Journal Article

Botensilimab (Fc-enhanced anti–CTLA-4 antibody) plus balstilimab (anti–PD-1 antibody) in patients with treatment-refractory ovarian cancer

Gordon, Michael S, El-Khoueiry, Anthony B, Moser, Justin, Joshi, Bishnu, Wu, Wei, Corr, Bradley R, Wilky, Breelyn A, Bullock, Andrea J, Matulonis, Ursula A, Stebbing, Justin, Bockorny, Bruno, Martynova, Anastasia, Chand, Dhan, Bourdelais, Sean, Mahadevan, Daruka, O’Day, Steven J, Johnson, Benny, Grossman, Joseph E, Porter, Rebecca, Hafez, Navid, Delepine, Chloe

2025

Overview

BackgroundPatients with platinum-resistant/refractory ovarian cancer (PROC) experience suboptimal outcomes, highlighting an immediate need for novel therapies. This phase 1b study investigated the safety and efficacy of botensilimab (BOT), a fragment crystallizable (Fc)-enhanced anti–cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) antibody with differentiated mechanisms of action from first-generation CTLA-4 inhibitors, plus balstilimab (BAL; anti–programmed cell death protein 1 antibody), in an expanded cohort of patients with treatment-refractory ovarian cancer.MethodsBOT was administered intravenously at 1 mg/kg or 2 mg/kg every 6 weeks in combination with BAL intravenously at 3 mg/kg every 2 weeks (up to 2 years). The primary objectives were to assess safety and tolerability. Efficacy end points included objective response rate (ORR), duration of response (DOR), and progression-free survival (PFS) by Response Evaluation Criteria in Solid Tumors (RECIST) V.1.1. Overall survival (OS) was an exploratory end point.ResultsOverall, 44 patients were evaluable for safety (with a median of 3 prior lines of therapy; median follow-up 9.6 months (range, 0.6—36.6)), and 35 for efficacy. The most common treatment-related adverse event was diarrhea/colitis (43%; 16% grade 3) with no treatment-related deaths. RECIST-confirmed ORR was 23% (8/35; 95% CI 10% to 40%; one complete (CR), seven partial responses (PRs)) and clinical benefit rate (CR, PR, or stable disease ≥24 weeks) was 31% (11/35; 95% CI 17% to 49%). Median DOR was 9.7 months (95% CI 2.8 to not reached (NR)), median PFS was 2.8 months (95% CI 1.4 to 5.5), median OS was 14.8 months (95% CI 12.1 to NR), and 12-month OS was 75% (95% CI 55% to 86%). Immune phenotypic analyses and biomarker data revealed significantly higher FcγRIIIA+CD11c+ cells and higher programmed death-ligand 1 expression in responding patients, a strong association between T-cell infiltrated tumors and clinical benefit, and differences in immune architecture across histologic subtypes.ConclusionThe BOT/BAL combination demonstrated deep, durable responses and complete remissions in patients with treatment-refractory ovarian cancer where no standard treatments are currently available. RECIST under-represented clinical benefit with 11 patients achieving prolonged/clinically meaningful stable disease (or better) for ≥24 weeks. Toxicities were manageable and reversible. The encouraging clinical activity of BOT/BAL in heavily pretreated patients, as well as biomarker associations, warrants further investigation of this combination.

• Publisher: BMJ Publishing Group Ltd,BMJ Publishing Group LTD,BMJ Publishing Group
• Subject: Adult / Aged / Aged, 80 and over / Antibodies / Antibodies, Monoclonal, Humanized - pharmacology / Antibodies, Monoclonal, Humanized - therapeutic use / Antigens / Antineoplastic Combined Chemotherapy Protocols - adverse effects / Antineoplastic Combined Chemotherapy Protocols - pharmacology / Antineoplastic Combined Chemotherapy Protocols - therapeutic use / Biomarker / Biomarkers / Cancer therapies / Cell death / Clinical Cancer Immunotherapy / Clinical outcomes / Cohort analysis / Combination therapy / CTLA-4 Antigen - antagonists & inhibitors / Cytotoxicity / Drug Resistance, Neoplasm / Female / Humans / Immune Checkpoint Inhibitor / Immune Checkpoint Inhibitors - pharmacology / Immune Checkpoint Inhibitors - therapeutic use / Immunotherapy / Laboratories / Ligands / Lymphocytes / Medical prognosis / Middle Aged / Oncology / Original Research / Ovarian Cancer / Ovarian Neoplasms - drug therapy / Ovarian Neoplasms - mortality / Ovarian Neoplasms - pathology / Programmed Cell Death 1 Receptor - antagonists & inhibitors / Software / Tumor necrosis factor-TNF / Tumors