Men with metastatic castration-resistant prostate cancer (CRPC) that had mutations in DNA repair genes were more likely to respond to the poly(ADP-ribose) polymerase (PARP) inhibitor olaparib. In the phase II TOPARP trial, 17 of the 49 evaluable men responded to olaparib. Six men had radiologic responses and 11 had biochemical responses, as determined by a reduction in prostate-specific antigen (PSA) levels of greater than 50%. Four of these patients had responses that lasted more than 12 months.
The results were presented at a press briefing at the American Association for Cancer Research (AACR) Annual Meeting, held April 18 to 22 in Philadelphia.