Ubamatamab Activity in Recurrent Low-Grade Serous Ovarian Cancer

Els Van Nieuwenhuysen, MD, of University Hospitals Leuven in Belgium, presents phase 1/2 results for ubamatamab, a bispecific antibody that links mucin-16 (MUC16)-positive tumor cells to CD3-expressing T cells, in 19 patients with recurrent low-grade serous ovarian cancer (LGSOC). Van Nieuwenhuysen explains that recurrent LGSOC carries a high unmet need, with response rates below 15% for both chemotherapy and endocrine therapy, and that the tumors show uniformly high MUC16 expression. Patients were heavily pretreated, with a median of 4 prior lines of therapy. Among 11 patients receiving the 800-mg go-forward dose, the confirmed objective response rate was 72.7%, with a median duration of response of 9 months and a median progression-free survival of 11.1 months. Cytokine release syndrome was the most frequent adverse event; all events were grade 1 or 2 and most occurred during step-up dosing. An ongoing prospective cohort of 100 patients is evaluating ubamatamab with sarilumab prophylaxis.