Medivation and Astellas Pharma have reported positive topline results from the Phase II TERRAIN trial comparing enzalutamide with bicalutamide in men with metastatic castration-resistant prostate cancer.
The trial achieved its primary endpoint showing a statistically significant increase in progression-free survival (PFS) for enzalutamide compared to bicalutamide.
A total of 375 people in North America and Europe were enrolled in the trial, which involved patients with metastatic prostate cancer whose disease progressed despite treatment with a luteinizing hormone-releasing hormone (LHRH) analogue therapy or following surgical castration.
The Phase II TERRAIN trial was designed to evaluate enzalutamide at a dose of 160mg taken once daily versus bicalutamide at a dose of 50mg taken once daily, the approved dose in combination with a LHRH analogue.
Carolina Urologic Research Center medical director and co-principal investigator of the TERRAIN study Dr Neal Shore said: "The results of this study showed that enzalutamide provides a longer duration of disease control in the studied patient population compared to bicalutamide.
"This robust data set adds to an impressive and consistent body of data for enzalutamide across multiple studies and stages of prostate cancer."
The trial's primary endpoint was defined as time from randomisation to centrally confirmed radiographic progression, skeletal related event, initiation of new anti-neoplastic therapy or death, whichever occurs first.
In the enzalutamide group, median PFS was 15.7 months versus 5.8 months in the bicalutamide group.
In the trial, median time on treatment was 11.7 months in the enzalutamide group compared to 5.8 months in the bicalutamide group.
The secondary endpoints and further safety data from the Phase II TERRAIN trial will be reported at an upcoming medical conference.
In the US, XTANDI (enzalutamide) capsules are approved for the treatment of patients with metastatic castration-resistant prostate cancer (CRPC).