Efficacy and safety of pertuzumab and trastuzumab administered in a single infusion bag, followed by vinorelbine: VELVET cohort 2 final results

Background. Cohort 1 demonstrated the applicability of pertuzumab, trastuzumab, and vinorelbine as an alternative first-line treatment regimen for patients with HER2-positive locally advanced or metastatic breast cancer (MBC) who cannot receive docetaxel. Co-infusion of pertuzumab and trastuzumab may reduce clinic time and medical resource utilization. We report results from Cohort 2, in which pertuzumab and trastuzumab were co-infused, followed by vinorelbine. Patients andMethods. During cycle 1, patients with HER2-positive locally advanced orMBC received loading doses of pertuzumab (840 mg) and trastuzumab (8 mg/kg) on consecutive days, followed by vinorelbine (25 mg/m²) on days two and nine. From cycle 2 onwards, patients received a co-infusion of pertuzumab (420 mg) and trastuzumab (6 mg/kg) on day one, followed by vinorelbine (30–35 mg/m²) on days one and eight (or days two and nine). The primary endpoint was objective response rate (ORR) in patients with measurable disease. Secondary endpoints included progression-free survival (PFS) and safety. Results. Cohort 2 enrolled 107 patients. The ORR was 63.7% (95% confidence interval [CI] 53.0–73.6) in patients with measurable disease (91/107; 85.0%). Median PFS was 11.5 months (95% CI 10.3–15.8). The most common adverse events [AEs] were diarrhea (57.9%), neutropenia (57.0%), and nausea (41.1%). Grade ≥3 AEs occurred in 85 patients (79.4%) and serious AEs in 44 patients (41.1%). Eighteen patients (16.8%) had AEs suggestive of congestive heart failure. Conclusion. These results support the feasibility of pertuzumab and trastuzumab co-infusion from a safety perspective and support Cohort 1 conclusions that vinorelbine offers an alternative chemotherapy companion for pertuzumab and trastuzumab.