Lenvatinib plus pembrolizumab in previously treated advanced endometrial cancer: 5-year outcomes from the randomized, phase 3 Study 309/KEYNOTE-775

Abstract

Background In Study 309/KEYNOTE-775 (NCT03517449), lenvatinib+pembrolizumab versus chemotherapy significantly improved progression-free survival (PFS), overall survival (OS), and objective response rate (ORR) in advanced endometrial cancer (EC). We report 5-year follow-up results.Methods Participants had advanced/recurrent/metastatic EC with progressive disease after one prior platinum-based chemotherapy regimen, measurable disease per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1), and no prior receipt of anti-programmed cell death protein 1 or anti-programmed cell death ligand 1 agents. Participants were randomized 1:1 to lenvatinib 20 mg orally once daily plus pembrolizumab 200 mg intravenously every 3 weeks or chemotherapy (doxorubicin or paclitaxel). Pembrolizumab was given for <= 35 cycles. Primary endpoints were OS and PFS per RECIST v1.1 by blinded independent central review (BICR). Secondary endpoints included ORR per RECIST v1.1 by BICR and safety. Efficacy endpoints were analyzed using Cox regression, Kaplan-Meier, and Miettinen and Nurminen methodology.Results 827 participants were randomized. At data cut-off (February 26, 2025), overall median follow-up was 68.8 months; 139 participants were alive (lenvatinib+pembrolizumab, n=86; chemotherapy, n=53), and all had ended their treatment in this study. Five-year OS rate was 16.7% with lenvatinib+pembrolizumab versus 7.3% with chemotherapy in mismatch repair-proficient EC, 36.5% versus 9.8% in mismatch repair-deficient EC, and 19.9% versus 7.7% in all-comers. Five-year PFS rates were 6.3% versus 2.1%, 26.4% versus 10.8%, and 9.8% versus 3.2%, respectively. In all-comers, treatment-related adverse events led to any treatment discontinuation in 32.3% versus 5.9%. Subsequent systemic anticancer therapy was used by 44.8% versus 51.2% (lenvatinib+pembrolizumab by 2.4% vs 10.1%).Conclusions Results were consistent with the primary analysis despite increased use of subsequent systemic anticancer therapy and crossover to lenvatinib+pembrolizumab in the chemotherapy group. The continued durable benefit, including OS, with lenvatinib+pembrolizumab and no new safety signals lend further support for this regimen as a standard of care therapy for EC.