Symbiotic-GU-06: A Study to Learn About PF-08634404 Alone or In Combination With Enfortumab Vedotin in Urothelial Cancer

Inclusion Criteria: * Age ≥18 years at the time of screening. * Histologically confirmed locally advanced or metastatic urothelial carcinoma (LA/mUC). * Measurable disease per RECIST v1.1 criteria. * ECOG performance status of 0 or 1. * Adequate organ function, including hematologic, hepatic, and renal parameters. * Willingness to comply with study procedures and provide informed consent. * For participants of childbearing potential: agreement to use effective contraception during the study and for a defined period after the last dose. Exclusion Criteria: Participants will be excluded if they meet any of the following: * History of another malignancy within 3 years before the first dose of study intervention, or any evidence of residual disease from a previously diagnosed malignancy * Known active CNS lesions, including leptomeningeal metastasis, brainstem, meningeal, or spinal cord metastases or compression * Active autoimmune diseases requiring systemic treatment within the past 2 years * Participation in another investigational study within 30 days or 5 half-lives of the investigational product. * Pregnant or breastfeeding individuals. * Inability or unwillingness to comply with study requirements. * Study staff or their immediate family members directly involved in the conduct of the study.