UBAMATAMAB in ovarian and endometrial cancer

Ubamatamab is a bispecific antibody targeting MUC16 on ovarian cancer cells and CD3 on T cells, inducing a cytotoxic T cell response. Its efficacy is being explored in recurrent ovarian cancer and endometrial cancer through a trial-in-progress. In ovarian cancer, dose escalation and early efficacy signals were presented at IGCS 2023. The current dose expansion cohort treats recurrent ovarian cancer (up to five prior lines) with either ubamatamab monotherapy at 250 mg Q3-weekly, 800 mg Q3-weekly, or 250 mg combined with cemiplimab 350 mg Q3-weekly.

For endometrial cancer, the study includes patients with 1-2 prior lines of treatment who have failed both platinum-based chemotherapy and prior IO. Unlike the ovarian cancer cohort, endometrial cancer patients are selected based on MUC16 expression (>25% in tumour cells). They receive one of three treatment regimens: ubamatamab 800 mg Q3-weekly, 250 mg Q3-weekly, or 250 mg combined with cemiplimab 300 mg Q3-weekly.

Additionally, a cohort of 50 ovarian cancer patients will receive sarilumab, an interleukin-6 inhibitor, to mitigate cytokine release syndrome (CRS) observed in the first cycle of treatment. Previously, only grade 1 and grade 2 CRS were observed in the phase 1 trial, with no grade 3 CRS. By using sarilumab, the aim is to reduce CRS severity and potentially eliminate the need for inpatient admission during the step-up dose. Efficacy data from the phase 2 trial are expected to be presented later this year.