Study to Assess the Efficacy and Safety of Rina-S Compared to Treatment of Investigator's Choice in Participants With Endometrial Cancer

The purpose of this study is to compare how well Rina-S (GEN1184) works compared to treatment of physician's choice (paclitaxel or doxorubicin) that are considered standard medical care for the treatment of recurrent or progressive endometrial cancer (EC) following prior therapy. There is an equal (50:50) chance of getting either Rina-S or a chemotherapy agent as treatment in this study. The study duration will be approximately 3 years. The treatment duration will be different for every participant, but an average of 4 to 6 months is expected. All participants will receive active drug; no one will be given placebo. Participation in the study will require visits to the study site(s).

This is a global, open-label, randomized Phase 3 study in approximately 544 participants with recurrent or progressive EC following prior therapy. Participants will be randomized in a 1:1 ratio to receive treatment with Rina-S vs investigator's choice (IC) (paclitaxel or doxorubicin). Investigators must select one of the IC treatment options for each participant prior to randomization so that this may be used for treatment assignment if the participant is randomized to the IC arm.