Karyopharm Therapeutics Inc. announced the completion of patient recruitment in the Phase 3 SIENDO study evaluating the efficacy and safety for front-line maintenance therapy with selinexor in patients with advanced or recurrent endometrial cancer. Endometrial cancer is the most common cancer of the female reproductive organs, with more than 66,000 new cases in the US in 2021. Unfortunately, prognosis is poor with an estimated 14,000 women progressing to advanced disease. There are currently no approved therapies in the maintenance setting for patients with advanced or recurrent endometrial cancer. The SIENDO study has exceeded its enrollment goal, with over 250 patients currently enrolled or in screening. The SIENDO study is a multicenter, blinded, placebo-controlled, randomized Phase 3 study evaluating the efficacy and safety for maintenance therapy with selinexor in patients with advanced or recurrent endometrial cancer. Participants with primary stage IV or recurrent disease who had a partial or complete response after a single line of at least 12 weeks of standard taxane-platinum combination chemotherapy are randomized in a 2:1 manner to receive either maintenance therapy of 80mg of selinexor taken once per week or placebo, until disease progression. The primary endpoint in the study is progression free survival with the goal of the study demonstrating a hazard ratio of 0.6.