Gedatolisib in combination with palbociclib and endocrine therapy in women with hormone receptor-positive, HER2-negative advanced breast cancer: results from the dose expansion groups of an open-label, phase 1b study

BACKGROUND

The PI3K-mTOR pathway is frequently dysregulated in breast cancer. Combining an inhibitor targeting all class I PI3K isoforms and mTOR complex 1 (mTORC1)-mTOR complex 2 (mTORC2) with endocrine therapy and a CDK4/6 inhibitor might provide more effective tumour control than standard-of-care therapy. To evaluate this hypothesis, gedatolisib, a pan-PI3K-mTOR inhibitor, was assessed in a phase 1b trial combined with palbociclib and endocrine therapy in patients with hormone receptor-positive, HER2-negative, advanced breast cancer. Results from the dose expansion portion of this trial are reported herein.

METHODS

This multicentre, open-label, phase 1b study recruited female patients aged at least 18 years from 17 sites across the USA with hormone-receptor-positive, HER2-negative, advanced breast cancer and an Eastern Cooperative Oncology Group performance status of 0-1. Four patient groups were studied in the dose expansion portion of the study: treatment-naive in the advanced setting (first line; group A), progression on 1-2 lines of endocrine therapy but CDK4/6 inhibitor-naive (group B); and one or more previous lines (second-line and higher) of therapy, including a CDK4/6 inhibitor (groups C and D). Gedatolisib 180 mg was administered intravenously weekly in 28-day treatment cycles for groups A-C, and on days 1, 8, and 15 for group D. Letrozole (group A), fulvestrant (groups B-D), and palbociclib (all groups) were administered at standard doses and schedules. The primary endpoint was investigator-assessed objective response rate per RECIST version 1.1 in the evaluable analysis set. This trial is completed and registered with ClinicalTrials.gov, NCT02684032.

FINDINGS

Between Dec 19, 2017, and June 19, 2019, 103 female participants were enrolled in the dose expansion groups A (n=31), B (n=13), C (n=32), and D (n=27). Median follow-up was 16·6 months (IQR 5·7-48·4) for group A, 11·0 months (7·6-16·9) for group B, 3·6 months (1·8-7·5) for group C, and 9·4 months (5·3-16·7) for group D for the primary endpoint. Gedatolisib, palbociclib, and endocrine therapy induced an objective response in 23 (85·2%; 90% CI 69·2-94·8) of 27 evaluable first-line participants (group A). In the second-line and higher setting, an objective response was observed in eight (61·5%; 90% CI 35·5-83·4) of 13 evaluable group B participants, seven (25·0%; 12·4-41·9) of 28 evaluable group C participants, and 15 (55·6%; 38·2-72·0) of 27 evaluable group D participants; this included participants with both wild-type and mutated PIK3CA tumours. The most common grade 3-4 treatment-related adverse events were neutropenia (65 [63%] of 103), stomatitis (28 [27%]), and rash (21 [20%]). Grade 3-4 hyperglycaemia was reported in six (6%) participants. 23 (22%) of 103 participants had a treatment-related serious adverse event, and there were no treatment-related deaths. Nine (9%) participants discontinued treatment because of a treatment-emergent adverse event.

INTERPRETATION

Gedatolisib plus palbociclib and endocrine therapy showed a promising objective response rate compared with the published results for standard-of-care therapies and had an acceptable safety profile.

FUNDING

Pfizer and Celcuity.

Atezolizumab in Combination With Carboplatin and Survival Outcomes in Patients With Metastatic Triple-Negative Breast Cancer: The TBCRC 043 Phase 2 Randomized Clinical Trial

Importance

Agents targeting programmed death ligand 1 (PD-L1) have demonstrated efficacy in triple-negative breast cancer (TNBC) when combined with chemotherapy and are now the standard of care in patients with PD-L1-positive metastatic disease. In contrast to microtubule-targeting agents, the effect of combining platinum compounds with programmed cell death 1 (PD-1)/PD-L1 immunotherapy has not been extensively determined.

Objective

To evaluate the efficacy of atezolizumab with carboplatin in patients with metastatic TNBC.

Design, Setting, and Participants

This phase 2 randomized clinical trial was conducted in 6 centers from August 2017 to June 2021.

Interventions

Patients with metastatic TNBC were randomized to receive carboplatin area under the curve (AUC) 6 alone or with atezolizumab, 1200 mg, every 3 weeks until disease progression or unacceptable toxic effects with a 3-year duration of follow-up.

Main Outcome and Measures

The primary end point was investigator-assessed progression-free survival (PFS). Secondary end points included overall response rate (ORR), clinical benefit rate (CBR), and overall survival (OS). Other objectives included correlation of response with tumor PD-L1 levels, tumor-infiltrating lymphocytes (TILs), tumor DNA- and RNA-sequenced biomarkers, TNBC subtyping, and multiplex analyses of immune markers.

Results

All 106 patients with metastatic TNBC who were enrolled were female with a mean (range) age of 55 (27-79) years, of which 12 (19%) identified as African American/Black, 1 (1%) as Asian, 73 (69%) as White, and 11 (10%) as unknown. Patients were randomized and received either carboplatin (n = 50) or carboplatin and atezolizumab (n = 56). The combination improved PFS (hazard ratio [HR], 0.66; 95% CI, 0.44-1.01; P = .05) from a median of 2.2 to 4.1 months, increased ORR from 8.0% (95% CI, 3.2%-18.8%) to 30.4% (95% CI, 19.9%-43.3%), increased CBR at 6 months from 18.0% (95% CI, 9.8%-30.1%) to 37.5% (95% CI, 26.0%-50.6%), and improved OS (HR, 0.60; 95% CI, 0.37-0.96; P = .03) from a median of 8.6 to 12.6 months. Subgroup analysis showed PD-L1-positive tumors did not benefit more from adding atezolizumab (HR, 0.62; 95% CI, 0.23-1.65; P = .35). Patients with high TILs (HR, 0.12; 95% CI, 0.30-0.50), high mutation burden (HR, 0.50; 95% CI, 0.23-1.06), and prior chemotherapy (HR, 0.59; 95% CI, 0.36-0.95) received greater benefit on the combination. Patients with obesity and patients with more than 125 mg/dL on-treatment blood glucose levels were associated with better PFS (HR, 0.35; 95% CI, 0.10-1.80) on the combination. TNBC subtypes benefited from adding atezolizumab, except the luminal androgen receptor subtype.

Conclusions and Relevance

In this randomized clinical trial, the addition of atezolizumab to carboplatin significantly improved survival of patients with metastatic TNBC regardless of PD-L1 status. Further, lower risk of disease progression was associated with increased TILs, higher mutation burden, obesity, and uncontrolled blood glucose levels.

Trial Registration

ClinicalTrials.gov Identifier: NCT03206203.

Efficacy of a Dual-Epitope Dendritic Cell Vaccine as Part of Combined Immunotherapy for HER2-Expressing Breast Tumors

Previous work from our group and others has shown that patients with breast cancer can generate a T cell response against specific human epidermal growth factor 2 (HER2) epitopes. In addition, preclinical work has shown that this T cell response can be augmented by Ag-directed mAb therapy. This study evaluated the activity and safety of a combination of dendritic cell (DC) vaccination given with mAb and cytotoxic therapy. We performed a phase I/II study using autologous DCs pulsed with two different HER2 peptides given with trastuzumab and vinorelbine to a study cohort of patients with HER2-overexpressing and a second with HER2 nonoverexpressing metastatic breast cancer. Seventeen patients with HER2-overexpressing and seven with nonoverexpressing disease were treated. Treatment was well tolerated, with one patient removed from therapy because of toxicity and no deaths. Forty-six percent of patients had stable disease after therapy, with 4% achieving a partial response and no complete responses. Immune responses were generated in the majority of patients but did not correlate with clinical response. However, in one patient, who has survived >14 y since treatment in the trial, a robust immune response was demonstrated, with 25% of her T cells specific to one of the peptides in the vaccine at the peak of her response. These data suggest that autologous DC vaccination when given with anti-HER2-directed mAb therapy and vinorelbine is safe and can induce immune responses, including significant T cell clonal expansion, in a subset of patients.

Body mass index and patient-reported function, quality of life and treatment toxicity in women receiving adjuvant chemotherapy for breast cancer

BACKGROUND

This study investigates whether high body mass index (BMI) in women diagnosed with early breast cancer (BC) is associated with patient-reported symptom severity during chemotherapy.

METHODS

Women with Stage I-III BC completed toxicity reports for 17 side effects throughout regularly scheduled chemotherapy infusions. Toxicity reports were compared in women with obesity (BMI >  = 30) versus no obesity (BMI < 30). Fisher's exact tests and 2-sample t-tests compared baseline patient characteristics. Risk ratios (RR) for women with obesity as compared to no obesity were estimated for individual symptoms that were patient-rated as moderate, severe or very severe (MSVS) severity, adjusting for marital status and race.

RESULTS

In a sample of 286 patients, Black women comprised 23% of the sample. The obesity rate was 76% among Black patients and 31% among White patients (p < .0001). Women with obesity rated an average of 6.9 side effects (standard deviation, SD 4.2) as MSVS vs 5.5 side effects (SD 3.7) among women with no obesity (p = .003). In adjusted analysis, women with obesity had significantly greater risk for MSVS fatigue (RR 1.18, 95% CI 1.01-1.36), dyspnea (RR 1.71, 95% CI 1.09-2.69), arthralgia (RR 1.47, 95% CI 1.10-1.97), peripheral neuropathy (RR 1.45, 95% CI 1.01-2.08), edema of limbs (RR 1.84, 95% CI 1.18-2.88), and abdominal pain (RR 1.75, 95% CI 1.07-2.87). There were no inter-group differences in BC stage or phenotype, chemotherapy treatment modifications, or hospitalizations.

CONCLUSIONS

Among women with early BC, patients with obesity reported higher chemotherapy toxicity as compared to patients without obesity; however, this did not result in differences in treatment completion.

Abstract PD13-05: PD13-05 Updated results of a Phase 1b study of gedatolisib plus palbociclib and endocrine therapy in women with hormone receptor positive advanced breast cancer: Subgroup analysis by PIK3CA mutation status

Background: Addition of PI3K/mTOR inhibitor after progression on CDK4/6 inhibitor (CDK4/6i) and endocrine therapy (ET) can potentially restore sensitivity to CDK4/6i and prevent adaptive activation of the PI3K/mTOR pathway. To evaluate this hypothesis, we conducted a Phase Ib study of gedatolisib (G), a dual inhibitor of PI3K/mTOR, palbociclib (P) a CDK4/6i, and ET (with letrozole [LET] or fulvestrant [FUL]) in women with hormone receptor positive (HR+)/HER2- advanced breast cancer (ABC). Manageable toxicity and preliminary antitumor activity were observed in 35 patients(pts) enrolled in the dose escalation portion of the study (Forero-Torres, ASCO 2018) and 103 pts enrolled in the expansion portion of the study (Layman, SABCS 2021). Here, we report updated efficacy and safety data and sub-group analysis by PIK3CA mutation status in the four expansion study arms with a March 3, 2022, data cut-off.

Methods: Pts with HR+/HER2- ABC were treated in four expansion arms: A) G+P+LET as first-line treatment, B) G+P+FUL as 2nd line treatment in pts without prior CDK4/6i; C & D) G+P+FUL as 2nd or 3rd line therapy in pts with prior CDK4/6i. P, LET, and FUL were administered at standard doses. G 180 mg was intravenously administered weekly in Arms A, B, and C and three weeks on/one week off in Arm D. The primary endpoint was investigator assessed objective response rate (ORR). Secondary endpoints included safety, duration of response and progression free survival (PFS).

Results: Of the 103 pts treated with G+P+ ET in the expansion arms (A-D), 100% had measurable disease at baseline, 71% (73/103) lacked PIK3CA mutations (wild type; WT), 27% (28/103) had PIK3CA-mutations (MT), 70% (72/103) had evidence of bone metastases, and 59% (61/103) had liver metastases. The most frequent grade 3 and 4 treatment related AEs (TRAE) with G+P+ET included neutropenia (63%), stomatitis (27%), rash (20%), fatigue (11%) and hyperglycemia (7%). Treatment discontinuation due to TRAEs was 6.5% in Arm A, 15.4% in Arm B, 9.4% in Arm C and 3.7% in Arm D. Efficacy data for each arm is presented in Table 1. Promising ORR and PFS were seen in all arms regardless of PIK3CA mutation status. In Arm D, ORR was 63% overall, 73% in PIK3CA-MT pts, and 60% in PIK3CA-WT pts. Median PFS in Arm D was 12.9 months with a median follow up of 29 months. 60% and 48% of pts in the PIK3CA-MT and PIK3CA-WT Arm D sub-groups, respectively, were progression free at 12 months.

Conclusions: These preliminary data demonstrate promising activity of G+P+ET combination in pts who were CDK4/6i-naïve and in those whose disease progressed on or after CDK4/6i therapy regardless of PIK3CA mutation status. Encouraging results in CDK4/6i treatment naïve patients warrant further evaluation of gedatolisib in combination with CDK4/6i treatment in the front-line setting. Arm D results provide a strong basis for the initiated Phase 3 study (VIKTORIA-1) in pts whose disease progressed on or after CDK4/6i therapy.

Table 1. Efficacy Data by Expansion Arms

Citation Format: Robert Wesolowski, Hope Rugo, Erica Stringer-Reasor, Hyo S. Han, Jennifer M. Specht, E. Claire Dees, Peter Kabos, Ulka Vaishampayan, Seth A. Wander, Janice Lu, Keerthi Gogineni, Alexander I. Spira, Anne F. Schott, Maysa Abu-Khalaf, Pratima Nayak, Brian F. Sullivan, Igor Gorbatchevsky, AND Rachel M. Layman. PD13-05 Updated results of a Phase 1b study of gedatolisib plus palbociclib and endocrine therapy in women with hormone receptor positive advanced breast cancer: Subgroup analysis by PIK3CA mutation status [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD13-05.

A phase II single-arm trial of memantine for prevention of cognitive decline during chemotherapy in patients with early breast cancer: Feasibility, tolerability, acceptability, and preliminary effects

BACKGROUND

Cognitive difficulties have been described after chemotherapy for breast cancer, but there is no standard of care to improve cognitive outcomes in these patients. This trial examined the feasibility, tolerability, acceptability, and preliminary effects of memantine to prevent cognitive decline during chemotherapy for breast cancer.

METHODS

Patients with stage I-III breast cancer, scheduled for neo/adjuvant chemotherapy, completed a cognitive battery prior to and 4 weeks after completing chemotherapy. Memantine (10 mg BID) was administered concurrent with chemotherapy. Our primary cognitive outcome was visual working memory assessed by the Delayed Matching to Sample test. We used the Brief Medication Questionnaire to assess acceptability.

RESULTS

Of 126 patients approached, 56 (44%) enrolled. Forty-five (80%) received ≥1 dose of memantine and completed pre-post assessments. Seventy-six percent reported taking ≥90% of scheduled doses. Participants were mean age of 56, 77% White, and 57% had stage I disease. Sixty-four percent had stable or improved Delayed Matching to Sample test scores. Stable or improved cognition was observed in 87%-91% across objective cognitive domain composite measures. Sixty-six percent self-reported stable or improved cognitive symptoms. There were seven greater than or equal to grade 3 adverse events; two were possibly related to memantine. Only 5% reported that taking memantine was a disruption to their lives.

CONCLUSIONS

Memantine was well-tolerated and consistently taken by a large majority of patients receiving breast cancer chemotherapy. The majority demonstrated stable or improved cognition from pre- to post-assessment. Randomized trials are needed to determine memantine's efficacy to ameliorate cognitive loss.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04033419.

A randomized phase 2 study of neoadjuvant carboplatin and paclitaxel with or without atezolizumab in triple negative breast cancer (TNBC) - NCI 10013

Atezolizumab with chemotherapy has shown improved progression-free and overall survival in patients with metastatic PD-L1 positive triple negative breast cancer (TNBC). Atezolizumab with anthracycline- and taxane-based neoadjuvant chemotherapy has also shown increased pathological complete response (pCR) rates in early TNBC. This trial evaluated neoadjuvant carboplatin and paclitaxel with or without atezolizumab in patients with clinical stages II-III TNBC. The co-primary objectives were to evaluate if chemotherapy and atezolizumab increase pCR rate and tumor infiltrating lymphocyte (TIL) percentage compared to chemotherapy alone in the mITT population. Sixty-seven patients (ages 25-78 years; median, 52 years) were randomly assigned - 22 patients to Arm A, and 45 to Arm B. Median follow up was 6.6 months. In the modified intent to treat population (all patients evaluable for the primary endpoints who received at least one dose of combination therapy), the pCR rate was 18.8% (95% CI 4.0-45.6%) in Arm A, and 55.6% (95% CI 40.0-70.4%) in Arm B (estimated treatment difference: 36.8%, 95% CI 8.5-56.6%; p = 0.018). Grade 3 or higher treatment-related adverse events occurred in 62.5% of patients in Arm A, and 57.8% of patients in Arm B. One patient in Arm B died from recurrent disease during the follow-up period. TIL percentage increased slightly from baseline to cycle 1 in both Arm A (mean ± SD: 0.6% ± 21.0%) and Arm B (5.7% ± 15.8%) (p = 0.36). Patients with pCR had higher median TIL percentages (24.8%) than those with non-pCR (14.2%) (p = 0.02). Although subgroup analyses were limited by the small sample size, PD-L1-positive patients treated with chemotherapy and atezolizumab had a pCR rate of 75% (12/16). The addition of atezolizumab to neoadjuvant carboplatin and paclitaxel resulted in a statistically significant and clinically relevant increased pCR rate in patients with clinical stages II and III TNBC. (Funded by National Cancer Institute).

A biomarker of aging, p16, predicts peripheral neuropathy in women receiving adjuvant taxanes for breast cancer

Identifying patients at higher risk of chemotherapy-induced peripheral neuropathy (CIPN) is a major unmet need given its high incidence, persistence, and detrimental effect on quality of life. We determined if the expression of p16, a biomarker of aging and cellular senescence, predicts CIPN in a prospective, multi-center study of 152 participants enrolled between 2014 and 2018. Any women with newly diagnosed Stage I–III breast cancer scheduled to receive taxane-containing chemotherapy was eligible. The primary outcome was development of grade 2 or higher CIPN during chemotherapy graded by the clinician before each chemotherapy cycle (NCI-CTCAE v5 criteria). We measured p16 expression in peripheral blood T cells by qPCR before and at the end of chemotherapy. A multivariate model identified risk factors for CIPN and included taxane regimen type, p16Age Gap, a measure of discordance between chronological age and p16 expression, and p16 expression before chemotherapy. Participants with higher p16Age Gap—higher chronological age but lower p16 expression prior to chemotherapy - were at the highest risk. In addition, higher levels of p16 before treatment, regardless of patient age, conferred an increased risk of CIPN. Incidence of CIPN positively correlated with chemotherapy-induced increase in p16 expression, with the largest increase seen in participants with the lowest p16 expression before treatment. We have shown that p16 expression levels before treatment can identify patients at high risk for taxane-induced CIPN. If confirmed, p16 might help guide chemotherapy selection in early breast cancer.

Clinical subtype, treatment response, and survival in De Novo and recurrent metastatic breast cancer

PURPOSE

This study evaluated whether patients with de novo metastatic breast cancer (MBC) have superior outcomes compared to those with recurrent MBC in a contemporary treatment era and examined factors related to outcome differentials.

METHODS

Using an institutional database, we examined patient and tumor characteristics, treatment response, and outcome among 232 patients with de novo and 612 patients with recurrent MBC diagnosed between 2011 and 2017.

RESULTS

De novo MBC had 9-month (m) longer overall survival (OS) than recurrent MBC (36.4 vs 27.4 m, p < 0.001). Contributions to this difference included nearly twofold more HER2-positive (29.3% vs 15.2%) and significantly fewer triple-negative breast cancers (20.3% vs 32.4%, both p < 0.001) in de novo compared with recurrent MBC cohorts. Stratified by clinical subtype, progression-free survival (PFS) on first-line therapy was significantly longer in de novo MBC in all but the triple-negative subtype, 25.5 vs 11.6 m (p < 0.001) among 390 patients with hormone receptor-positive, HER2-negative, 11.4 vs 5.4 m (p = 0.002) among 142 patients with HER2-positive, and 4.0 vs 3.0 m (p = 0.121) among 162 with triple-negative MBC. In multivariable analysis, de novo status remained independently associated with improved OS (hazard ratio 0.63, 95% CI 0.49-0.80), regardless of subtype and other features.

CONCLUSION

Patients with de novo MBC have better outcomes than those with recurrent MBC. Differences in clinical subtype and response to therapy in the metastatic setting contribute to, but do not fully explain, this difference. Longer PFS to first-line therapy in de novo MBC suggests biologic differences compared to recurrent MBC, which may be intrinsic or due to acquired resistance from treatment for prior localized breast cancer in recurrent disease.

Abstract CT524: A phase 1, first in human (FIH) study of autologous anti-HER2 chimeric antigen receptor macrophages (CAR-M) in HER2-overexpressing solid tumors (ST)

Background: Adoptive T cell therapies have led to remarkable advances in hematologic cancers but with less effect in ST. Actively recruited tumor associated macrophages (TAM) are abundant in the ST microenvironment (TME) and typically display immunosuppressive behavior. Macrophages engineered to be proinflammatory may be an ideal vector for adoptive ST cellular therapy. Engineered CAR-M selectively recognize and phagocytose antigen overexpressing cancer cells, reprogram TME and present neoantigens to T cells, leading to epitope spreading and immune memory. Human Epidermal Growth Factor Receptor 2 (HER2) overexpression promotes tumorigenesis in many cancers (Table 1). CT-0508 is a cell product comprised of autologous monocyte-derived proinflammatory macrophages expressing an anti-HER2 CAR. Pre-clinical studies show that CT-0508 induces targeted cancer cell phagocytosis while sparing normal cells, decreases tumor burden and prolongs survival, and was safe and effective in a semi-immunocompetent mouse model of human HER2-overexpressing ovarian cancer.

Methods: This FIH Phase 1 study is evaluating safety, tolerability, cell manufacturing feasibility, trafficking, and preliminary efficacy in 18 subjects with locally advanced/unresectable or metastatic ST overexpressing HER2, with progression on available therapies, including anti-HER2 therapies. Filgrastim is used to mobilize autologous hematopoietic progenitor cells for monocyte collection by apheresis prior to CT-0508 CAR macrophage infusion. Group 1 subjects receive CT-0508 on D1, 3, & 5. Group 2 subjects will receive full dose on D1. A Safety Review Committee will review dose limiting toxicities. Pre/post-treatment biopsies and blood samples will be collected for correlative analysis of immunogenicity, trafficking (PCR, RNA scope), CT-0508 persistence in blood and tumor, target antigen engagement, TME modulation (single cell RNA sequencing), immune response (TCR sequencing) and others.

Table 1. Her2 Overexpression Across Tumor Types Tumor HER2 Overexpression (%) Bladder 8–70 Salivary duct 30–40 Gastric 7–34 Ovarian 26 Breast 11–25 Salivary mucoepidermoid 17.6 Esophageal 12–14 Gallbladder 9.8–12.8 Cholangiocarcinoma 6.3–9 Colorectal 1.6–5 Cervical 2.8–3.9 Uterine 3 Testicular 2.4

Citation Format: Kim A. Reiss, Yuan Yuan, Naoto T. Ueno, Yara Abdou, Debora Barton, Ramona F. Swaby, Amy Ronczka, Daniel J. Cushing, Sascha Abramson, Thomas Condamine, Michael Klichinsky, E. Claire Dees. A phase 1, first in human (FIH) study of autologous anti-HER2 chimeric antigen receptor macrophages (CAR-M) in HER2-overexpressing solid tumors (ST) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT524.

Abemaciclib in Combination With Endocrine Therapy for Patients With Hormone Receptor-Positive, HER2-Negative Metastatic Breast Cancer: A Phase 1b Study

Background

Cyclin-dependent kinases (CDK) 4 and 6 regulate G1 to S cell cycle progression and are often altered in cancers. Abemaciclib is a selective inhibitor of CDK4 and CDK6 approved for administration on a continuous dosing schedule as monotherapy or as combination therapy with an aromatase inhibitor or fulvestrant in patients with advanced or metastatic breast cancer. This Phase 1b study evaluated the safety and tolerability, pharmacokinetics, and antitumor activity of abemaciclib in combination with endocrine therapy for metastatic breast cancer (MBC), including aromatase inhibitors (letrozole, anastrozole, or exemestane) or tamoxifen.

Patients and Methods

Women ≥18 years old with hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER2-) MBC were eligible for enrollment. Eligibility included measurable disease or non-measurable but evaluable bone disease by Response Evaluation Criteria in Solid Tumours (RECIST) v1.1, Eastern Cooperative Oncology Group performance status 0–1, and no prior chemotherapy for metastatic disease. Adverse events were graded by the National Cancer Institute Common Terminology Criteria for Adverse Events v4.0 and tumor response were assessed by RECIST v1.1.

Results

Sixty-seven patients were enrolled and received abemaciclib 200 mg every 12 hours in combination with letrozole (Part A, n=20), anastrozole (Part B, n=16), tamoxifen (Part C, n=16), or exemestane (Part D, n=15). The most common treatment-emergent adverse events (TEAE) were diarrhea, fatigue, nausea, and abdominal pain. Grade 4 TEAEs were reported in five patients (one each with hyperglycemia, hypertension, neutropenia, procedural hemorrhage, and sepsis). There was no effect of abemaciclib or endocrine therapy on the pharmacokinetics of any combination study drug. Across all treated patients, the median progression-free survival was 25.4 months (95% confidence interval: 18.0, 35.8). The objective response rate was 38.9% in 36 patients with measurable disease.

Conclusions

Abemaciclib in combination with multiple endocrine therapy options exhibited manageable safety and promising antitumor activity in patients with HR+, HER2- MBC.

Clinical Trial Registration

https://clinicaltrials.gov/, identifier NCT02057133

Evaluating the efficacy of a priming dose of cyclophosphamide prior to pembrolizumab to treat metastatic triple negative breast cancer

PURPOSE

Triple negative breast cancer (TNBC) is characterized by the presence of immune cells in the tumor microenvironment, however, the response to single-agent immune checkpoint inhibitor (ICI) therapy is modest. Preclinical models have demonstrated that intratumoral regulatory T cells (T_regs) dampen the antitumor response to ICI. We performed a single-arm phase II trial to evaluate the efficacy of a single low dose of cyclophosphamide (Cy) to deplete T_regs administered before initiating pembrolizumab.

PATIENTS AND METHODS

40 patients with pretreated metastatic TNBC were enrolled. The primary endpoints were progression-free survival (PFS) and change in peripheral blood T_regs after Cy. Secondary endpoints included overall response rate (ORR), duration of response, overall survival, treatment-related adverse events (AEs), and correlative evaluations.

RESULTS

Median PFS was 1.8 months, and the ORR was 21%. T_regs were not significantly decreased after Cy prior to ICI (-3.3%, p=0.19), and increased significantly after the first cycle of therapy (+21% between cycles 1 and 2, p=0.005). Immune-related AEs were similar to historical pembrolizumab monotherapy, and were associated with response to therapy (p=0.02). Patients with pretreatment tumors harboring increased expression of B cell metagene signatures and increased circulating B cell receptor repertoire diversity were associated with clinical response and immune-related toxicity (IRT).

CONCLUSIONS

Among patients with heavily pretreated TNBC, Cy prior to pembrolizumab did not significantly deplete T_regs, and in those with decreased numbers there was rapid recovery following therapy. Increased B cell gene expression in baseline samples was associated with clinical response and IRT.

Patient-reported treatment toxicity and adverse events in Black and White women receiving chemotherapy for early breast cancer

PURPOSE

It is not known whether chemotherapy-related symptom experiences differ between Black and White women with early breast cancer (Stage I-III) receiving current chemotherapy regimens and, in turn, influences dose delay, dose reduction, early treatment discontinuation, or hospitalization.

METHODS

Patients self-reported their race and provided symptom reports for 17 major side effects throughout chemotherapy. Toxicity and adverse events were analyzed separately for anthracycline and non-anthracycline regimens. Fisher's exact tests and two-sample t-tests compared baseline patient characteristics. Modified Poisson regression estimated relative risks of moderate, severe, or very severe (MSVS) symptom severity, and chemotherapy-related adverse events.Please check and confirm that the authors and their respective affiliations have been correctly identified and amend if necessary.no changes RESULTS: In 294 patients accrued between 2014 and 2020, mean age was 58 (SD13) and 23% were Black. For anthracycline-based regimens, the only significant difference in MSVS symptoms was in lymphedema (41% Black vs 20% White, p = .04) after controlling for axillary surgery. For non-anthracycline regimens, the only significant difference was MSVS peripheral neuropathy (41% Blacks vs. 23% White) after controlling for taxane type (p = .05) and diabetes (p = .05). For all other symptoms, severity scores were similar. Dose reduction differed significantly for non-anthracycline regimens (49% Black vs. 25% White, p = .01), but not for anthracycline regimens or in dose delay, early treatment discontinuation, or hospitalization for either regimen.

CONCLUSION

Except for lymphedema and peripheral neuropathy, Black and White patients reported similar symptom severity during adjuvant chemotherapy. Dose reductions in Black patients were more common for non-anthracycline regimens. In this sample, there were minimal differences in patient-reported symptoms and other adverse outcomes in Black versus White patients.

Abstract PS12-04: Rintodestrant (G1T48), an oral selective estrogen receptor degrader in ER+/HER2- locally advanced or metastatic breast cancer: Updated phase 1 results and dose selection

Background: Rintodestrant (G1T48) is a potent oral selective estrogen receptor degrader (SERD) that competitively binds to the estrogen receptor (ER) and blocks ER signaling in tumors resistant to other endocrine therapies. Preliminary results from Part 1 dose escalation showed robust target engagement on 18F-fluoroestradiol positron emission tomography (FES-PET), a favorable safety profile, and encouraging antitumor activity in patients with heavily pretreated ER+/HER2- advanced breast cancer (ABC), including those with ESR1 mutations (Dees et al., ESMO 2019 [abstract #3587]). Here, we present updated results from dose escalation and expansion (Parts 1 and 2). Methods: This Phase 1, first-in-human, open-label study evaluated rintodestrant monotherapy in women with ER+/HER2- ABC after progression on endocrine therapy. Part 1 was a 3+3 dose escalation (200-1000 mg once daily [QD]); Part 2 expanded 600 and 1000 mg QD; and Part 3 was added to assess rintodestrant with palbociclib in patients in earlier lines in the advanced setting. Primary objectives included dose-limiting toxicities (DLTs), maximum tolerated dose (MTD), safety, and recommended Phase 2 dose. Secondary objectives included pharmacokinetics and antitumor activity (RECIST v1.1). Exploratory objectives included pharmacodynamic inhibition of ER target engagement (FES-PET), mutation profiling (cell-free DNA [cfDNA]), and change in ER expression from baseline to on-treatment tumor biopsies. Results: As of May 13, 2020, 67 patients (Part 1: n = 26; Part 2: n = 41) were treated, with a median age of 61 years (range 34-83) and ECOG PS of 0 (49%) or 1 (51%). Median number of prior lines in the advanced setting was 2 (range 0-9), including prior fulvestrant (64%), CDK4/6 inhibitor (69%), mTOR inhibitor (22%), and/or chemotherapy (46%). Median number of prior lines of endocrine therapy in the advanced setting was 2 (range 0-5), with 61% of patients having received ≥2 lines. Treatment-related adverse events (TRAEs) were reported in 70% of patients. The most common TRAEs in ≥10% of patients included hot flush (24%), fatigue (21%), nausea (19%), diarrhea (18%), and vomiting (10%), mostly grade 1 or 2. No DLTs were reported and MTD was not reached. Dose reduction due to TRAEs occurred in 1 patient (1%), with elevated transaminases (grade 3 ALT and grade 2 AST) at 600 mg. Serious TRAEs occurred in 2 patients at 1000 mg (grade 5 cerebral hemorrhage in the setting of low molecular weight heparin and grade 2 upper abdominal pain). Two patients (3%) discontinued treatment due to TRAEs. Overall, the frequency of patients with TRAEs at 800 mg was comparable with that at 600 mg (57% vs 63%) and less than that at 1000 mg (81%). Of 67 patients, 16 were on study treatment for ≥24 weeks and 3 (n = 1 at 600 mg; n = 2 at 1000 mg, including 1 with ESR1 mutation) had a confirmed partial response (clinical benefit rate [CBR]: 28%). FES-PET standard uptake values decreased at week 4 with a mean reduction of 87% (±8%) at doses ≥ 600 mg. Of 59 patients tested for baseline cfDNA, 41% harbored ≥1 ESR1 mutation, with a similar CBR in both groups (33% in ESR1 mutant and 29% in ESR1 wild-type). Seven of 9 patients had a decrease in ER immunohistochemistry H-score at both 600 and 1000 mg (median [range]: -27.8% [-33.8%, -3.4%]), irrespective of ESR1 mutation status. Based on safety, efficacy, and ER degradation, 800 mg was selected as the optimal dose for further study. Conclusions: Rintodestrant continues to demonstrate an excellent safety/tolerability profile across all doses, with promising antitumor activity in patients with heavily pretreated ER+/HER2- ABC, including those with tumors harboring ESR1 mutations. Part 3 of this study, evaluating rintodestrant 800 mg QD with palbociclib in a more endocrine-sensitive population, is ongoing (NCT03455270).

Citation Format: Philippe Aftimos, Patrick Neven, Mark Pegram, Catharina Willemien Menke-van der Houven van Oordt, E. Claire Dees, Carolien Schröder, Agnes Jager, Iurie Bulat, Linnea Chap, Marina Maglakelidze, Erika Hamilton, Massimo Cristofanilli, Susanna Ulahannan, Jorianne Boers, Ramsha Iqbal, Adrian Crijanovschi, Curt D Wolfgang, Wenli Tao, Christina Sipes, Rajesh Malik, Sarika Jain. Rintodestrant (G1T48), an oral selective estrogen receptor degrader in ER+/HER2- locally advanced or metastatic breast cancer: Updated phase 1 results and dose selection [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 PS12-04.

Abstract PD8-07: Pharmacodynamic analysis from a phase 1 study of rintodestrant (G1T48), an oral selective estrogen receptor degrader, in ER+/HER2- locally advanced or metastatic breast cancer

Background: Rintodestrant is an orally bioavailable, potent and selective estrogen receptor degrader (SERD) that inhibits estrogen receptor (ER) gene transcription, degrades the ER, and delays tumor proliferation in preclinical models. Preliminary results from Part 1 dose escalation (200-1000 mg once daily) demonstrated that rintodestrant has a favorable safety profile and encouraging antitumor activity in patients (pts) with heavily pretreated ER+/HER2- advanced breast cancer (ABC) (Dees et al., ESMO 2019 [abstract #3587]). Here, we report the pharmacodynamic (PD) analysis in peripheral blood and tumor biopsies from pts who received rintodestrant in Part 1 and 2 (600 and 1000 mg dose expansion) to characterize the pt population and mechanisms of response. Methods: This Phase 1, first-in-human, open-label study evaluated rintodestrant in women with ER+/HER- ABC after progression on endocrine therapy. PD analysis included inhibition of ER target engagement with 18F-fluoroestradiol positron emission tomography (FES-PET), mutational profiling (cell-free DNA [cfDNA]), and circulating tumor cell (CTC) enumeration. Tumor biopsies sampled at baseline and 6 weeks on treatment were evaluated for ER degradation (immunohistochemistry [IHC]) and proliferation (Ki67, IHC) to understand the on-target effects of rintodestrant. Results: As of May 13, 2020, 67 pts had been treated. FES-PET data were obtained in 14 pts and showed a decrease in all pts, with maximum standard uptake values (SUVmax) ranging from 70% to 98% after 4 weeks of rintodestrant monotherapy across all doses. Fifty-nine pts were tested for cfDNA at baseline; 95% (n = 56) harbored ≥1 somatic variant (median = 3 mutations per pt). Among pts with somatic variants, 41% had ESR1 mutations, with D538G being the most common (58%). Additionally, 46% and 42% of pts harbored mutations in TP53 and PIK3CA, respectively, and 10% had mutations in both ESR1 and PIK3CA. Similar clinical benefit rates were observed in wild-type vs ESR1 and/or PIK3CA mutant tumors. An analysis of change of variant allele fraction (VAF) in 55 pts between baseline and 2 weeks of treatment revealed that 58% had a decrease in mean VAF, with a decrease in ESR1 VAF in 16/20 pts that had ESR1 mutations at baseline. Furthermore, of 24 pts who had samples collected at baseline and progression, 16 (67%) developed additional variants (median [range]: 2 [1, 15]), including EGFR, ERBB2, TP53, and ESR1. CTC analysis (n = 45) showed the mean value of Epi+CD45- CTCs decreased from 2.8 cells/mL to 1.8 cells/mL after 8 weeks of treatment. Tumor biopsies were collected in 9 pts (5 received 600 mg and 4 received 1000 mg) at baseline and 6 weeks on treatment. Of the 7/9 pts that had a decrease in the ER H-score (median [range]: -27.8% [-33.8%, -3.4%]), 4 had ≥1 variant in ESR1 at baseline. Overall, 4 pts had a decrease in Ki67, with reductions mostly observed in pts who received 600 mg rintodestrant. Additional analyses, including correlations with clinical response, are ongoing and will be presented. Conclusions: Rintodestrant demonstrated robust ER target engagement on FES-PET, as well as substantial decreases in ER H-score, cfDNA VAF, and Epi+CD45- CTCs. These data, along with promising clinical benefit in pts with heavily pretreated ER+/HER2- ABC, regardless of ESR1 or PIK3CA mutation status, warrant additional investigation of rintodestrant (NCT03455270).

Citation Format: Philippe Aftimos, Marina Maglakelidze, Andor WJM Glaudemans, Erika Hamilton, Linnea Chap, Elisabeth de Vries, Catharina Willemien Menke-van der Houven van Oordt, Agnes Jager, E. Claire Dees, Massimo Cristofanilli, Mark Pegram, Susanna Ulahannan, Patrick Neven, Iurie Bulat, Ruhi Rai, Wenli Tao, Sarika Jain, Andrew P Beelen, Jessica A Sorrentino. Pharmacodynamic analysis from a phase 1 study of rintodestrant (G1T48), an oral selective estrogen receptor degrader, in ER+/HER2- locally advanced or metastatic breast cancer [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 PD8-07.

Modernizing Clinical Trial Eligibility Criteria: Recommendations of the ASCO-Friends of Cancer Research Washout Period and Concomitant Medication Work Group

PURPOSE

Washout periods and concomitant medication exclusions are common in cancer clinical trial protocols. These exclusion criteria are often applied inconsistently and without evidence to justify their use. The authors sought to determine how washout period and concomitant medication allowances can be broadened to speed trial enrollment and improve the generalizability of trial data to a larger oncology practice population without compromising the safety of trial participants.

EXPERIMENTAL DESIGN

A multistakeholder working group was convened to define problems associated with excessively long washout periods and exclusion of patients due to concomitant medications. The group performed a literature search and evaluated study data from the Pancreatic Cancer Action Network (PanCAN), Emory University School of Medicine (Atlanta, GA), and the FDA to understand recent approaches to these eligibility criteria. The group convened to develop consensus recommendations for broadened eligibility criteria.

RESULTS

The data analysis found that exclusion criteria based on washout periods and concomitant medications are frequently inconsistent and lack scientific rationale. Scientific rationale for appropriate eligibility criteria are presented in the article; for washout periods, rationale is presented by treatment type.

CONCLUSIONS

Arbitrary or blanket washout and concomitant medication exclusions should be eliminated. Where there is evidence to support them, clinically relevant washout periods and concomitant medication-related eligibility criteria may be included.See related commentary by Giantonio, p. 2369.

Effects of Breast Cancer Adjuvant Chemotherapy Regimens on Expression of the Aging Biomarker, p16INK4a

BACKGROUND

Although chemotherapy saves lives, increasing evidence shows that chemotherapy accelerates aging. We previously demonstrated that mRNA expression of p16INK4a , a biomarker of senescence and molecular aging, increased early and dramatically after beginning adjuvant anthracycline-based regimens in early stage breast cancer patients. Here, we determined if changes in p16INK4a expression vary by chemotherapy regimen among early stage breast cancer patients.

METHODS

We conducted a study of stage I-III breast cancer patients receiving adjuvant or neoadjuvant chemotherapy. p16INK4a expression was analyzed prechemotherapy and postchemotherapy (median 6.2 months after the last chemotherapy) in peripheral blood T lymphocytes. Chemotherapy-induced change in p16INK4a expression was compared among regimens. All statistical tests were 2-sided.

RESULTS

In 146 women, chemotherapy was associated with a statistically significant increase in p16INK4a expression (accelerated aging of 17 years; P < .001). Anthracycline-based regimens were associated with the largest increases (accelerated aging of 23 to 26 years; P ≤ .008). Nonanthracycline-based regimens demonstrated a much smaller increase (accelerated aging of 9 to 11 years; P ≤ .15). In addition to the type of chemotherapy regimen, baseline p16INK4a levels, but not chronologic age or race, were also associated with the magnitude of increases in p16INK4a . Patients with lower p16INK4a levels at baseline were more likely to experience larger increases.

CONCLUSIONS

Our findings suggest that the aging effects of chemotherapy may be influenced by both chemotherapy type and the patient's baseline p16INK4a level. Measurement of p16INK4a expression is not currently available in the clinic, but nonanthracycline regimens offering similar efficacy as anthracycline regimens might be favored.

Patient-reported symptom severity, interference with daily activities, and adverse events in older and younger women receiving chemotherapy for early breast cancer

BACKGROUND

To the authors' knowledge, it is unknown whether patient-reported symptom severity and symptom interference with daily activities differ between younger (aged <65 years) and older (aged ≥65 years) women receiving similar chemotherapy regimens for early breast cancer (EBC).

METHODS

Study participants rated 17 side effects of chemotherapy regimens currently in use in clinical practice (2014-2019).

RESULTS

Of 284 women with EBC (stage I-III), approximately 57% were aged <65 years and 43% were aged ≥65 years. For anthracycline-based regimens, a higher percentage of younger women reported moderate, severe, or very severe (MSVS) hot flashes (49% vs 18%) (P < .001). For nonanthracycline regimens, a higher percentage of younger women reported MSVS hot flashes (38% vs 19%) (P = .009) and a lower percentage reported MSVS arthralgia (28% vs 49%) (P = .005). With regard to symptom interference with daily activities, a higher percentage of younger women being treated with anthracycline-based regimens reported MSVS hot flashes (32% vs 7%) (P = .001) and myalgia (38% vs 18%) (P = .02). For nonanthracycline chemotherapy, a higher percentage of younger women reported MSVS interference for hot flashes (26% vs 9%) (P = .006) and lower percentages reported abdominal pain (13% vs 28%) (P = .02). Overall, there were no significant differences noted among younger versus older patients with regard to hospitalizations (19% vs 12%; P = .19), dose reductions (34% vs 31%; P = .50), dose delays (22% vs 25%; P = .59), or early treatment discontinuation (16% vs 16%; P = .9546).

CONCLUSIONS

Older and younger women with EBC who were treated with identical chemotherapy regimens generally experienced similar levels of symptom severity, symptom-related interference with daily activities, and adverse events.

LAY SUMMARY

In this study, women receiving chemotherapy for early breast cancer rated the severity of 17 symptoms and symptom interference with their activities of daily living. Older (aged ≥65 years) and younger (aged <65 years) women who received identical chemotherapy regimens generally experienced similar levels of symptom severity, symptom-related interference with daily activities, and adverse events.

Clinical evaluation of germline polymorphisms associated with capecitabine toxicity in breast cancer: TBCRC-015

PURPOSE

Capecitabine is important in breast cancer treatment but causes diarrhea and hand-foot syndrome (HFS), affecting adherence and quality of life. We sought to identify pharmacogenomic predictors of capecitabine toxicity using a novel monitoring tool.

METHODS

Patients with metastatic breast cancer were prospectively treated with capecitabine (2000 mg/m²/day, 14 days on/7 off). Patients completed in-person toxicity questionnaires (day 1/cycle) and automated phone-in assessments (days 8, 15). Correlation of genotypes with early and overall toxicity was the primary endpoint.

RESULTS

Two hundred and fifty-nine patients were enrolled (14 institutions). Diarrhea and HFS occurred in 52% (17% grade 3) and 69% (9% grade 3), respectively. Only 29% of patients completed four cycles without dose reduction/interruption. In 39%, the highest toxicity grade was captured via phone. Three single nucleotide polymorphisms (SNPs) associated with diarrhea-DPYD*5 (odds ratio [OR] 4.9; P = 0.0005), a MTHFR missense SNP (OR 3.3; P = 0.02), and a SNP upstream of MTRR (OR 3.0; P = 0.03). GWAS elucidated a novel HFS SNP (OR 3.0; P = 0.0007) near TNFSF4 (OX40L), a gene implicated in autoimmunity including autoimmune skin diseases never before implicated in HFS. Genotype-gene expression analyses of skin tissues identified rs11158568 (associated with HFS via GWAS) with expression of CHURC1, a transcriptional activator controlling fibroblast growth factor (beta = - 0.74; P = 1.46 × 10^-23), representing a previously unidentified mechanism for HFS.

CONCLUSIONS

This is the first cancer pharmacogenomic study to use phone-in self-reporting, permitting augmented toxicity characterization. Three germline toxicity SNPs were replicated, and several novel SNPs/genes having strong functional relevance were discovered. If further validated, these markers could permit personalized capecitabine dosing.

Patient-Reported Cognitive Impairment Among Women With Early Breast Cancer Randomly Assigned to Endocrine Therapy Alone Versus Chemoendocrine Therapy: Results From TAILORx

PURPOSE

Cancer-related cognitive impairment (CRCI) is common during adjuvant chemotherapy and may persist. TAILORx provided a novel opportunity to prospectively assess patient-reported cognitive impairment among women with early breast cancer who were randomly assigned to chemoendocrine therapy (CT+E) versus endocrine therapy alone (E), allowing us to quantify the unique contribution of chemotherapy to CRCI.

METHODS

Women with a 21-gene recurrence score of 11 to 25 enrolled in TAILORX were randomly assigned to CT+E or E. Cognitive impairment was assessed among a subgroup of 552 evaluable women using the 37-item Functional Assessment of Cancer Therapy-Cognitive Function (FACT-Cog) questionnaire, administered at baseline, 3, 6, 12, 24, and 36 months. The FACT-Cog included the 20-item Perceived Cognitive Impairment (PCI) scale, our primary end point. Clinically meaningful changes were defined a priori and linear regression was used to model PCI scores on baseline PCI, treatment, and other factors.

RESULTS

FACT-Cog PCI scores were significantly lower, indicating more impairment, at 3, 6, 12, 24, and 36 months compared with baseline for both groups. The magnitude of PCI change scores was greater for CT+E than E at 3 months, the prespecified primary trial end point, and at 6 months, but not at 12, 24, and 36 months. Tests of an interaction between menopausal status and treatment were nonsignificant.

CONCLUSION

Adjuvant CT+E is associated with significantly greater CRCI compared with E at 3 and 6 months. These differences abated over time, with no significant differences observed at 12 months and beyond. These findings indicate that chemotherapy produces early, but not sustained, cognitive impairment relative to E, providing reassurance to patients and clinicians in whom adjuvant chemotherapy is indicated to reduce recurrence risk.

Abstract P1-17-03: Statin use, site of recurrence, and survival among post-menopausal women taking bisphosphonates as adjuvant therapy for breast cancer (SWOG S0307)

Purpose: Statins may mediate suppression of molecular pathways conferring benefit in cancer. Statins have shown anti-tumor effects in preclinical studies and have been associated with decreased recurrence and improved disease-specific survival. While designed to target cholesterol biosynthesis, statins can also have liver, bone and brain effects. We collected data on statin use in the S0307 adjuvant bisphosphonate trial to test the hypothesis that statin use may decrease risk of recurrence to liver, bone and brain as well as second primary (contralateral) breast cancers, and may act synergistically with bisphosphonates to decrease the risk of recurrence to bone.

Patients and Methods: In S0307, 6097 patients diagnosed with Stage I-III breast cancer who had undergone surgery and were receiving adjuvant systemic therapy were randomized to receive zoledronic acid, clodronate, or ibandronate for 3 years. No significant difference was found in disease-free survival (DFS) among the 3 groups, including a sub-analysis of patients &gt; age 55. Statin use was infrequent in younger women in S0307, consequently we analyzed statin use in those &gt; age 55. Cox proportional hazard models were used to determine which variables were independently associated with DFS and to estimate hazard ratios (HR) and 95% confidence intervals (CI).

Results: Among women aged ≥ 55 years, 684 (27%) reported taking a statin at baseline and 1,848 did not. Both groups were similar in terms of hormone receptor and HER2 status (p = 0.82). Median age in the statin group was 64.3 versus 61.0 years in the no statin group, mean BMI 31.2 v. 29.5, mean tumor size 2.1cm v. 2.3cm, negative lymph nodes 60% v. 54%, Stage I disease 47% v. 36%, and receipt of chemotherapy 62% v. 71% (all p &lt; 0.01). In the statin group, 122 (17.8%) experienced a DFS event compared to 313 (16.9%) in the no statin group (HR 1.18, CI 0.95-1.46). No difference was observed by statin use in overall recurrence (p=0.28), distant recurrence (p=0.64), or recurrences to the bone (p=0.64), liver (p=0.38) or brain (p=0.65) at initial recurrence. There was no synergy between statin use and specific bisphosphonates.

Recurrence and statin useOutcomeGroup 1: On stan at baseline n=684Group 2: No statin at baseline n=1848DFS events122 (17.8%)313 (16.9%)Died without recurrence51 7.5%)97 (5.2%)Recurrence71 (10.4%)216 (11.7%)Contralateral breast cancer9 (1.3%)17 (0.9%)Distant recurrence48 (7%)157 (8.5%)Bone as 1st site of distant recurrence (% distant recurrence)31 (65%)76 (48%)Liver as 1st site of distant recurrence (% distant recurrence)6 (13%)24 (16%)Brain/CNS as 1st site of distant recurrence (% distant recurrence)5 (10%)17 (11%)

Conclusions: We found no evidence that statins reduce risk of second primary breast cancers or distant metastases among post-menopausal women with early-stage breast cancer. Despite promising preclinical data, they did not appear to act in synergy with a specific bisphosphonate. Though women in the statin group had less advanced disease at study entry, statin use was not associated with improved DFS. Results are limited by lack of information about type of statin used, adherence, or initiation of statin in control group.

Citation Format: Kizub D, Miao J, Stopeck A, Thompson P, Paterson AH, Clemons M, Dees EC, Ingle JN, Falkson CI, Barlow W, Hortobagyi GN, Gralow JR. Statin use, site of recurrence, and survival among post-menopausal women taking bisphosphonates as adjuvant therapy for breast cancer (SWOG S0307) [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 P1-17-03.

Abstract GS4-07: Race, ethnicity and clinical outcomes in hormone receptor-positive, HER2-negative, node-negative breast cancer: results from the TAILORx trial

Background: Black race is associated with worse outcomes in localized hormone receptor (HR)-positive breast cancer in population-based and in clinical trial cohorts, whether using self-identified race (Albain et al. JNCI 2009 [PMID: 19584328; Sparano et al. JNCI 2012 [PMID: 22250182) or genetically-identified race (Schneider et al. J Precision Oncol 2017 [PMID: 29333527]). This disparity persists after adjustment for treatment delivery parameters (Hershman et al. JCO 2009 [PMID:19307504]). We evaluated clinicopathologic characteristics, treatment delivered and clinical outcomes in the Trial Assigning Individualized Options for Treatment (TAILORx) by race and ethnicity (Sparano et al. NEJM 2018 [PMID: 29860917]).

Methods: The analysis included 9719 evaluable TAILORx participants. The association between clinical outcomes and race (white, black, Asian, other/unknown) and ethnicity (Hispanic vs. non-Hispanic) was examined, including invasive disease-free survival (iDFS), distant relapse-free interval (DRFI), relapse-free interval (RFI), and overall survival (OS). Proportional hazards models were fit including age (5 categories), tumor size (&gt;2 cm vs. &lt;=2 cm), histologic grade (high vs. medium vs. low vs. unknown), continuous recurrence score (RS), race, and ethnicity in the overall population and randomized treatment arms in the RS 11-25 cohort.

Results: The study population included 8189 (84%) whites, 693 (7%) blacks, 405 (4%) Asians, and 432 (4%) with other/unknown race. Regarding ethnicity, 7635 (79%) were non-Hispanic, 889 (9%) Hispanic, and 1195 (12%) unknown. There was no significant difference in RS distribution (p=0.22) in blacks compared with whites, or in median (17 vs. 17) or mean RS (19.1 vs. 18.2). There was likewise no difference in Hispanic vs. non-Hispanic ethnicity for RS distribution (p=0.72) or median (17 vs. 17) or mean RS (18.5 vs. 18.0). Black race (39% vs. 30%) and Hispanic ethnicity (39% vs. 30%) were both associated with younger age (&lt;/=50 years) at diagnosis. The use and type of adjuvant chemotherapy and endocrine therapy, and duration of endocrine therapy, were similar in black (vs. white) and Hispanic (vs. non-Hispanic) populations. In proportional hazards models, black race (compared with white race) was associated with worse clinical outcomes in the entire population and in those with a RS 11-25 (see table). Hispanic ethnicity was generally associated with better outcomes (compared with non-Hispanic ethnicity). For the cohort with a RS of 11-25, there was no evidence for chemotherapy benefit for any racial or ethnic group.

Race (black vs.white) and clinical outcomes in proportional hazards modelsClinical endpointEntire Population (N=693 black) Hazard ratio for eventRS 11-25 (N=471 black) Hazard ratio for eveniDFS1.33 (p=0.005)1.49 (p=0.001)DRFI1.21 (p=0.28)1.60 (p=0.02)RFI1.39 (p=0.02)1.80 (p&lt;0.001)OS1.52 (p=0.005)1.67 (p=0.003

Conclusions: In patients eligible and selected for participation in TAILORx, black women had worse clinical outcomes despite similar 21-gene assay RS results and comparable systemic therapy. This adds to an emerging body of evidence suggesting a biologic basis or other factors contributing to racial disparities in HR-positive breast cancer that requires further evaluation.

Citation Format: Albain K, Gray RJ, Sparano JA, Makower DF, Pritchard KI, Hayes DF, Geyer, Jr. CE, Dees EC, Goetz MP, Olson, Jr. JA, Lively T, Badve SS, Saphner TJ, Wagner LI, Whelan TJ, Ellis MJ, Paik S, Wood WC, Ravdin PM, Keane MM, Gomez HL, Reddy PS, Goggins TF, Mayer IA, Brufsky AM, Toppmeyer DL, Kaklamani VG, Berenberg JL, Abrams J, Sledge, Jr. GW. Race, ethnicity and clinical outcomes in hormone receptor-positive, HER2-negative, node-negative breast cancer: results from the TAILORx 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 GS4-07.

Correction to: Measuring and understanding adherence in a home-based exercise intervention during chemotherapy for early breast cancer

In the original publication, the sixth author name was published incorrectly as A. Wood. The correct author name should read as W. A. Wood.

Phase I study of the gamma secretase inhibitor PF-03084014 in combination with docetaxel in patients with advanced triple-negative breast cancer

Background

The NOTCH signaling pathway may be involved in the survival of stem cell-like tumor-initiating cells and contribute to tumor growth. In this phase Ib, open-label, multicenter study (NCT01876251), we evaluated PF-03084014, a selective gamma-secretase inhibitor in patients with advanced triple-negative breast cancer.

Methods

The dose-finding part was based on a 2×3 matrix design using the modified toxicity probability interval method. Oral PF-03084014 was administered twice daily continuously in combination with intravenous docetaxel given on day 1 of each 21-day cycle. Primary endpoint was first-cycle dose-limiting toxicity (DLT) for the dose-finding part and 6-month progression-free survival (PFS) for the expansion cohort treated at the maximum tolerated dose (MTD). Secondary endpoints included safety, objective response, and pharmacokinetics of the combination.

Results and Conclusions

The MTD was estimated to be PF-03084014 100 mg twice daily / docetaxel 75 mg/m2. At this dose level, combination treatment was generally well tolerated (one DLT, grade 3 diarrhea, among eight DLT-evaluable patients). The most common all-grade, treatment-related adverse events reported in all patients (N = 29) were neutropenia (90%), fatigue (79%), nausea (72%), leukopenia (69%), diarrhea (59%), alopecia (55%), anemia (55%), and vomiting (48%). No effect was observed on the pharmacokinetics of docetaxel when administered in combination with PF-03084014. Four (16%) of 25 response-evaluable patients achieved a confirmed partial response; nine (36%) patients had stable disease, including five patients with unconfirmed partial response. In the expansion cohort, median PFS was 4.1 (95% CI 1.3-8.1) months (6-month PFS rate 17.1% [95% CI 0.8-52.6%]).

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.

Measuring and understanding adherence in a home-based exercise intervention during chemotherapy for early breast cancer

PURPOSE

Ensuring and measuring adherence to prescribed exercise regimens are fundamental challenges in intervention studies to promote exercise in adults with cancer. This study reports exercise adherence in women who were asked to walk 150 min/week throughout chemotherapy treatment for early breast cancer. Participants were asked to wear a Fitbit^TM throughout their waking hours, and Fitbit steps were uploaded directly into study computers.

METHODS

Descriptive statistics are reported, and both unadjusted and multivariable linear regression models were used to assess associations between participant characteristics, breast cancer diagnosis, treatment, chemotherapy toxicities, and patient-reported symptoms with average Fitbit steps/week.

RESULTS

Of 127 women consented to the study, 100 had analyzable Fitbit data (79%); mean age was 48 and 31% were non-white. Mean walking steps were 3956 per day. Nineteen percent were fully adherent with the target of 6686 steps/day and an additional 24% were moderately adherent. In unadjusted analysis, baseline variables associated with fewer Fitbit steps were: non-white race (p = 0.012), high school education or less (p = 0.0005), higher body mass index (p = 0.0024), and never/almost never drinking alcohol (p = 0.0048). Physical activity variables associated with greater Fitbit steps were: pre-chemotherapy history of vigorous physical activity (p = 0.0091) and higher self-reported walking minutes/week (p < 0.001), and higher outcome expectations from exercise (p = 0.014). Higher baseline anxiety (p = 0.03) and higher number of chemotherapy-related symptoms rates "severe/very severe" (p = 0.012) were associated with fewer steps. In multivariable analysis, white race was associated with 12,146 greater Fitbit steps per week (p = 0.004), as was self-reported walking minutes prior to start of chemotherapy (p < 0.0001).

CONCLUSIONS

Inexpensive commercial-grade activity trackers, with data uploaded directly into research computers, enable objective monitoring of home-based exercise interventions in adults diagnosed with cancer. Analysis of the association of walking steps with participant characteristics at baseline and toxicities during chemotherapy can identify reasons for low/non-adherence with prescribed exercise regimens.

A Phase I Trial of the PI3K Inhibitor Buparlisib Combined With Capecitabine in Patients With Metastatic Breast Cancer

BACKGROUND

Buparlisib is an oral pan-class I phosphotidyinositol-3-kinase (PI3K) inhibitor. The present phase I study evaluated the safety, pharmacokinetics, and efficacy of buparlisib with capecitabine in patients with metastatic breast cancer.

PATIENTS AND METHODS

Patients received buparlisib once daily (range, 50 to 100 mg) for 3 weeks with capecitabine twice daily (range, 1000 to 1250 mg/m²) for 2 weeks with a 1-week break. Dose escalation used a traditional "3 + 3" design with standard definitions of dose-limiting toxicity (DLT) and maximum tolerated dose.

RESULTS

Of the 25 patients enrolled, 23 were evaluable for DLT and 17 were evaluable for response. The maximum tolerated dose of the combination was buparlisib 100 mg daily and capecitabine 1000 mg/m² twice daily. DLTs included grade 3 hyperglycemia and grade 3 confusion. The most common grade 3 toxicities were diarrhea and elevation of aspartate aminotransferase and alanine transaminase. One patient exhibited a complete response to treatment and four had a confirmed partial response. In cohorts 3 and 4, in which the buparlisib dose remained constant but the capecitabine dose was increased, significant increases in the buparlisib plasma concentration were noted.

CONCLUSION

The combination of buparlisib with capecitabine in patients with metastatic breast cancer was generally well-tolerated, with several patients demonstrating prolonged responses. Unexpectedly low rates of PIK3CA mutations (3 of 17) were seen, and only 2 of 7 tumors with subtyping were luminal, making exploration of these putative predictive markers impossible. Further study of the combination is not unreasonable, with expanded pharmacokinetics and sequencing analysis to better elucidate potential drug-drug interactions and more accurate predictive biomarkers of response.

Changing Natural History of HER2-Positive Breast Cancer Metastatic to the Brain in the Era of New Targeted Therapies

BACKGROUND

Given the wide adoption of human epidermal growth factor receptor 2 (HER2)-targeted therapies for advanced HER2-positive breast cancer, we studied the natural history of patients with HER2-positive breast cancer brain metastases (BCBM) over time.

PATIENTS AND METHODS

Patients with HER2-positive BCBM identified from a prospectively maintained database at the University of North Carolina were divided into 3 cohorts by year of BCBM diagnosis. Cohorts were selected by year of HER2-targeted therapy US Food and Drug Administration approval. Overall survival (OS), time to first metastasis, time to BCBM, and BCBM survival were estimated by the Kaplan-Meier method. Associations between OS after BCBM and clinical variables were assessed by Cox proportional hazards regression models.

RESULTS

One hundred twenty-three patients were identified. Median age was 51 years, and 58% were white and 31% African American. OS from initial breast cancer diagnosis improved over time: 3.6 years (95% confidence interval [CI], 2.8-6.1) in the 1998-2007 cohort, 6.6 years (95% CI, 4.5-8.6) in the 2008-2012 cohort, and 7.6 years (95% CI, 4.4-9.6) in the 2013-2015 cohort (P = .05). While time from initial diagnosis to first metastasis did not differ (P = .12), time to BCBM increased over time (2.6 years [95% CI, 1.3-3.5] for 1998-2007; 2.6 years [95% CI, 2.1-4.3] for 2008-2012, and 3.3 years [95% CI, 2.2-6] for 2013-2015; P = .05). Although OS from BCBM did not significantly differ by cohort, patients who received HER2-targeted therapy after BCBM had a prolonged OS (2.1 years [95% CI, 1.6-2.6] vs. 0.65 years [95% CI, 0.4-1.3]; P = .001).

CONCLUSION

OS from initial breast cancer diagnosis significantly improved over time for patients with HER2-positive breast cancer who develop BCBM, now exceeding 7 years; survival from BCBM diagnosis may now exceed 2 years.

Nanoparticle-Delivered Chemotherapy: Old Drugs in New Packages

Cytotoxic chemotherapies have a narrow therapeutic window, with high peaks and troughs of plasma concentration. Novel nanoparticle formulations of cytotoxic chemotherapy drugs can enhance pharmacokinetic characteristics and facilitate passive targeting of drugs to tumors via the enhanced permeability and retention effect, thus mitigating toxicity. Nanoparticle vehicles currently in clinical use or undergoing clinical investigation for anticancer therapies include liposomes, polymeric micelles, protein-drug nanoparticles, and dendrimers. Multiple nanoparticle formulations of existing cytotoxic chemotherapies are approved for use in several indications, with clinical data indeed showing optimization of pharmacokinetics and different toxicity profiles compared with their parent drugs. There are also many new nanoparticle drug formulations in development and undergoing early- and late-phase clinical trials, including several that utilize active targeting or triggered release based on environmental stimuli. Here, we review the rationale for nanoparticle formulations of existing or previously investigated cytotoxic drugs, describe currently approved nanoparticle formulations of drugs, and discuss some of the most promising clinical trials currently underway.

Abstract P1-12-08: The incidence and outcomes of brain metastases in HER2-positive metastatic breast cancer with the advent of modern anti-HER2 therapies

Background: Human epidermal growth factor receptor 2 (HER2) is over-expressed in approximately 20 - 30% of breast cancers. HER2-positive breast cancers frequently metastasize to the brain. In recent years, many new drugs have been approved for HER2-positive metastatic breast cancer (MBC). In the metastatic setting, trastuzumab was approved in 2000, lapatinib 2007, and pertuzumab and ado-trastuzumab emtansine in 2012. We sought to describe the incidence, time course, and prognostic factors of BM in patients (pts) with HER2+ MBC during the time when dramatic changes in systemic therapy occurred.

Patients/methods: The study included pts with HER2-positive MBC treated at two academic hospitals: Dana Farber Cancer Institute (DFCI) (2000-2007 [DFCI-T1], 2008-2011 [DFCI-T2]) and University of North Carolina (UNC) (2012-2014). We examined the incidence of BM (at diagnosis [dx] and within 1-2 years of MBC dx). We combined the two cohorts to examine outcomes – time to BM, survival following MBC, and survival following BM – using the Kaplan Meier method and Cox regression modeling.

Results: We identified 185 (DFCI n=128, 97 diagnosed 2000-2007 and 31 diagnosed 2008-2011; UNC n=57, all diagnosed 2012-2014) pts with HER2-positive MBC. Through a median of 4 years follow-up after the MBC dx (min 2, max 11), 118 had died and 67 were censored. The median age at MBC dx was 52 (min 25, max 88), 149 (82%) were Caucasian, 88 (48%) had hormone receptor (HR) positive BC, and 67 (37%) had de-novo (i.e., non-recurrent) MBC. BM was present at the MBC dx for 8% of pts in DFCI-T1, 16 % of pts in DFCI-T2, and 16% of pts at UNC. Within 1 year of the MBC dx, BM was present in 21% of DFCI-T1, 29% in DFCI-T2, 23% of UNC pts. Within 2 years of the MBC dx, 67 (36%) pts had developed BM, of which one third (22) were diagnosed at initial MBC presentation. In unadjusted analyses, there were no differences in time to BM dx by age (p=0.2), race (p=0.1) or HR status (p=0.1). The median survival following the development of BM for all pts was 1.5 years. A multivariable model predicting survival after the MBC dx, found factors associated with shorter survival included having (vs. not having) BM at the initial MBC dx, having received (vs. not having received) adjuvant HER2-directed therapy prior to the MBC dx, and having recurrent (vs. de novo) MBC (P≤0.02 for all). Age, HR status, race and time period of MBC dx were not significant in the multivariable model.

Conclusions: Among pts diagnosed in the modern era, after new therapies became available, BM remains a common problem for pts with HER2-positive MBC. While no obvious trends in the incidence of HER2-positive MBC are suggested, conclusions regarding incidence trends should be considered hypothesis-generating until larger, population-based data become available. Nevertheless, a dx of BM early in the course of MBC treatment and prior receipt of adjuvant trastuzumab appeared to confer a more aggressive disease course. Coordinated, prospective collection of the incidence and outcomes of BM among pts with HER2-positive MBC, studies of pts who develop BM &gt;2 years after their MBC dx, and clinical trials of treatment strategies for pts with trastuzumab-resistant BM are needed.

Citation Format: Strulov Shachar S, Deal AM, Vaz-Luis I, Dees EC, Carey LA, Hassett MJ, Garrett AL, Benbow JM, Hughes ME, Mounsey L, Lin N, Anders CK. The incidence and outcomes of brain metastases in HER2-positive metastatic breast cancer with the advent of modern anti-HER2 therapies [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 P1-12-08.

Abstract P1-05-20: Comparing the frequency and types of genetic aberrations between older and younger women with metastatic breast cancer at the University of North Carolina at Chapel Hill

Background: Targeted therapies have the potential to revolutionize cancer treatment in older adults as they are often oral, convenient, may be better tolerated than cytotoxic chemotherapy, and can be tailored to an individual's biomarker profile. We explore the frequency and distribution of potentially actionable genomic alterations among older (≥65) and younger (&lt;65) patients (pts) with metastatic breast cancer (MBC).

Method: Next generation genetic sequencing (UNCseq™) of a dynamic panel of target genes was prospectively offered to pts with MBC treated at the University of North Carolina at Chapel Hill (UNC). DNA libraries were prepared separately from a retrieved archival FFPE tumor sample and a matched normal sample from each pt. Relevant targets were enriched by custom Agilent SureSelect hybrid capture baits using standard protocols. Samples were sequenced on Illumina HiSeq 2000/2500 platforms. Mutational findings were reviewed by a molecular tumor board; variants identified to be potentially actionable underwent confirmatory testing in a CLIA approved laboratory. Confirmed findings were inserted into the pt's EMR accessible by both the pt and the treating oncologist. Two-sided Fisher's exact test was used to compare percentages between age-specific groups.

Results: As of 3/31/16, results were available for 140 pts. 19% were 65 years or older. Breast cancer clinical subtypes were: HR+/HER2- 49%, HER2+ (HR any) 17%, TN 34% and metastatic location was: bone only 5%, visceral only 44%, bone & visceral 51%; no significant differences were observed between older and younger age groups. Older pts were more likely to be Caucasian compared to younger patients (92% v 75%, p=0.06). Overall, older patients had a higher total number of mutations compared to younger patients (see Table) (p=0.04). Mutation types were similar between age groups, although a trend for more PIK3CA mutations among older patients was seen (37% v 20%, p=0.07).

Observed Mutations by Age. ≥ 65 years (%) N=27&lt; 65 years (%) N=113pNumber of Mutations   01127.0414849.0423320.04374.04Type of mutation   PIK3CA3720.07CCND179.99NF-1115.37FGFR144.99PTEN49.69EGFR04.99

Conclusion: Genomic alterations may allow therapeutic tailoring in both older and younger patients with breast cancer. In this cohort with metastatic disease, older patients had significantly more mutations, but no clear difference in mutational types was seen by age. The relative small number of older pts in this cohort limits generalization, but supports the need for more extensive characterization of molecular aberrations among older pts with metastatic breast cancer in the new era of targeted therapy.

Research support by the University Cancer Research Fund, NCI Breast Cancer SPORE grant (CA58223), John A. Hartford Foundation and Susan G. Komen Foundation.

Citation Format: Jolly TA, Grilley-Olson JE, Deal AM, Ivanova A, Hayward MC, Benbow JM, Parker JS, Patel NM, Eberhard DA, Weck KE, Mieczkowski P, Dees EC, Muss HD, Reeder-Hayes KE, Earp HS, Sharpless NE, Carey LA, Hayes DN, Anders CK. Comparing the frequency and types of genetic aberrations between older and younger women with metastatic breast cancer at the University of North Carolina at Chapel Hill [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 P1-05-20.

Pharmacogenomics, Pharmacokinetics, and Pharmacodynamics in the Era of Targeted Therapies

The complex nature of the pharmacologic aspects of cancer therapeutics has become more apparent in the past several years with the arrival of a cascade of target-based agents and the difficult challenge of bringing individualized precision medicine to oncology. Interpatient variability in drug action, singularly in novel agents, is in part caused by pharmacogenomic (PG), pharmacokinetic, and pharmacodynamic (PD) factors, and drug selection and dosing should take this into consideration to optimize the benefit for our patients in terms of antitumor activity and treatment tolerance. In this regard, somatic genetic evaluation of tumors is useful in not only predicting response to initial targeted therapies but also in anticipating and guiding therapy after the development of acquired resistance; therapeutic drug monitoring of novel small molecules and monoclonal antibodies must be incorporated in our day-to-day practice to minimize the negative effect on clinical outcome of interindividual variability on pharmacokinetic processes of these drugs for all patients, but especially for fragile patient populations and those with organ dysfunction or comorbidities. For these populations, incorporating frailty assessment tools into trials of newer agents and validating frailty-based dose adjustment should be an important part of further drug development.

Ramucirumab With Eribulin Versus Eribulin in Locally Recurrent or Metastatic Breast Cancer Previously Treated With Anthracycline and Taxane Therapy: A Multicenter, Randomized, Phase II Study

BACKGROUND

Use of antiangiogenic agents in treatment of metastatic breast cancer (MBC) remains controversial. We evaluated the efficacy and safety of ramucirumab and eribulin versus eribulin alone as third- to fifth-line therapy in women with advanced breast cancer.

PATIENTS AND METHODS

In this randomized (1:1), open-label, phase II study, US women aged 18 years or older with 2 to 4 previous chemotherapy regimens for locally recurrent or MBC, previous anthracycline and taxane treatment, and Eastern Cooperative Oncology Group performance status of 0 or 1 received ramucirumab with eribulin or eribulin alone in 21-day cycles (eribulin 1.4 mg/m2 intravenously on days 1 and 8; ramucirumab 10 mg/kg intravenously on day 1). Randomization was stratified according to previous antiangiogenic therapy and triple-negative status. The primary end point was progression-free survival (PFS) in the intention to treat population.

RESULTS

One hundred forty-one women were randomized to ramucirumab with eribulin (n = 71) or eribulin alone (n = 70). Median PFS for ramucirumab with eribulin was 4.4 months (95% confidence interval [CI], 3.1-6.7) compared with 4.1 months (95% CI, 3.2-5.6) for eribulin (hazard ratio [HR], 0.83; 95% CI, 0.56-1.23; P = .35). Median overall survival in patients who received ramucirumab with eribulin was 13.5 months (95% CI, 10.4-17.9) compared with 11.5 months (95% CI, 9.0-17.3) in patients who received eribulin alone (HR, 0.91; 95% CI, 0.59-1.41; P = .68); objective response rate was 21% (13 of 62 patients) for the combination and 28% (17 of 60 patients) for eribulin alone. No unexpected toxicity was identified for the combination.

CONCLUSION

Ramucirumab combined with eribulin did not significantly improve PFS in advanced MBC.

Pharmacogenomics, Pharmacokinetics, and Pharmacodynamics in the Era of Targeted Therapies

The complex nature of the pharmacologic aspects of cancer therapeutics has become more apparent in the past several years with the arrival of a cascade of target-based agents and the difficult challenge of bringing individualized precision medicine to oncology. Interpatient variability in drug action, singularly in novel agents, is in part caused by pharmacogenomic (PG), pharmacokinetic, and pharmacodynamic (PD) factors, and drug selection and dosing should take this into consideration to optimize the benefit for our patients in terms of antitumor activity and treatment tolerance. In this regard, somatic genetic evaluation of tumors is useful in not only predicting response to initial targeted therapies but also in anticipating and guiding therapy after the development of acquired resistance; therapeutic drug monitoring of novel small molecules and monoclonal antibodies must be incorporated in our day-to-day practice to minimize the negative effect on clinical outcome of interindividual variability on pharmacokinetic processes of these drugs for all patients, but especially for fragile patient populations and those with organ dysfunction or comorbidities. For these populations, incorporating frailty assessment tools into trials of newer agents and validating frailty-based dose adjustment should be an important part of further drug development.

Pembrolizumab in Patients With Advanced Triple-Negative Breast Cancer: Phase Ib KEYNOTE-012 Study

PURPOSE

Immune checkpoint inhibition has been demonstrated to be an effective anticancer strategy. Several lines of evidence support the study of immunotherapy in triple-negative breast cancer (TNBC). We assessed the safety and antitumor activity of the programmed cell death protein 1 (PD-1) inhibitor pembrolizumab in patients with advanced TNBC.

METHODS

KEYNOTE-012 (ClinicalTrials.gov identifier: NCT01848834) was a multicenter, nonrandomized phase Ib trial of single-agent pembrolizumab given intravenously at 10 mg/kg every 2 weeks to patients with advanced PD-L1-positive (expression in stroma or ≥ 1% of tumor cells by immunohistochemistry) TNBC, gastric cancer, urothelial cancer, and head and neck cancer. This report focuses on the TNBC cohort.

RESULTS

Among 111 patients with TNBC whose tumor samples were screened for PD-L1 expression, 58.6% had PD-L1-positive tumors. Thirty-two women (median age, 50.5 years; range, 29 to 72 years) were enrolled and assessed for safety and antitumor activity. The median number of doses administered was five (range, 1 to 36 doses). Common toxicities were mild and similar to those observed in other tumor cohorts (eg, arthralgia, fatigue, myalgia, and nausea), and included five (15.6%) patients with grade ≥ 3 toxicity and one treatment-related death. Among the 27 patients who were evaluable for antitumor activity, the overall response rate was 18.5%, the median time to response was 17.9 weeks (range, 7.3 to 32.4 weeks), and the median duration of response was not yet reached (range, 15.0 to ≥ 47.3 weeks).

CONCLUSION

This phase Ib study describes preliminary evidence of clinical activity and a potentially acceptable safety profile of pembrolizumab given every 2 weeks to patients with heavily pretreated, advanced TNBC. A single-agent phase II study examining a 200-mg dose given once every 3 weeks (ClinicalTrials.gov identifier: NCT02447003) is ongoing.

Abstract PD6-07: Genomic sequencing in metastatic breast cancer patients to inform clinical practice at the University of North Carolina at Chapel Hill

Background: An increasing number of molecularly-targeted therapies for metastatic breast cancer (MBC) are clinically-available (approved and investigational). These anti-cancer agents target specific molecular abnormalities such as mutated, amplified, deleted, or rearranged genes. Reporting of unique tumor genetic alterations is not included in routine clinical/diagnostic panels. In MBC, knowledge of mutational status may foster efficient transitions in clinical care and trial enrollment at disease progression. We describe the development and implementation of a clinically-integrated genomic sequencing program and report how information regarding targetable genomic aberrations in MBC patients (pts) is used to improve clinical practice in an academic setting.

Methods: Genomic sequencing of investigative biomarkers was prospectively offered to pts with MBC. DNA libraries were prepared separately from a retrieved archival FFPE tumor sample and a matched normal sample from each pt. Relevant targets were enriched by custom Agilent SureSelect hybrid capture baits using standard protocols. Samples were sequenced on Illumina HiSeq 2000/2500 platforms. Mutational findings were reviewed by a molecular tumor board (MTB); variants identified to be potentially actionable underwent confirmatory testing in a CLIA-approved laboratory. Confirmed findings were inserted into the pt's EMR accessible by both the pt and the treating oncologist.

Results: Of the 725 MBC pts seen at UNC since 1/1/2012, 194 (27%) contributed samples for genomic sequencing. Of those whose tumors were sequenced, average age at MBC diagnosis was 54 (25 - 91); 73% were Caucasian, 16% African American. De novo MBC accounted for 39 (20%) sequenced pts. Of sequenced patients, sites of metastatic disease included bone only (7%), visceral only (46%), and both bone and visceral (47%). Approximately 1/3 of pts were consented for sequencing at time of initial MBC diagnosis, 1/4 after 1st line therapy for MBC, and the remaining at or beyond their 2nd line. In total, 131 (68%) pts have sequencing results available of which 43% of pts had reportable mutations deemed actionable by the MTB. Specific mutations and observed frequency by subtype are shown below. Pts (19%) whose tumors were sequenced were more commonly enrolled in a therapeutic clinical trial for MBC, a higher rate than seen in the non-sequenced group (7%) (p&lt;0.001). To date, 27% of pts' tumors harbored an alteration that is an eligibility requirement for a molecularly-targeted therapeutic trial accruing pts at UNC.

Observed Mutation by Clinical Subype Genes Total # (56 pts)HR+/HER2- (25 pts)HER2+ (13 pts)TNBC (18pts)PIK3CA15933TP5315456CCND19531NF-14103FGFR13300PTEN3012KRAS2011MDM22110PIK3R12002ROS12011TSC12011Other*14518TOTAL73281728*Mutations observed only once

Conclusion: Preemptive genomic sequencing can be integrated into the clinical and operational practice of a comprehensive cancer center. Currently this research tool and program provides valuable information that has the potential to foster both clinical trial eligibility and/or enrollment. With longer follow-up, we hope such an approach ultimately will improve patient outcomes.

Citation Format: Grilley-Olsen J, Keith KC, Hayward M, Dees EC, Deal A, Ivanova A, Benbow JM, Parker J, Patel NM, Eberhard D, Mieczkowski P, Weck KE, Hayes DN, Muss H, Jolly T, Reeder-Hayes K, Earp HS, Sharpless N, Carey L, Anders CK. Genomic sequencing in metastatic breast cancer patients to inform clinical practice at the University of North Carolina at Chapel Hill. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr PD6-07.

A Multidisciplinary Breast Cancer Brain Metastases Clinic: The University of North Carolina Experience

The University of North Carolina at Chapel Hill has created a clinic to provide medical and radiation oncology, neurosurgical, and supportive services to patients with breast cancer brain metastases. Of the 65 patients seen between January 2012 and January 2015, 78% returned for a follow-up visit and 32% were enrolled in a clinical trial. The clinic is a model that can be adapted at other centers.

Background.

Breast cancer brain metastasis (BCBM) confers a poor prognosis and is unusual in requiring multidisciplinary care in the metastatic setting. The University of North Carolina at Chapel Hill (UNC-CH) has created a BCBM clinic to provide medical and radiation oncology, neurosurgical, and supportive services to this complex patient population. We describe organization and design of the clinic as well as characteristics, treatments, and outcomes of the patients seen in its first 3 years.

Methods.

Clinical and demographic data were collected from patients in a prospectively maintained database. Descriptive statistics are reported as percentages and means. The Kaplan-Meier method was used to estimate time-to-event outcomes.

Results.

Sixty-five patients were seen between January 2012 and January 2015. At the time of presentation to the BCBM clinic, most patients (74%) had multiple (≥2) brain metastases and had received prior systemic (77%) and whole-brain radiation therapy and/or central nervous system stereotactic radiosurgery (65%) in the metastatic setting. Seventy-eight percent returned for a follow-up visit; 32% were enrolled in a clinical trial. Median time from diagnosis of brain metastasis to death was 2.11 years (95% confidence interval [CI] 1.31–2.47) for all patients, 1.15 years (95% CI 0.4–2.43) for triple-negative breast cancer, 1.31 years (95% CI 0.51–2.52) for hormone receptor-positive/HER2− breast cancer, and 3.03 years (95% CI lower limit 1.94, upper limit not estimable) for HER2+ breast cancer (p = .0037).

Conclusion.

Patients with BCBM have unique and complex needs that require input from several oncologic disciplines. The development of the UNC-CH multidisciplinary BCBM clinic is a model that can be adapted at other centers to provide coordinated care for patients with a challenging and complex disease.

Implications for Practice:

Patients with breast cancer brain metastases often require unique multidisciplinary care to meet the numerous and uncommon challenges associated with their conditions. Here, the development and characteristics of a clinic designed specifically to provide for the multidisciplinary needs of patients with breast cancer brain metastases are described. This clinic may serve as a model for other institutions interested in creating specialty clinics with similar objectives.

First-in-Human Phase I Study of GSK2126458, an Oral Pan-Class I Phosphatidylinositol-3-Kinase Inhibitor, in Patients with Advanced Solid Tumor Malignancies

PURPOSE

GSK2126458 (GSK458) is a potent inhibitor of PI3K (α, β, γ, and δ), with preclinical studies demonstrating broad antitumor activity. We performed a first-in-human phase I study in patients with advanced solid tumors.

MATERIALS AND METHODS

Patients received oral GSK458 once or twice daily in a dose-escalation design to define the maximum tolerated dose (MTD). Expansion cohorts evaluated pharmacodynamics, pharmacokinetics, and clinical activity in histologically and molecularly defined cohorts.

RESULTS

One hundred and seventy patients received doses ranging from 0.1 to 3 mg once or twice daily. Dose-limiting toxicities (grade 3 diarrhea,n= 4; fatigue and rash,n= 1) occurred in 5 patients (n= 3 at 3 mg/day). The MTD was 2.5 mg/day (MTD with twice daily dosing undefined). The most common grade ≥3 treatment-related adverse events included diarrhea (8%) and skin rash (5%). Pharmacokinetic analyses demonstrated increased duration of drug exposure above target level with twice daily dosing. Fasting insulin and glucose levels increased with dose and exposure of GSK458. Durable objective responses (ORs) were observed across multiple tumor types (sarcoma, kidney, breast, endometrial, oropharyngeal, and bladder cancer). Responses were not associated withPIK3CAmutations (OR rate: 5% wild-type vs. 6% mutant).

CONCLUSIONS

Although the MTD of GSK458 was 2.5 mg once daily, twice-daily dosing may increase duration of target inhibition. Fasting insulin and glucose levels served as pharmacodynamic markers of drug exposure. Select patients achieved durable responses; however,PIK3CAmutations were neither necessary nor predictive of response. Combination treatment strategies and novel biomarkers may be needed to optimally target PI3K.

Phase I Clinical Trials in Acute Myeloid Leukemia: 23-Year Experience From Cancer Therapy Evaluation Program of the National Cancer Institute

BACKGROUND

Therapy for acute myeloid leukemia (AML) has largely remained unchanged, and outcomes are unsatisfactory. We sought to analyze outcomes of AML patients enrolled in phase I studies to determine whether overall response rates (ORR) and mortality rates have changed over time.

METHODS

A retrospective analysis was performed on 711 adult AML patients enrolling in 45 phase I clinical trials supported by the Cancer Therapy Evaluation Program of the National Cancer Institute from 1986 to 2009. Changes in ORR and mortality rates for patients enrolled in 1986 to 1990, 1991 to 1995, 1996 to 2000, 2001 to 2005, and 2006 to 2009 were estimated with multivariable logistic regression models. All statistical tests were two-sided.

RESULTS

There was a statistically significant increase in AML patients enrolling in phase I clinical trials over time (1986 to 1990: n = 61; 2006 to 2009: n = 256; P = .03). The ORR for the entire cohort was 15.4% (1986 to 1990: 8.9%, 1991 to 1995: 21.1%; 1996 to 2000: 7.0%; 2001 to 2005: 10.0%; 2006 to 2009: 22.6%), and it statistically significantly improved over time (P < .001). There was a statistically significant improvement in ORRs with novel agents in combination vs single agents (ORR = 22.8% vs 4.7%, respectively, odds ratio = 5.95, 95% confidence interval = 3.22 to 11.9, P < .001). The 60-day mortality rate for the entire cohort was 22.6%, but it statistically significantly improved over time (P = .009).

CONCLUSIONS

There has been an encouraging increase in AML patients enrolling in phase I clinical studies over time. The improvement in ORRs appears to be partly because of the increase in combination trials and the inclusion of previously untreated poor-risk AML. Continued enrollment of AML patients in early phase clinical trials is vital for drug development and improvement in therapeutic outcomes.

Phase II Study of Lapatinib in Combination With Trastuzumab in Patients With Human Epidermal Growth Factor Receptor 2-Positive Metastatic Breast Cancer: Clinical Outcomes and Predictive Value of Early [18F]Fluorodeoxyglucose Positron Emission Tomography Imaging (TBCRC 003)

PURPOSE

Lapatinib plus trastuzumab improves outcomes relative to lapatinib alone in heavily pretreated, human epidermal growth factor receptor 2-positive metastatic breast cancer (MBC). We tested the combination in the earlier-line setting and explored the predictive value of [(18)F]fluorodeoxyglucose positron emission tomography ([(18)F]FDG-PET) for clinical outcomes.

PATIENTS AND METHODS

Two cohorts were enrolled (cohort 1: no prior trastuzumab for MBC and ≥ 1 year from adjuvant trastuzumab, if given; cohort 2: one to two lines of chemotherapy including trastuzumab for MBC and/or recurrence < 1 year from adjuvant trastuzumab). The primary end point was objective response rate by RECIST v1.0; secondary end points included clinical benefit rate (complete response plus partial response plus stable disease ≥ 24 weeks) and progression-free survival. [(18)F]FDG-PET scans were acquired at baseline, week 1, and week 8. Associations between metabolic response and clinical outcomes were explored.

RESULTS

Eighty-seven patients were registered (85 were evaluable for efficacy). The confirmed objective response rate was 50.0% (95% CI, 33.8% to 66.2%) in cohort 1 and 22.2% (95% CI, 11.3% to 37.3%) in cohort 2. Clinical benefit rate was 57.5% (95% CI, 40.9% to 73.0%) in cohort 1 and 40.0% (95% CI, 25.7% to 55.7%) in cohort 2. Median progression-free survival was 7.4 and 5.3 months, respectively. Lack of week-1 [(18)F]FDG-PET/computed tomography ([(18)F]FDG-PET/CT) response was associated with failure to achieve an objective response by RECIST (negative predictive value, 91% [95% CI, 74% to 100%] for cohort 1 and 91% [95% CI, 79% to 100%] for cohort 2).

CONCLUSION

Early use of lapatinib and trastuzumab is active in human epidermal growth factor receptor 2-positive MBC. Week-1 [(18)F]FDG-PET/CT may allow selection of patients who can be treated with targeted regimens and spared the toxicity of chemotherapy.

A first in man phase I trial of the oral immunomodulator, indoximod, combined with docetaxel in patients with metastatic solid tumors

BACKGROUND

Indoleamine 2,3-dioxygenase (IDO) is an enzyme that tumors use to create a state of immunosuppression. Indoximod is an IDO pathway inhibitor. Preclinical studies demonstrated that indoximod combined with chemotherapy was synergistic in a mouse model of breast cancer. A phase I 3+3 trial was designed to study the combination of docetaxel and indoximod.

METHODS

Docetaxel was administered at 60 mg/m2 intravenously every 3 weeks dose levels 1-4 and 75 mg/m2 for dose level 5. Indoximod was given at 300, 600, 1000, 2000, and 1200 mg PO twice daily continuously for levels 1-5, respectively. Serum drug levels were measured.

RESULTS

Twenty-seven patients were treated, with 22 evaluable for response. DLTs included grade 3 dehydration (level 1), hypotension(level 4), mucositis (level 4) and grade 5 enterocolitis (level 2). Dose level 5 is the recommended phase II dose. The most frequent adverse events were fatigue (58.6%), anemia (51.7%), hyperglycemia (48.3%), infection (44.8%), and nausea (41.4%). There were 4 partial responses (2 breast, 1 NSCLC, 1 thymic tumor). No drug-drug interactions were noted.

CONCLUSIONS

Docetaxel plus indoximod was well tolerated with no increase in expected toxicities or pharmacokinetic interactions. It was active in a pretreated population of patients with metastatic solid tumors.

Safety and activity of alisertib, an investigational aurora kinase A inhibitor, in patients with breast cancer, small-cell lung cancer, non-small-cell lung cancer, head and neck squamous-cell carcinoma, and gastro-oesophageal adenocarcinoma: a five-arm phase 2 study

BACKGROUND

Alisertib is an investigational, oral, selective inhibitor of aurora kinase A. We aimed to investigate the safety and activity of single-agent alisertib in patients with predefined types of advanced solid tumours.

METHODS

We did a multicentre phase 1/2 study at 40 centres in four countries (Czech Republic, France, Poland, and the USA). Here, we report results from phase 2; enrolment for the study began on Feb 16, 2010, and ended on May 3, 2013. Adult patients were eligible for the study if they had either breast cancer, small-cell lung cancer, non-small-cell lung cancer, head and neck squamous-cell carcinoma, or gastro-oesophageal adenocarcinoma that had relapsed or was refractory to chemotherapy. Patients had to have undergone two or fewer previous cytotoxic regimens (four or fewer for breast cancer patients), not including adjuvant or neoadjuvant treatments. Enrolment followed a two-stage design: to proceed to the second stage, two or more objective responses were needed in the first 20 response-assessable patients in each of the five tumour cohorts. Alisertib was administered orally in 21-day cycles at the recommended phase 2 dose of 50 mg twice daily for 7 days followed by a break of 14 days. The protocol-specified primary endpoint was the proportion of patients with an objective response, assessed by Response Evaluation Criteria In Solid Tumors version 1.1 in the response-assessable population (ie, patients with measurable disease who received at least one dose of alisertib and had undergone at least one post-baseline tumour assessment). This completed trial is registered with ClinicalTrials.gov, NCT01045421.

FINDINGS

By May 31, 2013, 249 patients had been treated, 53 with breast cancer, 60 with small-cell lung cancer, 26 with non-small-cell lung cancer, 55 with head and neck squamous-cell carcinoma, and 55 with gastro-oesophageal adenocarcinoma. Among response-assessable patients, an objective response was noted in nine (18%, 95% CI 9-32) of 49 women with breast cancer, ten (21%, 10-35) of 48 participants with small-cell lung cancer, one (4%, 0-22) of 23 patients with non-small-cell lung cancer, four (9%, 2-21) of 45 people with head and neck squamous-cell carcinoma, and four (9%, 2-20) of 47 individuals with gastro-oesophageal adenocarcinoma; all were partial responses. Adverse events were similar across tumour types. The most frequent drug-related grade 3-4 adverse events included neutropenia (n=107 [43%]), leukopenia (53 [21%]), and anaemia (26 [10%]). Serious drug-related adverse events were reported in 108 (43%) patients.

INTERPRETATION

These data support further clinical assessment of alisertib in patients with solid tumours, particularly those with breast cancer and small-cell lung cancer.

FUNDING

Millennium Pharmaceuticals, Inc, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited.

Phase I dose-escalation study of LCL161, an oral inhibitor of apoptosis proteins inhibitor, in patients with advanced solid tumors

PURPOSE

LCL161 antagonizes the function of inhibitor of apoptosis proteins (IAPs), thereby promoting cancer cell death. This first-in-human dose-escalation study assessed the maximum-tolerated dose (MTD), safety, pharmacokinetics, and pharmacodynamics of LCL161 in patients with advanced solid tumors. A second part of the study assessed the relative bioavailability of a tablet versus solution formulation.

PATIENTS AND METHODS

LCL161 was administered orally, once weekly, on a 21-day cycle to adult patients with advanced solid tumors by using an adaptive Bayesian logistic regression model with overdose control-guided dose escalation.

RESULTS

Fifty-three patients received at least one dose of LCL161 (dose range, 10 to 3,000 mg). LCL161 was well tolerated at doses up to 1,800 mg. Cytokine release syndrome (CRS) was the only dose-limiting toxicity (in three [6%] of 53 patients) and was the most common grades 3 to 4 event (in five [9%] of 53 patients). Vomiting, nausea, asthenia/fatigue, and anorexia were common but not severe. Although the MTD was not formally determined, an 1,800-mg dose was selected in compliance with the protocol for additional study, given the dose-limiting CRS at higher doses and pharmacodynamic activity at lower doses. LCL161 was rapidly absorbed, and exposure was generally increased with dose. The tablet formulation of LCL161 was better tolerated than the solution; tablet and solution formulations had similar exposures, and the solution was discontinued. No patient had an objective response. LCL161 induced degradation of cellular IAP1 protein in the blood, skin, and tumor and increased circulating cytokine levels.

CONCLUSION

The 1,800-mg dose of LCL161, administered as a single agent once weekly, in tablet formulation is the recommended dose for additional study. This combined dose and formulation was well tolerated and had significant pharmacodynamic activity, which warrants additional investigation.

Genetic heterogeneity beyond CYP2C8*3 does not explain differential sensitivity to paclitaxel-induced neuropathy

The development of paclitaxel-induced peripheral neuropathy (PIPN) is influenced by drug exposure and patient genetics. The purpose of this analysis was to expand on a previous reported association of CYP2C8*3 and PIPN risk by investigating additional polymorphisms in CYP2C8 and in hundreds of other genes potentially relevant to paclitaxel pharmacokinetics. Clinical data was collected prospectively in an observational registry of newly diagnosed breast cancer patients. Patients treated with paclitaxel-containing regimens were genotyped using the Affymetrix DMET™ Plus chip. Patients who carried the CYP2C8*2, *3, or *4 variant were collapsed into a low-metabolizer CYP2C8 phenotype for association with PIPN. Separately, all SNPs that surpassed quality control were assessed individually and as a composite of genetic ancestry for associations with PIPN. 412 paclitaxel-treated patients and 564 genetic markers were included in the analysis. The risk of PIPN was significantly greater in the CYP2C8 low-metabolizer group (HR = 1.722, p = 0.018); however, the influences of the *2 and *4 SNPs were not independently significant (*2: p = 0.847, *4: p = 0.408). One intronic SNP in ABCG1 (rs492338) surpassed the exploratory significance threshold for an association with PIPN in the Caucasian cohort (p = 0.0008) but not in the non-Caucasian replication group (p = 0.54). Substantial genetic variability was observed within self-reported racial groups but this genetic variability was not associated with risk of grade 2+ PIPN. The pharmacogenetic heterogeneity within a cohort of breast cancer patients is dramatic, though we did not find evidence that this heterogeneity directly influences the risk of PIPN beyond the contribution of CYP2C8*3.

Abstract P2-16-13: Phase I dose escalation clinical trial of the PI3K inhibitor BKM120 and capecitabine (C) in metastatic breast cancer (MBC)

Background: PIK3CA is one of the most frequently mutated genes in human breast cancer, and the high expression of a PIK3CA-pathway signature is associated with the poor prognosis Luminal B and Basal-like expression subtypes. BKM120 is an oral pan-class I phosphatidylinositol-3-kinase (PI3K) inhibitor, which has shown activity in preclinical and early clinical testing, and synergy with both endocrine and chemotherapy. In this trial we sought to evaluate the safety and estimate the maximum tolerated dose (MTD) of the combination of BKM120 and C in patients (pts) with MBC.

Methods: In a 3+3 dose escalation design, we evaluated four cohorts of BKM 120 daily plus C BID x 14 days in 21 day cycles. Standard definitions for DLT and MTD were used and evaluated on the first cycle. Toxicity was graded by CTCAE version 4. Response was evaluated after 2 cycles by RECIST criteria. Pts with MBC appropriate for treatment with C who had &lt;4 prior chemotherapy regimens and normal organ, bone marrow and cardiac parameters were eligible.

Results: 21 pts (11 hormone receptor (HR)+, 3 HER2+, 9 HR/HER2-negative) were enrolled and treated. All were evaluable for toxicity and 14 for response to date. Median age was 54 (range 35-65). Median prior chemotherapy regimens for MBC was 2 (range 1-4). The following dose levels (DL) were evaluated: BKM120 50 mg/d + C 1000 mg/m2/BID x 14(DL 1-4 pts), BKM120 80 mg/d + C 1000 mg/m2/BID x 14 (DL2-3 pts), BKM120 100 mg/d + C 1000 mg/m2/BID x 14 (DL3-9 pts), BKM120 100 mg/d + C 1250 mg/m2/BID x 14 (DL4-5 pts). Most frequent adverse events (all grades) included: Nausea (12), mood disorders (11), PPE (9), diarrhea (8), fatigue (7), vomiting (5) mucositis (4), rash (4), photosensitivity (3), hyperglycemia (3). Grade 3 or higher AEs in any cycle were transaminitis (3) diarrhea (2) mood disorder (2), hyperglycemia, fatigue, photosensitivity, PPE (1 pt each). DLTs: grade 3 hyperglycemia (1/6 pts at DL3), and grade 3 mood disorder in 1/5 pts DL 4. Additionally 4 of 5 patients at DL 4 required dose reduction or delay prior to C3D1. Thus DL 4 exceeded the MTD and DL 3 was expanded for further safety evaluation. Antitumor activity was seen with best responses of 1 CR (at DL 3), 3 PR (DL1 and 4) and 7 SD.

PK analysis, assessment of tumor PIK3CA mutation status and intrinsic subtype by PAM50 is ongoing.

Conclusions: The combination of BKM120 100 mg po q day and C 1000 mg/m2 / BID x 14 d in 21 day cycles is tolerable and appears active. PK and biomarker analysis are ongoing. A phase II trial is planned.

Acknowledgements: This study was funded by Novartis Pharmaceuticals and by a grant from Susan G. Komen for the Cure (SAC 110044).

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-16-13.

Drug interaction potential of trastuzumab emtansine (T-DM1) combined with pertuzumab in patients with HER2-positive metastatic breast cancer

Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate comprised of trastuzumab and the cytotoxic agent DM1 (derivative of maytansine) linked by a stable linker N-succinimidyl 4-(N-maleimidomethyl) cyclohexane-1-carboxylate (SMCC). T-DM1 targets an epitope located at subdomain IV of human epidermal growth factor receptor 2 (HER2). Pertuzumab is a monoclonal antibody that targets an epitope located at subdomain II of HER2, distinct from the epitope recognized by T-DM1. The pharmacokinetics (PK), safety, and efficacy of T-DM1 combined with pertuzumab were studied in a phase 1b/2 trial in 67 patients with HER2-positive, locally advanced or metastatic breast cancer (MBC). The therapeutic protein-drug interaction (TP-DI) potential of T-DM1 plus pertuzumab was evaluated. The PK of T-DM1-related analytes and pertuzumab were compared with historical PK data. The results show that the exposure of T-DM1 and DM1, as estimated by noncompartmental analyses, was comparable with that reported by historical single-agent studies in patients with HER2-positive MBC. T-DM1 clearance and volume of distribution in the central compartment, as estimated by population PK analysis, were also comparable between this study and historical single-agent studies in patients with HER2-positive MBC. Summary statistics of pertuzumab trough and maximal exposure (concentrations at predose and 15-30 minutes after the end of infusion at cycle 1 and at steady state) were similar with those observed in a representative historical single-agent study with the same dosing regimen. The visual predictive check plot by population simulation further confirmed that T-DM1 did not alter pertuzumab PK. Based on these data and the PK and pharmacodynamic properties of T-DM1 and pertuzumab, the risk of TP-DI appears to be low when T-DM1 and pertuzumab are given together.

CYP2C8*3 increases risk of neuropathy in breast cancer patients treated with paclitaxel

BACKGROUND

Paclitaxel-induced neuropathy is an adverse event that often leads to therapeutic disruption and patient discomfort. We attempted to replicate a previously reported association between increased neuropathy risk and CYP2C8*3 genotype.

PATIENTS AND METHODS

Demographic, treatment, and toxicity data were collected for paclitaxel-treated breast cancer patients who were genotyped for the CYP2C8*3 K399R (rs10509681) variant. A log-rank test was used in the primary analysis of European-American patients. An additional independent replication was then attempted in a cohort of African-American patients, followed by modeling of the entire patient cohort with relevant covariates.

RESULTS

In the primary analysis of 209 European patients, there was an increased risk of paclitaxel-induced neuropathy related to CYP2C8*3 status [HR (per allele) = 1.93 (95% CI: 1.05-3.55), overall log-rank P = 0.006]. The association was replicated in direction and magnitude of effect in 107 African-American patients (P = 0.043). In the Cox model using the entire mixed-race cohort (n = 411), each CYP2C8*3 allele approximately doubled the patient's risk of grade 2+ neuropathy (P = 0.004), and non-Europeans were at higher neuropathy risk than Europeans of similar genotype (P = 0.030).

CONCLUSIONS

The increased risk of paclitaxel-induced neuropathy in patients who carry the CYP2C8*3 variant was replicated in two racially distinct patient cohorts.

Abstract PD10-07: Patients carrying CYP2C8*3 are at increased risk of paclitaxel-induced neuropathy

Background: Paclitaxel-induced neuropathy is a common, severe adverse event that seems to be related to cumulative drug exposure. Examining a neoadjuvantly treated cohort, we previously found increased neuropathy risk in patients carrying the CYP2C8*3 variant, which is associated with altered paclitaxel metabolism. To confirm this association, we examined the univariate association of CYP2C8*3 genotype and paclitaxel-induced neuropathy first in an independent cohort, then as a combined multivariable analysis.

Methods: CYP2C8*3 is more common in Caucasians (Allele Frequency [AF]=0.14) than other racial groups (African-American AF=0.04). To avoid potential issues with population stratification, initial univariate analysis was performed on 209 self-reported Caucasian breast cancer patients from a prospective cohort study (LCCC 9830) who were treated with paclitaxel-based regimens and had not been previously analyzed. The CYP2C8*3 (K399R) variant was genotyped on the Affymetrix DMET™ Plus Chip (Affymetrix, Inc., Santa Clara, CA, USA) at Gentris Corp. (Gentris Corp. Morrisville, NC) from germline DNA collected at diagnosis. The primary endpoint was the dose-at-grade 2+ neuropathy as defined by NCI CTC criteria. Statistical analysis was carried out using the log-rank test across the three genotype groups (*1/*1, *1/*3, *3/*3). The Caucasian cohort was then combined with 78 Caucasian patients from our previous neoadjuvant study and 124 non-Caucasian patients to build a multivariate Cox proportional hazards model. We performed model selection using backward elimination with AIC on a main effects model that included potential covariates: race, age, diabetes, paclitaxel schedule, and supplemental neuropathy therapy. A standard alpha=0.05 was used as the significance threshold for the primary log-rank analysis.

Results: The allele frequencies were similar to that expected and the distribution of alleles conformed to Hardy-Weinberg proportions for the Caucasian and non-Caucasian cohorts. 209 Caucasian breast cancer patients treated with paclitaxel were evaluated in the primary analysis, 35 (17%) of whom experienced grade 2+ peripheral neuropathy. The risk of neuropathy was significantly associated with CYP2C8*3 in the primary analysis (log-rank p = 0.006). A combined cohort of 411 patients were evaluable in the Cox model, 76 (18%) of whom experienced grade 2+ neuropathy during treatment. After backward elimination of covariates that did not contribute to the Cox model, increased age (HR = 1.02 [95% CI: 1.00–1.04], p = 0.102), non-Caucasian race (HR = 1.76 [1.05–2.93], p = 0.031), and CYP2C8*3 (Additive Model: HR=1.98 [1.25–3.13], p = 0.004, no model assumed: p = 0.023) were associated with increased risk of paclitaxel-induced neuropathy.

Conclusions: We have replicated in an independent population the finding that patients carrying CYP2C8*3 are at increased risk of paclitaxel-induced neuropathy, with risk approximately doubling for each *3 variant carried. After adjusting for CYP2C8 genotype we detected an increase in neuropathy risk for non-Caucasians which is consistent with a previous finding and supports the need to better understand the overall etiology of neuropathy risk.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr PD10-07.