A phase 3 study of ipilimumab among patients with metastatic, castration-resistant prostate cancer (mCRPC) did not meet its primary endpoint of overall survival improvement, according to a study published in the Journal of Clinical Oncology.1

Few treatment options exist for patients with castration-resistant prostate cancer. Ipilimumab, an antibody that binds to cytotoxic T-lymphocyte antigen 4, can lead to T-cell activation and increased life expectancy among particular patient groups.

In this randomized trial (ClinicalTrials.gov Identifier: NCT01057810), researchers enrolled 602 chemotherapy-naive patients to receive ipilimumab or placebo.

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Among the 399 treated with ipilimumab and the 199 given placebo, median overall survival was 28.7 months and 29.7 months, respectively. Median progression free survival was, however, superior in the ipilimumab arm, at 5.6 months versus 3.8 months in the placebo arm.

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Nine patients died from a treatment-related adverse events with ipilimumab.

The authors conclude that while the drug does not improve overall survival among patients with mCRPC, ipilimumab does show some anti-tumor activity, and should be studied further to establish which patients are likely to benefit from its use.


  1. Beer TM, Kwon ED, Drake CG, et al. Randomized, double-blind, phase III trial of ipilimumab versus placebo in asymptomatic or minimally symptomatic patients with metastatic chemotherapy-naive castration-resistant prostate cancer. J Clin Oncol. 2016 Oct 10. doi: 10.1200/JCO.2016.69.1584 [Epub ahead of print]