Phase II study of the safety and efficacy of the anti-PD-1 antibody balstilimab in patients with recurrent and/or metastatic cervical cancer
This phase II clinical trial evaluated the safety and antitumor activity of balstilimab, an anti-PD-1 antibody, in patients with previously-treated, recurrent/metastatic cervical cancer. Eligible patients were 18 years or older with recurrent and/or metastatic cervical cancer and who had relapsed after a prior platinum-based treatment regimen for advanced disease. Balstilimab was administered intravenously at 3 mg/kg once every two weeks, for up to 24 months. The primary endpoint was objective response rate (ORR, RECIST v1.1) as assessed by an independent review committee. At data cutoff, 161 women (median age, 53 years [range 25-81]) were enrolled and treated with balstilimab. Of these, 140 had measurable disease at baseline and one prior line of platinum-based therapy in the metastatic, persistent, or recurrent setting; these patients were included in the efficacy analyses. The ORR was 15% (95% CI, 10.0%-21.8%) and included 5 patients with a complete response and 16 with a partial response. The median duration of response was 15.4 months. In patients with PD-L1-positive tumors the ORR was 20%, however patients with PD-L1-negative tumors also responded to balstilimab (ORR, 7.9%). Responses were not restricted to tumors of squamous cell histology, and an ORR of 12.5% was seen in the subset of patients with cervical adenocarcinoma. The disease control rate was 49.3% (95% CI, 41.1%-57.5%). Immune-mediated enterocolitis (3.1%) and diarrhea (1.9%) were the most common grade 3 or higher treatment-related adverse events. Balstilimab demonstrated meaningful and durable clinical activity, with manageable safety, in patients with previously-treated, recurrent/metastatic cervical cancer.