Background: Eribulin is a non-taxane microtubule dynamics inhibitor. In a previous Phase III trial, eribulin demonstrated a statistically significant improvement in overall survival (OS) versus current treatments and a manageable toxicity profile, in heavily pre-treated patients (pts) with metastatic breast cancer (MBC). Here we report results from a Phase III trial of eribulin compared with capecitabine in earlier-line pts with MBC (NCT00337103). Patients and methods: Pts were randomized 1:1 to eribulin mesylate 1.4 mg/m2 given on Days 1 and 8 of a 21 day cycle or capecitabine 2.5 g/m2/day administered orally BID on Days 1 to 14 of a 21 day cycle. Eligible pts had received prior therapy including an anthracycline and taxane, and were receiving study drug as 1st, 2nd, or 3rd line therapy for advanced disease. The co-primary endpoints of this study were OS and progression free survival (PFS): pre-specified statistical significance at final analysis for eribulin versus capecitabine were p ≤ 0.0372 for OS and p < 0.01 for PFS. Secondary endpoints included objective response rate (ORR), quality of life (QoL) measured using the EORTC questionnaire, duration of response, 1-, 2- and 3-year survival, and safety. The study was stratified for geographic region and HER2 status. Results: Of 1102 pts, 554 were randomized to eribulin and 548 capecitabine (375 and 380 pts were HER2[−], respectively). The median age was 54.0 years (range 24–80). Pts received study treatment as their 1st (27.2%), 2nd (57.4%) or 3rd-line (14.7%) chemotherapeutic regimen in the setting of metastatic disease. The median number of treatment cycles was 6 for eribulin and 5 for capecitabine. Median OS was 15.9 and 14.5 months (hazard ratio [HR] 0.879; 95% confidence intervals [CI] 0.770–1.003; p = 0.056), and PFS (independent review) was 4.1 and 4.2 months (HR 1.079; 95% CI 0.932–1.250; p = 0.305) for eribulin and capecitabine, respectively. ORR (independent review) were 11.0% (95% CI 8.5–13.9) and 11.5% (95% CI 8.9–14.5; p = 0.849), respectively. OS for HER2(−) pts was 15.9 months for eribulin and 13.5 months for capecitabine (HR 0.838; 95% CI 0.715–0.983; p = 0.030). AEs were consistent with the known side-effect profiles of both drugs. The most common AEs for eribulin and capecitabine (>20% all grades) were neutropenia (54.2% vs 15.9%), hand-foot syndrome (0.2% vs 45.1%) alopecia (34.6% vs 4.0%), leukopenia (31.4% vs 10.4%), diarrhea (14.3% vs 28.8%), and nausea (22.2% vs 24.4%), respectively. Conclusion: In this Phase III trial, eribulin demonstrated a trend favoring improved OS, compared with capecitabine, although this improvement does not meet the pre-defined criteria for statistical significance. This study confirms eribulin as an active drug in pts with MBC, and exploratory analyses suggest possible benefits of eribulin in specific subsets of pts, sufficient to warrant further study. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr S6-6.

Background: Eribulin mesylate (ERI), a nontaxane microtubule inhibitor with effects on tumor biology (increased vascular perfusion, reversal of epithelial to mesenchymal transition), is approved as a monotherapy for the treatment of patients (pts) with metastatic breast cancer who received ≥2 prior chemotherapeutic regimens for metastatic disease. In a pooled analysis, ERI significantly prolonged OS compared with capecitabine or treatment of physician's choice in pts with metastatic triple-negative breast cancer (mTNBC; 12.9 vs 8.2 mo, n=428). Pembrolizumab (PEM) is a human programmed death (PD) receptor-1–blocking antibody approved for the treatment of several advanced cancers. In a phase (Ph) 2 study in mTNBC, PEM monotherapy as first-line therapy demonstrated ORR, 23%; median PFS, 2.1 mo [95% CI 2.0-3.9], and in pts pretreated with ≥1 prior chemotherapy demonstrated ORR, 5%; median OS, 8.9 mo [95% CI 7.2-11.2]). Methods:This open-label Ph 1b/2 trial enrolled pts (aged ≥18 yrs; ECOG PS ≤1) with mTNBC treated with ≤2 prior lines of chemotherapy for metastatic disease. Ph 1b included a safety cohort of ≥6 pts who received intravenous (IV) ERI 1.4 mg/m2 on day (d) 1 and d8 and IV PEM 200 mg on d1 of a 21-d cycle. In Ph 2, pts were enrolled based on prior chemotherapy in the metastatic setting [0 vs 1–2 lines]. Primary endpoints: safety, tolerability (Ph 1b), and ORR (Ph 2); secondary endpoints: PFS, OS, and efficacy in PD-L1+ pts. Results: We report data from 82 of 104 enrolled pts (data cut-off Nov 1, 2016).The RP2D was ERI 1.4 mg/m2 on d1 and d8 and PEM 200 mg on d1 of a 21-d cycle. Most common treatment-emergent adverse events (TEAEs) were fatigue (73.2%), nausea (51.2%), peripheral sensory neuropathy (46.3%), alopecia (43.9%), and pyrexia (36.6%). Most common Grade (G) 3 or 4 TEAEs related to ERI: neutropenia (29.3%), peripheral neuropathy (8.5%), and asthenia/fatigue (7.3%). G3/4 immune-related TEAEs related to PEM: 19.5% of pts. TEAEs that led to drug withdrawal/dose reduction: 18.3%/28.0% of pts. G5 events: 3 pts (respiratory failure, pleural effusion, and multiple organ failure; none related to study drug). Response was irrespective of PD-L1 status (Table1). Results of the final analysis will be available for presentation.  Overall (n=82)No prior chemotherapy in metastatic setting (n=48)1-2 Prior lines of chemotherapy in metastatic setting (n=34)PD-L1+ (n=35)PD-L1- (n=36)ORR, n (%) [95% CIa]21 (25.6) [16.8, 35.4]12 (25.0) [14.0, 37.8]9 (26.5) [13.3, 41.8]9 (25.7) [12.9, 40.8]9 (25.0) [12.5, 39.8]CBRb, n (%)25 (30.5)13 (27.1)12 (35.3)10 (28.6)12 (33.3)DCRc, n (%)46 (56.1)28 (58.3)18 (52.9)19 (54.3)21 (58.3)Median PFS, mo [95% CI]4.1 [2.3-4.8]4.1 [2.2-4.9]3.9 [2.1-6.3]4.1 [2.1-4.8]4.1 [2.3-6.3]Median OS, mo [95% CI]NE [17.7-NE]17.7 [13.7-NE]NE [13.1-NE]----a Credible interval from Bayesian analysis; b clinical benefit rate = CR+PR+SD; c disease control rate = CR+PR+SD ≥24 weeks. NE, not estimable. Conclusions: ERI+PEM was well tolerated and demonstrated activity in pts with mTNBC. The combination resulted in improved ORR, with longer PFS, OS, and comparable TEAEs to those observed with either treatment as monotherapy. Further exploration of this combination is warranted. Citation Format: Tolaney SM, Kalinsky K, Kaklamani V, Savulsky C, Olivo M, Aktan G, Kaufman PA, Xing D, Almonte A, Misir S, Karantza V, Diab S. Phase 1b/2 study to evaluate eribulin mesylate in combination with pembrolizumab in patients with metastatic triple-negative breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD6-13.