Pembrolizumab Plus Paclitaxel Improves Survival in Recurrent Ovarian Carcinoma Compared to Paclitaxel Alone

BACKGROUND: Epithelial ovarian cancer frequently recurs and becomes resistant to platinum chemotherapy. We investigated whether adding pembrolizumab to weekly paclitaxel, with or without bevacizumab, improves progression-free survival and overall survival compared with weekly paclitaxel, with or without bevacizumab, in participants with platinum-resistant recurrent ovarian cancer who had received one to two previous systemic regimens. METHODS: ENGOT-ov65/KEYNOTE-B96 is a randomised, double-blind, phase 3 study conducted at 187 gynaecologic oncology centres in 25 countries in the Americas, Asia, Europe, and Oceania. Adults (≥18 years) with histologically confirmed epithelial ovarian, fallopian tube, or primary peritoneal carcinoma, who received one to two previous systemic therapies including at least one platinum regimen and who progressed 6 months or less after the last platinum regimen, were eligible. Participants were randomly assigned 1:1 to intravenous pembrolizumab 400 mg every 6 weeks for up to 18 cycles plus open-label intravenous paclitaxel 80 mg/m on days 1, 8, and 15 of each 21-day cycle or intravenous placebo (saline solution) every 6 weeks for up to 18 cycles plus open-label intravenous paclitaxel 80 mg/m on days 1, 8, and 15 of each 21-day cycle; intravenous bevacizumab 10 mg/kg every 2 weeks was permitted per investigator. Randomisation was stratified by planned bevacizumab use, region, and PD-L1 combined positive score (CPS). The primary endpoint was investigator-assessed progression-free survival per RECIST version 1.1; the key secondary endpoint was overall survival. Results from two interim analyses and the final analysis are included in this Article. This study is registered with ClinicalTrials.gov, NCT05116189, and is now completed. FINDINGS: Between Dec 13, 2021, and July 3, 2023, 643 female participants were randomly assigned; 322 to pembrolizumab plus paclitaxel and 321 to placebo plus paclitaxel. At the first interim analysis, pembrolizumab plus paclitaxel significantly improved progression-free survival versus placebo plus paclitaxel in both the PD-L1 CPS 1 or higher (median 8·3 months vs 7·2 months; hazard ratio [HR] 0·72; 95% CI 0·58-0·89; p=0·0014 α=0·012]) and overall populations (median 8·3 months vs 6·4 months; HR 0·70, 95% CI 0·58-0·84; p<0·0001, [α=0·0023]), meeting the prespecified criteria for confirmatory efficacy. At the second interim analysis, overall survival was significantly improved in the PD-L1 CPS 1 or higher population (median 18·2 months vs 14·0 months; HR 0·76, 95% CI 0·61-0·94; p=0·0053, [α=0·0083]). At the final analysis, overall survival was significantly improved in the overall population (median 17·7 months vs 14·0 months; HR 0·82, 95% CI 0·69-0·97; p=0·011 [α=0·024]). Grade 3 or worse treatment-related adverse events occurred in 217 (68%) of 320 participants in the pembrolizumab plus paclitaxel group versus 176 (55%) of 318 participants in the placebo plus paclitaxel group. The most common treatment-related adverse events (any grade) included anaemia, peripheral neuropathy, alopecia, fatigue, and nausea. Treatment-related adverse events resulted in death in four participants (1%) in the pembrolizumab plus paclitaxel group (colitis, interstitial lung disease, acute myeloid leukaemia, and intestinal perforation) and in five participants (2%) in the placebo plus paclitaxel group (cardiac failure, intestinal perforation [in two participants], and large-intestine perforation [in two participants]). INTERPRETATION: Pembrolizumab plus weekly paclitaxel, with or without bevacizumab, significantly improved progression-free survival and overall survival in participants with platinum-resistant recurrent ovarian cancer who had received one to two previous systemic regimens, supporting this regimen as a new treatment option for this population. FUNDING: Funded by Merck Sharp & Dohme LLC, a subsidiary of Merck & Co, Inc, Rahway, NJ, USA.