Study Endpoint Fulfillment and FDA Approval Success in Phase III Clinical Trials of Genitourinary Malignancies

This study investigates the impact of Phase-III genitourinary oncology trial endpoint fulfillment (EF+) on FDA approval probability over the past 15 years.

We identified urothelial/bladder cancer (UCa), renal cancer (RCa), and prostate cancer (PCa) trials from ClinicalTrials.gov. The primary analysis compared the time from primary completion to FDA approval between trials with overall survival EF+ (OS+) and those without (OS-). Secondary analyses assessed the impact of OS+ versus non-OS primary EF (PE+) studies on FDA approval, considering disease site, disease status, and treatment line.

Of 183 trials screened, 78 (42.6%) met inclusion criteria: 41 (52.6%) PCa, 23 (29.5%) RCa, and 14 (17.9%) UCa. FDA approval was granted in 40/78 trials. OS+ (n = 31 [39.7%]) significantly increased approval likelihood (HR 8.38, 95% CI, 4.1-17.1, P < 0.001) compared to OS- trials. The median time to approval was 348 days (95% CI, 294-380) in the OS+ group and was not reached in the OS- group. One- and two-year approval rates were 63.3% and 8.5%, and 86.6% and 19.2%, respectively. Among trials with PE+, 39/50 received approval. Trials with both OS and non-OS PE+ had higher approval rates (HR 2.3, 95% CI, 1.04-5.3, P = 0.041), particularly in PCa studies (Log HR 0.51, 95% CI, 0.29-1.06, P < 0.001) and metastatic disease (HR 0.74, 95% CI, 0.30-1.17, P = 0.001).

OS EF+ remains a strong predictor of FDA approval. Non-OS PE+ benefit trials gain better success when accompanied by OS+. These findings can guide future trial designs to optimize regulatory success in GU oncology.