70P - Overall survival of eribulin, trastuzumab, and pertuzumab as first-line therapy for patients with HER2-positive metastatic breast cancer: A phase II, single-arm clinical trial

Background

The efficacy and safety of the three-drug combination of eribulin (E), trastuzumab (T), and pertuzumab (P) in patients with HER2-positive metastatic breast cancer (MBC) as first-line treatment was reported. The overall response rate (complete response [CR] + partial response [PR]) was 80.0% (95% confidence interval [CI], 59.3–93.2%), and the clinical benefit rate (CR + PR + stable disease ≥24 weeks; CBR) was 84.0% (95% CI, 63.9–95.5%). Median time to treatment failure with E was 9.1 months (95% CI, 4.3–13.9 months), and median progression-free survival was 23.1 months (95% CI, 14.4–31.8 months). The most common treatment-emergent adverse events (TEAEs) were alopecia (92.0%), fatigue (68.0%), and sensory peripheral neuropathy (60.0%). Grade 3/4 TEAEs occurred in 11 patients (44.0%). The only grade 4 TEAE was neutrophil count decreased (16.0%). Neither grade 4 peripheral neuropathy nor febrile neutropenia occurred (Inoue K et al Investigational New Drugs 2019; 180:135–46). We report the overall survival results and the efficacy of post-ETP treatments at 5.5 years after the last enrollment.

Methods

E 1.4 mg/m² (days 1 and 8), T 8 mg/kg over 90 min and 6 mg/kg over 30 min, and P 840 mg/body over 60 min and 420 mg/body over 30 min were administered intravenously in 21-day cycles.

Results

From April 2016 to November 2017, 25 women received ETP therapy and 12 of the 25 survived with a median OS of 78.4 months, 95% CI 26.4-NA months. Subset analysis by log-rank test showed a significant difference (P=0.0114) and hazard ratio; 3.063 95% CI 1.002-9.361 in hemoglobulin (≥12 vs. ≤12 mg/dl), but not in estrogen receptor status and neutrophil/lymphocyte ratio (≥2 vs. <2). T-emtansine, capecitabine + TP, T-deruxtecan, and epirubicin + cyclophosphamide were administered after ETP with CBR of 72.2% (13/18 patients), 80.0% (4/5 patients), 66.7% (2/3 patients) and 33.3% (1/3 patients), respectively.

Conclusions

ETP therapy showed acceptable efficacy and overall survival as first-line therapy for patients with HER2-positive Japanese MBC.

Clinical trial identification

UMIN000021585.

Editorial acknowledgement

Legal entity responsible for the study

Saitama breast cancer clinical study group.

Funding

Has not received any funding.

Disclosure

K. Inoue: Financial Interests, Institutional, Funding: AstraZeneca, Chugai Pharma, Daiichi Sankyo, Eisai, Eli Lilly, Kyowa-Kirin, MSD, Novartis, Pfizer, Taiho, Ono, Astellas, Sanofi. All other authors have declared no conflicts of interest.