Study of Avelumab and Tuvusertib in Participants With Advanced Urothelial Cancer That Has Progressed on Prior Anti-PD-(L)1 Therapy (JAVELIN DDRiver Bladder)

Inclusion Criteria: * Histologically confirmed, locally advanced, and unresectable or metastatic urothelial carcinoma. * No more than 2 lines of therapy for advanced disease. Chemotherapy followed by avelumab (switch maintenance) counts as 1 line of therapy. Additionally, (neo)-adjuvant chemotherapy for Muscle invasive bladder cancer with recurrence or progression within 12 months of last dose, counts as a line of therapy. * Measurable disease by RECIST 1.1, as assessed by the Investigator. * Eastern Cooperative Oncology Group Performance status 0 to 1. * Adequate hematologic function as indicated by: * Platelet count more than or equal to 100,000 per microliter * Absolute neutrophil count more than or equal to 1,500 per microliter with no growth factor treatment within the last 14 days * Hemoglobin more than or equal to 9.0 gram/deciliter with no erythropoietin or red blood cell transfusion within the last 14 days * Only one line of an antibody-drug conjugate (ADC) is allowed. * Other protocol defined inclusion criteria could apply. Exclusion Criteria: * Any condition, including any uncontrolled disease state other than aUC, that in the Investigator's opinion constitutes an inappropriate risk or a contraindication for participation in the study or that could interfere with the study objectives, conduct, or evaluation. * Any known additional malignancy that is progressing and/or requires active treatment including adjuvant hormonal therapy. * Presence of brain metastases unless clinically stable (without evidence of progression by imaging for at least 4 weeks prior to the first dose of study intervention and any neurologic symptoms have returned to baseline and sequelae that are a consequence of the treatment of the brain metastases are acceptable), no evidence of new brain metastases, and on a stable or decreasing dose or without steroids for at least 14 days prior to first dose of study intervention. Participants with carcinomatous meningitis are excluded regardless of clinical stability. * Serious gastrointestinal bleeding within 3 months, refractory nausea and vomiting, uncontrolled diarrhea, known malabsorption, significant small bowel resection or gastric bypass surgery, use of feeding tubes, other chronic gastrointestinal disease (including exocrine pancreatic insufficiency requiring pancreatic enzyme replacement therapy), and/or other situations that may preclude adequate absorption of oral medications. * Other protocol defined exclusion criteria could apply.