A Study of Erdafitinib in Participants With Metastatic or Locally Advanced Urothelial Cancer

Inclusion Criteria:

* Histologic demonstration of transitional cell carcinoma of the urothelium. Variant urothelial carcinoma histologies such as glandular or squamous differentiation, or evolution to more aggressive phenotypes such as sarcomatoid or micropapillary change are acceptable
* Metastatic or locally advanced urothelial cancer
* Must have measurable disease by radiological imaging according to the Response Evaluation Criteria in Solid Tumors (RECIST, version 1.1) at baseline
* Prior systemic therapy for metastatic urothelial cancer: (a) For Phase 1b erdafitinib + cetrelimab cohort: Any number of lines of prior therapy; (b) For Phase 1b erdafitinib + cetrelimab + platinum chemotherapy cohort: No prior systemic therapy for metastatic disease; and renal function for participants must have a creatinine clearance (CrCl) greater than (\>) 30 milliliter per minute (mL/min) to receive carboplatin and \>60 mL/min to receive cisplatin as calculated by Cockcroft Gault and (c) Phase 2: No prior systemic therapy for metastatic disease and cisplatin-ineligible based on: ECOG PS 0-1 and at least one of the following criteria: Renal function defined as creatinine clearance (CrCl) less than (˂) 60 mL/min as calculated by Cockcroft-Gault; Grade 2 or higher peripheral neuropathy per NCI-CTCAE version 5.0; Grade 2 or higher hearing loss per NCI-CTCAE version 5.0 OR ECOG PS 2
* Eastern Cooperative Oncology Group (ECOG) performance status (PS) grade of: (a) Phase 1b erdafitinib + cetrelimab cohort: ECOG 0-2; (b) Phase 1b erdafitinib + cetrelimab + platinum chemotherapy cohort: ECOG 0-1 for cisplatin and 0-2 for carboplatin (c) Phase 2: ECOG 0-2

Exclusion Criteria:

* Treatment with any other investigational agent or participation in another clinical study with therapeutic intent within 30 days prior to Cycle 1 Day 1. For Phase 1b, participants who have received the following prior antitumor therapy: received nitrosoureas and mitomycin C within 6 weeks
* Phase 1b erdafitinib + cetrelimab cohort: Chemotherapy within 3 weeks of Cycle 1 Day 1; Phase 1b erdafitinib + cetrelimab + platinum chemotherapy cohort and Phase 2: Prior neoadjuvant/adjuvant chemotherapy is allowed if the last dose was given \>12 months prior to recurrent disease progression and did not result in drug-related toxicity leading to treatment discontinuation
* Prior anti-programmed death receptor-1 (PD-1), anti-programmed death ligand-1 (PD-L1), or anti-programmed death ligand-2 (PD-L2) therapy. Prior neoadjuvant/adjuvant checkpoint inhibitor therapy is allowed if the last dose was given more than (\>)12 months prior to recurrent disease progression and did not result in drug-related toxicity leading to treatment discontinuation. PD-1 for non-muscle invasive bladder cancer is also allowed
* Active malignancies requiring concurrent therapy other than urothelial cancer
* Symptomatic central nervous system metastases