Objectives This study (ClinicalTrials.gov identifier: NCT03676959) is a phase I plus expansion study investigating the antitumor activity and safety of socazolimab, an anti-PD-L1 monoclonal antibody, in recurrent or metastatic cervical cancer.

Methods All patients received one or more lines of chemotherapy for recurrent or metastatic disease. Patients received 5mg/kg socazolimab every 2 weeks as one cycle for total of 24 cycles. Tumor imaging was performed every 8 weeks for 48 weeks. The primary end points were safety and objective response rate (ORR) assessed per RECIST 1.1 evaluated by independent radiology review committee (IRC). Progression free survival (PFS), duration of response (DOR) and overall survival (OS) were the secondary end points.

Results Ninety-four patients were treated. Median age was 51.5 years, and 58.5% of patients had ECOG performance status of 1. Fifty-six patients had PD-L1-positive tumors (CPS ≥ 1%). Twenty-nine patients had PD-L1-negative tumors (CPS<1). Median follow-up was 14.75 months. ORR was 18.1% (95% CI, 10.9% to 27.4%), with 3 complete and 14 partial responses. PD-L1-positive patients had an ORR of 19.6% (95% CI, 10.2% to 32.4%). PD-L1-negative patients had an ORR of 20.7% (95% CI, 8.0% to 39.7%). Median PFS and OS were 4.5 and 15.8 months respectively. Median DOR was not reached. TRAE occurred in 62.1% of patients. Grade 3 to 4 TRAE occurred in 8.4% of patients.

Conclusions Socazolimab demonstrated durable antitumor activity and manageable safety in patients with recurrent or metastatic cervical cancer. Based on these results, China National Medical Products Administration (NMPA) grants breakthrough Therapy Designation to socazolimab for the cervical cancer indication.