Xtandi Improves Progression-Free Survival Over Casodex in Metastatic Prostate Cancer

Recent results from the phase 2 TERRAIN trial showed Xtandi (enzalutamide) increased progression-free survival (PFS) by nearly 10 months compared with Casodex (bicalutamide) in patients with metastatic castration-resistant prostate cancer (mCRPC). Xtandi is approved for advanced prostate cancer that has progressed on prior therapy.

"The results of this study showed that enzalutamide provides a longer duration of disease control in the studied patient population compared to bicalutamide," Neal Shore, co-principal investigator of the TERRAIN study and medical eirector of the Carolina Urologic Research Center said in a statement. "This robust data set adds to an impressive and consistent body of data for enzalutamide across multiple studies and stages of prostate cancer."

releasing hormone (LHRH) analogue or following surgical castration. Patients in the trial had metastatic, progressive disease, ongoing hormone therapy or surgical castration, and life expectancy of at least one year.

Patients were randomly selected to receive either 160 mg of Xtandi or 50 mg of Casodex, each taken once daily. Shore noted that this was generally a second-line therapy for patients and was administered prior to chemotherapy.

The primary endpoint was PFS, defined as time from randomization to progression, skeletal-related event, start of new antineoplastic therapy or death. Secondary endpoints focused on PSA response and time to PSA progression.

Median PFS was 15.7 months in the Xtandi arm compared with 5.8 months in the Casodex arm. Median time on treatment was 11.7 months and 5.8 months in the Xtandi and Casodex arms, respectively.

Adverse events between the two arms differed slightly. In total, 31.1 percent of patients treated with Xtandi experienced serious adverse events, while 23.3 percent of patients who received Casodex experienced serious adverse events. Diarrhea, fatigue, hot flush, hypertension, pain in extremities and weight loss all occurred more frequently in the Xtandi arm. Additional safety data will be submitted for presentation at a future medical conference.

The TERRAIN study enrolled 375 patients with mCRPC whose disease continued to progress following treatment with a luteinizing hormone-