Efficacy and safety of the anti-PD-L1 monoclonal antibody socazolimab for recurrent or metastatic cervical cancer: Results from the phase I dose-escalation and expansion study.

5526 Background: The study (NCT03676959) is an open-label, phase I study investigating the safety and efficacy of the recombinant, fully human anti-programmed death-ligand 1 (PD-L1) monoclonal antibody socazolimab for recurrent or metastatic cervical cancer. Methods: Patients received socazolimab every 2 weeks until disease progression. The study was divided into a dose-escalation phase and a dose-expansion phase. Safety and tolerability were primary endpoints of the dose-escalation phase. Primary endpoints of the dose-expansion phase were safety and overall response rate (ORR) of the 5mg/kg dose. Efficacy was assessed by a third-party independent review committee (IRC) using the Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1) as the evaluation standard. Pharmacokinetics and pharmacodynamics were also studied. Results: One hundred four patients were enrolled. Twelve patients were included in the dose-escalation phase, with one complete and two partial responses in the 5mg/kg treatment group. Ninety-two patients (5mg/kg) were enrolled in the dose-expansion phase, with 54 patients (59.3%) expressing baseline PD-L1-positive tumors. ORR was 15.4% (95% CI, 8.7 to 24.5%). Median PFS was 4.44 months (95% CI, 2.37 to 5.75 months), and the median OS was 14.72 months (95% CI, 9.59 to NE months). ORRs for PD-L1-positive and PD-L1-negative patients were 16.7% and 17.9%, respectively. Treatment-related grade 3 to 4 adverse events occurred in 7.7% of patients. No treatment-related deaths had occurred. Conclusions: Our study demonstrates that socazolimab has remarkable safety and efficacy for the treatment of recurrent or metastatic cervical cancer and exhibits a safety profile similar to other anti–PD-1/PD-L1 monoclonal antibodies. Clinical trial information: NCT03676959. [Table: see text]