A randomized, double-blind, placebo-controlled, phase II study to assess the efficacy/safety of farletuzumab in combination with carboplatin plus paclitaxel or carboplatin plus pegylated liposomal doxorubicin (PLD) in women with low CA-125 platinum-sensitive ovarian cancer

Objectives: The primary objective of this study (MORAb-003-011/ENGOT-ov27) was to determine if farletuzumab (FAR) had superior efficacy compared with placebo (PLB) in improving progression-free survival (PFS) when added to carboplatin (carbo)/paclitaxel (pacli) or carbo/PLD, in subjects with platinum-sensitive ovarian cancer in first relapse (platinum-free interval: 6-36 months) with low cancer antigen 125 (CA-125). CA-125 inhibits target cell killing via antibody-dependent cellular cytotoxicity, thereby reducing the efficacy of immunotherapeutic antibodies. Subgroup analysis in a prior randomized Phase III study±FAR suggested that subjects with CA-125 levels ≤3 x upper limit of normal (ULN), showed superior PFS (hazard risk [HR] = 0.49) and overall survival (OS, HR = 0.44) compared with PLB. Methods: Eligibility included age ≥18 years old, CA-125 ≤3 x ULN (105 U/mL), high-grade serous epithelial ovarian cancer, and previous treatment with debulking surgery and first-line platinum-based chemotherapy. Subjects received 6 cycles with either carbo/pacli every 3 weeks or carbo/PLD in combination with either FAR [5 mg/kg weekly] or PLB in a 2:1 ratio. Maintenance treatment with FAR (5 mg/kg weekly) or PLB was given until disease progression. Tumor assessments were every 6 weeks during the Combination Treatment Phase and every 9 weeks during the Maintenance Treatment Phase. The study was designed to detect a PFS HR of 0.667 (33.3% risk reduction) with FAR compared with PLB with approximately 85% power and a 1-sided type I error rate of 0.10. The comparison of PFS between treatment groups was based on the log-rank test. The HR was estimated based on Cox's proportional-hazards model. Results: A total of 214 subjects were randomized and enrolled, 142 with FAR+chemotherapy (FAR-CT) and 72 with placebo+chemotherapy (PLB-CT). The median PFS in the Intent-to-Treat [ITT] Population was not significantly different between treatment groups; 11.7 months (95% confidence interval [CI]: 10.2, 13.6) versus 10.8 months (95% CI: 9.5, 13.2) for FAR-CT and PLB-CT, respectively (HR = 0.89; 80% CI: 0.71, 1.11). An interim analysis of OS showed no significant difference between treatment groups. The overall response rate (ORR) was 69.6% in 96 subjects treated with FAR-CT versus 73.5% in 50 subjects treated with PLB-CT (p=0.53). No significant differences between treatment groups were observed for any other efficacy parameters. The safety profile of the 2 treatment groups was similar except for an increase in interstitial lung disease among the FAR cohort. Interstitial lung disease occurred in 7 of 141 (5.0%) subjects treated with FAR-CT (1 with Grade 1, 4 with Grade 2, and 2 with Grade 3) and none in subjects treated with PLB-CT. Download : Download high-res image (71KB) Download : Download full-size image Conclusions: The combination of FAR-CT did not show signals of superior efficacy compared with PLB-CT in improving PFS or other efficacy parameters in subjects with platinum-sensitive recurrent ovarian cancer in first relapse who had low CA-125 levels. No new safety concerns were identified with the combination of FAR-CT. Since FAR binds to the folate receptor alpha, a novel antibody-drug conjugate has been developed and clinical studies are ongoing to assess the safety/efficacy of this modification. Clinical Trial Registry: NCT02289950.