Trilaciclib, a CDK 4/6 Inhibitor, in Patients With Advanced/Metastatic Bladder Cancer Receiving Chemotherapy Then Avelumab

Participants will be randomly assigned (1:1) to receive standard of care platinum-based chemotherapy (with or without the addition of trilaciclib) administered intravenously (IV) in 21-day cycles followed by standard of care avelumab maintenance therapy (with or without the addition of trilaciclib) administered IV in 14-day cycles. Participants enrolled in the study will be eligible to receive 4-6 cycles of platinum-based chemotherapy, and participants without progressive disease (PD) as per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 guidelines (i.e., with an ongoing complete response \[CR\], partial response \[PR\], or stable disease \[SD\]) after platinum-based chemotherapy will be eligible to receive avelumab maintenance therapy until disease progression, unacceptable toxicity, withdrawal of consent, Investigator decision, or the end of the trial, whichever comes first. Participants will be followed for survival approximately every 3 months after receiving the last dose of study medication.