Phase II Trial of Ubamatamab Alone or in Combination With Cemiplimab in MUC16-Expressing SMARCB1-Deficient Malignancies

Primary Objectives • To determine the objective response rate (ORR) and disease control rate (DCR), per RECIST 1.1, of ubamatamab alone and in combination with cemiplimab in patients with locally advanced or metastatic MUC16-expressing SMARCB1-deficient malignancies, RMC or ES, who have progressed on at least one prior line of therapy.

Secondary Objectives

• To determine the efficacy and safety of ubamatamab alone or in combination with cemiplimab in participants with locally advanced or metastatic MUC16-expressing SMARCB1-deficient malignancies such as RMC or ES who have progressed on at least one prior line of therapy. Efficacy will be measured by overall survival (OS), progression-free survival (PFS), and duration of response (DOR).

Exploratory Objectives

* To determine the objective response rate (ORR) and disease control rate (DCR), per RECIST 1.1, of the overall strategy of ubamatamab alone followed by combination with cemiplimab in participants with locally advanced or metastatic MUC16-expressing SMARCB1-deficient malignancies, RMC or ES, who have progressed on at least one prior line of therapy. * To evaluate potential biomarkers, such as serum CA-125 and tumor tissue MUC16 expression levels for participant stratification, and to determine via the molecular profiling of biopsy and blood specimens, the mechanisms of resistance to ubamatamab alone or in combination with cemiplimab.