RecruitingPhase 1Drug trialA Phase 1b, Open-Label Study Of REC-617, A Selective CDK7 Inhibitor, In Patients With Metastatic Or Unresectable RB1-Negative Leiomyosarcoma After Prior Systemic TherapyTo learn if the study drug REC-617 can help to control LMS. The safety of REC-617 will also be studied.