Results from a phase II randomized, placebo-controlled, double-blind trial suggest improved PFS with the addition of pertuzumab to gemcitabine in patients with platinum-resistant ovarian, fallopian tube, or primary peritoneal cancer

5507 Background: Pertuzumab (P) is a humanized monoclonal antibody that blocks the ability of HER2 to heterodimerize with other HER/ErbB receptors. As a single agent, P has demonstrated clinical activity in relapsed/refractory epithelial ovarian cancer (EOC). Since platinum-resistant (CDDP-R) EOC remains a difficult disease to treat, this phase II study was conducted to determine if addition of P to gemcitabine (G) would improve results. Methods: Patients with CDDP-R EOC (including ovarian, fallopian tube, or primary peritoneal cancer) who had received up to one prior treatment for CDDP-R disease were randomized to Gem 800 mg/m2 on D1, 8 of a 21-day cycle ± P or placebo (pl). P was given as an 840 mg initial dose followed by 420mg IV every 3 weeks. Tumor response was assessed by RECIST every 6 weeks using GOG criteria. The primary endpoint was progression free survival (PFS). Results: One hundred thirty patients (n = 65 each treatment cohort) were treated. Clinical characteristics were balanced between the treatment groups. Pts received a median of 2 prior regimens (range 1–6) for EOC. Based on 83 events, the adjusted hazard ratio for PFS was 0.67 (95% CI: 0.43–1.02), p =0.06 in favor of P+Gem. The median PFS was 3.0 months (0–8.7 months) vs. 2.6 months (0–9+ months), and the PFS rate at 4 months was 49% vs. 34% in the P+Gem and Gem/pl arms, respectively. The most common AEs increased in the P-treated pts were fatigue, nausea, diarrhea, back pain, Gr 3–4 neutropenia, rash, headache, stomatitis, epistaxis, and rhinorrhea. Clinically significant CHF was reported in one patient in the pertuzumab cohort. There was no imbalance in the LVEF results between treatment arms. One patient who received pertuzumab + gemcitabine experienced an adverse event that resulted in death (hemolytic-uremic syndrome). Conclusions: These data suggest that pertuzumab may add activity to gemcitabine as reflected by improvements in PFS in patients with CDDP-R ovarian, primary peritoneal, or fallopian tube cancer. Survival data will be presented at ASCO. No significant financial relationships to disclose.