Clinical Perspectives from Randomized Phase 3 Trials on Prostate Cancer: An Analysis of the ClinicalTrials.gov Database

Background: It is not easy to overview pending phase 3 trials on prostate cancer (PCa), and awareness of these trials would benefit clinicians. Objective: To identify all phase 3 trials on PCa registered in the ClinicalTrials.gov database with pending results. Design and setting: On September 29, 2014, a database was established from the records for 175 538 clinical trials registered on ClinicalTrials.gov. A search of this database for the substring "prostat" identified 2951 prostate trials. Phase 3 trials accounted for 441 studies, of which 333 concerned only PCa. We selected only ongoing or completed trials with pending results, that is, for which the primary endpoint had not been published in a peer-reviewed medical journal. Results and limitations: We identified 123 phase 3 trials with pending results. Trials were conducted predominantly in North America (n = 63; 51%) and Europe (n = 47; 38%). The majority were on nonmetastatic disease (n = 82; 67%), with 37 (30%) on metastatic disease and four trials (3%) including both. In terms of intervention, systemic treatment was most commonly tested (n = 71; 58%), followed by local treatment 34 (28%), and both systemic and local treatment (n = 11; 9%), with seven (6%) trials not classifiable. The 71 trials on systemic treatment included androgen deprivation therapy (n = 34; 48%), chemotherapy (n = 15; 21%), immunotherapy (n = 9; 13%), other systemic drugs (n = 9; 13%), radiopharmaceuticals (n = 2; 3%), and combinations (n = 2; 3%). Local treatments tested included radiation therapy (n = 27; 79%), surgery (n = 5; 15%), and both (n = 2; 2%). A limitation is that not every clinical trial is registered on ClinicalTrials.gov. Conclusion: There are many PCa phase 3 trials with pending results, most of which address questions regarding systemic treatments for both nonmetastatic and metastatic disease. Radiation therapy and androgen deprivation therapy are the interventions most commonly tested for local and systemic treatment, respectively. Patient summary: This report describes all phase 3 trials on prostate cancer registered in the ClinicalTrials.gov database with pending results. Most of these trials address questions regarding systemic treatments for both nonmetastatic and metastatic disease. Radiation therapy and androgen deprivation therapy are the interventions most commonly tested for local and systemic treatment, respectively. In this report we describe all phase 3 trials on prostate cancer registered in the ClinicalTrials.gov database with pending results. The majority of the trials identified address questions regarding systemic treatments for both nonmetastatic and metastatic disease. Radiation therapy and androgen deprivation therapy are interventions most frequently tested for local and systemic treatment, respectively.