Ribociclib plus Endocrine Therapy in Early Breast Cancer

BACKGROUND

Ribociclib has been shown to have a significant overall survival benefit in patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer. Whether this benefit in advanced breast cancer extends to early breast cancer is unclear.

METHODS

In this international, open-label, randomized, phase 3 trial, we randomly assigned patients with HR-positive, HER2-negative early breast cancer in a 1:1 ratio to receive ribociclib (at a dose of 400 mg per day for 3 weeks, followed by 1 week off, for 3 years) plus a nonsteroidal aromatase inhibitor (NSAI; letrozole at a dose of 2.5 mg per day or anastrozole at a dose of 1 mg per day for ≥5 years) or an NSAI alone. Premenopausal women and men also received goserelin every 28 days. Eligible patients had anatomical stage II or III breast cancer. Here we report the results of a prespecified interim analysis of invasive disease-free survival, the primary end point; other efficacy and safety results are also reported. Invasive disease-free survival was evaluated with the use of the Kaplan-Meier method. The statistical comparison was made with the use of a stratified log-rank test, with a protocol-specified stopping boundary of a one-sided P-value threshold of 0.0128 for superior efficacy.

RESULTS

As of the data-cutoff date for this prespecified interim analysis (January 11, 2023), a total of 426 patients had had invasive disease, recurrence, or death. A significant invasive disease-free survival benefit was seen with ribociclib plus an NSAI as compared with an NSAI alone. At 3 years, invasive disease-free survival was 90.4% with ribociclib plus an NSAI and 87.1% with an NSAI alone (hazard ratio for invasive disease, recurrence, or death, 0.75; 95% confidence interval, 0.62 to 0.91; P = 0.003). Secondary end points - distant disease-free survival and recurrence-free survival - also favored ribociclib plus an NSAI. The 3-year regimen of ribociclib at a 400-mg starting dose plus an NSAI was not associated with any new safety signals.

CONCLUSIONS

Ribociclib plus an NSAI significantly improved invasive disease-free survival among patients with HR-positive, HER2-negative stage II or III early breast cancer. (Funded by Novartis; NATALEE ClinicalTrials.gov number, NCT03701334.).

Intrinsic Subtype and Overall Survival of Patients with Advanced HR+/HER2- Breast Cancer Treated with Ribociclib and ET: Correlative Analysis of MONALEESA-2, -3, -7

PURPOSE

The MONALEESA-2, -3, -7 trials demonstrated statistically significant and clinically meaningful progression-free survival and overall survival (OS) benefits with ribociclib plus endocrine therapy (ET) versus ET alone in hormone receptor-positive, HER2-negative (HR+/HER2-) advanced breast cancer (ABC). Understanding the association of intrinsic subtypes with survival outcomes could potentially guide treatment decisions. Here, we evaluated the association of intrinsic subtypes with OS in MONALEESA-2, -3, -7.

EXPERIMENTAL DESIGN

Tumor samples from MONALEESA-2, -3, -7 underwent PAM50-based subtyping. The relationship between subtypes and OS was assessed using univariable and multivariable Cox proportional hazards models. Multivariable models were adjusted for clinical prognostic factors.

RESULTS

Overall, 990 tumors (among 2,066 patients) from ribociclib (n = 580) and placebo (n = 410) arms were profiled. Subtype distribution was luminal A, 54.5%; luminal B, 28.0%; HER2-enriched (HER2E) 14.6%; and basal-like, 2.8%; and was consistent across treatment arms. The luminal A subtype had the best OS outcomes in both arms, while basal-like had the worst. Patients with HER2E (HR, 0.60; P = 0.018), luminal B (HR, 0.69; P = 0.023), and luminal A (HR, 0.75; P = 0.021) subtypes derived OS benefit with ribociclib. Patients with basal-like subtype did not derive benefit from ribociclib (HR, 1.92; P = 0.137); however, patient numbers were small (n = 28).

CONCLUSIONS

The prognostic value of intrinsic subtypes for OS was confirmed in this pooled analysis of the MONALEESA trials (largest dataset in HR+/HER2- ABC). While basal-like subtype did not benefit, a consistent OS benefit was observed with ribociclib added to ET across luminal and HER2E subtypes.

HER2 heterogeneity and treatment response-associated profiles in HER2-positive breast cancer in the NCT02326974 clinical trial

BACKGROUNDHER2-targeting therapies have great efficacy in HER2-positive breast cancer, but resistance, in part due to HER2 heterogeneity (HET), is a significant clinical challenge. We previously described that in a phase II neoadjuvant trastuzumab emtansine (T-DM1) and pertuzumab (P) clinical trial in early-stage HER2-positive breast cancer, none of the patients with HER2-HET tumors had pathologic complete response (pCR).METHODSTo investigate cellular and molecular differences among tumors according to HER2 heterogeneity and pCR, we performed RNA sequencing and ERBB2 FISH of 285 pretreatment and posttreatment tumors from 129 patients in this T-DM1+P neoadjuvant trial. A subset of cases was also subject to NanoString spatial digital profiling.RESULTSPretreatment tumors from patients with pCR had the highest level of ERBB2 mRNA and ERBB signaling. HER2 heterogeneity was associated with no pCR, basal-like features, and low ERBB2 expression yet high ERBB signaling sustained by activation of downstream pathway components. Residual tumors showed decreased HER2 protein levels and ERBB2 copy number heterogeneity and increased PI3K pathway enrichment and luminal features. HET tumors showed minimal treatment-induced transcriptomic changes compared with non-HET tumors. Immune infiltration correlated with pCR and HER2-HET status.CONCLUSIONResistance mechanisms in HET and non-HET tumors are distinct. HER2-targeting antibodies have limited efficacy in HET tumors. Our results support the stratification of patients based on HET status and the use of agents that target downstream components of the ERBB signaling pathway in patients with HET tumors.TRIAL REGISTRATIONClinicalTrials.gov NCT02326974.FUNDINGThis study was funded by Roche and the National Cancer Institute.

Matching-adjusted indirect comparison of PFS and OS comparing ribociclib plus letrozole versus palbociclib plus letrozole as first-line treatment of HR+/HER2- advanced breast cancer

Background

Current standard-of-care first-line treatment of patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced breast cancer (ABC) is cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) + endocrine therapy. In the MONALEESA-2 trial, first-line ribociclib + letrozole demonstrated statistically significant overall survival (OS) benefit versus placebo + letrozole in postmenopausal patients with HR+/HER2- ABC. In the PALOMA-2 trial, first-line palbociclib + letrozole did not show OS benefit versus placebo + letrozole in a similar patient population. Understanding OS outcomes in the respective trials is critical for treatment decisions; however, there are no head-to-head clinical trial data comparing ribociclib and palbociclib.

Objectives

To conduct a matching-adjusted indirect comparison (MAIC) to compare progression-free survival (PFS) and OS of first-line ribociclib + letrozole versus palbociclib + letrozole in postmenopausal patients with HR+/HER2- ABC.

Design

Letrozole-anchored MAIC using individual patient data from MONALEESA-2 and published summary data from PALOMA-2.

Methods

Using individual data, patients from MONALEESA-2 who matched inclusion criteria from PALOMA-2 were selected, and weighting was conducted to ensure baseline characteristics were similar to those in published aggregated data from PALOMA-2. The Bucher method was used to generate corresponding hazard ratios (HRs).

Results

The final effective sample size compared n = 150 (ribociclib) and n = 112 (placebo) MONALEESA-2 patients with n = 444 (palbociclib) and n = 222 (placebo) PALOMA-2 patients. After matching and weighting, patient characteristics were well balanced. MAIC analysis showed a numerical PFS benefit [HR, 0.80; 95% confidence interval (CI), 0.58-1.11; p = 0.187] and significant OS benefit (HR, 0.68; 95% CI, 0.48-0.96; p = 0.031) with ribociclib + letrozole versus palbociclib + letrozole.

Conclusion

Results of this cross-trial MAIC analysis showed a numerical PFS benefit and significantly greater OS benefit with first-line ribociclib + letrozole versus palbociclib + letrozole. These results support letrozole + ribociclib as the preferred first-line CDK4/6i for postmenopausal patients with HR+/HER2- ABC.

Trial registration

NCT01958021; https://www.clinicaltrials.gov/study/NCT01958021 (MONALEESA-2) and NCT01740427; https://clinicaltrials.gov/study/NCT01740427 (PALOMA-2).

Endocrine Therapy Synergizes with SMAC Mimetics to Potentiate Antigen Presentation and Tumor Regression in Hormone Receptor-Positive Breast Cancer

Immunotherapies have yet to demonstrate significant efficacy in the treatment of hormone receptor-positive (HR+) breast cancer. Given that endocrine therapy (ET) is the primary approach for treating HR+ breast cancer, we investigated the effects of ET on the tumor immune microenvironment (TME) in HR+ breast cancer. Spatial proteomics of primary HR+ breast cancer samples obtained at baseline and after ET from patients enrolled in a neoadjuvant clinical trial (NCT02764541) indicated that ET upregulated β2-microglobulin and influenced the TME in a manner that promotes enhanced immunogenicity. To gain a deeper understanding of the underlying mechanisms, the intrinsic effects of ET on cancer cells were explored, which revealed that ET plays a crucial role in facilitating the chromatin binding of RelA, a key component of the NF-κB complex. Consequently, heightened NF-κB signaling enhanced the response to interferon-gamma, leading to the upregulation of β2-microglobulin and other antigen presentation-related genes. Further, modulation of NF-κB signaling using a SMAC mimetic in conjunction with ET augmented T-cell migration and enhanced MHC-I-specific T-cell-mediated cytotoxicity. Remarkably, the combination of ET and SMAC mimetics, which also blocks prosurvival effects of NF-κB signaling through the degradation of inhibitors of apoptosis proteins, elicited tumor regression through cell autonomous mechanisms, providing additional support for their combined use in HR+ breast cancer.

SIGNIFICANCE

Adding SMAC mimetics to endocrine therapy enhances tumor regression in a cell autonomous manner while increasing tumor immunogenicity, indicating that this combination could be an effective treatment for HR+ patients with breast cancer.

Neoadjuvant palbociclib plus either giredestrant or anastrozole in oestrogen receptor-positive, HER2-negative, early breast cancer (coopERA Breast Cancer): an open-label, randomised, controlled, phase 2 study

BACKGROUND

The development of more potent selective oestrogen receptor antagonists and degraders (SERDs) that can be orally administered could help to address the limitations of current endocrine therapies. We report the primary and final analyses of the coopERA Breast Cancer study, designed to test whether giredestrant, a highly potent, non-steroidal, oral SERD, would show a stronger anti-proliferative effect than anastrozole after 2 weeks for oestrogen receptor-positive, HER2-negative, untreated early breast cancer.

METHODS

In this open-label, randomised, controlled, phase 2 study, postmenopausal women were eligible if they were aged 18 years or older; had clinical T stage (cT)1c to cT4a-c (≥1·5 cm within cT1c) oestrogen receptor-positive, HER2-negative, untreated early breast cancer; an Eastern Cooperative Oncology Group performance status of 0-1; and baseline Ki67 score of at least 5%. The study was conducted at 59 hospital or clinic sites in 11 countries globally. Participants were randomly assigned (1:1) to giredestrant 30 mg oral daily or anastrozole 1 mg oral daily on days 1-14 (window-of-opportunity phase) via an interactive web-based system with permuted-block randomisation with block size of four. Randomisation was stratified by cT stage, baseline Ki67 score, and progesterone receptor status. A 16-week neoadjuvant phase comprised the same regimen plus palbociclib 125 mg oral daily on days 1-21 of a 28-day cycle, for four cycles. The primary endpoint was geometric mean relative Ki67 score change from baseline to week 2 in patients with complete central Ki67 scores at baseline and week 2 (window-of-opportunity phase). Safety was assessed in all patients who received at least one dose of study drug. The study is registered with ClinicalTrials.gov (NCT04436744) and is complete.

FINDINGS

Between Sept 4, 2020, and June 22, 2021, 221 patients were enrolled and randomly assigned to the giredestrant plus palbociclib group (n=112; median age 62·0 years [IQR 57·0-68·5]) or anastrozole plus palbociclib group (n=109; median age 62·0 [57·0-67·0] years). 15 (7%) of 221 patients were Asian, three (1%) were Black or African American, 194 (88%) were White, and nine (4%) were unknown races. At data cutoff for the primary analysis (July 19, 2021), the geometric mean relative reduction of Ki67 from baseline to week 2 was -75% (95% CI -80 to -70) with giredestrant and -67% (-73 to -59) with anastrozole (p=0·043), meeting the primary endpoint. At the final analysis (data cutoff Nov 24, 2021), the most common grade 3-4 adverse events were neutropenia (29 [26%] of 112 in the giredestrant plus palbociclib group vs 29 [27%] of 109 in the anastrozole plus palbociclib group) and decreased neutrophil count (17 [15%] vs 16 [15%]). Serious adverse events occurred in five (4%) patients in the giredestrant plus palbociclib group and in two (2%) patients in the anastrozole plus palbociclib group. There were no treatment-related deaths. One patient died due to an adverse event in the giredestrant plus palbociclib group (myocardial infarction).

INTERPRETATION

Giredestrant offers encouraging anti-proliferative and anti-tumour activity and was well tolerated, both as a single agent and in combination with palbociclib. Results justify further investigation in ongoing trials.

FUNDING

F Hoffmann-La Roche.

Rationale and trial design of NATALEE: a Phase III trial of adjuvant ribociclib + endocrine therapy versus endocrine therapy alone in patients with HR+/HER2- early breast cancer

Background

Ribociclib has demonstrated a statistically significant overall survival benefit in pre- and postmenopausal patients with hormone receptor positive/human epidermal growth factor receptor 2 negative (HR+/HER2-) advanced breast cancer. New Adjuvant Trial with Ribociclib [LEE011] (NATALEE) is a trial evaluating the efficacy and safety of adjuvant ribociclib plus endocrine therapy (ET) versus ET alone in patients with HR+/HER2- early nonmetastatic breast cancer (EBC).

Methods/design

NATALEE is a multicenter, randomized, open-label, Phase III trial in patients with HR+/HER2- EBC. Eligible patients include women, regardless of menopausal status, and men aged ⩾18 years. Select patients with stage IIA, stage IIB, or stage III disease (per the anatomic classification in the AJCC Cancer Staging Manual, 8th edition) with an initial diagnosis ⩽18 months prior to randomization are eligible. Patients receiving standard (neo)adjuvant ET are eligible if treatment was initiated ⩽12 months before randomization. Patients undergo 1:1 randomization to ribociclib 400 mg/day (3 weeks on/1 week off) +ET (letrozole 2.5 mg/day or anastrozole 1 mg/day [investigator's discretion] plus goserelin [men or premenopausal women]) or ET alone. Ribociclib treatment duration is 36 months; ET treatment duration is ⩾60 months. The primary end point is invasive disease-free survival.

Discussion

The 36-month treatment duration of ribociclib in NATALEE is extended compared with that in other adjuvant cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitor trials and is intended to maximize efficacy due to longer duration of CDK4/6 inhibition. Compared with the 600-mg/day dose used in advanced breast cancer, the reduced ribociclib dose used in NATALEE may improve tolerability while maintaining efficacy. NATALEE includes the broadest population of patients with HR+/HER2- EBC of any Phase III trial currently evaluating adjuvant CDK4/6 inhibitor treatment.

Trial registration

ClinicalTrials.gov identifier: NCT03701334 (https://clinicaltrials.gov/ct2/show/NCT03701334).

Adjuvant paclitaxel and trastuzumab for node-negative, HER2-positive breast cancer: final 10-year analysis of the open-label, single-arm, phase 2 APT trial

BACKGROUND

We aimed to report on long-term outcomes of patients with small, node-negative, HER2-positive breast cancer treated with adjuvant paclitaxel and trastuzumab and to establish potential biomarkers to predict prognosis.

METHODS

In this open-label, single-arm, phase 2 study, patients aged 18 years or older, with small (≤3 cm), node-negative, HER2-positive breast cancer, and an Eastern Cooperative Oncology Group performance status of 0-1, were recruited from 16 institutions in 13 cities in the USA. Eligible patients were given intravenous paclitaxel (80 mg/m²) with intravenous trastuzumab (loading dose of 4 mg/kg, subsequent doses 2 mg/kg) weekly for 12 weeks, followed by trastuzumab (weekly at 2 mg/kg or once every 3 weeks at 6 mg/kg) for 40 weeks to complete a full year of trastuzumab. The primary endpoint was 3-year invasive disease-free survival. Here, we report 10-year survival outcomes, assessed in all participants who received protocol-defined treatment, with exploratory analyses using the HER2DX genomic tool. This study is registered on ClinicalTrials.gov, NCT00542451, and is closed to accrual.

FINDINGS

Between Oct 29, 2007, and Sept 3, 2010, 410 patients were enrolled and 406 were given adjuvant paclitaxel and trastuzumab and included in the analysis. Mean age at enrolment was 55 years (SD 10·5), 405 (99·8%) of 406 patients were female and one (0·2%) was male, 350 (86·2%) were White, 28 (6·9%) were Black or African American, and 272 (67·0%) had hormone receptor-positive disease. After a median follow-up of 10·8 years (IQR 7·1-11·4), among 406 patients included in the analysis population, we observed 31 invasive disease-free survival events, of which six (19·4%) were locoregional ipsilateral recurrences, nine (29·0%) were new contralateral breast cancers, six (19·4%) were distant recurrences, and ten (32·3%) were all-cause deaths. 10-year invasive disease-free survival was 91·3% (95% CI 88·3-94·4), 10-year recurrence-free interval was 96·3% (95% CI 94·3-98·3), 10-year overall survival was 94·3% (95% CI 91·8-96·8), and 10-year breast cancer-specific survival was 98·8% (95% CI 97·6-100). HER2DX risk score as a continuous variable was significantly associated with invasive disease-free survival (hazard ratio [HR] per 10-unit increment 1·24 [95% CI 1·00-1·52]; p=0·047) and recurrence-free interval (1·45 [1·09-1·93]; p=0·011).

INTERPRETATION

Adjuvant paclitaxel and trastuzumab is a reasonable treatment standard for patients with small, node-negative, HER2-positive breast cancer. The HER2DX genomic tool might help to refine the prognosis for this population.

FUNDING

Genentech.

Margetuximab Versus Trastuzumab in Patients With Previously Treated HER2-Positive Advanced Breast Cancer (SOPHIA): Final Overall Survival Results From a Randomized Phase 3 Trial

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.Final overall survival (OS) in SOPHIA (ClinicalTrials.gov identifier: NCT02492711), a study of margetuximab versus trastuzumab, both with chemotherapy, in patients with previously treated human epidermal growth factor receptor 2-positive advanced breast cancer, is reported with updated safety. Overall, 536 patients in the intention-to-treat population were randomly assigned to margetuximab (15 mg/kg intravenously once every 3 weeks; n = 266) plus chemotherapy or trastuzumab (6 mg/kg intravenously once every 3 weeks after a loading dose of 8 mg/kg; n = 270) plus chemotherapy. Primary end points were progression-free survival, previously reported, and OS. Final OS analysis was triggered by 385 prespecified events. The median OS was 21.6 months (95% CI, 18.89 to 25.07) with margetuximab versus 21.9 months (95% CI, 18.69 to 24.18) with trastuzumab (hazard ratio [HR], 0.95; 95% CI, 0.77 to 1.17; P = .620). Preplanned, exploratory analysis of CD16A genotyping suggested a possible improvement in OS for margetuximab in CD16A-158FF patients versus trastuzumab (median OS, 23.6 v 19.2 months; HR, 0.72; 95% CI, 0.52 to 1.00) and a possible improvement in OS for trastuzumab in CD16A-158VV patients versus margetuximab (median OS, 31.1 v 22.0 months; HR, 1.77; 95% CI, 1.01 to 3.12). Margetuximab safety was comparable with trastuzumab. Final overall OS analysis did not demonstrate margetuximab advantage over trastuzumab. Margetuximab studies in patients with human epidermal growth factor receptor 2-positive breast cancer with different CD16A allelic variants are warranted.

Neoadjuvant giredestrant (GDC-9545) plus palbociclib (P) versus anastrozole (A) plus P in postmenopausal women with estrogen receptor–positive, HER2-negative, untreated early breast cancer (ER+/HER2– eBC): Final analysis of the randomized, open-label, international phase 2 coopERA BC study

589

Background: Endocrine therapy (ET) is the therapeutic mainstay for ER+ BC. Giredestrant is a highly potent, nonsteroidal, oral, selective ER antagonist and degrader (SERD) which has demonstrated robust ER occupancy, is well tolerated, and has previously shown encouraging antitumor activity as monotherapy and in combination with P in metastatic BC. coopERA BC (NCT04436744) evaluated giredestrant in eBC and met its primary endpoint, highlighting superior Ki67 suppression with single-agent giredestrant vs A at Week 2. Giredestrant was well tolerated. Here, we report the final analysis. Methods: Eligible patients (pts) with measurable ER+/HER2– untreated eBC and baseline Ki67 score ≥5% (202 planned) were randomized 1:1 to receive, on Days 1–14 of a neoadjuvant window-of-opportunity phase, 30 mg oral daily (PO QD) giredestrant or 1 mg PO QD A followed by a 16-week neoadjuvant phase of QD giredestrant or A for four 28-day cycles with 125 mg PO P on Days 1–21. Randomization was stratified by tumor size, baseline Ki67 score, and progesterone receptor status. Endpoints assessed here included Ki67 suppression from baseline to surgery, complete cell cycle arrest (CCCA; Ki67 ≤2.7%) at surgery, objective response rate (ORR), and safety. Results: At final analysis (cutoff: Nov 24, 2021), 112 and 109 pts were randomized to the giredestrant and A arms, respectively (median age: 62 years each; stage I/IIa disease: 60% vs 54%). Consistent with the primary analysis, greater suppression of Ki67 was observed at surgery with giredestrant + P (–81% [95% confidence interval (CI): –86%, –75%]) vs A + P (–74% [95% CI: –80%, –67%]). Similarly, greater CCCA was achieved at surgery with giredestrant + P (20%) vs A + P (14%). ORR was similar between the two arms (giredestrant + P: 50% [95% CI: 40%, 60%]; A + P: 49% [95% CI: 39%, 59%]). ET-related adverse events (AEs) were non-serious and occurred at similar rates between the two arms. Related Grade ≥3 AE rates were also similar at 6% each. Interruption/withdrawal of ET due to AEs was low and similar for both arms. Conclusions: In this final analysis of coopERA BC, the greater suppression of Ki67 with giredestrant vs A observed at Week 2 in the primary analysis was maintained at surgery, and safety data remained consistent with the known safety profile of giredestrant. coopERA BC is the first randomized study to show superior antiproliferative activity of an oral SERD (giredestrant) over an aromatase inhibitor (A) in ER+/HER2– eBC; studies are ongoing to further assess giredestrant’s clinical benefit. Clinical trial information: NCT04436744.

Abstract GS2-00: Correlative analysis of overall survival by intrinsic subtype across the MONALEESA-2, -3, and -7 studies of ribociclib + endocrine therapy in patients with HR+/HER2− advanced breast cancer

Background: The MONALEESA (ML)-2, -3, and -7 trials have shown a significant benefit in overall survival (OS) with ribociclib (RIB) + endocrine therapy (ET) over placebo (PBO) + ET in HR+/HER2− advanced breast cancer. HR+ breast cancer is a clinically and biologically heterogeneous disease, with identified intrinsic subtypes that vary in incidence, survival rate, and response to treatment. In a pooled analysis of the ML studies, patients with both luminal and HER2-enriched (HER2E) subtypes exhibited a consistent progression-free survival benefit with RIB + ET. The HER2E subtype (RIB, 14%; PBO, 11%), which is associated with ET resistance and poor outcomes, exhibited the greatest relative reduction in risk of progression or death (61%) with RIB + ET. Here, we report a pooled analysis of the ML-2, -3, and -7 trials, presenting OS by intrinsic subtype.. Methods: Tumor samples from patients enrolled in the ML-2, -3, and -7 trials underwent PAM50-based subtyping (blinded from clinical data), and the correlation between intrinsic subtype and OS was analyzed. Gene expression profiling of formalin-fixed, paraffin-embedded tumor samples was performed using a customized NanoString nCounter GX 800-gene panel. The prognostic and/or predictive relationship between PAM50-based subtypes and OS was evaluated using univariable and multivariable Cox proportional hazards models. Multivariable models were adjusted for known clinical prognostic factors, including age, prior chemotherapy, prior ET, ECOG performance status, visceral disease (presence of liver/lung metastases), bone-only metastases, histological grade, number of metastatic sites, tumor type, and de novo metastatic disease.. Results: From the pooled patient population (N = 2066), 997 tumor (71% primary) samples from the RIB (n = 585) and PBO (n = 412) arms of the ML trials (ML-2, n = 318; ML-3, n = 414; ML-7, n = 265) were profiled. Subtype distribution was consistent across treatment arms (Table). A similar benefit with RIB vs PBO was observed in the ITT (hazard ratio [HR], 0.76; 95% CI, 0.67-0.86) and biomarker (HR, 0.75; 95% CI, 0.63-0.89) populations. In both univariable and multivariable analyses, intrinsic subtype was prognostic for OS in both the RIB and PBO arms (P < .0001 for both arms); patients with luminal A subtype had the best OS outcomes in both arms, whereas patients with basal-like subtype had the worst OS outcomes. Intrinsic subtype was also predictive of OS (subtype-treatment interaction: P = .016 [univariable], P = .007 [multivariable]) with a consistent OS benefit with RIB treatment in all subtypes except for basal-like (Table). Patients with HER2E (HR, 0.60; P = .018), luminal B (HR, 0.69; P = .023), and luminal A (HR, 0.75; P = .021) subtypes all derived benefit from RIB. In patients with the basal-like subtype (n = 30), the HR was 1.89 (P = .148); these results should be interpreted with caution due to the small sample size (3% in each arm) and exploratory nature of this analysis.Conclusions: This pooled analysis of the ML trials confirmed the prognostic and predictive value of intrinsic subtype (PAM50 based) for OS. The addition of RIB to ET resulted in consistent OS benefit across all subtypes except for basal-like. The. consistent survival benefit in the HER2E subtype, which is associated with endocrine resistance and a very poor prognosis compared with luminal disease, warrants further investigation.

SubtypeTreatment ArmDistribution, n (%)OS, median (95% CI), monthsHR (95% CI)P ValueaLuminal ARIB320 (55)68.0 (61.5-NR)0.75 (0.58-0.96).021PBO222 (54)54.6 (48.3-66.2)Luminal BRIB154 (26)58.8 (48.3-79.2)0.69 (0.50-0.95).023PBO124 (30)44.9 (35.5-52.6)HER2-enrichedRIB95 (16)40.3 (33.4-49.0)0.60 (0.40-0.92).018PBO52 (13)29.4 (23.9-42.0)Basal-likeRIB16 (3)19.4 (10.7-33.2)1.89 (0.80-4.47).148PBO14 (3)21.2 (12.8-NR)aP values are all two-sided. NR, not reached.

Citation Format: Lisa Carey, Nadia Solovieff, Fabrice André, Joyce O'Shaughnessy, David A Cameron, Wolfgang Janni, Gabe S Sonke, Yoon-Sim Yap, Denise A Yardley, Juan Pablo Zarate, Tetiana Taran, Faye Su, Agnes Lteif, Aleix Prat. Correlative analysis of overall survival by intrinsic subtype across the MONALEESA-2, -3, and -7 studies of ribociclib + endocrine therapy in patients with HR+/HER2− advanced breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr GS2-00.

Abstract PD13-03: Ribociclib, everolimus, exemestane triplet therapy in HR+/HER2− advanced breast cancer after progression on a CDK4/6 inhibitor: Final efficacy, safety, and biomarker results from TRINITI-1

Background: Combination cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) and endocrine therapy (ET) is a standard-of-care treatment for hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2−) advanced breast cancer (ABC). However, disease progression inevitably occurs during CDK4/6i + ET treatment, highlighting the need for effective subsequent regimens. TRINITI-1 (NCT02732119) assessed triplet therapy with CDK4/6i ribociclib (RIB), mTORi everolimus (EVE), and ET exemestane (EXE) in patients (pts) with HR+/HER2− ABC who experienced disease progression on CDK4/6i treatment. We previously reported pooled Phase I/II results from TRINITI-1 demonstrating promising efficacy (per investigator assessment) and tolerability with RIB + EVE + EXE triplet therapy (Bardia, et al. Clin Cancer Res. 2021). Here we present the final efficacy (central review and OS) and safety data from the phase 2 study, and the final biomarker data. Methods: TRINITI-1 was a phase 1/2, multicenter, open-label study that enrolled postmenopausal women with ET-refractory HR+/HER2− ABC with most recent disease progression after ≥ 4 months of CDK4/6i treatment. Pts received once-daily, oral EXE 25 mg with either RIB 300 mg + EVE 2.5 mg (group 1) or RIB 200 mg + EVE 5 mg (group 2); all pts were given a prophylactic steroid mouthwash. Group 1 was enrolled first, followed by group 2; both began enrollment in phase 1 and were expanded in phase 2. Endpoints included clinical benefit rate (CBR) by 24 weeks (primary endpoint), progression-free survival (PFS), overall survival (OS), tumor response, and safety/tolerability. Results: A total of 79 pts (n = 46, group 1; n = 33, group 2) were enrolled and treated. Median age was 58.0 years (range, 32.0-83.0 years) and median prior CDK4/6i duration was 12.1 months (range, 3.5-34.0 months). As of the cutoff date (June 15, 2020), 73 pts (92.4%) had discontinued study treatment; the primary reasons included progressive disease (67.1%) and physician decision (16.5%). The CBR by week 24 (central review) was 65.2% and 59.4% for groups 1 and 2, respectively; the objective response rate was 6.5% and 9.4%, respectively (Table). Median PFS by central review was 8.0 months in group 1 and 4.7 months in group 2. For pts with ≥ 12 months of prior CDK4/6i, median PFS was 12.8 months in group 1 and 5.5 months in group 2; for those with < 12 months of prior CDK4/6i, median PFS was 5.3 months in group 1 and 3.6 months in group 2. Biomarker analysis showed numerically shorter median PFS when tumors expressed ESR1 or PIK3CA alterations. Median OS was 27.4 months in group 1 and not reached (NR) in group 2 at study end. For pts with ≥ 12 months of prior CDK4/6i, median OS was NR in both groups, and was 20.3 months (group 1) and 18.8 months (group 2) for pts with < 12 months of prior CDK4/6i. The most common all-grade adverse events were stomatitis (54.3%), infections (50.0%), neutropenia (43.5%), and fatigue (43.5%) in group 1, and infections (48.5%), nausea (42.4%), stomatitis (36.4%), and thrombocytopenia (36.4%) in group 2. There was no grade > 2 QTc prolongation. Conclusions: Results from TRINITI-1 demonstrate that triplet therapy with RIB + EVE + EXE is a relatively well tolerated and clinically active regimen directly following treatment with a CDK4/6i. There was a trend toward better outcomes in pts with longer durations of prior CDK4/6i treatment, wild-type ESR1, and wild-type PIK3CA.

Tumor response by central reviewGroup 1: RIB 300 mg,. EVE 2.5 mg, EXE 25 mg (n = 46)Group 2: RIB 200 mg,. EVE 5 mg, EXE 25 mg (n = 32)aCBR, n (%) by week 24b30 (65.2)c19 (59.4)dORR, n (%)e3 (6.5)3 (9.4)SurvivalMedian PFS by central review, months8.04.7HR (95% CI) = 0.740 (0.424-1.291)Median OS, months27.4NESurvival by duration of prior CDK4/6iGroup 1: RIB 300 mg,. EVE 2.5 mg, EXE 25 mg (n = 46)Group 2: RIB 200 mg,. EVE 5 mg, EXE 25 mg (n = 32)a< 12 months. (n = 27)≥ 12 months. (n = 19)< 12 months (n = 11)≥ 12 months (n = 21)Median PFS, months5.312.83.65.5Median OS, months20.3NR18.8NRMedian PFS by tumor mutation status, monthsWTAlteredHR (95% CI)ESR19.1 (n = 59)2.8 (n = 30)1.678 (0.995-2.828)PIK3CA 9.1 (n = 59)5.7 (n = 30)1.275 (0.756-2.150)BOR, best overall response; CBR, clinical benefit rate; CDK4/6i, cyclin-dependent kinase 4/6 inhibitor; CI, confidence interval; CR, complete response; ESR1, estrogen receptor 1; EVE, everolimus; EXE, exemestane; HR, hazard ratio; NR, not reached; ORR, objective response rate; OS, overall survival; PD, progressive disease; PIK3CA, phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha; PFS, progression-free survival; PR, partial response; pt, patient; RIB, ribociclib; SD, stable disease; WT, wild type. aOne pt did not progress on prior CDK4/6i and thus was not evaluable for efficacy. bBOR of CR, PR, SD, or non-CR/non-PD. cn = 10 required to show a clinical benefit. dn = 8 required to show a clinical benefit. eBOR of CR or PR.

Citation Format: Sara A. Hurvitz, Amy S. Clark, Hope S. Rugo, Aditya Bardia, Amelia Zelnak, Denise A. Yardley, Meghan Karuturi, Tara Sanft, Sibel Blau, Lowell Hart, Cynthia Ma, Das Purkayastha, Colleen Eppig, Angela DeMichele. Ribociclib, everolimus, exemestane triplet therapy in HR+/HER2− advanced breast cancer after progression on a CDK4/6 inhibitor: Final efficacy, safety, and biomarker results from TRINITI-1 [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD13-03.

Next-Generation Sequencing of Patients With Breast Cancer in Community Oncology Clinics

PURPOSE

Molecular biomarkers informing disease diagnosis, prognosis, and treatment decisions in patients with breast cancer are being uncovered by next-generation sequencing (NGS) technologies. In this study, we survey how NGS is used for patients with breast cancer in real-world settings with a focus on physician behaviors and sequencing results.

METHODS

We conducted a retrospective analysis of patients with breast cancer who received NGS testing from commercial vendors as part of standard of care from 2014 to 2019. A total of 2,635 NGS reports from 2,316 unique breast cancer patients were assessed. Hormone receptor and human epidermal growth factor receptor 2 statuses were abstracted from patient medical records. Comparative gene amplification and mutation frequencies were analyzed using Pearson's correlation and Lin's concordance statistics.

RESULTS

The number of physicians ordering NGS tests for patients with breast cancer increased more than six-fold from 2014 to 2019. Tissue- and plasma-based tests were ordered roughly equally by 2019, with plasma-based testing ordered most frequently in hormone receptor-positive subtypes. Patients with triple-negative breast cancer were most likely to receive NGS testing. Gene amplifications including ERBB2 were detected less frequently in our real-world data set as compared to previous genomic landscape studies, whereas the opposite was true for gene mutations including ESR1. Pathogenic mutations in the PI3K pathway (38.6%) and DNA damage repair pathway (11.0%) were frequently reported. Alterations were also reported across other cellular pathways.

CONCLUSION

Overall, we found that an increasing number of physicians in community settings are adopting NGS in the care of patients with breast cancer. Discrepancies between our real-world NGS data and previous genomic landscape studies are likely owed to the prevalence of plasma-based testing in community oncology clinics, as the reference data were from tissue-based NGS alone.

A Phase II Study Evaluating Orteronel, an Inhibitor of Androgen Biosynthesis, in Patients With Androgen Receptor (AR)-Expressing Metastatic Breast Cancer (MBC)

BACKGROUND

AR is a targetable pathway with AR modulation inhibiting estrogen- and androgen-mediated cell proliferation. Orteronel is an oral, selective, nonsteroidal inhibitor of 17, 20-lyase, a key enzyme in androgen biosynthesis. This study evaluated single-agent orteronel in AR+ metastatic breast cancer (MBC).

METHODS

Male/female patients with AR+ MBC were grouped in Cohort 1: AR+ TNBC with l-3 prior chemotherapy regimens or Cohort 2: AR+ HR+ (estrogen [ER+]/ progesterone receptor [PR+] positive) HER2+/- with 1 to 3 prior hormonal and at least 1 prior chemotherapy regimen. Patients with HER2+ MBC must have received at least 2 lines of HER2-targeted therapy. Orteronel was administered at 300 mg BID; response rate was the primary endpoint.

RESULTS

Seventy patients were enrolled (Cohort 1, n = 26 and Cohort 2, n = 44). Median treatment duration was 7.1 weeks. Seven patients were on treatment for ≥6 months. One of the 21 evaluated patients in Cohort 1 (4.8%) had an objective response. In Cohort 2, none of the first 23 patients to be evaluated had a response and accrual was stopped. Median progression-free and overall survival were 1.8 and 8.3 months, respectively. Toxicities were predominantly Grade 1 or 2 nausea/vomiting (36%) and fatigue (31%). Grade 3 or 4 events in ≥5% of patients included increased amylase/lipase (10%) and hypertension (6%).

CONCLUSIONS

Orteronel demonstrated limited clinical activity in heavily pre-treated AR+ MBC. Further development of orteronel in MBC is not recommended. Further efforts to validate the AR as a therapeutic target should focus on identifying new markers predictive of sensitivity to AR-targeted agents.

Impact of HER2 Heterogeneity on Treatment Response of Early-Stage HER2-Positive Breast Cancer: Phase II Neoadjuvant Clinical Trial of T-DM1 Combined with Pertuzumab

Intratumor heterogeneity is postulated to cause therapeutic resistance. To prospectively assess the impact of HER2 (ERBB2) heterogeneity on response to HER2-targeted therapy, we treated 164 patients with centrally confirmed HER2-positive early-stage breast cancer with neoadjuvant trastuzumab emtansine plus pertuzumab. HER2 heterogeneity was assessed on pretreatment biopsies from two locations of each tumor. HER2 heterogeneity, defined as an area with ERBB2 amplification in >5% but <50% of tumor cells, or a HER2-negative area by FISH, was detected in 10% (16/157) of evaluable cases. The pathologic complete response rate was 55% in the nonheterogeneous subgroup and 0% in the heterogeneous group (P < 0.0001, adjusted for hormone receptor status). Single-cell ERBB2 FISH analysis of cellular heterogeneity identified the fraction of ERBB2 nonamplified cells as a driver of therapeutic resistance. These data suggest HER2 heterogeneity is associated with resistance to HER2-targeted therapy and should be considered in efforts to optimize treatment strategies. SIGNIFICANCE: HER2-targeted therapies improve cure rates in HER2-positive breast cancer, suggesting chemotherapy can be avoided in a subset of patients. We show that HER2 heterogeneity, particularly the fraction of ERBB2 nonamplified cancer cells, is a strong predictor of resistance to HER2 therapies and could potentially be used to optimize treatment selection.See related commentary by Okines and Turner, p. 2369.This article is highlighted in the In This Issue feature, p. 2355.

Chemotherapy-related amenorrhea (CRA) after adjuvant ado-trastuzumab emtansine (T-DM1) compared to paclitaxel in combination with trastuzumab (TH) (TBCRC033: ATEMPT Trial)

PURPOSE

Chemotherapy-related amenorrhea (CRA) is a surrogate for ovarian toxicity and associated risk of infertility and premature menopause. Here, we compare CRA rate with paclitaxel (T)-trastuzumab (H) to that with ado-trastuzumab emtansine (T-DM1).

METHODS

Patients with T1N0 HER2 + early-stage breast cancer (eBC) enrolled on the ATEMPT trial and were randomized 3:1 to T-DM1 3.6 mg/kg IV every (q) 3 weeks (w) × 17 vs. T 80 mg/m² with H IV qw × 12 (4 mg/kg load → 2 mg/kg), followed by H (6 mg/kg IV q3w × 13). Enrollees who self-reported as premenopausal were asked to complete menstrual surveys at baseline and every 6-12 months for 60 months. 18-month CRA (no periods reported during prior 6 months on 18-month survey) was the primary endpoint of this analysis.

RESULTS

Of 512 ATEMPT enrollees, 123 who began protocol therapy and answered baseline and at least one follow-up menstrual survey were premenopausal at enrollment. 76 had menstrual data available at 18 months without having received a gonadotropin-releasing hormone agonist or undergone hysterectomy and/or oophorectomy. Median age was 45 (range 23-53) among 18 who had received TH and 46 (range 34-54) among 58 who had received T-DM1. The 18-month rate of CRA was 50% after TH and 24% after T-DM1 (p = 0.045).

CONCLUSION

Amenorrhea at 18 months was less likely in recipients of adjuvant T-DM1 than TH. Future studies are needed to understand how T-DM1 impacts risk of infertility and permanent menopause, and to assess amenorrhea rates when T-DM1 is administered after standard HER2-directed chemotherapy regimens.

Adjuvant Trastuzumab Emtansine Versus Paclitaxel in Combination With Trastuzumab for Stage I HER2-Positive Breast Cancer (ATEMPT): A Randomized Clinical Trial

PURPOSE

The ATEMPT trial was designed to determine if treatment with trastuzumab emtansine (T-DM1) caused less toxicity than paclitaxel plus trastuzumab (TH) and yielded clinically acceptable invasive disease-free survival (iDFS) among patients with stage I human epidermal growth factor receptor 2-positive (HER2+) breast cancer (BC).

METHODS

Patients with stage I centrally confirmed HER2+ BC were randomly assigned 3:1 to T-DM1 or TH and received T-DM1 3.6 mg/kg IV every 3 weeks for 17 cycles or T 80 mg/m² IV with H once every week × 12 weeks (4 mg/kg load →2 mg/kg), followed by H × 39 weeks (6 mg/kg once every 3 weeks). The co-primary objectives were to compare the incidence of clinically relevant toxicities (CRTs) in patients treated with T-DM1 versus TH and to evaluate iDFS in patients receiving T-DM1.

RESULTS

The analysis population includes all 497 patients who initiated protocol therapy (383 T-DM1 and 114 TH). CRTs were experienced by 46% of patients on T-DM1 and 47% of patients on TH (P = .83). The 3-year iDFS for T-DM1 was 97.8% (95% CI, 96.3 to 99.3), which rejected the null hypothesis (P < .0001). Serially collected patient-reported outcomes indicated that patients treated with T-DM1 had less neuropathy and alopecia and better work productivity compared with patients on TH.

CONCLUSION

Among patients with stage I HER2+ BC, one year of adjuvant T-DM1 was associated with excellent 3-year iDFS, but was not associated with fewer CRT compared with TH.

Trial in progress: A phase 3, randomized, double-blind trial of trilaciclib versus placebo in patients receiving first- or second-line gemcitabine and carboplatin for locally advanced unresectable or metastatic triple-negative breast cancer (PRESERVE 2)

TPS1107

Background: Trilaciclib is an intravenous (IV), highly potent and selective, reversible cyclin-dependent kinase (CDK) 4/6 inhibitor that protects hematopoietic stem and progenitor cells during chemotherapy (myeloprotection) and may directly enhance antitumor immunity (anticancer efficacy). In a randomized phase 2 trial of trilaciclib administered prior to gemcitabine and carboplatin (GC) versus GC alone in advanced/metastatic triple-negative breast cancer (mTNBC), although the primary endpoint of myeloprotection was not met, the addition of trilaciclib resulted in a substantial improvement in median overall survival (OS; 19.8 months with trilaciclib vs 12.6 months with placebo, hazard ratio [95% CI] = 0.37 [0.21–0.63]; O’Shaughnessy et al. SABCS 2020 [PD1-06]). Clinically meaningful improvements in OS and progression-free survival (PFS) were also observed in both programmed death ligand-1 (PD-L1)–positive and –negative subsets. Methods: The PRESERVE 2 trial (EudraCT: 2020-004930-39) is a randomized, double-blind, placebo-controlled, international phase 3 trial evaluating the efficacy of trilaciclib administered prior to GC in patients with mTNBC. Two mTNBC patient populations will be studied and analyzed separately: cohort 1 (N = 170) will evaluate first-line, PD-1/PD-L1 inhibitor–naïve patients with ≥6 months between completion of last curative treatment and first recurrence; cohort 2 (N = 80) will evaluate second-line PD-L1–positive patients following ≥4 months of PD-1/PD-L1 inhibitor therapy in the advanced setting. Key eligibility criteria for both cohorts include age ≥18 years, Eastern Cooperative Oncology Group performance status of 0/1, and available tumor tissue. Patients will be randomized (1:1) to trilaciclib 240 mg/m2 or placebo prior to gemcitabine 1000 mg/m2 and carboplatin area under the curve 2 IV on days 1 and 8, every 21 days. Stratification factors (cohort 1 only) include tumor PD-L1 status by Ventana SP-142 IVD assay, disease-free interval, and country. Study treatment will continue until progressive disease per RECIST v1.1, unacceptable toxicity, or investigator/patient decision, after which, patients will be followed every 3 months for survival. Up to 80 patients will be consented for optional paired baseline and on-treatment biopsies. Archival tissue and serial peripheral blood will be collected from all patients. The primary endpoint is OS, and the key secondary endpoint is time to confirmed deterioration in fatigue. Other secondary endpoints include PFS, myeloprotection, and safety/tolerability. Exploratory endpoints will assess pharmacodynamic parameters, including those related to immune-based mechanisms, and efficacy by CDK4/6-dependence signatures. Study enrollment is open. Clinical trial information: 2020-004930-39 .

Glembatumumab vedotin for patients with metastatic, gpNMB overexpressing, triple-negative breast cancer ("METRIC"): a randomized multicenter study

The METRIC study (NCT#0199733) explored a novel antibody–drug conjugate, glembatumumab vedotin (GV), targeting gpNMB that is overexpressed in ~40% of patients with triple-negative breast cancer (TNBC) and associated with poor prognosis. The study was a randomized, open-label, phase 2b study that evaluated progression-free survival (PFS) of GV compared with capecitabine in gpNMB-overexpressing TNBC. Patients who had previously received anthracycline and taxane-based therapy were randomized 2:1 to receive, GV (1.88 mg/kg IV q21 days) or capecitabine (2500 mg/m² PO daily d1–14 q21 days). The primary endpoint was RECIST 1.1 PFS per independent, blinded central review. In all, 327 patients were randomized to GV (213 treated) or capecitabine (92 treated). Median PFS was 2.9 months for GV vs. 2.8 months for capecitabine. The most common grade ≥3 toxicities for GV were neutropenia, rash, and leukopenia, and for capecitabine were fatigue, diarrhea, and palmar-plantar erythrodysesthesia. The study did not meet the primary endpoint of improved PFS over capecitabine or demonstrate a relative risk/benefit improvement over capecitabine.

Correlation between work productivity loss (WPL) and European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLQ-C30) domains from the MONALEESA-7 (ML-7) trial of premenopausal women with HR+/HER2- advanced breast cancer (ABC)

1051

Background: The international, randomized, double-blind, placebo-controlled, Phase III ML-7 trial (NCT02278120) assessed ribociclib + endocrine therapy (ET) vs ET alone in premenopausal women with HR+/HER2– ABC. To our knowledge, the relationship between WPL and domains of the EORTC QLQ-C30 and the tumor-specific module for breast cancer (QLQ-BR23) has not been explored in ABC. In this post hoc analysis (data cutoff, November 30, 2018) of all patients (pts) enrolled in ML-7, we assessed the correlation between the WPL component of the Work Productivity and Activity Impairment: General Health (WPAI:GH) questionnaire and domains of the EORTC QLQ-C30/BR23. Methods: We analyzed EORTC and WPAI:GH data from all pts enrolled in ML-7 who were employed at any point during the trial (N = 329 of 672 total pts). Domains of the EORTC QLQ-C30 and QLQ-BR23 that had the greatest correlation (pairwise Pearson correlation) with WPL were prioritized for analysis. Separate univariable mixed-model repeated-measures regression models were fitted for each domain, with WPL as the dependent variable and each EORTC domain as a single fixed-effect covariate. Linear and quadratic relationships were considered. Model selection was based on the Akaike information criterion (AIC). Results: Linear models were favored over quadratic models. WPL was negatively correlated with global health status (GHS) and the physical, role, social, and emotional functioning domains and was positively correlated with the fatigue and pain domains of the QLQ-C30 ( P <.001; Table). The coefficients indicated the estimated mean change in WPL was associated with a 1-unit increase in each QLQ-C30 domain. For example, a 10-point increase in GHS was associated with an estimated mean decrease of 7.8% (95% CI, 7.1%-8.5%) in WPL. Conclusions: Greater WPL was associated with higher levels of fatigue and pain and with lower levels of overall quality of life and physical, role, social, and emotional functioning among pts with HR+/HER2− ABC in ML-7. Further investigation of the correlation with QLQ-BR23 and multivariable analysis could determine which EORTC domains and items independently drive these findings. Clinical trial information: NCT02278120 .[Table: see text]

Efficacy of Margetuximab vs Trastuzumab in Patients With Pretreated ERBB2-Positive Advanced Breast Cancer: A Phase 3 Randomized Clinical Trial

Question

Does margetuximab plus chemotherapy prolong progression-free survival and/or overall survival of patients with pretreated ERBB2-positive advanced breast cancer, relative to trastuzumab plus chemotherapy?

Findings

In the SOPHIA phase 3 randomized clinical trial of 536 patients with pretreated ERBB2-positive advanced breast cancer, margetuximab plus chemotherapy generated a statistically significant 24% relative risk reduction in the hazard of progression vs trastuzumab plus chemotherapy. After the second planned interim analysis of 270 deaths, median OS was 21.6 months with margetuximab vs 19.8 months with trastuzumab, and final analysis of OS will be reported subsequently.

Meaning

This trial demonstrates a head-to-head advantage of margetuximab (an Fc-engineered ERBB2-targeted antibody) compared with trastuzumab in a pretreated ERBB2-positive advanced breast cancer population.

Importance

ERRB2 (formerly HER2)–positive advanced breast cancer (ABC) remains typically incurable with optimal treatment undefined in later lines of therapy. The chimeric antibody margetuximab shares ERBB2 specificity with trastuzumab but incorporates an engineered Fc region to increase immune activation.

Objective

To compare the clinical efficacy of margetuximab vs trastuzumab, each with chemotherapy, in patients with pretreated ERBB2-positive ABC.

Design, Setting, and Participants

The SOPHIA phase 3 randomized open-label trial of margetuximab plus chemotherapy vs trastuzumab plus chemotherapy enrolled 536 patients from August 26, 2015, to October 10, 2018, at 166 sites in 17 countries. Eligible patients had disease progression on 2 or more prior anti-ERBB2 therapies and 1 to 3 lines of therapy for metastatic disease. Data were analyzed from February 2019 to October 2019.

Interventions

Investigators selected chemotherapy before 1:1 randomization to margetuximab, 15 mg/kg, or trastuzumab, 6 mg/kg (loading dose, 8 mg/kg), each in 3-week cycles. Stratification factors were metastatic sites (≤2, >2), lines of therapy (≤2, >2), and chemotherapy choice.

Main Outcomes and Measures

Sequential primary end points were progression-free survival (PFS) by central blinded analysis and overall survival (OS). All α was allocated to PFS, followed by OS. Secondary end points were investigator-assessed PFS and objective response rate by central blinded analysis.

Results

A total of 536 patients were randomized to receive margetuximab (n = 266) or trastuzumab (n = 270). The median age was 56 (27-86) years; 266 (100%) women were in the margetuximab group, while 267 (98.9%) women were in the trastuzumab group. Groups were balanced. All but 1 patient had received prior pertuzumab, and 489 (91.2%) had received prior ado-trastuzumab emtansine. Margetuximab improved primary PFS over trastuzumab with 24% relative risk reduction (hazard ratio [HR], 0.76; 95% CI, 0.59-0.98; P = .03; median, 5.8 [95% CI, 5.5-7.0] months vs 4.9 [95% CI, 4.2-5.6] months; October 10, 2018). After the second planned interim analysis of 270 deaths, median OS was 21.6 months with margetuximab vs 19.8 months with trastuzumab (HR, 0.89; 95% CI, 0.69-1.13; P = .33; September 10, 2019), and investigator-assessed PFS showed 29% relative risk reduction favoring margetuximab (HR, 0.71; 95% CI, 0.58-0.86; P < .001; median, 5.7 vs 4.4 months; September 10, 2019). Margetuximab improved objective response rate over trastuzumab: 22% vs 16% (P = .06; October 10, 2018), and 25% vs 14% (P < .001; September 10, 2019). Incidence of infusion-related reactions, mostly in cycle 1, was higher with margetuximab (35 [13.3%] vs 9 [3.4%]); otherwise, safety was comparable.

Conclusions and Relevance

In this phase 3 randomized clinical trial, margetuximab plus chemotherapy had acceptable safety and a statistically significant improvement in PFS compared with trastuzumab plus chemotherapy in ERBB2-positive ABC after progression on 2 or more prior anti-ERBB2 therapies. Final OS analysis is expected in 2021.

Trial Registration

ClinicalTrials.gov Identifier: NCT02492711

Baseline characteristics and first-line treatment patterns in patients with HER2-positive metastatic breast cancer in the SystHERs registry

BACKGROUND

Systemic Therapies for HER2-Positive Metastatic Breast Cancer Study (SystHERs, NCT01615068) was a prospective, observational disease registry designed to identify treatment patterns and clinical outcomes in patients with HER2-positive metastatic breast cancer (MBC) in real-world treatment settings.

METHODS

SystHERs enrolled patients aged ≥ 18 years with recently diagnosed HER2-positive MBC. Treatment regimens and clinical management were determined by the treating physician. In this analysis, patients were compared descriptively by first-line treatment, age, or race. Multivariate logistic regression was used to examine the associations between baseline variables and treatment selections. Clinical outcomes were assessed in patients treated with trastuzumab (Herceptin [H]) + pertuzumab (Perjeta [P]).

RESULTS

Patients were enrolled from June 2012 to June 2016. As of February 22, 2018, 948 patients from 135 US treatment sites had received first-line treatment, including HP (n = 711), H without P (n = 175), or no H (n = 62) (with or without chemotherapy and/or hormonal therapy). Overall, 68.7% received HP + taxane and 9.3% received H without P + taxane. Patients aged < 50 years received HP (versus H without P) more commonly than those ≥ 70 years (odds ratio 4.20; 95% CI, 1.62-10.89). Chemotherapy was less common in patients ≥ 70 years (68.2%) versus those < 50 years (88.0%) or 50-69 years (87.4%). Patients treated with HP had median overall survival of 53.8 months and median progression-free survival of 15.8 months.

CONCLUSIONS

Our analysis of real-world data shows that most patients with HER2-positive MBC received first-line treatment with HP + taxane. However, older patients were less likely to receive dual HER2-targeted therapy and chemotherapy.

Abstract PS10-12: Integrated safety summary of single agent and combination margetuximab in phase 1, 2, and 3 studies of HER2-positive advanced cancers and metastatic breast cancer (MBC)

Background Margetuximab (M) is an investigational Fc-engineered anti-HER2 monoclonal antibody that targets the same epitope as trastuzumab (T). Compared with T, M has higher affinity for both the 158V (high-binding) and 158F (low-binding) allotypes of the activating Fc receptor CD16A. M enhances innate immunity more effectively than T in vitro, including CD16A-mediated antibody-dependent cellular cytotoxicity. Samples collected from patients (pts) before and after single-agent treatment also demonstrate that M induces HER2-specific adaptive immune responses, including both T- and B-cell responses. The SOPHIA trial (NCT02492711) in pts with pretreated HER2+ MBC showed that M+chemotherapy (chemo) improved progression-free survival vs T+chemo, with comparable safety. A pooled analysis of M safety across 3 clinical trials is presented. Methods Study 01 (NCT01148849), an ongoing Phase 1 dose-finding/safety study of M monotherapy, enrolled 66 pts with advanced HER2+ carcinomas, including 27 with MBC. Study 02 (NCT01828021), a completed Phase 2 study of M monotherapy in low-expressing HER2+ MBC, enrolled 25 pts. Study 04 (NCT02492711), an ongoing Phase 3 study in pts with pretreated HER2+ MBC to compare M + chemo vs T + chemo, randomized 536 pts, of whom 264 and 265 received M and T, respectively. The pooled safety population includes all pts who received any M in Study 01 (cutoff 01Oct2015), Study 02 (cutoff 02Aug2017), and Study 04 (cutoff 10OCT2018). Treatment-emergent adverse events (AEs), defined as AEs that began or worsened in severity on or after first dose of study drug through an End of Treatment Visit or 28 days after last study treatment, are reported. Results Of 355 pts that received at least 1 dose of M, 295 received 15 mg/kg Q3W, and 60 received other doses from 0.1 - 18 mg/kg. Median (mean, range) number of cycles for all dose levels was 5.0 (6.6, 1-43), higher on Study 04 (6.0) than Study 01 (1-3 across dose groups) or Study 02 (2.0). Most pts (347 [97.7%]) experienced at least 1 AE, and about half (173 [48.7%]) had at least 1 Grade &gt;/= 3 AE. Serious AE (SAE) incidence across studies was low (58 [16.3%]), and 21 pts (5.9%) discontinued M due to AEs. Most frequently reported AEs (&gt;/= 20%) were fatigue (124 [34.9]), nausea (103 [29.0%]), diarrhea (75 [21.1%]), and neutropenia (75 [21.1%]). Blood/lymphatic system disorders were the most frequent events by SOC, and largely restricted to Study 04. Increased neutropenia on M (26.1%), relative to T (20.4%), was observed in Study 04 yet both febrile neutropenia (M 3.0%, T 4.5%) and infections (M 36.4%, T 39.6%) were higher on T. By contrast, Study 01 and Study 02 revealed no tendency of M monotherapy to cause neutropenia. Overall, infusion related reactions (IRRs) were observed in 51 pts (14.4%), primarly at first infusion, including serious IRRs in 5 (1.4%). Also, 34 pts (9.6%) had &gt; 15% reduction in LVEF with a median time to &gt; 15% reduction of 49 days. In all pts with complete follow-up, these LVEF reductions were asymptomatic and reversible. No M-induced cardiac conduction abnormalities were noted. In Study 04, similar proportions in both groups experienced AEs (M 97.7%, T 96.2%), including Grade &gt;/= 3 AEs (M 52.3%, T 48.3%), SAEs (M 14.8%, T 17.4%), discontinuations due to AEs (M 3.0%, T 2.6%), and deaths due to AEs (M 0.8%, T 0.8%). As of the 23Feb2020 safety update, 2 pts remain on M in Study 01, after 116 and 109 cycles (6.7 and 6.3 years), respectively. In Study 04, 16 pts (6%) continued on M, and 7 (2.6%) remained on T. Discussion M has demonstrated an acceptable safety profile across Phase 1, 2, and 3 studies. It has been administered for over 6 years without long-term cumulative safety issues. Combined M plus chemotherapy Q3W demonstrated acceptable safety and tolerability, similar to that for T plus chemotherapy Q3W in Study 04.

Citation Format: Seock-Ah Im, Fatima Cardoso, Javier Cortes, Giuseppe Curigliano, Mark D. Pegram, Hope S. Rugo, Ursa Brown-Glaberman, Denise A. Yardley, Sung-Bae Kim, Maaike de Boer, Zbigniew Nowecki, Vesna Glavicic, Ido Wolf, Nele Claes, Joo Hyuk Sohn, Thomas Bachelot, Peter A. Kaufman, Jan Baughman, Shengyan Hong, Kenneth Jacobs, Edwin Rock, William J. Gradishar. Integrated safety summary of single agent and combination margetuximab in phase 1, 2, and 3 studies of HER2-positive advanced cancers and metastatic breast cancer (MBC) [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 PS10-12.

Abstract GS4-01: Results from CONTESSA: A phase 3 study of tesetaxel plus a reduced dose of capecitabine versus capecitabine alone in patients with HER2-, hormone receptor + (HR+) metastatic breast cancer (MBC) who have previously received a taxane

Objectives: The key objectives of CONTESSA are to evaluate the efficacy and safety of tesetaxel plus a reduced dose of capecitabine as an all-oral regimen versus capecitabine alone in patients with HER2-, HR+ MBC previously treated with a taxane.

Rationale: Tesetaxel is a novel, oral taxane with several properties that make it unique, including: oral administration with a low pill burden; a long (8-day) terminal plasma half-life in humans, enabling infrequent, once-every-3 weeks (Q3W) dosing; no observed hypersensitivity reactions; and significant activity against chemotherapy-resistant breast cancer cell lines. More than 1,000 patients have been treated with tesetaxel in clinical studies. Tesetaxel had encouraging monotherapy activity in a Phase 2 study in 38 patients with HER2-, HR+ MBC, with a confirmed objective response rate (ORR) per RECIST 1.1 of 45% and median progression-free survival (PFS) of 5.4 months (Seidman et al, 2018 ASCO Annual Meeting).

Methodology: CONTESSA is a multinational, multicenter, randomized (1:1), Phase 3 registration study comparing tesetaxel (27 mg/m2 on Day 1 of a 21-day cycle) plus a reduced dose of capecitabine (1,650 mg/m2/day on Days 1-14 of a 21-day cycle) to the approved dose of capecitabine alone (2,500 mg/m2/day on Days 1-14 of a 21-day cycle) in patients with HER2-, HR+ MBC who have received no more than one chemotherapy regimen for advanced disease and have received a taxane in the (neo)adjuvant setting. There was no restriction on the disease-free interval following taxane therapy. The primary endpoint is PFS assessed by an Independent Radiologic Review Committee (IRC). CONTESSA was designed with 90% power to detect a 2.5-month improvement in median PFS (HR=0.71). Secondary endpoints are overall survival (OS), ORR and disease control rate.

Results: CONTESSA, which enrolled 685 patients, met the primary endpoint of improved PFS as assessed by the IRC. Median PFS was 9.8 months for tesetaxel plus a reduced dose of capecitabine versus 6.9 months for capecitabine alone, an improvement of 2.9 months [HR=0.716 (95% CI: 0.573-0.895); p=0.003]. ORR was 57% for tesetaxel plus a reduced dose of capecitabine versus 41% for capecitabine alone (p=0.0002). OS data are immature. Tesetaxel plus capecitabine was associated with a manageable side effect profile consistent with previous clinical studies. Grade ≥3 treatment-emergent adverse events (TEAEs) that occurred in ≥5% of patients (tesetaxel plus capecitabine vs. capecitabine alone) were: neutropenia (71.2% vs. 8.3%); diarrhea (13.4% vs. 8.9%); hand-foot syndrome (6.8% vs. 12.2%); febrile neutropenia (12.8% vs. 1.2%); fatigue (8.6% vs. 4.5%); hypokalemia (8.6% vs. 2.7%); leukopenia (10.1% vs. 0.9%); and anemia (8.0% vs. 2.1%). TEAEs resulting in treatment discontinuation in ≥1% of patients (tesetaxel plus capecitabine vs. capecitabine alone) were: neutropenia or febrile neutropenia (4.2% vs. 1.5%); neuropathy (3.6% vs. 0.3%); diarrhea (0.9% vs. 1.5%); and hand-foot syndrome (0.6% vs. 2.1%). Treatment discontinuation due to any adverse event occurred in 23.1% of patients treated with tesetaxel plus capecitabine versus 11.9% of patients treated with capecitabine alone. Grade 2 alopecia occurred in 8.0% of patients treated with tesetaxel plus capecitabine versus 0.3% of patients treated with capecitabine alone. Grade ≥3 neuropathy occurred in 5.9% of patients treated with tesetaxel plus capecitabine versus 0.9% of patients treated with capecitabine alone.

Conclusion: An all-oral regimen of tesetaxel plus a reduced dose of capecitabine significantly improved PFS versus capecitabine alone. Neutropenia was the most frequent Grade ≥3 TEAE. Rates of clinically significant alopecia and neuropathy were low.

Citation Format: Joyce O'Shaughnessy, Lee Schwartzberg, Martine Piccart, Hope S. Rugo, Denise A Yardley, Javier Cortes, Michael Untch, Nadia Harbeck, Gail S. Wright, Igor Bondarenko, John Glaspy, Zbigniew Nowecki, Fadi Kayali, Arlene Chan, Christelle Levy, Mei-Ching Liu, Sung-Bae Kim, Julie Lemieux, Alexey Manikhas, Sara Tolaney, Elaine Lim, Andrea Gombos, Agostina Stradella, Mark Pegram, Peter Fasching, Laszlo Mangel, Vladimir Semiglazov, Veronique Dieras, Luca Gianni, Michael A Danso, Jeff Vacirca, Stew Kroll, Joseph O'Connell, Kevin Tang, Thomas Wei, Andrew Seidman. Results from CONTESSA: A phase 3 study of tesetaxel plus a reduced dose of capecitabine versus capecitabine alone in patients with HER2-, hormone receptor + (HR+) metastatic breast cancer (MBC) who have previously received a taxane [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 GS4-01.

Abstract PS11-29: A phase 2 study evaluating orteronel, an inhibitor of androgen biosynthesis, in patients with androgen receptor (AR)-expressing metastatic triple-negative breast cancer (TNBC)

Background: Treatment options for TNBC are limited by the lack of estrogen and progesterone receptors as well as the absence of HER2 overexpression. AR is present in all breast cancer subtypes and up to 40% of TNBC have AR overexpression (AR+). Thus AR positivity in TNBC represents a potential targetable signaling pathway. Preclinical studies demonstrated that AR modulation inhibits cell proliferation, and clinical activity with anti-androgen monotherapy has been reported in breast cancer. Orteronel is a novel, oral, selective, nonsteroidal inhibitor of 17, 20-lyase, a key enzyme in androgen biosynthesis under evaluation as a potential therapeutic strategy in hormone-sensitive cancers. In this phase 2 study, we evaluated androgen blockade with single agent orteronel in AR+ metastatic breast cancer (MBC). Methods: Male or female pts with AR+ MBC (≥10% staining by central immunohistochemistry) were eligible. Pts were grouped into 2 cohorts for analysis: Cohort 1-TNBC (AR+/ER-/PR-/HER2-) and Cohort 2-ER+ (AR+/ER+/HER2 +/-). Results in Cohort 2 (ER+) have been previously reported; here we report results in the AR+ TNBC cohort. TNBC pts must have been previously treated with standard therapy (1-3 chemotherapy regimens for MBC). All pts received 300 mg orteronel PO BID over a 4 week cycle and underwent response assessment every 2 cycles. Treatment continued until disease progression or unacceptable toxicity. The hypothesized response rate for pts with previously treated metastatic AR+ TNBC was 11%. Results: From 7/2014 to 2/2019 a total of 26 AR+ TNBC pts were enrolled on cohort 1. The trial closed early due to slow accrual. Median age was 57 years (range, 33-92); 96% ECOG 0-1; all pts had ≥ 1 prior chemotherapy; 42% prior targeted therapy; 8% prior immunotherapy. All tumors were ER and PR negative per institutional standards. PI3K was mutated in 16% (3/19) tumors tested and 65% (13/20) were PTEN-negative. Median duration of treatment was 8 weeks (range 0.7-35.7) with 15% of pts on treatment ≥ 6 months (mo). All pts have discontinued treatment, 85% due to disease progression, and 15% due to AEs. Nausea and fatigue [8 pts each (31%)] were the most common AEs noted. G 3/4 AEs included hypertension, increased amylase and lipase [2 pts each (8%)] with 4 patients reporting SAEs (G2 pneumonitis, G2 chest pain and G2 peripheral edema, G4 prolonged QT and G4 hypokalemia). The ORR was 4% and DCR was 15%. Median PFS was 2.0 mo and median OS was 10.2 mo. Conclusions: Orteronel monotherapy was well tolerated but demonstrated limited clinical activity in this heavily pre-treated metastatic AR+ TNBC patient population. As novel AR targeting agents are being developed, future studies are needed to identify AR+ breast cancer patients most likely to benefit from AR inhibition.

Citation Format: Denise A Yardley, Robyn R Young, Kerin B Adelson, Andrea L Silber, Michael D Kommor, Jose E Najera, Davey B Daniel, Nancy W Peacock, Mythili Shastry, John D Hainsworth, Howard A Burris, III. A phase 2 study evaluating orteronel, an inhibitor of androgen biosynthesis, in patients with androgen receptor (AR)-expressing metastatic triple-negative breast cancer (TNBC) [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 PS11-29.

Real-world survival outcomes of heavily pretreated patients with refractory HR+, HER2-metastatic breast cancer receiving single-agent chemotherapy-a comparison with MONARCH 1

PURPOSE

In MONARCH 1 (NCT02102490), single-agent abemaciclib demonstrated promising efficacy activity and tolerability in a population of heavily pretreated women with refractory HR+, HER2- metastatic breast cancer (MBC). To help interpret these results and put in clinical context, we compared overall survival (OS) and duration of therapy (DoT) between MONARCH 1 and a real-world single-agent chemotherapy cohort.

METHODS

The real-world chemotherapy cohort was created from a Flatiron Health electronic health records-derived database based on key eligibility criteria from MONARCH 1. The chemotherapies included in the cohort were single-agent capecitabine, gemcitabine, eribulin, or vinorelbine. Results were adjusted for baseline demographics and clinical differences using Mahalanobis distance matching (primary analysis) and entropy balancing (sensitivity analysis). OS and DoT were analyzed using the Kaplan-Meier method and Cox proportional hazards regression.

RESULTS

A real-world single-agent chemotherapy cohort (n = 281) with eligibility criteria similar to the MONARCH 1 population (n = 132) was identified. The MONARCH 1 (n = 108) cohort was matched to the real-world chemotherapy cohort (n = 108). Median OS was 22.3 months in the abemaciclib arm versus 13.6 months in the matched real-world chemotherapy cohort with an estimated hazard ratio (HR) of 0.54. The median DoT was 4.1 months in MONARCH 1 compared to 2.9 months in the real-world chemotherapy cohort with HR of 0.76.

CONCLUSIONS

This study demonstrates an approach to create a real-world chemotherapy cohort suitable to serve as a comparator for trial data. These exploratory results suggest a survival advantage and place the benefit of abemaciclib monotherapy in clinical context.

Overall survival (OS) in patients (pts) with advanced breast cancer (ABC) with visceral metastases (mets), including those with liver mets, treated with ribociclib (RIB) plus endocrine therapy (ET) in the MONALEESA (ML) -3 and -7 trials

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Background: In the Phase III ML-3 (NCT02422615) and ML-7 (NCT02278120) trials, RIB + ET demonstrated a significant OS benefit (ML-3: HR, 0.72, P = 0.00455; ML-7: HR, 0.71, P = 0.00973) over placebo (PBO) + ET in pts with HR+/HER2- ABC (Im et al. N Engl J Med. 2019; Slamon et al. N Engl J Med. 2019). The presence of visceral mets generally portends a poor prognosis, which is especially poor in pts with liver mets (He et al. Ann Oncol. 2019). Here we report OS in pts with visceral mets with a focus on those with liver mets in ML-3 and ML-7. Methods: In ML-3, postmenopausal pts were randomized 2:1 to receive RIB + fulvestrant (FUL) or PBO + FUL as first- (1L) or second-line (2L) treatment. In ML-7, premenopausal pts were randomized 1:1 to receive RIB + ET or PBO + ET (this analysis included only pts who received an NSAI as ET partner to match approved indication). Results: Visceral mets were identified in 293 pts (60.5%) in the RIB arm and 147 (60.7%) in the PBO arm in ML-3 and 150 (44.8%) and 142 pts (42.1%), respectively, in ML-7. In ML-3, the median age of pts with visceral mets was 63 and 65 years in the RIB and PBO arms, and in ML-7 it was 42.5 and 45.0 years, respectively. In ML-3, 214 pts with visceral mets received 1L therapy (RIB, n = 137; PBO, n = 77), while 219 pts received 2L therapy or had early relapse (RIB, n = 151; PBO, n = 68). Lung and liver were the most common sites of visceral mets for pts in ML-3 (49.8% and 44.8%, respectively) and ML-7 (51.4% and 58.2%, respectively). OS HRs in pts with visceral mets were consistent with the benefit in the overall pt populations and suggested a particularly substantial OS benefit in pts with liver mets (HR for liver mets group in ML-3, 0.629 [95% CI, 0.421-0.942]; HR in ML-7, 0.531 [95% CI, 0.321-0.877]; Table). No new safety signals were observed. Conclusions: Approximately half of the pts in ML-3 and ML-7 had visceral mets. The OS data in these pts are consistent with the benefit observed with RIB in the overall populations of each trial. In pts with liver mets, a group with an especially poor prognosis, RIB + ET demonstrated a substantial OS benefit compared with PBO + ET. Clinical trial information: NCT02422615; NCT02278120 . [Table: see text]

SOPHIA analysis by chemotherapy (Ctx) choice: A phase III (P3) study of margetuximab (M) + Ctx versus trastuzumab (T) + Ctx in patients (pts) with pretreated HER2+ metastatic (met) breast cancer (MBC)

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Background: Despite advances, pretreated HER2+ MBC remains incurable with ongoing need for new therapies. Investigational M has similar HER2 binding and antiproliferative effects as T. Relative to T, M Fc engineering increases binding affinity for both variants of activating Fc receptor (FcR) CD16A and decreases affinity for inhibitory FcR CD32B, coordinately activating innate and adaptive immunity. In a Phase 3 (P3) trial, M prolonged PFS over T (Table). Second interim OS results from Sept 2019 also favor M (hazard ratio [HR], 0.89; 95% CI 0.69–1.13; nominal P=0.326). Methods: SOPHIA (NCT02492711), an open-label P3 trial, enrolled pts with HER2+ MBC after pertuzumab and 1–3 lines of prior treatment (Tx) for MBC. Randomization was 1:1 to M (15 mg/kg IV q3w + Ctx) or T (6 [8 for loading dose] mg/kg IV q3w + Ctx), stratified by met sites (≤2, >2), lines of Tx for met disease (≤2, >2), and Ctx choice, including capecitabine (Cap), eribulin (Eri), gemcitabine (Gem), or vinorelbine (Vin). Primary endpoints were central blinded PFS and OS, assessed sequentially using the stratified log-rank test. Results: Investigator chemotherapy choices and results by chemotherapy are shown in the table. Subjects receiving Eri and Gem had the lowest PFS hazards ratios (HRs), favoring M over T, although no statistical significance of individual chemotherapy subgroups was seen. There was variable toxicity among Ctx subgroups, and fewer subjects receiving Cap had Ctx related Grade 3 or higher (>=Gr 3) AEs. In this unblinded study, more subjects on M than T in all subgroups discontinued Ctx while continuing study antibody. Conclusions: In combination with chemotherapy in pretreated HER2+ MBC, M improved PFS over T. Safety was manageable in all Ctx subgroups. Differences among HRs for chemotherapy subgroups may be driven by selection bias and/or sensitivity differences. Clinical trial information: NCT02492711 . [Table: see text]

Baseline Characteristics, Treatment Patterns, and Outcomes in Patients with HER2-Positive Metastatic Breast Cancer by Hormone Receptor Status from SystHERs

PURPOSE

We report treatments and outcomes in a contemporary patient population with HER2-positive metastatic breast cancer (MBC) by hormone receptor (HR) status from the Systemic Therapies for HER2-positive Metastatic Breast Cancer Study (SystHERs).

EXPERIMENTAL DESIGN

SystHERs (NCT01615068) was an observational, prospective registry study of U.S.-based patients with newly diagnosed HER2-positive MBC. Endpoints included treatment patterns and clinical outcomes.

RESULTS

Of 977 eligible patients (enrolled from 2012 to 2016), 70.1% (n = 685) had HR-positive and 29.9% (n = 292) had HR-negative disease. Overall, 59.1% (405/685) of patients with HR-positive disease received any first-line endocrine therapy (with or without HER2-targeted therapy or chemotherapy); 34.9% (239/685) received HER2-targeted therapy + chemotherapy + sequential endocrine therapy. Patients with HR-positive versus HR-negative disease had longer median overall survival (OS; 53.0 vs 43.4 months; hazard ratio, 0.70; 95% confidence interval, 0.56-0.87). Compared with patients with high HR-positive staining (10%-100%, n = 550), those with low HR-positive staining (1%-9%, n = 60) received endocrine therapy less commonly (64.2% vs 33.3%) and had shorter median OS (53.8 vs 40.1 months). Similar median OS (43.4 vs 40.1 months) was observed in patients with HR-negative versus low HR-positive tumors (1%-9%).

CONCLUSIONS

Despite evidence that first-line HER2-targeted therapy, chemotherapy, and sequential endocrine therapy improves survival in patients with HR-positive, HER2-positive disease, only 34.9% of patients in this real-world setting received such treatment. Patients with low tumor HR positivity (1%-9%) had lower endocrine therapy use and worse survival than those with high tumor HR positivity (10%-100%).

Phase II trial of eribulin in patients who do not achieve pathologic complete response (pCR) following neoadjuvant chemotherapy

PURPOSE

Women with residual invasive breast cancer at the primary site or axillary lymph nodes following neoadjuvant chemotherapy have a high risk of recurrence. Eribulin improves survival in patients with metastatic breast cancer who progress after anthracycline and taxane therapy. This phase 2 trial assessed the efficacy of postoperative eribulin in breast cancer patients who did not achieve a pCR following standard neoadjuvant chemotherapy.

METHODS

Women with localized breast cancer who had residual invasive cancer following ≥ 4 cycles of standard anthracycline and/or taxane-containing neoadjuvant chemotherapy received adjuvant eribulin treatment. HER2-positive patients also received trastuzumab for 1 year. Adjuvant hormonal therapy and locoregional radiotherapy were administered as per institutional guidelines. Primary endpoint was the 2-year DFS rate. Three patient cohorts were analyzed: TNBC (Cohort A), HR+/HER2- (Cohort B), and HER2+ (Cohort C).

RESULTS

One hundred twenty-six patients (Cohort A-53, Cohort B-42, and Cohort C-31) were enrolled. Neoadjuvant chemotherapy included a taxane and an anthracycline in 70%. Eribulin was well tolerated; 84% of patients received the planned 6 cycles. After a median follow-up of 28 months, the 24-month DFS rates were 56% (95% CI 42, 69), 83% (95% CI 67, 91), and 73% (95% CI 53, 86) for Cohorts A, B, and C, respectively. The most common grade 3/4 treatment-related adverse events were neutropenia (26%), leukopenia (13%), and neuropathy (7%).

CONCLUSION

Administration of adjuvant eribulin after neoadjuvant chemotherapy was feasible and well tolerated. The 24-month DFS rate did not reach the study target levels in any of the cohorts and was similar to DFS previously described in these cohorts following neoadjuvant chemotherapy alone.

nab-Paclitaxel plus carboplatin or gemcitabine versus gemcitabine plus carboplatin as first-line treatment of patients with triple-negative metastatic breast cancer: results from the tnAcity trial

Background

Metastatic triple-negative breast cancer (mTNBC) has a poor prognosis and aggressive clinical course. tnAcity evaluated the efficacy and safety of first-line nab-paclitaxel plus carboplatin (nab-P/C), nab-paclitaxel plus gemcitabine (nab-P/G), and gemcitabine plus carboplatin (G/C) in patients with mTNBC.

Patients and methods

Patients with pathologically confirmed mTNBC and no prior chemotherapy for metastatic BC received (1 : 1 : 1) nab-P 125 mg/m2 plus C AUC 2, nab-P 125 mg/m2 plus G 1000 mg/m2, or G 1000 mg/m2 plus C AUC 2, all on days 1, 8 q3w. Phase II primary end point: investigator-assessed progression-free survival (PFS); secondary end points included overall response rate (ORR), overall survival (OS), percentage of patients initiating cycle 6 with doublet therapy, and safety.

Results

In total, 191 patients were enrolled (nab-P/C, n = 64; nab-P/G, n = 61; G/C, n = 66). PFS was significantly longer with nab-P/C versus nab-P/G [median, 8.3 versus 5.5 months; hazard ratio (HR), 0.59 [95% CI, 0.38-0.92]; P = 0.02] or G/C (median, 8.3 versus 6.0 months; HR, 0.58 [95% CI, 0.37-0.90]; P = 0.02). OS was numerically longer with nab-P/C versus nab-P/G (median, 16.8 versus 12.1 months; HR, 0.73 [95% CI, 0.47-1.13]; P = 0.16) or G/C (median, 16.8 versus 12.6 months; HR, 0.80 [95% CI, 0.52-1.22]; P = 0.29). ORR was 73%, 39%, and 44%, respectively. In the nab-P/C, nab-P/G, and G/C groups, 64%, 56%, and 50% of patients initiated cycle 6 with a doublet. Grade ≥3 adverse events were mainly hematologic.

Conclusions

First-line nab-P/C was active in mTNBC and resulted in a significantly longer PFS and improved risk/benefit profile versus nab-P/G or G/C.

First-Line Doublet Chemotherapy for Metastatic Triple-Negative Breast Cancer: Circulating Tumor Cell Analysis of the tnAcity Trial

Purpose

Circulating tumor cells (CTCs) are prognostic biomarkers in metastatic breast cancer, but their role in predicting treatment outcomes in metastatic triple-negative breast cancer (mTNBC) is less clear. The tnAcity trial demonstrated a significant progression-free survival (PFS) benefit with nab-paclitaxel (nab-P)/carboplatin (C) over nab-P/gemcitabine (G) or G/C in patients with mTNBC. We assessed the correlation between CTC dynamics and clinical benefit in all patients and by treatment arm.

Methods

CTC enumeration, performed using CELLSEARCH technology (Menarini Silicon Biosystems, Huntingdon Valley, PA, USA), was a prespecified exploratory endpoint in the tnAcity trial. Patients with TNBC were categorized based on pre- and post-treatment CTC levels: Group 1 (+ + +; elevated CTCs at baseline and postbaseline), Group 2 (+ ± ±; CTCs elevated at baseline and cleared postbaseline [cycle 3 and/or cycle 5]), or Group 3 (−; no CTCs detected at baseline). The baseline cutoff was ≥1 CTC/7.5 mL for the main analysis; cutoffs of ≥2 and ≥5 CTCs were used for supporting analyses.

Results

The main analysis included 126 patients (Group 1, n = 24; Group 2, n = 54; and Group 3, n = 48). The median PFS was longer in Group 2 vs Group 1 (8.5 vs 4.7 months; HR, 0.30 [95% CI, 0.17–0.54]). These results were supported by the ≥2- and ≥5-CTC cutoff analyses. The median overall survival rates were 17.8, 16.0, and 9.8 months in Groups 2, 3, and 1, respectively. The overall response rates were 79.6%, 43.8%, and 29.2%, respectively. A numerically higher percentage of patients had CTC clearance during nab-P/C treatment vs nab-P/G or G/C.

Conclusion

Efficacy outcomes trended positively with chemotherapy-induced elimination of CTCs, suggesting that CTC clearance may predict the chemosensitivity of mTNBC tumors.

Trial registration

EudraCT Number: 2013-000113-20; ClinicalTrials.gov number: NCT01881230.

De Novo Versus Recurrent HER2-Positive Metastatic Breast Cancer: Patient Characteristics, Treatment, and Survival from the SystHERs Registry

Background

Limited data exist describing real‐world treatment of de novo and recurrent HER2‐positive metastatic breast cancer (MBC).

Materials and Methods

The Systemic Therapies for HER2‐Positive Metastatic Breast Cancer Study (SystHERs) was a fully enrolled (2012–2016), observational, prospective registry of patients with HER2‐positive MBC. Patients aged ≥18 years and ≤6 months from HER2‐positive MBC diagnosis were treated and assessed per their physician's standard practice. The primary endpoint was to characterize treatment patterns by de novo versus recurrent MBC status, compared descriptively. Secondary endpoints included patient characteristics, progression‐free and overall survival (PFS and OS, by Kaplan‐Meier method; hazard ratio [HR] and 95% confidence interval [CI] by Cox regression), and patient‐reported outcomes.

Results

Among 977 eligible patients, 49.8% (n = 487) had de novo and 50.2% (n = 490) had recurrent disease. A higher proportion of de novo patients had hormone receptor–negative disease (34.9% vs. 24.9%), bone metastasis (57.1% vs. 45.9%), and/or liver metastasis (41.9% vs. 33.1%), and a lower proportion had central nervous system metastasis (4.3% vs. 13.5%). De novo patients received first‐line regimens containing chemotherapy (89.7%), trastuzumab (95.7%), and pertuzumab (77.8%) more commonly than recurrent patients (80.0%, 85.9%, and 68.6%, respectively). De novo patients had longer median PFS (17.7 vs. 11.9 months; HR, 0.69; 95% CI, 0.59–0.80; p < .0001) and OS (not estimable vs. 44.5 months; HR, 0.55; 95% CI, 0.44–0.69; p < .0001).

Conclusion

Patients with de novo versus recurrent HER2‐positive MBC exhibit different disease characteristics and survival durations, suggesting these groups have distinct outcomes. These differences may affect future clinical trial design. Clinical trial identification number. NCT01615068 (http://clinicaltrials.gov).

Implications for Practice

SystHERs was an observational registry of patients with HER2‐positive metastatic breast cancer (MBC), which is a large, modern, real‐world data set for this population and, thereby, provides a unique opportunity to study patients with de novo and recurrent HER2‐positive MBC. In SystHERs, patients with de novo disease had different baseline demographics and disease characteristics, had superior clinical outcomes, and more commonly received first‐line chemotherapy and/or trastuzumab versus those with recurrent disease. Data from this and other studies suggest that de novo and recurrent MBC have distinct outcomes, which may have implications for disease management strategies and future clinical study design.

The SystHERs breast cancer study was a fully enrolled, prospective registry study that explored contemporary treatment patterns and outcomes in patients with HER2‐positive metastatic breast cancer (MBC), resulting in one of the largest real‐world datasets for this population and providing a unique opportunity to assess patients with de novo and recurrent HER2‐positive MBC. This article reports baseline characteristics, treatment patterns, patient‐reported outcomes, and clinical outcomes in these patient subsets.

Everolimus Plus Exemestane vs Everolimus or Capecitabine Monotherapy for Estrogen Receptor-Positive, HER2-Negative Advanced Breast Cancer: The BOLERO-6 Randomized Clinical Trial

Importance

Everolimus plus exemestane and capecitabine are approved second-line therapies for advanced breast cancer.

Objective

A postapproval commitment to health authorities to estimate the clinical benefit of everolimus plus exemestane vs everolimus or capecitabine monotherapy for estrogen receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer.

Design

Open-label, randomized, phase 2 trial of treatment effects in postmenopausal women with advanced breast cancer that had progressed during treatment with nonsteroidal aromatase inhibitors.

Interventions

Patients were randomized to 3 treatment regimens: (1) everolimus (10 mg/d) plus exemestane (25 mg/d); (2) everolimus alone (10 mg/d); and (3) capecitabine alone (1250 mg/m2 twice daily).

Main Outcomes and Measures

Estimated hazard ratios (HRs) of progression-free survival (PFS) for everolimus plus exemestane vs everolimus alone (primary objective) or capecitabine alone (key secondary objective). Safety was a secondary objective. No formal statistical comparisons were planned.

Results

A total of 309 postmenopausal women were enrolled, median age, 61 years (range, 32-88 years). Of these, 104 received everolimus plus exemestane; 103, everolimus alone; and 102, capecitabine alone. Median follow-up from randomization to the analysis cutoff (June 1, 2017) was 37.6 months. Estimated HR of PFS was 0.74 (90% CI, 0.57-0.97) for the primary objective of everolimus plus exemestane vs everolimus alone and 1.26 (90% CI, 0.96-1.66) for everolimus plus exemestane vs capecitabine alone. Between treatment arms, potential informative censoring was noted, and a stratified multivariate Cox regression model was used to account for imbalances in baseline characteristics; a consistent HR was observed for everolimus plus exemestane vs everolimus (0.73; 90% CI, 0.56-0.97), but the HR was closer to 1 for everolimus plus exemestane vs capecitabine (1.15; 90% CI, 0.86-1.52). Grade 3 to 4 adverse events were more frequent with capecitabine (74%; n = 75) vs everolimus plus exemestane (70%; n = 73) or everolimus alone (59%; n = 61). Serious adverse events were more frequent with everolimus plus exemestane (36%; n = 37) vs everolimus alone (29%; n = 30) or capecitabine (29%; n = 30).

Conclusions and Relevance

These findings suggest that everolimus plus exemestane combination therapy offers a PFS benefit vs everolimus alone, and they support continued use of this therapy in this setting. A numerical PFS difference with capecitabine vs everolimus plus exemestane should be interpreted cautiously owing to imbalances among baseline characteristics and potential informative censoring.

Trial Registration

ClinicalTrials.gov identifier: NCT01783444.

MONALEESA clinical program: a review of ribociclib use in different clinical settings

Ribociclib has received approval in the pre/peri- and postmenopausal disease settings on the basis of the MONALEESA trials. MONALEESA-2 demonstrated that ribociclib plus letrozole significantly improved progression-free survival compared with placebo plus letrozole as first-line therapy in postmenopausal patients with HR-positive, HER2-negative advanced breast cancer. Subsequently, ongoing trials reported significant progression-free survival improvements with ribociclib in combination with either fulvestrant in postmenopausal patients with advanced breast cancer who were either treatment naive or received ≤1 line of prior endocrine therapy in the advanced disease setting (MONALEESA-3) or tamoxifen/nonsteroidal aromatase inhibitor with ovarian function suppression in pre/perimenopausal women (MONALEESA-7). This review summarizes the MONALEESA clinical program. ClinicalTrials.gov identifiers: NCT01958021 (MONALEESA-2), NCT02422615 (MONALEESA-3), NCT02278120 (MONALEESA-7).

Efficacy and safety of talazoparib (TALA) or physician's choice of therapy (PCT) in United States patients (pts) with HER2- germline BRCA1/2-mutated (gBRCAm) locally advanced/metastatic breast cancer (LA/MBC) in the EMBRACA study

1044

Background: TALA is a poly(ADP-ribose) polymerase (PARP) inhibitor approved in the US for HER2- g BRCAm LA/MBC. Approval was based on results from the Phase 3 EMBRACA trial comparing efficacy/safety of TALA (1 mg/d) to PCT (capecitabine, eribulin, gemcitabine, vinorelbine) in HER2- g BRCAm LA/MBC pts. This analysis describes outcomes in US pts included in the pivotal study. Methods: Clinical findings from US pts enrolled in EMBRACA were analyzed. Pt characteristics, progression-free survival (PFS), objective response rate (ORR), clinical benefit rate (CBR), and safety/adverse events (AEs) were among the parameters assessed. Results: Of 431 randomized pts, 156 pts (36%) were from the US (TALA: 99; PCT: 57). Pt characteristics were balanced, although a higher percentage in the TALA arm had more poor prognostic features (eg, triple-negative breast cancer, disease-free interval < 12 mo, and more disease sites). TALA improved PFS, ORR, CBR, and duration of response (DOR) vs PCT (Table). 22% of pts in the TALA arm had a continued objective response at month 12 vs 0 pts in the PCT arm. The most common AEs in the TALA arm included anemia, neutropenia, thrombocytopenia, fatigue, nausea, alopecia, and headache; hematologic grade 3/4 AEs occurred more often than nonhematologic AEs. Conclusions: In US pts with HER2- g BRCAm LA/MBC, TALA demonstrated significant improvements in outcomes vs PCT with a manageable safety profile. Clinical trial information: NCT01945775. [Table: see text]

Triplet therapy (continuous ribociclib, everolimus, exemestane) in HR+/HER2− advanced breast cancer postprogression on a CDK4/6 inhibitor (TRINITI-1): Efficacy, safety, and biomarker results

1016

Background: The combination of CDK4/6 inhibitor (CDK4/6i) + endocrine therapy (ET) provides consistent improvement in PFS and response rates compared with single-agent ET as first- or subsequent-line therapy in HR+, HER2− advanced breast cancer (ABC), but the optimal regimen postCDK4/6i progression, including the role of continued CDK 4/6 blockade, is unclear. Methods: TRINITI-1 is a Phase I/II, open-label trial (NCT02732119) of triplet therapy: ribociclib (RIB; CDK4/6i) + everolimus (EVE; mTORi) + exemestane (EXE; ET) in men or postmenopausal women with HR+, HER2− ABC that progressed on prior CDK4/6i and up to 3 lines of therapy (≥ 1 ET and ≤ 1 chemotherapy regimen). Phase I determined RP2D; Phase II assessed efficacy/safety of RIB 300 or 200 mg + EVE 2.5 or 5 mg + EXE 25 mg/day. Here we present the first results in the entire patient population who received this triplet regimen and the correlation of biomarkers with outcomes. Results: As of October 24, 2018, 95 patients were evaluable (ET refractory and postCDK4/6i) in Phases I (n = 17) and II (n = 78). Continuous RIB + EVE + EXE demonstrated clinical benefit at week 24 in 39 patients (41.1%), exceeding the predefined primary end point threshold (> 10%). ORR was 8.4% by investigator assessment, median PFS was 5.7 months, and 1-year PFS was 33%. AEs were consistent with known safety profile of RIB, EVE, and EXE. Most common AEs were neutropenia (all grades, 41.7%; grade 3/4, 31.3%), stomatitis (41.7%; 3.1%), and fatigue (35.4%; 1.0%). No grade 3/4 QTc prolongation was noted. ctDNA genotyping revealed patients with certain tumor alterations, eg ESR1, had shorter median PFS vs wild-type: 3.5 vs 6.9 mo (HR 1.76, 95% CI 1.01–3.05). Additional genomic results, including PIK3CA, will be presented. Conclusions: TRINITI-1 met its primary efficacy end point and is the first trial to demonstrate clinical benefit and tolerability of continuous triplet therapy with ET + mTORi + CDK4/6i in patients with ET-refractory HR+, HER2− ABC postCDK4/6i progression. Tumor genomic profile might impact the clinical outcome with triplet therapy and warrants additional research to guide rational therapy selection. Clinical trial information: NCT02732119.

A phase II study of abemaciclib in patients (pts) with brain metastases (BM) secondary to HR+, HER2- metastatic breast cancer (MBC)

1017

Background: Abemaciclib is a selective CDK4 & 6 inhibitor approved to treat HR+, HER2- MBC pts on a continuous dosing schedule as monotherapy or in combination with endocrine therapy (ET). Clinical data demonstrate abemaciclib penetrates the blood brain barrier resulting in comparable concentrations in tissues and plasma. Methods: JPBO is a Simon 2-stage trial evaluating abemaciclib in 6 pt cohorts with BM secondary to HR+ MBC, non-small cell lung cancer, or melanoma. Here, we report on HR+, HER2- MBC pts. Eligible pts had ≥1 new or not previously irradiated measurable BM ≥10mm or a progressive previously irradiated BM. Pts receiving ET at the time of enrollment were permitted to continue the same ET provided that extracranial (EC) disease was stable ≥3 months and the CNS progression occurred on the ET. Abemaciclib was orally administered 200mg BID. Primary endpoint was objective intracranial response rate (OIRR; [CR+PR]) based on Neuro-Oncology BM response assessment criteria (RANO-BM). Secondary endpoints included intracranial clinical benefit rate, PFS, and safety. Results: 58 HR+, HER2- MBC pts were enrolled and 52 pts were evaluable. Pts had a median of 4 prior systemic therapies, 75% of pts had prior chemotherapies (0-6, median of 2), and 71% of pts had prior ET (0-4, median of 1), in the metastatic setting. 50% of pts had prior whole brain radiotherapy, 39% stereotactic radiosurgery, and 8% surgical resection of BM. Median time from radiation to study enrollment was 9.4 months. Out of the 52 evaluable patients, 3 pts had a confirmed intracranial response (6% OIRR), and 38% of pts showed a decrease in the sum of their intracranial target lesions. Intracranial clinical benefit rate (CR+PR+SD persisting for ≥ 6 months) was 25%. Median PFS was 4.4 months (95% CI, 2.6-5.5). Safety and tolerability were similar to previous reports for abemaciclib. Conclusions: Abemaciclib demonstrated intracranial clinical benefit in heavily pretreated HR+, HER2- MBC pts with BM in this study. Further evaluations are ongoing to identify ABC patients with BM who might benefit most from abemaciclib. Clinical trial information: NCT02308020.

HER2 heterogeneity as a predictor of response to neoadjuvant T-DM1 plus pertuzumab: Results from a prospective clinical trial

502

Background: HER2 targeted therapy without chemotherapy may be insufficient to completely eradicate a HER2+ cancer in cases of significant intratumor HER2 heterogeneity (ITH-HER2). Methods: We conducted a single-arm phase II study enrolling centrally confirmed HER2+ breast cancer. Pts received 6 cycles of T-DM1 plus Pertuzumab before surgery. Central ITH-HER2 was assessed on baseline ultrasound-guided core biopsies from 2 distinct areas of each tumor (3 cores/site). ITH-HER2 was defined as at least one of the six areas demonstrating either 1) HER2 positivity by FISH in > 5% and < 50% of tumor cells (i.e., CAP guideline) or 2) an area of tumor that tested HER2 negative. The primary objective is the association between pathologic complete response (pCR) and ITH, stratified by ER status. pCR defined as residual cancer burden (RCB) 0. Results: 164 pts with centrally confirmed HER2+ tumors were enrolled from 1/2015 to 1/2018. 2 pts withdrew consent. Median tumor size by imaging was 2.8 cm (IQR 2.1-3.8cm); 111 (69%) were ER+ and 51 (32%) ER-. 8 pts discontinued tx (6 due to disease progression, 2 due to toxicity). 49% of pts had a pCR (RCB-0), 14% RCB-I, 26% RCB-II and 11% RCB-III. Higher rates of RCB-0 were seen in ER- (65%) versus ER+ (42%). ITH-HER2 was detected in 10% (16/157) of evaluable cases. No pCR was observed among cases classified as heterogeneous (RCB-I 25%, RCB-II 25%, RCB-III 50%). The study met its primary endpoint by demonstrating a significant association between ITH-HER2 and pCR stratified by ER status (p < .0001). Secondary analysis also demonstrated a significant association between ITH-HER2 and pathologic response defined as RCB 0 or I (OR = 5.6, p = 0.004). Exploratory analysis revealed higher rates of RCB-0 among tumors centrally classified as HER2 3+ (56% [66/118]) versus HER2 2+ (27% [10/37]), (OR = 3.4, p = 0.002). The association of ITH-HER2 and pCR was maintained when stratifying by ER status and HER2 IHC (2+ vs. 3+), (p = 0.002). Conclusions: ITH-HER2 assessed by routine pathology evaluation is a strong predictor of pCR to a dual-HER2 targeted therapy regimen. If validated, ITH-HER2 may need to be considered in selection of pts for HER2-targeted regimens without chemotherapy in the curative setting. Clinical trial information: NCT02326974.

CONTESSA: A multinational, multicenter, randomized, phase III registration study of tesetaxel plus a reduced dose of capecitabine in patients (pts) with HER2-, hormone receptor + (HR+) locally advanced or metastatic breast cancer (LA/MBC) who have previously received a taxane

TPS1107

Background: Chemotherapy treatments with robust efficacy that preserve quality of life are needed. Tesetaxel (T) is a novel, oral taxane that has potential advantages over currently available taxanes, including: oral administration with a low pill burden and Q3W dosing regimen; no observed hypersensitivity reactions; preclinical evidence of CNS penetration; and improved activity against chemotherapy-resistant tumors. Over 600 pts have been treated with T in clinical studies. T had robust monotherapy activity in a Phase 2 study in 38 pts with HER2-, HR+ MBC who received T Q3W, with a confirmed ORR per RECIST 1.1 of 45% and median PFS of 5.4 mo. The confirmed ORR in taxane-pretreated pts was 45%. Preclinical and clinical studies suggest that reducing the dose of capecitabine (C) in combination with a taxane may result in reduced toxicity without reduction in efficacy. Preclinical data also suggest that T may penetrate the brain at clinically relevant concentrations. CONTESSA investigates T plus a reduced dose of C as an all-oral regimen in HER2-, HR+ LA/MBC, with revised eligibility criteria to allow inclusion of pts with CNS metastases. Methods: CONTESSA is a 600-pt, multinational, multicenter, randomized (1:1), Phase 3 registration study comparing T (27 mg/m2 on Day 1 of a 21-day cycle) plus a reduced dose of C (1,650 mg/m2/day on Days 1-14 of a 21-day cycle) to the approved dose of C alone (2,500 mg/m2/day on Days 1-14 of a 21-day cycle) in pts with HER2-, HR+ LA/MBC previously treated with a taxane in the (neo)adjuvant setting. The protocol was newly amended to allow pts with known CNS metastases. The primary endpoint is PFS assessed by an Independent Radiologic Review Committee (IRC). CONTESSA is 90% powered to detect a 42% improvement in PFS (HR = 0.71). Secondary endpoints are OS, ORR, and disease control rate. Enrollment began in Dec 2017. Following review in Jan 2019, the Independent Data Monitoring Committee recommended that the Study continue as planned. Clinical trial information: NCT03326674.

Local-regional recurrence in women with small node-negative, HER2-positive breast cancer: results from a prospective multi-institutional study (the APT trial)

PURPOSE

Women with HER2-positive breast cancer treated prior to effective anti-HER2 therapy have higher rates of local-regional recurrence (LRR) than those with HER2-negative disease. Effective systemic therapy, however, has been shown to decrease LRR. This study examines LRR in women with HER2-positive breast cancer treated on a single-arm prospective multicenter trial of adjuvant trastuzumab (H) and paclitaxel (T).

METHODS

Patients with HER2-positive tumors ≤ 3.0 cm with negative axillary nodes or micrometastatic disease were eligible. Systemic therapy included weekly T and H for 12 weeks followed by continuation of H to complete 1 year. Radiation therapy (RT) was required following breast-conserving surgery (BCS), but dose and fields were not specified. Disease-free survival (DFS) and LRR-free survival were calculated using the Kaplan-Meier method.

RESULTS

Of the 410 patients enrolled from September 2007 to September 2010, 406 initiated protocol therapy and formed the basis of this analysis. A total of 272 (67%) had hormone receptor-positive tumors. Of 162 patients undergoing mastectomy, local therapy records were unavailable for two. None of the 160 for whom records were available received RT. Among 244 BCS patients, detailed RT records were available for 217 (89%). With a median follow-up of 6.5 years, 7-year DFS was 93.3% (95% CI 90.4-96.2), and LRR-free survival was 98.6% (95% CI 97.4-99.8).

CONCLUSION

LRR in this select group of early-stage patients with HER2-positive disease receiving effective anti-HER2 therapy is extremely low. If confirmed in additional studies, future investigational efforts should focus on de-escalating local therapy.

Seven-Year Follow-Up Analysis of Adjuvant Paclitaxel and Trastuzumab Trial for Node-Negative, Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer

PURPOSE

The Adjuvant Paclitaxel and Trastuzumab trial was designed to address treatment of patients with small human epidermal growth factor receptor 2 (HER2)-positive breast cancer. The primary analysis of the Adjuvant Paclitaxel and Trastuzumab trial demonstrated a 3-year disease-free survival (DFS) of 98.7%. In this planned secondary analysis, we report longer-term outcomes and exploratory results to characterize the biology of small HER2-positive tumors and genetic factors that may predispose to paclitaxel-induced peripheral neuropathy (TIPN).

PATIENTS AND METHODS

In this phase II study, patients with HER2-positive breast cancer with tumors 3 cm or smaller and negative nodes received paclitaxel (80 mg/m²) with trastuzumab for 12 weeks, followed by trastuzumab for 9 months. The primary end point was DFS. Recurrence-free interval (RFI), breast cancer-specific survival, and overall survival (OS) were also analyzed. In an exploratory analysis, intrinsic subtyping by PAM50 (Prosigna) and calculation of the risk of recurrence score were performed on the nCounter analysis system on archival tissue. Genotyping was performed to investigate TIPN.

RESULTS

A total of 410 patients were enrolled from October 2007 to September 2010. After a median follow-up of 6.5 years, there were 23 DFS events. The 7-year DFS was 93% (95% CI, 90.4 to 96.2) with four (1.0%) distant recurrences, 7-year OS was 95% (95% CI, 92.4 to 97.7), and 7-year RFI was 97.5% (95% CI, 95.9 to 99.1). PAM50 analyses (n = 278) showed that most tumors were HER2-enriched (66%), followed by luminal B (14%), luminal A (13%), and basal-like (8%). Genotyping (n = 230) identified one single-nucleotide polymorphism, rs3012437, associated with an increased risk of TIPN in patients with grade 2 or greater TIPN (10.4%).

CONCLUSION

With longer follow-up, adjuvant paclitaxel and trastuzumab is associated with excellent long-term outcomes. Distribution of PAM50 intrinsic subtypes in small HER2-positive tumors is similar to that previously reported for larger tumors.

Efficacy and Safety of Ribociclib With Letrozole in US Patients Enrolled in the MONALEESA-2 Study

BACKGROUND

In the Mammary Oncology Assessment of LEE011's (Ribociclib's) Efficacy and Safety (MONALEESA-2) study, combination treatment with the selective inhibitor of cyclin-dependent kinases 4/6 ribociclib with letrozole significantly improved progression-free survival (PFS) versus letrozole alone in postmenopausal women with hormone receptor-positive HR⁺/HER2^- advanced breast cancer (ABC). Herein we present results from the subset of US patients enrolled in MONALEESA-2.

PATIENTS AND METHODS

Postmenopausal women with HR⁺/HER2^- ABC without previous treatment for advanced disease were randomized (1:1) to ribociclib 600 mg/d (3 weeks on/1 week off) with letrozole 2.5 mg/d (continuous) or placebo with letrozole. The primary end point was locally assessed PFS.

RESULTS

Overall, 213 US patients were enrolled in MONALEESA-2 (ribociclib, n = 100; placebo, n = 113). Baseline characteristics were similar between treatment groups and consistent with the global population. With a median follow-up of 27 months, 38 (38%) and 29 (26%) patients in the ribociclib and placebo groups, respectively, had continued to receive treatment. Median PFS was 27.6 months with ribociclib and 15.0 months with placebo (hazard ratio, 0.53). The most common all-cause adverse events were neutropenia (ribociclib, 72.0% [n = 72]; placebo, 4.6% [n = 5]), nausea (ribociclib, 69.0% [n = 69]; placebo, 44.0% [n = 48]), and fatigue (ribociclib, 60.0% [n = 60]; placebo, 50.5% [n = 55]). Two patients (ribociclib, 2.0%; placebo, 0%) experienced febrile neutropenia.

CONCLUSION

In the US subset of MONALEESA-2, ribociclib with letrozole showed superior efficacy versus letrozole alone. These findings are consistent with the global population and support first-line use of ribociclib with letrozole in patients with HR⁺/HER2^- ABC.

Abstract P6-17-36: Consensus and disagreement among experts for treatment of patients with HER2+ early-stage breast cancer suggests unmet need for online decision support tool

Treatment (tx) choices for HER2+ early stage breast cancer (EBC) have become increasingly complex. Clinicians and patients must decide 1) which chemotherapy and HER2-targeted agents to use, 2) the sequence of surgery and chemotherapy: either neoadjuvant (neoadj) or adjuvant (adj) tx, and 3) whether to shorten or extend maintenance HER2-targeted tx.

As tx options expand, so does the need for online decision aids. One online decision support tool was developed in 2015 to provide specific tx recommendations for pts with EBC and showed that community healthcare providers (HCPs) did not consistently align with experts for neoadj or adj tx of many pts with EBC (SABCS 2015 Abs P5-09-04).

This study includes analysis of neoadj and adj tx practice patterns of 5 breast cancer experts based on their tx recommendations for 270 unique HER2+ EBC case scenarios made for development of a 2018 online decision tool. We aim to compare these recommendations with the intended treatment of clinicians using the tool.

Results

Experts agree on neoadj tx approaches: initial surgery, no neoadj tx for pts with cT1a/b N0 tumors; neoadj tx before surgery for pts with ≥cT2 or N+ tumors. There was disparity among experts for pts with cT1c N0 disease: 3 experts recommend neoadj TCH±P and 2 recommend proceeding directly to surgery.

Experts generally recommend adj TCHP for pts with stage II N+ or higher HER2+ EBC who did not receive neoadj tx. In addition, 5/5 experts would consider extended adj tx with neratinib for these pts if HR+ and 2/5 experts would also consider neratinib if HR–.

In pts who received neoadj chemo+HER2 tx, post-surgery management depends on response to neoadj tx. For pts with pCR, 5/5 experts generally agree on continuing H+P if both were given as neoadj tx or H alone if only H given as neoadj tx for a total of 1 yr of anti-HER2 Ab tx and 2/5 experts would consider extended adj tx with neratinib for HR+ disease. For pts with residual disease, experts would recommend continuing H+P if both were given as neoadj tx and most would add P for subsequent adj tx if H alone was given to complete a total of 1 yr of anti-HER2 Ab tx (Table1). All experts would consider extended adj tx with neratinib for HR+ disease and 3/5 experts would also consider neratinib for HR– disease. None of the experts recommended less than 12 mos of adj HER2-targeted tx.

We will present analyses of cases entered into our online tool and detailed comparisons of expert and the intended treatment of clinicians using the tool.

Conclusions

Practice patterns are changing rapidly and are more complex in response to the evolving treatment landscape for HER2+ EBC. This analysis highlights several areas of expert consensus; however, disparities remain for select cases. The current tool addresses an unmet medical need for expert-led evaluation of HER2+ EBC tx choices and warrants further investigation.

Expert Recommendations: Initial Adj HER2 Ab Tx After Neodj Tx With H Alone ExpertsResponse12345pCR (HR-)HHHHHpCR (HR+)HHHHHypT1a-c N0 (HR-)H + PHH + PH + PH + PypT1a-c N0 (HR+)H + PHHH + PHypT2 N0 (HR-)H + PH + PH + PH + PH + PypT2 N0 (HR+)H + PH + PHH + PH + PypTany N+ (HR+ or HR-)H + PH + PH + PH + PH + P

Citation Format: Holmes FA, Rosenthal KM, Hurvitz S, Pegram MD, Yardley DA, Obholz KL, O'Shaughnessy J. Consensus and disagreement among experts for treatment of patients with HER2+ early-stage breast cancer suggests unmet need for online decision support tool [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 P6-17-36.

Abstract P6-18-15: Ribociclib + endocrine therapy in hormone receptor-positive, HER2-negative advanced breast cancer: A pooled safety analysis

Background: In Phase III trials, ribociclib (RIB; cyclin-dependent kinase 4/6 inhibitor) + various endocrine therapy (ET) partners has demonstrated significantly prolonged progression-free survival vs placebo (PBO) + ET in patients (pts) with hormone receptor-positive (HR+), HER2-negative (HER2–) advanced breast cancer (ABC). Here we further evaluate the safety of RIB-based regimens of interest for the proposed indication (i.e. with a non-steroidal aromatase inhibitor [NSAI] or fulvestrant [FUL]) using pooled data from three Phase III trials (MONALEESA [ML]-2 [NCT01958021], -3 [NCT02422615], and -7 [NCT02278120]).

Methods: Postmenopausal pts with HR+, HER2– ABC received RIB (600 mg/day; 3-weeks-on/1-week-off) or PBO + letrozole (LET; 2.5 mg/day; ML-2 [no prior ET for ABC]) or FUL (500 mg, Days 1 and 15 of Cycle 1, then Day 1 of every cycle thereafter; ML-3; no or ≤1 prior line of ET for ABC]). Premenopausal pts (ML-7; no prior ET and ≤1 chemotherapy for ABC]) received RIB or PBO + anastrozole (1 mg/day)/LET (2.5 mg/day) + goserelin (3.6 mg every 28 days). Adverse events (AEs) were characterized per Common Terminology Criteria for Adverse Events v4.03; safety analyses included time to first event, duration of event, and rate of associated RIB/PBO discontinuations.

Results: Data for 1883 pts were pooled; 1065 pts received RIB + ET and 818 pts received PBO + ET (median exposure to study treatment: 17 and 13 months, respectively). Exposure-adjusted incidence rates for AEs of special interest were 561 and 131 per 100 pt-years in the RIB and PBO arms, respectively. The most common all-causality Grade 3/4 AEs (≥10% in any arm; RIB vs PBO) were neutropenia (59% vs 2%), leukopenia (18% vs 1%), and hypertension (13% vs 13%). A new Fridericia's corrected QT interval (QTcF) &gt;480 ms occurred in (n/N) 52/1054 (5%) vs 11/814 (1%) pts in the RIB vs PBO arms; a new QTcF &gt;500 ms occurred in 14/1054 (1%) vs 1/814 (&lt;1%) pts. Median time to first event for Grade ≥2 neutropenia, elevated alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST), and QTc prolongation in the RIB arm was 2, 12, and 2 weeks, respectively; median duration of first Grade ≥2 event was 4, 4, and 2 weeks. In the RIB arm vs PBO arms, 7% vs 3% of pts discontinued study treatment due to AEs; common all-grade AEs leading to RIB/PBO discontinuation (≥2% in any arm) were elevated ALT (4% vs &lt;1%) and elevated AST (2% vs 1%). Discontinuation due to QT prolongation occurred in 4 pts in the RIB arm and 2 in the PBO arm (both &lt;1%). All-grade serious AEs occurred in 25% of pts in the RIB arm vs 15% of pts in the PBO arm.

Conclusions: RIB in combination with various ET partners continues to demonstrate a predictable and manageable tolerability profile across a broad population of pts with HR+, HER2– ABC.

Citation Format: Burris HA, Chan A, Im S-A, Chia S, Tripathy D, Esteva FJ, Campone M, Bardia A, Kong O, Bao W, Diaz-Padilla I, Rodriguez Lorenc K, Yardley DA. Ribociclib + endocrine therapy in hormone receptor-positive, HER2-negative advanced breast cancer: A pooled safety analysis [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 P6-18-15.

Abstract P6-18-07: Ribociclib + endocrine therapy in patients with hormone receptor-positive, HER2-negative advanced breast cancer presenting with visceral metastases: Subgroup analysis of phase III MONALEESA trials

Background: Patients (pts) with advanced breast cancer (ABC) who present with visceral metastases (mets) have a poorer prognosis vs pts with non-visceral disease. In the Phase III MONALEESA (ML) trials, ribociclib (RIB) + endocrine therapy (ET) prolonged progression-free survival (PFS) vs placebo (PBO) + ET in hormone receptor-positive (HR+), HER2-negative (HER2–) ABC. Here we show data for pts with and without visceral mets from the ML-2, -3, and -7 trials.

Methods: Data were collated from 3 trials in HR+, HER2– ABC: in ML-2 (NCT01958021; data cutoff [DCO] Jan 2/4, 2017), postmenopausal pts (no prior ET for ABC) received RIB or PBO + letrozole; in ML-3 (NCT02422615; DCO Nov 3, 2017), postmenopausal pts (no prior ET for ABC subgroup only) received RIB or PBO + fulvestrant; in ML-7 (NCT02278120; DCO Aug 20, 2017), premenopausal pts (no prior ET and ≤1 chemotherapy for ABC) received RIB or PBO + goserelin + anastrozole/letrozole. Endpoints; primary: local PFS; secondary: overall response rate (ORR), clinical benefit rate (CBR), safety.

Results: Of all 820 pts treated with RIB + ET, 484 (59%) had visceral mets (ML-2 197/334; ML-3 137/238; ML-7 150/248); of all 710 pts treated with PBO + ET, 416 (59%) had visceral mets (ML-2 196/334; ML-3 77/129; ML-7 143/247). Median PFS was prolonged for RIB vs PBO in pts with and without visceral mets (Table). ORR and CBR were also higher for RIB vs PBO in pts with and without visceral mets. The most common (≥10% of pts in any arm) Grade [G] 3 and 4 adverse events (AEs) for each trial are shown in the table; no G4 AEs occurred in ≥10% of pts in ML-3.

 Visceral metsNo visceral metsML-2 Median PFS (RIB/PBO), months (95% CI)24.9 (22.2–30.9)/13.4 (12.7–16.5)25.3 (22.2–NR)/18.2 (15.0–24.6)Hazard ratio (95% CI)0.538 (0.408–0.709)0.634 (0.448–0.897) ORR (RIB/PBO),* %48/3735/17 CBR (RIB/PBO),† %79/7282/75 Most common (≥10% in any arm) G3 AEs (RIB/PBO), %Neutropenia56/147/1Leukopenia19/121/&lt;1Hypertension11/1115/15 Most common (≥10% in any arm) G4 AEs (RIB/PBO), %Neutropenia10/09/0 ML-3 Median PFS (RIB/PBO), months (95% CI)NR (19.1–NR)/16.5 (9.0–NR)NR (NR–NR)/21.9 (14.8–NR)Hazard ratio (95% CI)0.610 (0.403–0.926)0.521 (0.295–0.921) ORR (RIB/PBO),* %46/2931/21 CBR (RIB/PBO),† %74/6075/81 Most common (≥10% in any arm) G3 AEs (RIB/PBO), %Neutropenia50/045/0Leukopenia12/010/0Increased ALT6/012/0 ML-7 Median PFS (RIB/PBO), months (95% CI)23.8 (14.8–NR)/10.4 (7.2–12.9)27.5 (NR–NR)/19.3 (16.5–NR)Hazard ratio (95% CI)0.507 (0.367–0.700)0.609 (0.377–0.984) ORR (RIB/PBO),* %45/3630/19 CBR (RIB/PBO),† %79/5783/81 Most common (≥10% in any arm) G3 AEs (RIB/PBO), %Neutropenia54/356/4Leukopenia14/116/1 Most common (≥10% in any arm) G4 AEs (RIB/PBO), %Neutropenia11/&lt;19/0CI, confidence interval; NR, not reached. *ORR = complete response + partial response; †CBR = complete response + partial response + (stable disease + non-complete response/non-progressive disease ≥24 weeks).

Conclusions: Although the presence of visceral mets is associated with a poorer prognosis, RIB + ET is an effective and well-tolerated treatment option for pts with HR+, HER2– ABC irrespective of the presence of visceral mets.

Citation Format: Yardley DA, Chan A, Nusch A, Sonke GS, Yap Y-S, Bachelot T, Esteva FJ, Slamon DJ, Burris HA, Gaur A, Kong O, Diaz-Padilla I, Rodriguez Lorenc K, Wheatley-Price P. Ribociclib + endocrine therapy in patients with hormone receptor-positive, HER2-negative advanced breast cancer presenting with visceral metastases: Subgroup analysis of phase III MONALEESA trials [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-18-07.

Abstract OT2-06-04: MORPHEUS: A phase Ib/II trial platform evaluating the safety and efficacy of multiple cancer immunotherapy combinations in patients with hormone receptor–positive and triple-negative breast cancer

Background:

Cancer immunotherapy (CIT) has significantly improved overall survival across multiple tumor types, but only subsets of patients experience durable response with single-agent CIT. Combinations of CIT with targeted therapy or chemotherapy may be needed in order to target multiple cancer immune escape mechanisms simultaneously, thus providing personalized treatment options that extend clinical benefit to more patients. The MORPHEUS platform includes multiple phase Ib/II trials designed to identify early signals of safety and activity of CIT combinations. Using a randomized trial design, multiple CIT combination arms are compared with a single standard-of-care control arm. These trials have the flexibility to open new treatment arms with novel CIT combinations as they become available and to close arms that show minimal activity or unacceptable toxicity. Here we describe MORPHEUS trials in patients with metastatic or unresectable locally advanced hormone receptor–positive (HR+BC) or triple-negative breast cancer (TNBC), 2 patient populations in need of more treatment options.

Trial design:

MORPHEUS-HR+BC (NCT03280563) will enroll patients with metastatic or unresectable locally advanced HR+BC who have progressed during or after first-line treatment with a cyclin-dependent kinase (CDK) 4/6 inhibitor and whose tumors do not express human epidermal growth factor 2 (HER2). MORPHEUS-TNBC (NCT03424005) will enroll patients with metastatic or unresectable locally advanced TNBC who have progressed during or after first-line treatment with chemotherapy. For both studies, key inclusion criteria include Eastern Cooperative Oncology Group performance status of 0-1 (stage 1) or 0-2 (stage 2) and measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1. Key exclusion criteria include prior treatment with T-cell co-stimulating or immune checkpoint blockade therapies, and symptomatic, untreated, or actively progressing central nervous system metastases. Patients in both trials will be randomized to one of the CIT atezolizumab combination arms or a control arm (up to 5 arms in HR+BC and up to 6 arms in TNBC). Patients experiencing loss of clinical benefit or unacceptable toxicity in stage 1 may be eligible to switch to a different CIT atezolizumab combination arm in stage 2. Primary endpoints are safety measures and investigator-assessed objective response rate per RECIST v1.1. Progression-free survival, overall survival, duration of response, clinical benefit rate (HR+BC) or disease control rate (TNBC) are among the secondary endpoints. Exploratory biomarkers will also be examined.

Citation Format: Yardley DA, Abu-Khalaf M, Boni V, Brufsky A, Emens LA, Gutierrez M, Hurvitz S, Im S-A, Loi S, McCune SL, Schmid P, O'Hear C, Zhang X, Vidal GA. MORPHEUS: A phase Ib/II trial platform evaluating the safety and efficacy of multiple cancer immunotherapy combinations in patients with hormone receptor–positive and triple-negative breast cancer [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 OT2-06-04.

Central Nervous System Metastasis in Patients with HER2-Positive Metastatic Breast Cancer: Patient Characteristics, Treatment, and Survival from SystHERs

PURPOSE

Patients with HER2-positive metastatic breast cancer (MBC) with central nervous system (CNS) metastasis have a poor prognosis. We report treatments and outcomes in patients with HER2-positive MBC and CNS metastasis from the Systemic Therapies for HER2-positive Metastatic Breast Cancer Study (SystHERs).

EXPERIMENTAL DESIGN

SystHERs (NCT01615068) was a prospective, U.S.-based, observational registry of patients with newly diagnosed HER2-positive MBC. Study endpoints included treatment patterns, clinical outcomes, and patient-reported outcomes (PRO).

RESULTS

Among 977 eligible patients enrolled (2012-2016), CNS metastasis was observed in 87 (8.9%) at initial MBC diagnosis and 212 (21.7%) after diagnosis, and was not observed in 678 (69.4%) patients. White and younger patients, and those with recurrent MBC and hormone receptor-negative disease, had higher risk of CNS metastasis. Patients with CNS metastasis at diagnosis received first-line lapatinib more commonly (23.0% vs. 2.5%), and trastuzumab less commonly (70.1% vs. 92.8%), than patients without CNS metastasis at diagnosis. Risk of death was higher with CNS metastasis observed at or after diagnosis [median overall survival (OS) 30.2 and 38.3 months from MBC diagnosis, respectively] versus no CNS metastasis [median OS not estimable: HR 2.86; 95% confidence interval (CI), 2.05-4.00 and HR 1.94; 95% CI, 1.52-2.49]. Patients with versus without CNS metastasis at diagnosis had lower quality of life at enrollment.

CONCLUSIONS

Despite advances in HER2-targeted treatments, patients with CNS metastasis continue to have a poor prognosis and impaired quality of life. Observation of CNS metastasis appears to influence HER2-targeted treatment choice.