST. Exploratory endpoints, which will be studied using peripheral blood testing and chest wall tumor biopsies at baseline and after 2 cycles of treatment, include determining associations of response with changes in tumor and peripheral blood immune composition, soluble PD-L1 expression, circulating tumor cells, cell free DNA, and tumor PD-L1 and MYC genomic expression. Ultimately this study promises to improve our understanding of checkpoint inhibition and chemotherapy for chest wall disease, and the underlying mechanism of action. This study is open for enrollment and 2 patients are currently enrolled. (NCT03095352).

Citation Format: Vidula N, Goga A, Hwang J, Liu MC, Park BH, Nanda R, Pohlmann PR, Storniolo AM, Brufsky A, Abramson V, Rugo HS. A randomized phase II study of pembrolizumab in combination with carboplatin versus carboplatin alone in breast cancer patients with chest wall disease, with immunologic and genomic correlative studies [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT3-04-04.

Abstract P5-19-05: Health-related quality of life during a phase 2 study of talazoparib in patients with advanced breast cancer and germline BRCA1/2 mutations (ABRAZO)

Background: Talazoparib (TALA; 1 mg/d) was well tolerated and exhibited promising antitumor activity in ABRAZO, a 2-cohort, 2-stage, open-label phase 2 study (NCT02034916) in patients (pts) with locally advanced or metastatic breast cancer and gBRCA1/2 mutations following platinum-based therapy (cohort 1 [C1]) or ≥3 platinum-free cytotoxic-based regimens (cohort 2 [C2]). This analysis evaluates health-related quality of life (QoL) for both cohorts.

Methods: QoL was assessed on day 1 (baseline) and every 6 weeks for the initial 24 weeks and every 12 weeks thereafter, or sooner if progression was clinically suspected, using the EORTC QLQ-C30 and its breast cancer module, QLQ-BR23. For all scales, results were summarized using descriptive statistics for each cohort and at each time point, based on Characters (max 3400 including title, body and table [including spaces]): 3363 No abbreviations in title; title sentence case; define acronyms; no figures Category: Psychosocial, QOL, and Educational Aspects – Other 2 observed values and changes from baseline (clinically meaningful defined as ≥10-point change from baseline). Time to deterioration (TTD; defined as ≥10-point decrease in global health status [GHS]/functional scales or increase in symptom scales) analyses using survival analysis methods were carried out on the GHS/functional scales of QLQ-C30 and symptom scales of QLQ-BR23.

Results:GHS was maintained from baseline across all time points for both C1 and C2 except at week 24 in C2, when a statistically significant but not clinically meaningful improvement in GHS was observed. In C1, statistically significant and clinically meaningful improvement was observed at specific time points in 4 functional scales (body image, week 6; sexual functioning, week 24; sexual enjoyment, week 36; and future perspective, weeks 6, 18, and 24) and in 3 symptom scales (dyspnea, week 24; insomnia, week 24; and breast symptoms, weeks 6 and 36). Statistically significant and clinically meaningful deterioration in C1 was observed in 2 functional scales (emotional functioning, week 12 and end of treatment, and role functioning, end of treatment) and in 1 symptom scale (fatigue, week 6). In C2, statistically significant and clinically meaningful improvement was observed at specific time points in 4 functional scales (role functioning, week 24; social functioning, week 24; sexual enjoyment, week 18; and future perspective, weeks 6, 12, and 18) and in 5 symptom scales (nausea/vomiting, week 18; pain, weeks 12, 18, and 24; insomnia, week 24; breast symptoms, weeks 12 and 18; and arm symptoms, week 48). For C2, no statistically significant and clinically meaningful deterioration was observed for any functional or symptoms scales across all time points, except in the dyspnea symptom scale at week 18. For C1 and C2, the median (95% confidence interval) TTD of GHS was 2.8 (2.1-3.0) and 5.5 (4.2-5.7) months, respectively. The median TTD for all QLQ-C30 functional scales for C1 and C2 ranged 2.1-3.1 and 4.2-5.6 months, respectively; the median TTD for all QLQ-BR23 symptoms scales ranged 2.6-4.0 and 4.2-5.6 months, respectively.

Conclusions: The QoL of TALA-treated patients during ABRAZO was maintained. QoL is being evaluated among atients with germline BRCA1/2 mutated advanced BC treated with TALA vs physician's choice chemotherapy in the phase 3 EMBRACA trial (NCT01945775).

Citation Format: Hurvitz SA, Turner NC, Telli ML, Rugo HS, Mailliez A, Ettl J, Grischke E-M, Mina LA, Balmaña J, Fasching PA, Tudor C, Quek RGW, Hannah AL, Robson ME, Wardley AM. Health-related quality of life during a phase 2 study of talazoparib in patients with advanced breast cancer and germline BRCA1/2 mutations (ABRAZO) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-19-05.

Abstract OT2-07-06: Phase Ib study to assess the safety, tolerability, and clinical activity of gedatolisib in combination with palbociclib and either letrozole or fulvestrant in women with metastatic or locally advanced/recurrent breast cancer (B2151009)

Background:Hormone receptor positive (HR+) disease is the most common subset of advanced breast cancer (BC). The majority of women with HR+ metastatic BC (MBC) develop resistance to endocrine therapy (ET), with a median survival of 2-3 years. A new strategy to treat HR+ MBC involves the combination of ET and a cyclin-dependent kinase 4/6 inhibitor (CDKi 4/6), which has demonstrated improved progression-free survival (PFS) in both first-and later-line MBC. Preclinical evidence in PI3K-mutant cell-line xenografts demonstrated that combinations of PI3K and CDK4/6i reduced intrinsic and adaptive resistance to ET, leading to tumor regression (Vara, 2004; Pfizer data). Inhibition of the PI3K/mTOR pathway by gedatolisib (G) may provide a new therapy to overcome ET resistance. These findings support developing the triplet combination of G with the CDKi 4/6 palbociclib (P)+letrozole (L) or fulvestrant (F) for the treatment of patients (pts) with ER+/HER2- BC.

Methods: This ongoing study in women with ER+/HER2- MBC, in first- and later-line settings, includes a dose-escalation (DE) to evaluate dose-limiting toxicities (DLTs, primary endpoint [pEP]) and determine the maximum tolerated dose and recommended phase 2 dose (RP2D) for a triplet regimen of G+P+L or G+P+F. The escalation rules follow the modified toxicity probability interval method (G doses: 180 and 215 mg IV weekly). Treatment assignment to the triplet is based on investigator decision and bone-only disease is permitted. After RP2D determination for each triplet, a 3-arm expansion for early signs of efficacy (ESOE) will investigate objective response rate (ORR) compared to historical controls [pEP] of Arm A) G+P+L in first-line, B) G+P+F in pts with no prior CDKi 4/6 in second-line and C) G+P+F in pts who have received prior CDKi 4/6. Pts receive G+P (125 mg oral daily for 21 days [D] on and 7 D off) + L (2.5 mg oral daily) or F (500 mg IM on D1, 15 of cycle [C] 1; D1 of C2 and then 500 mg IM on D1 of all 28-D cycles). Secondary endpoints include safety, tumor response (DE), PFS (ESOE), pharmacokinetics (PK), and biomarker correlations associated with the PI3K/mTOR pathway.

Results: 27 pts received G (180 mg/week) in combination with P+L (L cohort, n=12) or P+F (F cohort, n=15). Median prior therapies were: L cohort: 1 (range: 0-4); F cohort: 2 (range 1-5). The 3 most common, drug-related adverse events (%) were in L cohort: nausea (75), neutropenia (67), and stomatitis (67); F cohort: stomatitis (67), nausea (60), and neutropenia (53). C1 DLTs were: L cohort: grade (gr) 3 neutropenia (n=1); F cohort: gr 3 stomatitis (n=1). Preliminary rates of stable disease/partial response were: L cohort: 33%/16%; F cohort: 40%/13%. PK parameters and next-generation sequencing of PI3K-related mutations are pending.

Conclusions: G can be combined with P+L or P+F with manageable toxicity and promising preliminary antitumor activity, even in heavily pretreated pts. Dose escalation, followed by expansion for ESOE, is ongoing.

This study is sponsored by Pfizer. Editorial support was provided by Engage Scientific Solutions and was funded by Pfizer.

Citation Format: Forero A, Han HS, Dees EC, Wesolowski R, Bardia A, Kabos P, Kern KA, Perea R, Pierce KJ, Houk B, Rugo HS. Phase Ib study to assess the safety, tolerability, and clinical activity of gedatolisib in combination with palbociclib and either letrozole or fulvestrant in women with metastatic or locally advanced/recurrent breast cancer (B2151009) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT2-07-06.

Abstract OT2-07-05: A phase III, randomized trial of sacituzumab govitecan (IMMU-132) vs treatment of physician choice (TPC) for metastatic triple-negative breast cancer (mTNBC)

Background: Metastatic TNBC has an aggressive course with limited therapy options and poor survival. Sacituzumab govitecan (IMMU-132) is a novel antibody drug conjugate consisting of SN-38, the active metabolite of the topoisomerase I inhibitor, irinotecan, conjugated to a humanized mAb targeting Trop-2, which is highly expressed in most epithelial cancers, including TNBC. We previously reported that patients (pts) with mTNBC treated with IMMU-132 after a median of 5 prior therapies from initial diagnosis achieved a 30% objective response rate (ORR), 8.9 mo median duration of response (DOR), and an acceptable safety profile with nausea, neutropenia, and diarrhea the most common toxicities (Bardia et al., JCO, 2017). IMMU-132 was awarded Breakthrough Designation by the FDA based on this data. Accordingly, we are enrolling additional patients with relapsed/refractory mTNBC with intention of seeking regulatory approval as a ≥3rd-line therapeutic option.

Trial design: An international, open-label, Phase III study in pts with refractory/relapsed mTNBC after ≥2 prior chemotherapies for advanced disease or &gt;1 therapy for pts who progress within 12 months of adjuvant therapy (NCT02574455). Pts are randomized 1:1 to receive either IMMU-132 (10 mg/kg IV, days 1 and 8 every 21 days) or TPC from one of 4 prespecified single-agent regimens (capecitabine, eribulin, vinorelbine or gemcitabine). Pts continue treatment until progression requiring discontinuation or unacceptable toxicity. The primary endpoint is progression-free survival (PFS) and additional endpoints include overall survival (OS), ORR, DOR, safety and quality of life. Independent, blinded reads of scans will be performed.

Eligibility criteria: Adults &gt;18 yrs old, with metastatic breast cancer, triple-negative by most recent biopsy, measurable disease by CT or MRI as per RECIST1.1, ECOG performance score 0 or 1, adequate safety laboratories. Refractory/relapsed after ≥2 prior standard chemotherapy regimens for advanced disease, or &gt;1 therapy for pts who progress within 12 months of adjuvant therapy. Pts must have received taxane and be eligible by investigator to receive at least one of the TPC agents. Pts with treated, non-progressive brain metastases are eligible.

Specific aims: To compare IMMU-132 to TPC as measured by PFS, OS, ORR, DOR,QOL, adverse events, safety laboratories, incidence of dose delays and reductions, and treatment discontinuations due to toxicity.

Statistical methods: Assuming a median PFS of 3 mo. and OS of 10 mo. with TPC vs. 5 and 15 mo. with IMMU-132, respectively, a study size of 328 patients has &gt;95% and &gt;80% power to detect a statistically significant difference in PFS and OS, respectively, between the two treatment arms.

Present accrual and target accrual: Trial enrollment will begin prior to SABCS 2017 with approximately 328 patients expected to be enrolled over 18 months at approximately 100 institutions in North America, Europe and potentially elsewhere.

Contact: Immu132@Immunomedics.com

Citation Format: Bardia A, Rugo HS, Horne H, Wegener WA, Goldenberg DM, O'Shaughnessy J. A phase III, randomized trial of sacituzumab govitecan (IMMU-132) vs treatment of physician choice (TPC) for metastatic triple-negative breast cancer (mTNBC) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT2-07-05.

Abstract OT1-02-03: TBCRC 044: A randomized phase II study of pembrolizumab in combination with carboplatin versus carboplatin alone in breast cancer patients with chest wall disease

Background: Patients with breast cancer (BC) and chest wall disease have limited treatment options. We hypothesize that checkpoint inhibition may be an effective treatment approach due to the inflammatory nature of chest wall infiltration, and the association of PD-1 expression with lymphocytic infiltration. Platinum chemotherapy may facilitate anti-tumor immunity in a synergistic manner, and clinical studies of the PD-1 inhibitor pembrolizumab with platinum combinations have been effective in the treatment of advanced lung cancer. In this study, we will evaluate the combination of carboplatin and pembrolizumab in BC patients with chest wall disease.

Methods: This is a randomized phase II multicenter study in the TBCRC including patients with advanced, unresectable BC with hormone resistant or triple negative chest wall disease. Patients may have had prior surgery, prior chest wall radiation is not required, and other sites of distant metastases are allowed. Eighty-four patients at TBCRC sites will be randomized 2:1 to receive pembrolizumab and carboplatin (n=56, Arm A) or carboplatin alone (n=28, Arm B) until disease progression. Patients randomized to Arm B may cross-over following progression to pembrolizumab alone (Arm Bx). Patients in Arm A will be treated with pembrolizumab 200 mg IV and carboplatin AUC 5 IV every 3 weeks for at least 6 cycles followed by maintenance pembrolizumab 200 mg IV every 3 weeks if stable or responding disease. Patients in Arm B will be treated with carboplatin AUC 5 IV every 3 weeks until progression, then may cross-over to pembrolizumab 200 mg IV every 3 weeks alone (Arm Bx). An interim analysis for futility will be performed after 18 patients are enrolled into Arm B to allow early closure of that arm for lack of efficacy. The primary endpoint is disease control rate at 18 weeks of treatment; the study is powered to detect a 20% difference in disease control rates between arms (hazard ratio 0.52, α= 0.10, β= 0.20). Secondary endpoints include progression free survival, toxicity, and response based on PD-L1 expression and irRECIST. Exploratory endpoints include association of response with a number of biomarkers including tumor PD-L1 gene expression, tumor and peripheral blood immune composition and cytokine expression, peripheral T-cell PD-1 expression, circulating tumor DNA, circulating tumor cells, and tumor MYC genomic expression using tumor biopsy and peripheral blood testing before and after treatment. This study should be open to accrual by August of 2017. (NCT03095352)

Citation Format: Vidula N, Goga A, Krummel M, Hwang J, Liu M, Park BH, Nanda R, Pohlmann P, Storniolo AM, Van Poznak C, Brufsky A, Abramson V, Wolff A, Rugo HS. TBCRC 044: A randomized phase II study of pembrolizumab in combination with carboplatin versus carboplatin alone in breast cancer patients with chest wall disease [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT1-02-03.

Abstract OT3-05-02: BYLieve: A phase 2 study of alpelisib with fulvestrant or letrozole for treatment of PIK3CA mutant, hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2–) advanced breast cancer (aBC) progressing on/after cyclin-dependent kinase (CDK)4/6 inhibitor therapy

Background: Endocrine therapy (ET) is the standard of care for treatment of HR+, HER2– aBC. However, ET resistance occurs frequently leading to disease progression. Dysregulation of the PI3K/AKT/mTOR pathway, specifically mutations in PIK3CA, the gene encoding the p110alpha subunit of PI3K, has been implicated in ET resistance. In a phase 1 study, alpelisib, a PI3Kα-specific inhibitor, in combination with fulvestrant has shown antitumor activity in patients with PIK3CA mutant, HR+, HER2– aBC. The present BYLieve (NCT03056755) study aims to assess the efficacy and safety of alpelisib + fulvestrant/letrozole in PIK3CA-mutant, HR+, HER2– aBC progressing on/after prior CDK4/6 inhibitor (CDK4/6i) therapy.

Methods: BYLieve is a phase 2, multicenter, open-label, 2-cohort, non-comparative study. Men and postmenopausal women (≥ 18 years) with PIK3CA-mutant, HR+, HER2− locally advanced or metastatic breast cancer that has progressed on/after prior CDK4/6i therapy are eligible. Other eligibility criteria include ≥ 1 measurable lesion (RECIST v1.1) or predominantly lytic bone lesion; ECOG PS ≤ 2; and no prior PI3K inhibitor therapy. Patients are allocated to 2 cohorts based on the prior ET partner (aromatase inhibitor (AI) or fulvestrant) used in combination with CDK4/6i. Cohort A (patients who had received CDK4/6i + AI): oral alpelisib (300 mg once daily) + intramuscular fulvestrant (500 mg on days 1 and 15 of cycle 1, and day 1 of cycles ≥ 2 [28-day cycles]) and cohort B (patients who had received CDK4/6i + fulvestrant): oral alpelisib (300 mg once daily) + oral letrozole (2.5 mg once daily). Study treatment will continue until disease progression or intolerable toxicity. The primary end point is the proportion of patients who are alive without disease progression at 6 months (RECIST v1.1; local assessment), which will be evaluated separately in each cohort and presented together with 2-sided 90% confidence intervals using Clopper and Pearson (1934) exact method. Evidence of treatment effect will be demonstrated if the lower bound of the 90% CI is greater than 30%. A total sample size of 80 patients in each cohort is planned. Secondary end points include progression-free survival (PFS), PFS on next-line treatment (PFS2), overall response rate, clinical benefit rate, duration of response, safety, and tolerability. Detection of frequency of PIK3CA mutations in ctDNA and its correlation with response is an exploratory end point.

Citation Format: Rugo HS, Turner N, Chia S, Ciruelos E, Nienstedt C, Ridolfi A, Kong O, Sankaran B, Juric D. BYLieve: A phase 2 study of alpelisib with fulvestrant or letrozole for treatment of PIK3CA mutant, hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2–) advanced breast cancer (aBC) progressing on/after cyclin-dependent kinase (CDK)4/6 inhibitor therapy [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT3-05-02.

Abstract P5-19-01: Impact of palbociclib plus letrozole on patient-reported general health status compared with letrozole alone in ER+/HER2- advanced/metastatic breast cancer

BACKGROUND: Palbociclib plus letrozole significantly improved progression-free survival (PFS) compared with letrozole plus placebo in treatment-naive postmenopausal patients with estrogen receptor-positive (ER+), human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC) in the phase 3 PALOMA-2 trial. Here, we compare patient-reported general health status with extended (max 53 cycles) follow-up (data cut off May31st, 2017) (Pfizer: NCT01740427).

METHODS: PALOMA-2 randomized patients 2:1 to palbociclib + letrozole (n=444) or placebo + letrozole (n=222). Patient-reported outcomes were assessed at baseline, day 1 of cycles 1, 2, and 3, and day 1 of every other cycle from cycle 5 until the end of treatment using the EuroQol 5-Dimension Questionnaire (EQ-5D). The EQ-5D is a standardized measure of health status that consists of a descriptive system comprising the following 5 dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression rated at 3 levels (no, some, or extreme problems) and a single index score for health status (ranges generally from 0 [dead] to 1 [full health]) calculated using a standard algorithm. In addition, a visual analog scale (VAS) measured self-rated health status from 0 (worst imaginable) to 100 (best imaginable). Repeated measures mixed-effects analyses were performed to compare overall index and VAS scores between treatments, controlling for baseline.

RESULTS: Completion rates at baseline were &gt;95% in each group. The mean (SD) scores at baseline were comparable between palbociclib plus letrozole and letrozole alone for the VAS (71.3 [21.2] vs 72.3 [19.8]) and the EQ-5D index scores (0.70 [0.25]) vs (0.73 [0.21]). Median follow up was 38 months for palbociclib plus letrozole and 37 months for letrozole only. No statistically significant difference in overall change from baseline in general health status was observed between the treatment arms. The proportion of patients reporting the presence of a problem at baseline was similar for palbociclib plus letrozole and letrozole, respectively: mobility (39% vs 39%), self-care (12% vs 12%), usual activities (44% vs 39%), pain (69% vs 65%), and anxiety/depression (54% vs 54%). No statistically significant difference in overall mean EQ-5D index scores (0.73 vs. 0.71) was observed between the treatment arms.

CONCLUSION: Addition of palbociclib to letrozole maintained general health status and EQ-5D index scores in ER+ HER2- advanced/metastatic breast cancer with no statistically significant differences observed compared to letrozole alone.

Citation Format: Harbeck N, Dieras V, Finn R, Gelmon KA, Walshe JM, Shparyk Y, Mori A, Lui DR, Bhattacharyya H, Iyer S, Johnston S, Rugo HS. Impact of palbociclib plus letrozole on patient-reported general health status compared with letrozole alone in ER+/HER2- advanced/metastatic breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-19-01.

Abstract P1-14-03: ABRAZO: Exposure-efficacy and -safety analyses of breast cancer patients with germline BRCA1/2 mutations receiving talazoparib in a phase 2 open-label trial

Background: Talazoparib (TALA) is a dual-mechanism poly (ADP-ribose) polymerase (PARP) inhibitor that traps PARP on DNA. Efficacy results of this phase 2 trial were previously presented (Turner et al, ASCO 2017, abstract 1007). This study included sparse pharmacokinetic (PK) sampling for patients through cycle 4 of therapy. Exploratory analyses included assessment of exposure versus parameters of efficacy and safety.

Methods: ABRAZO (NCT02034916) was a parallel-cohort, open-label phase 2 study of TALA (1 mg/d) following (i) platinum-based therapy (cohort 1) or (ii) ≥3 platinum-free cytotoxic-based regimens (cohort 2) in patients with locally advanced or metastatic breast cancer and germline BRCA1/2 mutation. Sparse PK sampling was performed on day 1 of cycles 1-4, consisting of a predose sample collected ≤60 minutes prior to dosing and 2 postdose samples collected ≥30 minutes after dosing (time of food ingestion prior to the dose was collected). The collection times of the 2 postdose samples were separated by ≥2 hours. Efficacy parameters included radiographic progression-free survival (rPFS) by central review and objective response rate (ORR). Safety parameters included incidence of overall adverse events (AEs) and grade ≥3 AEs. Individual AUCs (area under concentration-time curves) for exposure-response analyses were predicted by population PK analyses.

Results: Patients were divided into AUC tertiles: low (median, 109.0 ng*hr/mL; n=27), intermediate (median, 170.8 ng*hr/mL; n=27), and high (median, 219.2 ng*hr/mL; n=27). Median rPFS was 5.3 months (95% confidence interval [CI], 3.1, 8.3) in the lowest AUC tertile, 5.6 months (95% CI, 3.7, 8.4) in the intermediate AUC tertile, and 5.3 months (95% CI, 3.9, 5.6) in the highest AUC tertile. The ORR was 22.2% (95% CI, 8.6, 42.3) in the lowest AUC tertile, 25.9% (95% CI, 11.1, 46.3) in the intermediate AUC tertile, and 37.0% (95% CI, 19.4, 57.6) in the highest AUC tertile. AEs of any grade were reported in 11 patients (40.7%) in the lowest AUC tertile, 21 patients (77.8%) in the intermediate AUC tertile, and 22 patients (81.5%) in the highest AUC tertile. Grade ≥3 AEs were reported in 8 patients (29.6%) in the lowest AUC tertile and in 18 patients (66.7%) in the intermediate and highest AUC tertiles. The most common AEs in all 3 exposure tertiles were anemia, thrombocytopenia, and neutropenia.

Conclusions: Median rPFS did not change with increasing systemic exposure. There may be a trend to higher ORR in patients with highest systemic exposure. A larger percentage of patients experienced AEs with elevated systemic exposure. Increased response rates with greater exposure does not translate to improved rPFS. These results should be interpreted with caution due to the low patient numbers in each cohort.

Citation Format: Telli ML, Turner NC, Mailliez A, Ettl J, Grischke E-M, Mina LA, Balmaña J, Hurvitz SA, Wardley AM, Fasching PA, Tudor C, Nguyen L, Hannah AL, Robson ME, Rugo HS. ABRAZO: Exposure-efficacy and -safety analyses of breast cancer patients with germline BRCA1/2 mutations receiving talazoparib in a phase 2 open-label trial [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-14-03.

Abstract P1-07-04: Physical activity, weight and outcomes in patients receiving first-line chemotherapy for metastatic breast cancer: Results from CALGB 40502 (Alliance)

Background: Obesity and inactivity are associated with an increased risk of cancer-related and overall mortality in women with early-stage breast cancer, but there are few data in advanced breast cancer.

Methods: C40502 was a Phase III trial of first-line chemotherapy for patients with metastatic breast cancer (MBC). Participants were randomized to weekly paclitaxel, nab-paclitaxel or ixabepilone. Height and weight at the time of study enrollment were abstracted from medical records. After study activation, the protocol was amended to collect physical activity (PA) data. Participants completed the Nurses' Health Study Exercise Questionnaire, indicating the frequency, type and duration of recreational PA in which they engaged at study enrollment. Metabolic equivalent (MET)-hours of weekly PA (MET-hrs/wk) were calculated using the Ainsworth Compendium. PA was dichotomized to 0-9 or 9+ MET-hrs/wk based on data in early stage breast cancer suggesting that women who engaged in &gt; 9 MET-hrs of PA/wk had lower cancer-specific mortality. Association with clinical endpoints was evaluated using multivariate Cox proportional hazard models adjusting for treatment assignment, age, tumor hormone-receptor status, prior taxane use, disease-free interval and visceral metastases.

Results: 799 patients enrolled in C40502 between 2008 and 2011. Baseline body mass index (BMI) was available for 792 patients and PA data for 500 participants. Median follow up was 60 months. Median age was 56.7 years; 72% of patients had hormone receptor (HR)-positive cancers. Median BMI was 28.6 kg/m2 (IQR: 24.7-33.1 kg/m2). Patients engaged in a median of 3.3 MET-hrs/wk of PA (about 1 hour of moderate-intensity PA/wk) (IQR: 0.7-12.7 MET-hrs/wk). Neither BMI nor PA was significantly associated with progression-free (PFS) or overall survival (OS).

BMI and OutcomesBMI (kg/m2)N (%)PFS (months)Adj HRP valueOS (months)Adj HRP value18.5-24.9209 (26.4)10.0 (9.1-11.2)ref0.4826.1 (23.3-33.2)ref0.5425-29.9248 (31.3)9.0 (7.6-10.3)1.00 (0.83-1.22) 22.0 (20.0-25.4)1.05 (0.85-1.30) ≥30335 (42.3)8.7 (7.7-9.7)0.97 (0.81-1.17) 25.5 (23.1-29.5)0.95 (0.78-1.16) 

PA and OutcomesPA (MET-hrs/wk)N (%)PFS (months)Adj HRP valueOS (months)Adj HRP value0-9344 (68.8)7.9 (7.4-9.2)ref0.1323.6 (20.1-26.8)ref0.21&gt;9156 (31.2)9.8 (8.9-12.0)0.86 (0.71-1.05) 27.4 (22.3-35.6)0.87 (0.70-1.08) 

There was a trend toward longer PFS and OS in patients who reported PA &gt; 9 MET-hrs/wk vs 0-9 MET-hrs/wk, especially in individuals with HR+ cancers (median PFS 11.7 vs 9.2 months [adj HR = 0.84 (0.66-1.05)] and OS 34.0 vs 26.5 months [adj HR = 0.83 (0.66-1.05)] with PA &gt;9 vs 0- 9 MET-hrs/wk).

Conclusions: In some of the first data looking at the relationship between lifestyle factors and outcomes in MBC, there was no relationship between BMI and PFS or OS in patients receiving first-line chemotherapy for advanced disease. A trend toward improved PFS and OS was seen in multivariate analysis in patients who reported higher levels of PA, but results were not statistically significant and could have been influenced by other patient factors. More information is needed regarding the relationship between PA and cancer outcomes, especially in patients with HR+ cancers.

Citation Format: Ligibel JA, Huebner LJ, Rugo HS, Burstein H, Toppmeyer DL, Anders CK, Ma C, Hudis CA, Winer EP, Barry WT. Physical activity, weight and outcomes in patients receiving first-line chemotherapy for metastatic breast cancer: Results from CALGB 40502 (Alliance) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-07-04.

Abstract OT2-07-10: ATTAIN: Phase 3 study of etirinotecan pegol (EP) vs treatment of physician's choice (TPC) in patients (pts) with metastatic breast cancer (MBC) who have stable brain metastases (BM) previously treated with an anthracycline, a taxane, and capecitabine (ATC)

Background: EP is a next generation topoisomerase I inhibitor-polymer conjugate that provides continuous exposure to SN-38, the active metabolite. A BM mouse model showed high penetration and retention of SN-38 in CNS lesions, resulting in decreased size of CNS lesions and improved survival (OS) at concentrations achieved at the recommended dose in pts (Adkins BMC Cancer 2015). A Phase 3 trial (BEACON) of EP vs TPC in 852 pts with advanced BC did not meet its primary endpoint of OS (HR 0.087 p=0.08); a subset of 67 pts with stable BM showed improved OS (HR 0.51 [95% CI 0.30-0.86] p&lt;0.01) (Perez Lancet Oncol 2015). The current Phase 3 trial (ATTAIN) was designed for this subpopulation of pts having high unmet medical need.

Methods: Pts with MBC with locally treated stable BM will be randomized 1:1 to EP vs TPC in an open-label, randomized Phase 3 study. Eligibility includes ECOG PS 0 or 1; adequate organ function who received prior ATC (in neo/adjuvant or locally advanced/MBC setting) pts must have had ≥1 prior cytotoxic regimen for MBC (triple negative BC) ≥2 prior cytotoxic regimens and either 1 prior hormone therapy (HR+ BC) or 1 prior HER2 targeted therapy (HER2+ BC). Pts must have undergone definitive local therapy of BM (whole brain radiation [RT] stereotactic RT or surgical resection as single-agent or combination) signs/symptoms of BM must be stable with steroids unchanged or decreasing for ≥ 7 days prior to randomization. Primary endpoint is OS. Key secondary endpoints: ORR and PFS by RECIST v1.1 and RANO-BM, clinical benefit rate (ORR+SD ≥ 6 months) and QoL. Pts randomized to TPC will receive 1 of 7 IV cytotoxic agents. Pts are stratified by region, PS and receptor status. 350 pts will be randomized to obtain number of events required at 90% power to detect a statistically significant improvement in OS (hypothesizing HR=0.67) 1 interim analysis at 50% of deaths (130 events) will be performed. PK sampling and UGT1A1 testing will be performed in the EP arm; plasma ctDNA will be assessed for potential predictive markers of efficacy. Enrollment began early 2017. For enrollment information contact Dr. Alison Hannah, Dr. Mary Tagliaferri, or Minnie Kuo at StudyInquiry@nektar.com. NCT02915744

Citation Format: Tripathy D, Sara T, Seidman AD, Anders CK, Ibrahim N, Rugo HS, Twelves CJ, Diéras V, Müller V, Hannah A, Tagliaferri M, Cortés J. ATTAIN: Phase 3 study of etirinotecan pegol (EP) vs treatment of physician's choice (TPC) in patients (pts) with metastatic breast cancer (MBC) who have stable brain metastases (BM) previously treated with an anthracycline, a taxane, and capecitabine (ATC) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT2-07-10.

Abstract P5-21-03: Palbociclib (PAL) + letrozole (LET) as first-line therapy in estrogen receptor–positive (ER+)/human epidermal growth factor receptor 2–negative (HER2−) advanced breast cancer (ABC): Efficacy and safety updates with longer follow-up across patient subgroups

BACKGROUND: Endocrine therapy (ET) has been the primary first-line (1L) therapy for ER+ ABC. In the PALOMA-2 study (NCT01740427), PAL (P)+LET (L) significantly prolonged progression-free survival (PFS; HR=0.58, P&lt;.001) after a median 23 mo follow-up (FU) (Finn et al. NEJM 2016). Here we report more mature PFS overall and in subgroups, with (w/) longer FU. The study is ongoing for overall survival FU.

METHODS: Postmenopausal pts w/ ER+/HER2- ABC and no prior systemic therapy in the ABC setting were randomized 2:1 to P (125 mg/d) + L (2.5 mg QD) or placebo (PBO) + L. Key endpoints: investigator-assessed PFS and safety. Median PFS (mPFS) was estimated (intent-to-treat population).

RESULTS: 666 pts (444, P+L; 222, PBO+L) were enrolled. Arms were well balanced: visceral (48%)/nonvisceral (52%) disease and prior ET (56%)/no prior ET (44%). After a median FU of 38 mo w/ P+L and 37 mo w/ PBO+L, mPFS was 27.6 and 14.5 mo, respectively, in the overall population (HR=0.56, P&lt;.0001; Table).

TABLE. mPFS overall and by relevant subgroupsP+LPBO+LP+L vs PBO+LmPFS, mo (95% CI)mPFS, mo (95% CI)HR (95% CI)P* Overall27.6 (22.4–30.3)14.5 (12.3–17.1)0.56 (0.46–0.69)&lt;.0001 Measurable disease23.7 (19.3–27.6)14.5 (12.3–18.5)0.63 (0.50–0.79)&lt;.0001 Nonmeasurable disease36.2 (27.6?NE)16.5 (8.3–19.6)0.39 (0.25–0.60)&lt;.0001 Visceral19.3 (16.4–24.2)12.3 (8.4–16.4)0.62 (0.47–0.81)&lt;.0005 Nonvisceral35.9 (27.7–NE)17.0 (13.8–24.8)0.50 (0.37–0.67)&lt;.0001 Bone only†36.2 (27.6–NE)11.2 (8.2–22.0)0.41 (0.26–0.63)&lt;.0001 Not bone only24.2 (19.4–27.7)14.5 (12.9–18.5)0.62 (0.50–0.78)&lt;.0001 De novo metastatic27.9 (22.1–33.4)22.0 (13.9–27.4)0.61 (0.44–0.85)&lt;.005 Prior ET24.2 (18.8–27.6)11.2 (8.4–14.5)0.54 (0.42–0.71)&lt;.0001 No prior ET30.3 (24.5–35.7)21.9 (15.9–27.4)0.59 (0.43–0.80)&lt;.0005 Nonvisceral36.2 (27.9–NE)27.6 (19.1–35.6)0.59 (0.38–0.92)&lt;.01 Visceral23.7 (16.8–30.3)13.9 (10.2–22.2)0.55 (0.36–0.85)&lt;.005 Disease sites130.4 (24.8–NE)16.5 (11.0–22.1)0.52 (0.36–0.75)&lt;.0005228.1 (19.4–NE)16.3 (11.0–27.4)0.57 (0.37–0.89)&lt;.01323.7 (19.2–27.6)13.8 (8.8–17.0)0.61 (0.46–0.82)&lt;.0005NE=not estimable. *Not adjusted for multiple analyses; 1-sided P values. †Per tumor site.

All subgroups benefited from addition of P to L. Notably, pts w/ low disease burden (bone only, nonvisceral disease, few disease sites) derived significant PFS benefit, including those w/ both nonvisceral disease and no prior ET (mPFS, 36.2 vs 27.6 mo; HR=0.59, P&lt;.01). Importantly, median time from randomization to start of 2nd subsequent systemic anticancer therapy was 39 vs 29 mo for P+L vs PBO+L (HR=0.72, P&lt;.005). There were no new safety signals w/ longer FU.

CONCLUSIONS: This is the longest FU of a phase 3 study of a cyclin-dependent kinase 4/6 inhibitor for ABC. P+L continues to consistently improve PFS vs PBO+L across all subgroups while toxicity remains manageable; notably P+L delays time to starting 2nd subsequent anticancer therapies by 10 mo. Pts w/ low disease burden or sensitivity to ET alone had PFS &gt;3 y (significant vs PBO+L), demonstrating the clinical benefit of P+ET. These data confirm P+L should be a 1L therapy option for pts w/ HR+/HER2- ABC.

Funding: Pfizer

Citation Format: Rugo HS, Finn RS, Dieras V, Ettl J, Lipatov O, Joy A, Harbeck N, Castrellon A, Lu DR, Mori A, Gauthier ER, Huang C, Gelmon KA, Slamon DJ. Palbociclib (PAL) + letrozole (LET) as first-line therapy in estrogen receptor–positive (ER+)/human epidermal growth factor receptor 2–negative (HER2−) advanced breast cancer (ABC): Efficacy and safety updates with longer follow-up across patient subgroups [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-21-03.

Abstract P2-02-06: Biomarker analysis by next generation circulating tumor DNA (ctDNA) sequencing in patients with advanced breast cancer

Background: Next-generation sequencing is of increasing interest to identify specific targets for both drug development and treatment. The study of metastatic cancer is complicated by lack of tissue and the potential for change in biology over treatment. We evaluated ctDNA in patients with advanced breast cancer to explore the relationship between specific DNA mutations and prognosis as well as therapeutic decision making.

Methods:Peripheral blood was collected in EDTA at the time of diagnosis of advanced disease. Samples were sent to Geneplus-Beijing for sequencing. Indexed Illumina libraries were prepared from germline and circulating DNA using the KAPA Library Preparation Kit; the capture probe was designed based on genomic regions selected with 1021 genes, covering the most frequently mutated genes and exons in solid tumors. Clinical characteristics, treatment and outcome data were collected. We analyzed progression free survival (PFS) from first-line therapy and overall survival (OS), endpoints were correlated with observed gene mutations.

Results: 54 patients were enrolled; 27 (50%) HER2+, 22 (41%) hormone receptor + (HR+)/HER2-, and 5 (9%) triple negative (TNBC). Median age was 48 (range 26-74). The median follow-up was 8 years (range 12-180 months). First-line therapy included chemotherapy with trastuzumab for HER2+ disease, chemotherapy with endocrine maintenance (17) or endocrine therapy alone (5) for HR+/HER2- disease, and chemotherapy for TNBC. Mutations were found in TP53, PIK3CA, PIK3CA 3140 A&gt;G(p.H1047R) and ERBB (including ERBB1-4), at 40.7%, 35.2%, 20.4% and 25.9%, respectively. In univariate analysis, patients with tumor mutations in TP53 had a shorter OS (median 64 vs 121 months, p=0.006). The PIK3CA 3140 A&gt;G mutation was more frequent in HER2+ (7/27, 25.9%) than HR+/HER2- (4/22 (18.2%) or TNBC (0/5), and was associated with shorter median PFS in HER2+ disease (mutant vs. wild type: 4 (range 2-9) vs. 8 (range 2-22) months, p=0.006). The frequency of ERBB mutation was similar in HER2- 7/27(25.9%) (p=0.707) or HER2+ 7/27(25.9%) disease (p=0.066); there was no significant impact on PFS in any subset. Multivariate analysis for HER2+ disease including age, ER, Ki67, TP53, PIK3CA, PIK3CA 3140 A&gt;G and ERBB), demonstrated that the PIK3CA 3140 A&gt;G mutation was the only factor associated with shorter PFS (p=0.025); further analysis by receiver operating characteristic (ROC) curve showed that the PIK3CA 3140 A&gt;G mutation and the mutation in PIK3CA 3140 A&gt;G and ERBB combination pathway had a large area under the curve (AUC), with AUC of 0.789, and 0.734 respectively.

Conclusions: Using NGS in ctDNA, we found that the PIK3CA 3140A&gt;G mutation was more frequent in HER2+ disease, and was the only mutation associated with shorter PFS on multivariate analysis. The presence of a TP53 mutation was associated with worse OS. Evaluation of ctDNA is feasible in a general breast cancer population and has prognostic impact; further correlation of these findings with tumor samples is ongoing.

Citation Format: Li H, Wang J, Rugo HS, Zhang Y, Yang L, Liu X, Shao B, Xu Y, Yang L, Zhang R, Ran R, Chang L. Biomarker analysis by next generation circulating tumor DNA (ctDNA) sequencing in patients with advanced breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-02-06.

Abstract P2-01-01: Trajectory patterns of circulating tumor cells (CTC) in chemotherapy-treated metastatic breast cancer (MBC) patients predict poor clinical outcomes: CALGB 40502 (Alliance)/NCCTG N063H study

Little is known about the dynamics of CTCs during treatment and its clinical significance. We examined the predictive utility of serial CTC analysis in ER+HER2- MBC patients (pts) treated with chemotherapy in the CALGB 40502/NCCTG N063H study, a randomized phase III trial of weekly paclitaxel compared to weekly nanoparticle albumin bound nab-paclitaxel or ixabepilone +/- bevacizumab as first-line therapy (ClinicalTrials.gov Identifier: NCT00785291, Support: U10CA180821, U10CA180882).

Methods: Of the 783 pts treated, 469 had ≥3 serial blood samples (including baseline) successfully analyzed for CTCs by CellSearch® and were included in this analysis (n=2,202). Samples with ≥5 CTCs per 7.5 mLs of blood were considered CTC+. The prognostic and predictive performance of baseline CTCs (bCTC) and CTC status from baseline to cycle 2 (b2CTC) were compared to a novel latent mixture model classification based on trajectory of CTCs (tCTC). Akaike Information Criterion (AIC) was used to select the model (bCTC vs b2CTC vs tCTC) that best predicts overall survival (OS), progression-free survival (PFS), and time-to-treatment failure (TTF).

Results: 53% of the pts were CTC+ at baseline. b2CTC status changed in 36% of the pts, most of whom were CTC+CTC- (35%), and very few CTC-CTC+ (1%); the rest of the pts did not experience a change in b2CTC status (46% CTC-CTC- and 19% CTC+CTC+). Mixture model analysis revealed 4 groups of pts that show distinct tCTC patterns over the course of treatment: consitently very low/undectectable CTCs (tCTCneg, 56%), low (tCTClo, 24%), intermediate (tCTCmid, 15%), or high (tCTChi, 5%). bCTC, b2CTC, and tCTC were significantly correlated with tumor subtype (all p &lt;0.0022) and presence of bone metastasis (all p &lt;0.0001). Multivariate analysis showed that pts who were CTC+ at baseline, and those whose b2CTC status remained positive (CTC+CTC+) had significantly reduced OS, PFS and TTF.

 OSPFSTTFModelsHR (95% CI)p-valueHR (95% CI)p-valueHR (95% CI)p-valuebCTC (vs CTC-)      → CTC+2.5(1.8-3.3)&lt;0.00011.6(1.3-2.0)&lt;0.00011.3(1.1-1.6)0.0046b2CTC (vs CTC+CTC-)      → CTC-CTC+1.6(0.5-5.4)0.41491.6(0.6-4.5)0.39051.6(0.6-4.3)0.3961→ CTC+CTC+2.7(1.9-3.8)&lt;0.00011.8(1.4-2.5)&lt;0.00011.8(1.3-2.4)&lt;0.0001→ CTC-CTC-0.5(0.4-0.8)0.00020.8(0.6-0.9)0.01600.9(0.7-1.1)0.2771tCTC (vs tCTCneg)      → tCTClo2.6(1.9-3.7)&lt;0.00011.9(1.4-2.4)&lt;0.00010.9(0.7-1.1)0.0033→ tCTCmid5.3(3.6-8.0)&lt;0.00012.5(1.8-3.4)&lt;0.00011.8(1.4-2.5)0.0001→ tCTChi10.8(6.1-19)&lt;0.00013.0(1.8-5.0)&lt;0.00012.3(1.4-3.7)0.0009CTC- (&lt;5 CTCs per 7.5 mLs); CTC+ (≥5 CTCs per 7.5 mLs)

Pts with tCTClo, tCTCmid and tCTChi had significantly shorter OS, PFS and TTF compared to those with tCTCneg. After adjustment for potential confounders, AIC analysis revealed that the tCTC model best predicts OS and PFS, while b2CTC best predicts TTF.

 AIC Score*ModelsOSPFSTTFbCTC243240514199b2CTC240540384186tCTC237940264188*The lowest AIC score indicates the best model.

Conclusions: Analysis of CTC trajectory patterns identified pts with poor outcome who could potentially benefit from more effective treatment. Validation in independent cohorts is warranted to confirm the findings in this study.

Citation Format: Magbanua MJ, Hendrix L, Hyslop T, Barry WT, Winer EP, Hudis C, Toppmeyer D, Burnstein H, Qadir M, Ma C, Scott JH, Park JW, Rugo HS. Trajectory patterns of circulating tumor cells (CTC) in chemotherapy-treated metastatic breast cancer (MBC) patients predict poor clinical outcomes: CALGB 40502 (Alliance)/NCCTG N063H study [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-01-01.

Abstract PD5-06: Adjuvant palbociclib plus endocrine therapy for hormone receptor positive/HER2 negative breast cancer: A phase II feasibility study

Background:

The CDK4/6 inhibitor palbociclib (P) combined with endocrine therapy (ET) prolongs progression-free survival in previously untreated and treated hormone receptor positive/HER2 negative (HR+/HER2-) metastatic breast cancer (MBC). The most common toxicity with P is neutropenia, typically non-cumulative and uncomplicated. Given observed benefits of P in metastatic BC, this single arm phase II trial was designed to determine the feasibility and toxicity of combination adjuvant P and ET for HR+/HER2- early BC (EBC).

Methods:

Eligible patients (pts) had HR+/HER2- stage II (not T2N0)-III EBC, with prior completion of 3-24 mo of ET (either AI or tamoxifen) without significant adverse events (AE). Pts received P at 125 mg daily, 3 wk on/1 wk off in a 28d cycle, plus continuous ET, for planned duration 2 yrs. Pts were removed from study for toxicity, non-adherence, or other events related to tolerability; pts who recurred or completed 2 yrs of therapy were censored for the primary endpoint. The primary objective was to evaluate the treatment discontinuation rate at 2 yrs; a rate of &gt;50%, would indicated a non-feasible treatment duration (null hypothesis). Discontinuation rates at 2 yrs are estimated by Kaplan Meier with 95% confidence bands. A sample size of 160 pts provided 92% power to reject the null hypothesis using a one-sided alpha = 0.025 if the true rate of discontinuation is &lt;33.3%, and accounting for a censoring rate of up to 20% over the 2 yrs. Secondary endpoints include toxicity, adherence, QOL, and pharmacogenomics.

Results:

Between 3/2014 and 11/2015, 162 pts initiated P; the majority had stage III EBC (52%) and received prior chemotherapy (63%). As of 05/2017, 120 (74%) have completed at least 1 yr of P + ET, and 50 (31%) have completed 2 yrs of P + ET. Early discontinuation of protocol treatment was reported for 59 pts (36%), including 49 events (30%) related to protocol-mandated (9%) and non-mandated (21%) tolerability. The cumulative rate of all discontinuations was 15.1% at 6 mos, 20.9% at 12 mos and 27.8% at 18 mos. Half of all non-mandated discontinuations occurred within the first 6 mos of initiation of therapy, and the rate decreased with greater provider and pt education. Median duration of pts still on treatment is 20 mos (inter-quartile range: 18 to 21 mos). The rate of grade 3/4 neutropenia was 77%, with 0 cases of febrile neutropenia. Other common all-grade P-related AE &gt; 20% included fatigue 65%, alopecia 25%, mucositis 24%, and anemia 24%. 32% of pts required one dose reduction, 16% required two. There have been 2 BC recurrence events and 1 chemotherapy-related AML. Updated data for the primary analysis of feasibility and tolerability, as well as pharmacogenomics, QOL, and adherence, will be presented.

Conclusions:

In this single arm phase II trial, the majority of pts have completed at least 1 year of adjuvant P + ET therapy, with no new toxicity signals. Non-protocol discontinuations have decreased with education. Updated results for the primary analysis will be presented. As in the MBC setting, extended duration palbociclib appears feasible and tolerable for most pts. The efficacy of 2 years of P and ET will be addressed by the phase III PALLAS trial (NCT NCT02513394).

Citation Format: Mayer EL, DeMichele AM, Guo H, Miller KD, Rugo HS, Schneider B, Waks AG, Come SE, Mulvey T, Huang Bartlett C, Koehler M, Barry W, Winer EP, Burstein HJ. Adjuvant palbociclib plus endocrine therapy for hormone receptor positive/HER2 negative breast cancer: A phase II feasibility study [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD5-06.

Abstract OT1-04-05: A phase 2 randomized, double-blind, placebo-controlled trial of radium-223 dichloride with exemestane and everolimus in patients with HER2-negative, hormone receptor–positive breast cancer and bone metastases

Background: Treatment options for bone-dominant metastatic breast cancer (MBC) are limited. Radium-223, a first-in-class α emitter with a targeted antitumor effect on bone metastases (mets), was well tolerated and reduced bone biomarker levels in a phase 2 study in patients with bone-dominant MBC (Coleman et al. Breast Cancer Res Treat. 2014). In patients with HER2- estrogen receptor+ (ER+) bone-dominant MBC, everolimus + exemestane (EVE+EXE) improved progression-free survival (PFS) versus EXE alone. Radium-223 combined with EVE+EXE may improve outcomes in patients with HER2- ER+ bone-dominant MBC; this trial will evaluate efficacy and safety of radium-223 versus placebo in these patients (NCT02258451).

Trial design: Patients are randomized to receive (1:1) radium-223 (50 kBq/kg [55 kBq/kg after National Institute of Standards and Technology update] IV) or placebo × 6 cycles q 4 wk + EXE (25 mg PO q d) + EVE (10 mg PO q d) plus best supportive care. EXE+EVE continues until disease progression or unacceptable toxicity. Stratification is by geographic region (EU/N America vs Asia), prior hormone therapy (1 vs ≥ 2), and presence of visceral disease (yes vs no).

Eligibility criteria: Eligible patients are pre- or postmenopausal with HER2- ER+ MBC and have ≥ 2 bone mets or have soft tissue and/or visceral mets. Patients must have measurable disease per RECIST v1.1, ≥ 1 prior line of hormone therapy for MBC, and 1-2 prior skeletal-related events; be on bisphosphonates or denosumab; and have an ECOG score of 0-1. Patients must have had no past or current need for chemotherapy for MBC, no unresolved spinal cord compression, and no prior EVE treatment.

Specific aims: The primary end point is symptomatic skeletal event–free survival (SSE-FS). Secondary end points are overall survival; times to opiate use, pain progression, and cytotoxic chemotherapy; radiologic PFS; and safety. Safety and efficacy are assessed every 4 weeks. Long-term safety is assessed until study termination.

Statistical methods: Assuming a 1-sided α of 0.1, 90% power, ∼ 160 SSE-FS events will be required for the analysis. Efficacy will be analyzed by a stratified log-rank test. Safety analysis will be descriptive.

Present and target accrual: Estimated enrollment is ∼ 311 patients. Currently, 74 patients are randomized.

Contact Oana Petrenciuc, Bayer HealthCare Pharmaceuticals, oana.petrenciuc@bayer.com, for more information.

Citation Format: Rugo HS, Drumea KC, Campone M, Barnadas A, Petrenciuc O, Zhang A, Li R, Coleman RE. A phase 2 randomized, double-blind, placebo-controlled trial of radium-223 dichloride with exemestane and everolimus in patients with HER2-negative, hormone receptor–positive breast cancer and bone metastases [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT1-04-05.

Abstract P5-11-17: Body image in women with breast cancer using a scalp cooling system to reduce chemotherapy induced alopecia

Background: Most women consider hair to be an important part of body image. Alopecia is an emotionally traumatic side effect for breast cancer patients undergoing adjuvant chemotherapy. The DigniCap™ Scalp Cooling System is the first scalp cooling system cleared by the US Food and Drug Administration to reduce the likelihood of chemotherapy induced alopecia.

Methods: Quality of Life (QOL) data were collected as part of a prospective clinical trial evaluating the clinical performance of scalp cooling in women with early stage BC receiving adjuvant chemotherapy.

The study's primary endpoint was hair loss as evaluated by patient self-assessment. Treatment success was defined as ≤ 50% hair loss. QOL was evaluated by the EORTC-QLQ-BR23 (BR23) administered at baseline, last chemotherapy cycle, and one month later. For BR23, 4 response categories were collapsed to 2 categories (Not at all/A little bit and Quite a bit/Very much) for analysis. QOL was compared between those with success vs. failure of scalp cooling.

Results: 101 patients were evaluable for the primary endpoint: Success was seen in 67 (66.3%) pts. QOL at study entry was comparable between pts with scalp cooling success or failure for each item in the BR23 questionnaire. Results reported as percentages of patients in each group who answered either quite a bit or very much to body image-related questions on the BR23 questionnaire are displayed in Table 1.

BR23 results (% quite a bit/very much) one month after chemotherapyBR23 ItemsTreatment Success % (95% CI)Treatment Failure % (95% CI)Felt physically less attractive18.5% (9.0%, 27.9%)52.2% (31.8%, 72.6%)Felt less feminine15.4% (6.6%, 24.2%)29.1% (19.2%, 59.1%)Found it difficult to see themselves naked13.8% (5.5%, 22.2%)21.7% (4.9%, 38.6%)Felt dissatisfied with their body12.3% (4.3%, 20.3%)26.1% (8.1%, 44.0%)

Conclusions: Women with breast cancer using scalp cooling during chemotherapy who had hair preservation experienced improved quality of life, according to self-assessment of body image, compared to women who had significant hair loss.

Citation Format: Cigler T, Melin SA, Klein P, Hurvitz SA, Melisko M, Moore A, Park GD, Bageman E, Ver Hoeve ES, Rugo HS. Body image in women with breast cancer using a scalp cooling system to reduce chemotherapy induced alopecia [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-11-17.

Abstract P4-22-03: Palbociclib in combination with endocrine therapy in treatment-naive and previously treated elderly women with HR+, HER2– advanced breast cancer: a pooled analysis from randomized phase 2 and 3 studies

Background: At least 40% of breast cancers are diagnosed in women ≥65 y old and most are hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-). Palbociclib (PAL) is an oral, small-molecule inhibitor of cyclin-dependent kinases 4 and 6. Randomized studies of PAL combined with endocrine therapy (ET) demonstrated significantly improved progression-free survival (PFS) in patients (pts) with treatment-naive and previously treated advanced breast cancer (ABC).

Methods: We evaluated the efficacy of PAL+ET vs ET alone in pts aged ≥65-74 and ≥75 y across multiple pivotal randomized phase 2 and 3 studies. Safety and pharmacokinetics (PK) data (blood samples collected from pts in phase 1/2 [PALOMA-1] and phase 1 studies [NCT00141297 and NCT00420056]) for PAL+ET were pooled and compared across age groups. Pts who had not received treatment for ABC were randomized to receive PAL+letrozole (LET) or LET alone/with placebo (PBO; PALOMA-1, open-label/PALOMA-2, double-blind). Pts who had progressed on prior ET were randomized to receive PAL+fulvestrant (FUL) or PBO+FUL (PALOMA-3, double-blind). The primary endpoint for these studies was investigator-assessed PFS. Safety assessments and blood counts occurred at baseline and every 2 weeks for the first 2 cycles and on day 1 of subsequent cycles.

Results: Among 872 pts treated with PAL+ET, 221 (25%) were aged ≥65-74 y and 83 (10%) were ≥75 y (PAL+LET: n=528, 162 and 56, respectively; PAL+FUL: n=347, 59 and 27). Median (range) treatment durations were 440 (1-1615) d, 502 (1-1615) d, and 459 (21-1404) d, respectively. Improvement in efficacy endpoints was seen with PAL+ET vs ET across all age groups (Table 1). Incidence of adverse events (AEs), serious AEs and discontinuations due to AEs were similar in the overall population (99%, 19%, 3%) and in pts aged ≥65-74 (99%, 25%, 5%) and ≥75 y (100%, 30%, 6%). Incidence of all grades and grade 3/4 neutropenia were also similar across age groups (overall: 67% and 54%; ≥65-74 y: 64% and 51%; ≥75 y: 77% and 60%). PK analysis showed no clinically relevant differences between arithmetic means, medians, and geometric means of the apparent oral clearance across age groups.

Conclusions: PAL in combination with ET is an effective and well-tolerated treatment option for elderly pts with HR+/HER2- endocrine-sensitive and -resistant ABC. A dose adjustment based on age is not required.

Sponsor: Pfizer

Table 1. PFS in pts ?65-74 and ?75 y (ITT populations)OverallAged ≥65-74 yAged ≥75 yPALOMA-1/PALOMA-2PAL+LET vs528 vs 303162 vs 9456 vs 26LET/LET+PBO,* nHR (95% CI);0.53 (0.44-0.64);0.66 (0.45-0.97);0.31 (0.16-0.61);1-sided P value&lt;0.00010.01620.0002Median PFS (95% CI), mo24.4 (22.0-26.2) vs27.5 (24.2-NR) vsNR (19.2-NR) vs13.6 (11.1-16.4)21.8 (16.3-31.3)10.9 (4.9-24.9)PALOMA-3PAL+FUL vs347 vs 17459 vs 3727 vs 6FUL+PBO, nHR (95% CI);0.46 (0.36-0.59);0.25 (0.14-0.45);0.87 (0.27-2.79);1-sided P value&lt;0.0001&lt;0.00010.4074Median PFS (95% CI), mo9.5 (9.2-11.0) vs16.1 (12.0-NR) vs13.6 (7.5-NR) vs4.6 (3.5-5.6)3.7 (1.9-5.3)7.4 (1.9-NR)HR=hazard ratio; ITT=intent to treat; NR=not reached. *Does not include 5 pts from phase 1 of PALOMA-1.

Citation Format: Rugo HS, Turner NC, Finn RS, Joy AA, Verma S, Harbeck N, Moulder S, Masuda N, Im Y-H, Zhang K, Kim S, Sun W, Schnell P, Huang-Bartlett C, Slamon D. Palbociclib in combination with endocrine therapy in treatment-naive and previously treated elderly women with HR+, HER2– advanced breast cancer: a pooled analysis from randomized phase 2 and 3 studies [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-22-03.

Abstract OT1-02-07: SOPHIA: A phase 3, randomized study of margetuximab plus chemotherapy vs trastuzumab plus chemotherapy in the treatment of patients with HER2+ metastatic breast cancer

Background: Despite significant advances in targeted therapy, HER2+ metastatic breast cancer (MBC) remains incurable. Ideal treatment includes pertuzumab and trastuzumab in combination with a taxane in the first line setting, followed by ado-trastuzumab emtansine on progression. Optimal treatment regimens in the third and greater line of therapy are not defined, but continued anti-HER2 therapy is recommended. Margetuximab is a Fc-modified monoclonal antibody to HER2 that recognizes the same epitope on HER2 as does trastuzumab, with similar affinity. Margetuximab demonstrates increased affinity to the activating CD16A Fc-receptor found on NK cells and macrophages and decreased affinity to the inhibitory CD32B receptor compared to trastuzumab. In vitro studies showed enhanced antibody dependent cell-mediated cytotoxicity compared to trastuzumab. In a Phase 1 dose escalation and expansion trial, margetuximab showed single agent clinical activity against HER2+ tumors in patients previously treated with trastuzumab and other anti-HER2 agents. Methods: SOPHIA is a randomized, prospective study testing the hypothesis that margetuximab plus chemotherapy (CTX) is more effective than trastuzumab plus CTX in patients previously treated for HER2+ MBC. Sequential primary endpoints are centrally assessed progression free survival (PFS) and overall survival (OS). The study size of 530 patients is determined to have 80% power to detect a hazard ratio for OS of 0.75. Secondary endpoints are investigator assessed PFS and centrally assessed overall response rate. Eligibility includes prior treatment with trastuzumab, pertuzumab, and ado-trastuzumab emtansine; no more than 3 prior lines of therapy in the metastatic setting; prior demonstration of HER2+ status at a local reference laboratory; and absence of active brain metastases. Eligible patients are randomized 1:1 to receive CTX (physician's choice: capecitabine, eribulin, gemcitabine or vinorelbine) plus either margetuximab or trastuzumab until disease progression or toxicity. Antibody may be continued after stopping CTX in patients with responding or stable disease. Progress to date: The trial was initiated July 2015 and is ongoing in the US and Europe with planned expansion to Korea and Israel. ClinicalTrials.gov Identifier NCT02492711; Eudract 2015-000380-13.

Citation Format: Rugo HS, Pegram MD, Gradishar WJ, Cortes J, Curigliano G, Hong S, Wigginton JM, Lechleider RJ, Cardoso F. SOPHIA: A phase 3, randomized study of margetuximab plus chemotherapy vs trastuzumab plus chemotherapy in the treatment of patients with HER2+ metastatic breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT1-02-07.

Abstract OT2-01-04: SOLAR-1: A phase III study of alpelisib and fulvestrant in men and postmenopausal women with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2–) advanced breast cancer (BC) progressing on or after aromatase inhibitor (AI) therapy

Background: The phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathway is often dysregulated in HR+ BC and is associated with resistance to endocrine therapy (ET). Alpelisib (BYL719; PI3Kα-specific inhibitor) and fulvestrant showed signs of antitumor activity in patients (pts) with estrogen receptor-positive (ER+), HER2– advanced BC (phase I), especially in PIK3CA-altered tumors (Janku et al. SABCS 2014, PD5-5).

Methods: SOLAR-1 (NCT02437318) is a phase III, randomized, double-blind study in men and postmenopausal women with HR+, HER2– advanced BC. Pts are assigned to 1 of 2 cohorts based on PIK3CA tumor status (mutant vs non-mutant), and randomized 1:1 to oral alpelisib/placebo (300 mg once daily) and intramuscular fulvestrant (500 mg on Day 1 and 15 of Cycle 1; Day 1 of Cycles ≥2 [28-day cycles]) until disease progression or discontinuation. Randomization is stratified by presence of liver and/or lung metastases and prior CDK4/6 inhibitor therapy. Key inclusion criteria: recurrence or progression on or after AI therapy, ≥1 measurable lesion (RECIST v1.1) or predominantly lytic bone lesion, and ECOG performance status ≤1. Key exclusion criteria: symptomatic visceral disease or disease burden precluding ET, acute pancreatitis ≤1 year prior to screening or history of chronic pancreatitis, and prior therapy with fulvestrant, chemotherapy (except [neo]adjuvant), or PI3K/AKT/mTOR inhibitors.

The primary and key secondary endpoints are progression-free survival (PFS; RECIST v1.1; local assessment) and overall survival (OS), respectively, in the PIK3CA-mutant cohort. Other secondary endpoints include PFS and OS in the PIK3CA non-mutant cohort, PFS (Blinded Independent Central Review; RECIST v1.1), the association between PFS and baseline PIK3CA status in circulating tumor DNA, overall response rate, clinical benefit rate, safety, and pharmacokinetics. The primary endpoint will be analyzed by a stratified log-rank test at one-sided 2% level of significance.

Recruitment of the planned 560 pts is ongoing.

Citation Format: Andre F, Kaufman B, Juric D, Ciruelos EM, Iwata H, Mayer IA, Rugo HS, Conte P, Liobl S, Rubovszky G, Inoue K, Tesch H, Lu Y-S, Ryvo L, Longin A-S, Mills D, Wilke C, Germa C, Campone M. SOLAR-1: A phase III study of alpelisib and fulvestrant in men and postmenopausal women with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2–) advanced breast cancer (BC) progressing on or after aromatase inhibitor (AI) therapy [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT2-01-04.

Abstract OT2-01-13: A phase 3, open-label, randomized, 2-arm international study of the oral dual PARP inhibitor talazoparib in germline BRCA mutation subjects with locally advanced and/or metastatic breast cancer (EMBRACA)

Background: Cancer cells with deleterious mutations in breast cancer susceptibility genes 1 and 2 (BRCA1/2) are deficient in the DNA double-strand break repair mechanism, rendering them highly dependent on the single-strand break repair pathway, regulated by poly(ADP-ribose) polymerase (PARP). Inhibition of PARP results in synthetic lethality in cells with a BRCA1/2 mutation because of accumulation of irreparable DNA damage; PARP inhibitors have the potential to be selectively toxic for BRCA-mutated cells. In addition to catalytic inhibition, it has been shown that some PARP inhibitors induce PARP trapping at sites of DNA damage. The capacity to trap PARP-DNA complexes varies widely across different PARP inhibitors and is not correlated with PARP catalytic inhibition. Preclinical models have shown trapping PARP on DNA is more potent at inducing cancer cell death than enzymatic inhibition of PARP alone. Talazoparib is a dual-mechanism PARP inhibitor that both inhibits the PARP enzyme and effectively traps PARP on DNA, preventing DNA damage repair and resulting in cell death in BRCA1/2-mutated cells. In preclinical studies, talazoparib at nanomolar concentrations showed the highest efficiency at trapping PARP-DNA complexes relative to other PARP inhibitors. In a previous phase 1/2 clinical study, talazoparib as monotherapy (1 mg once daily) resulted in a 50% response rate and an 86% clinical benefit rate at 24 weeks in 14 patients with a germline BRCA1/2 mutation and advanced breast cancer (aBC).

Methods: This open-label, randomized, 2-arm, international phase 3 trial (EMBRACA)

compares the efficacy and safety of talazoparib with protocol-specific physician's choice (capecitabine, eribulin, gemcitabine or vinorelbine) in patients with aBC. The primary objective is progression-free survival by central imaging. Secondary objectives are objective response rate, overall survival, safety and pharmacokinetics of talazoparib. Exploratory objectives include health-related quality of life measurements and biomarker research in blood and tumor samples that may permit characterization of mechanisms involved in tumor sensitivity and resistance to talazoparib. Key patient eligibility criteria include aged ≥18 years with histologically/cytologically confirmed breast cancer; locally advanced and/or metastatic disease appropriate for systemic single-agent cytotoxic chemotherapy; deleterious or pathogenic germline BRCA1/2 mutations by central laboratory; ≤3 prior cytotoxic chemotherapy regimens for advanced disease (prior platinum is allowed provided patients did not relapse within 6 months in the adjuvant setting or did not progress on platinum therapy); prior treatment with a taxane and/or anthracycline unless medically contraindicated; and ECOG performance status ≤2. Patients (N=429) will be randomized 2:1 to receive either talazoparib capsules (1 mg/day, 21-day cycles) or physician's choice treatment. This trial is currently enrolling patients from the USA, Europe, Israel, Ukraine, Russia, Korea, Australia, Taiwan and Brazil (NCT01945775).

This study is funded by Medivation, Inc.

Citation Format: Litton J, Ettl J, Hurvitz SA, Mina LA, Rugo HS, Lee K-H, Yerushalmi R, Woodward N, Goncalves A, Moreno F, Roche H, Im Y-H, Martin M, Bhattacharya S, Peterson A, Hannah A, Eiermann W, Blum J. A phase 3, open-label, randomized, 2-arm international study of the oral dual PARP inhibitor talazoparib in germline BRCA mutation subjects with locally advanced and/or metastatic breast cancer (EMBRACA) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT2-01-13.

Abstract P4-22-10: Evaluation of the effects of palbociclib (PAL) + letrozole (LET) on QTc

Background: PAL , an oral cyclin dependent kinase (CDK) 4/6 inhibitor, is under investigation in multiple oncologic clinical trials and is currently approved for use in multiple countries in patients with hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER2–) advanced breast cancer (ABC).

International Conference on Harmonization guidance recommends that all new drugs be evaluated for effects on cardiac repolarization in a well-controlled clinical study. For drugs for which such evaluation cannot be conducted in healthy volunteers (eg, most non-adjuvant anticancer agents), collection of robust corrected QT (QTc) interval data from a dedicated QTc study (hybrid thorough QT/QTc study) in patients [pts] is required in the registration dossier. The phase 3 PALOMA-2 study (N=666) confirmed the superior clinical benefit of PAL+LET vs placebo (P) + LET in postmenopausal women with estrogen receptor positive/HER2– ABC who have not received any prior systemic anticancer therapies for ABC. One of the secondary objectives of the study was to evaluate the effects of PAL+LET on QTc.

Methods: 12 lead (with a 10 second rhythm strip) tracings were performed in triplicate ∼2 min apart but within 10 min for all 3 ECGs. On the day preceding the initiation of treatment (Day 0), triplicate ECGs were obtained at time 0, 2, 4, 6, and 8 hrs (baseline). On Cycle 1 Day 14, when PAL concentrations were at steady-state, triplicate ECGs time-matched to baseline ECGs collected on Day 0 (±35 min) were obtained following PAL or P dosing. All ECGs were sent to a central laboratory for blinded manual adjudication and these data were used for analysis. ECG measurements included PR interval, QT interval, RR interval and QRS complex. The QT interval was corrected for the effect of heart rate using Fridericia's correction (QTcF), Bazett's correction (QTcB), and a study-specific correction factor (QTcS).

Approximately 60 pts were to be included for QTc evaluation to ensure 40 evaluable pts in the PAL+LET arm (2:1 randomization) of PALOMA-2 and thus, to establish noninferiority between post-baseline and baseline (ΔQTc) at all 5 QTc sampling timepoints on Cycle 1 Day 14 with 90% power. The test was based on a 1-sided difference in means t test for paired ΔQTc (α= 0.05). The difference in means between ΔQTc under the alternative hypothesis is 10 ms, assuming a noninferiority margin of 20 ms and the standard deviation of the paired differences equal to 16 ms based on PALOMA-1 study. If the upper bounds (UB) of 1-sided 95% confidence intervals (CI) of ΔQTc for all 5 QTc time points were &lt;20 ms, the post-baseline QTc will be considered noninferior to baseline and PAL+LET effect on QTc will be concluded to be not of clinical relevance.

Results: A total of 77 pts were enrolled for intensive QTc assessment in PAL+LET arm. No pts had a post-baseline absolute maximum QTcF, QTcS or QTcB ≥500 ms or a ΔQTc ≥60 ms during the intensive QTc assessment period. A random effect analysis of the mean ΔQTc data demonstrated that the UB of the 1-sided 95% CI for QTcF, QTcS, and QTcB were &lt;8 ms at all 5 QTc sampling time points.

Conclusion: PAL+LET does not have a clinically relevant effect on QTc.

Sponsor: Pfizer

Citation Format: Ruiz A, Gauthier E, Durairaj C, Huang X, Hoffman J, Finn RS, Moulder S, Joy AA, Ettl J, Rugo HS, Wang D. Evaluation of the effects of palbociclib (PAL) + letrozole (LET) on QTc [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-22-10.

Abstract OT1-04-04: A phase 2 randomized, double-blind, placebo-controlled trial of endocrine therapy ± radium-223 dichloride in HER2-negative, hormone receptor–positive breast cancer patients with bone metastases

Background: Bone-metastatic breast cancer (MBC) treatment is limited. In a phase 2a study of bone-dominant MBC patients, radium-223, a first-in-class α emitter with targeted cytotoxic effect on bone metastases (mets), reduced bone biomarker levels with favorable safety (Coleman et al. Breast Cancer Res Treat. 2014).

Trial design: This study evaluates efficacy and safety of radium-223 versus placebo (pbo), each + endocrine treatment (ET), in patients with HER2- estrogen receptor+ (ER+)bone-dominant MBC (NCT02258464). Patients receive (1:1) radium-223 50 kBq/kg IV or pbo q 4 wk (6 cycles) + ET + denosumab or bisphosphonates + best supportive care. Stratification is by geographic region (EU/N America vs Asia), number of prior ET lines (1 vs ≥ 2) for MBC, and number of prior skeletal-related events (SREs) (1 vs 2).

Eligibility criteria: Eligible patients are pre- or postmenopausal with HER2- ER+ bone-dominant MBC and ≥ 2 bone mets or with soft tissue and/or visceral mets, and 1-2 prior SREs (external beam radiotherapy, pathologic bone fracture, spinal cord compression, orthopedic surgery); they have received ≥ 1 line of ET for MBC and are considered appropriate for further ET. Patients must have evaluable disease (RECIST 1.1), be taking bisphosphonates or denosumab for ≥ 1 month before study treatment, have an ECOG score 0-1, and have adequate hematologic, renal, and liver function. Patients must not have had visceral or brain mets or leptomeningeal disease, or need chemotherapy for MBC, and must not be suitable for everolimus for MBC. Patients are not eligible if they had prior radium-223 treatment or have untreated spinal cord compression.

Specific aims: The primary end point is SSE-free survival (SSE-FS). Secondary end points are radiologic progression-free survival; overall survival; times to opioid use, pain progression, and cytotoxic chemotherapy; pain improvement rate; and safety. Patients are assessed for efficacy and safety and are followed to SSE, radiologic progression, death, or withdrawal.

Statistical methods: Assuming 1-sided α 0.1, power 90%, ∼ 119 SSE-FS events are needed for analysis. Time-to-event analysis will use a log-rank test, accounting for stratification. Kaplan-Meier estimates and survival curves will be given for each treatment group. Safety analyses will be descriptive.

Present and target accrual: Target accrual is ∼ 227. Currently, 40 patients are randomized.

Contact Oana Petrenciuc, Bayer HealthCare Pharmaceuticals, oana.petrenciuc@bayer.com, for more information.

Citation Format: Coleman RE, Fried G, Petrenciuc O, Sawhney A, Li R, Rugo HS. A phase 2 randomized, double-blind, placebo-controlled trial of endocrine therapy ± radium-223 dichloride in HER2-negative, hormone receptor–positive breast cancer patients with bone metastases [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT1-04-04.

Abstract P4-22-07: Long-term safety of palbociclib in combination with endocrine therapy in treatment-naive and previously treated women with HR+ HER2– advanced breast cancer: A pooled analysis from randomized phase 2 and 3 studies

Background: Palbociclib (PAL) is a selective and reversible oral cyclin-dependent kinase 4 and 6 inhibitor. Large randomized phase (ph) 2 and 3 trials showed significant improvement in progression-free survival (PFS) when PAL was combined with endocrine therapy (ET) vs ET alone in treatment (trt)-naive and previously treated hormone receptor?positive human epidermal growth factor receptor 2?negative (HR+ HER2–) advanced breast cancer (ABC) patients (pts). The median PFS with PAL+ET is &gt;2 years as a first-line therapy for ABC and 11.2 mo in endocrine-resistant ABC. We evaluated the long-term safety in PALOMA-1, -2, and -3.

Methods: We analyzed the tolerability of PAL in combination with ET in 3 randomized trials. Pts untreated for ABC were randomized to receive PAL+letrozole (LET) vs LET alone in PALOMA-1 (ph 2, open-label; 1:1) or randomized to receive PAL+LET vs placebo (PBO)+LET in PALOMA-2 (ph 3, double-blind; 2:1). PALOMA-3 included pts who progressed on prior ET, randomized to receive PAL+fulvestrant (FUL) or PBO+FUL (ph 3, double-blind; 2:1). Safety assessments, including a complete blood count, were done at baseline, on D1 of each cycle, and on D14 of the first 2 cycles. We evaluated adverse events (AEs) by 6-mo intervals (out to 36 mo) and cumulatively (12-, 24-, and 36-mo time points), and assessed latency (event onset) of pertinent adverse drug reactions (ADRs) in all pts treated in PALOMA-1, -2, and -3.

Results: A total of 1352 pts were pooled for this analysis; 872 pts received PAL+ET (527 pts, PAL+LET; 345 pts, PAL+FUL). Median duration of trt was 421 days in PALOMA-1 (January 2015), 603 days in PALOMA-2 (February 2016), and 330 days in PALOMA-3 (July 2015). PAL+LET was received by 119 pts as first-line trt in PALOMA-1 and 2 for 24–&lt;30 months and 11 pts were treated for &gt;36 mo. PAL+FUL was received by 140 pts for &gt;12 mo as second-line trt in PALOMA-3. The most commonly reported ADRs across all studies were neutropenia, fatigue, nausea, anemia, and leukopenia. The 6-mo-interval analyses of the most common (&gt;15%) AEs (by preferred term [PT]) from PALOMA-1, -2, and -3 indicated that these AEs were reported with the highest frequency during the first 6-mo interval and typically decreased in incidence over time to 30–&lt;36-mo; the most common hematologic AEs (clustered PTs) are shown (Table). The cumulative incidence of AEs after the first vs the second and third years showed similar frequencies of most AEs, including the most common ADRs.

Conclusions: Based on these long-term safety analyses, there is no evidence of specific cumulative or delayed toxicity resulting from prolonged trt with PAL+ET for HR+ HER2– ABC. This supports the ongoing investigation of PAL+ET in early breast cancer (NCT02513394).

Table. Pooled hematologic AEs: all grades and all causality clustered PTs reported for ≥10% of PAL+ET (LET/FUL)-treated ptsTime interval, mo0–&lt;66–&lt;1212–&lt;1818–&lt;2424–&lt;3030–&lt;36≥36Patients, N8726764912891192711TEAEs, %       Neutropenia75.758.649.349.842.937.054.5Leukopenia40.027.416.711.87.611.118.2Anemia20.812.710.011.19.211.118.2Thrombocytopenia15.18.76.15.55.914.836.4TEAEs=treatment-emergent adverse events.

Sponsor: Pfizer.

Citation Format: Diéras V, Rugo HS, Gelmon K, Finn RS, Cristofanilli M, Loi S, Colleoni M, Lu D, Gauthier E, Huang-Bartlett C, Turner NC, Schnell P. Long-term safety of palbociclib in combination with endocrine therapy in treatment-naive and previously treated women with HR+ HER2– advanced breast cancer: A pooled analysis from randomized phase 2 and 3 studies [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-22-07.