An Efficacy and Safety Study of Erdafitinib (JNJ-42756493) in Participants With Urothelial Cancer

The purpose of this study is to evaluate the objective response rate (complete response \[CR\]+ partial response \[PR\]) of the selected dose regimen in participants with metastatic or surgically unresectable urothelial cancers that harbor specific FGFR genomic alterations.

This is a multicenter, open-label study (participants will know the identity of study drugs administered) to evaluate the efficacy and safety of erdafitinib in participants with urothelial cancer. The study comprises a 30-days Screening Phase, a Treatment Phase comprised of 28-day treatment cycles that will continue until disease progression or unacceptable toxicity occurs in a long-term extension (LTE) phase, and a post-treatment Follow-up Phase that will extend from the End-of-Treatment Visit until the participant has died, withdraws consent, is lost to follow-up, or the end of the study, whichever comes first. The end of study is defined as the date when all participants have completed the study treatment (Regimens 1 to 3) and all participants enrolled under the drug-drug interaction (DDI) substudy are no longer receiving treatment with erdafitinib. The purpose of DDI sub-study is to evaluate the interaction of repeated doses of erdafitinib with a sensitive cytochrome 450 (CYP) 3A substrate (midazolam) and with an organic cation transporter 2 (OCT2) probe substrate (metformin). Safety will be monitored throughout the study.

Eligibility Criteria:
Inclusion Criteria:

* Must have histologic demonstration of metastatic or surgically unresectable urothelial cancer. Minor components of variant histology such as glandular or squamous differentiation, or evolution to more aggressive phenotypes such as sarcomatoid or micropapillary change are acceptable
* Must have measurable disease according to the Response Evaluation Criteria in Solid Tumors (RECIST, version 1.1) at baseline
* Must have an Eastern Cooperative Oncology Group (ECOG) performance status score 0, 1, or 2
* Must have adequate bone marrow, liver, and renal function as described in protocol
* Negative pregnancy test (urine or serum beta human chorionic gonadotropin \[b-hCG\]) at Screening for women of child bearing potential who are sexually active
* Must have shown disease progression according to RECIST, version 1.1, following prior chemotherapy for metastatic or surgically unresectable urothelial cancer. Participants who received neoadjuvant or adjuvant chemotherapy and showed disease recurrence or progression according to RECIST, version 1.1, within 12 months of the last dose are considered to have received chemotherapy in the metastatic setting. These participants will be referred to as chemo-refractory participants. (Participants who have shown disease progression according to RECIST, version 1.1 following prior treatment with anti-Programmed death-ligand 1 (anti PDL1/PD1) antibodies are also eligible) For DDI substudy
* Disease progression following prior chemotherapy for metastatic or surgically unresectable urothelial cancer. Participants who received neoadjuvant or adjuvant chemotherapy and showed disease recurrence or progression within 12 months of the last dose are considered to have received chemotherapy in the metastatic setting

Exclusion Criteria:

* Received chemotherapy, targeted therapies, definitive radiotherapy, or treatment with an investigational anticancer agent within 2 weeks (in the case of nitrosoureas and mitomycin C, within 6 weeks; in the case of immunotherapy, within 4 weeks) before the first administration of study drug. Localized palliative radiation therapy (but should not include radiation to target lesions) and ongoing bisphosphonates and denosumab, are permitted
* Has persistent phosphate level greater than upper limit of normal (ULN) during screening (within 14 days of treatment and prior to Cycle 1 Day 1) and despite medical management
* Has a history of or current uncontrolled cardiovascular disease
* Females who are pregnant, breast-feeding, or planning to become pregnant within 3 months after the last dose of study drug and males ho plan to father a child while enrolled in this study or within 5 months after the last dose of study drug
* Has not recovered from reversible toxicity of prior anticancer therapy (except toxicities which are not clinically significant such as alopecia, skin discoloration, or Grade 1 neuropathy)