(CLONEVO): Cell cycLe inhbitiON to Target the EVolution of UrOthelial Cancer

A Window-of-Opportunity Trial of Abemaciclib followed by radical cystectomy in patients with Platinum-Ineligible Urothelial Carcinoma to Evaluate CDK4/6-Dependent Phosphorylation of Pocket Proteins and Clonal Evolution Dynamics. Subjects will be treated with Abemaciclib at 200 mg every 12 hours for at least 4 weeks (and likely slightly longer depending upon surgical date). Individual dose reductions will be made on the basis of the AEs observed. In the absence of treatment delays due to adverse event(s), treatment will be continued until the surgical date unless any of the following criteria applies: 1-Disease progression; 2-Intercurrent illness that prevents further administration of treatment; 3-Unacceptable adverse event(s) as a result of Abemaciclib; 4- Patient decides to withdraw from the study; 5-General or specific changes in the patient's condition render the patient unacceptable for further treatment in the judgment of the investigator. Patients will be followed with history, physical, and blood tests at each visit to monitor for toxicity. Patients will be followed for survival endpoints following completion of this study for 3 years after surgery or until death. Patients removed from study for unacceptable adverse events will be followed until resolution or stabilization of the adverse event.