Erdafitinib for the Treatment of Patients With Castration-Resistant Prostate Cancer

PRIMARY OBJECTIVE: I. To evaluate efficacy of erdafitinib in subjects with advanced prostate cancer who have progressed on a second-generation androgen receptor (AR)-targeting agents (SART). SECONDARY OBJECTIVES: I. To evaluate the objective response rate II. To measure Time on Treatment (ToT) as a surrogate of clinical efficacy and Progression-Free Survival (PFS) III. To measure PFS. IV. To correlate bone specific alkaline phosphatase (BAP) modulation with response, ToT and PFS. V. To correlate prostate specific antigen (PSA) modulation with response, ToT and PFS. VI. To characterize the safety profile of subjects treated with erdafitinib. VII. To measure overall survival. VIII. To collect and archive bone marrow biopsies and aspirates, serum and plasma in study patients for later hypothesis generating associations. EXPLORATORY OBJECTIVE: I. To evaluate DNA, ribonucleic acid (RNA), or protein biomarkers in tissue and blood samples which potentially predict tumor response or resistance to erdafitinib. OUTLINE: Patients receive erdafitinib orally (PO) once daily (QD) on days 1-21. Cycles repeat every 21 days in the absence of disease progression or unacceptable toxicity. Patients may also undergo collection of blood and bone marrow via biopsy and aspirates. After completion of study treatment, patients are followed up at 30 days, every 16 weeks for 1 year, and then every 6 months thereafter.