Today both Medivation (MDVN) and Astellas Pharma Inc. (ALPMY) reported that Xtandi - Enzalutamide - was able to achieve better efficacy results than AstraZeneca (AZN) Casodex - bicalutamide. The phase 2 clinical trial known as "STRIVE" recruited up to 396 castration-resistant prostate cancer patients in the United States. What castration-resistant prostate cancer means is that the cancer has spread to other parts of the body besides the prostate and any type of treatment has failed to suppress the cancer from spreading. About 257 patients had metastatic prostate cancer and the other 139 patients were non-metastatic prostate cancer. What Metastatic means is that the cancer has gotten progressively spread in the body of the patient despite of care therapy. 

A lot of these prostate-cancer patients first, do an undergo treatment with a luteinizing hormone-releasing hormone - LHRH - that is specifically used ideally to lower the hormones in the prostate thus diminishing the cancer slightly. But these initial treatments don't offer the same amount of efficacy as actually taking a drug therapy treatment. The trial was testing 160 mg once daily Xtandi against 50 mg once daily Casodex to determine which one produced greater efficacy in the primary endpoint. 

The primary endpoint of the trial was looking for progression-free survival - PFS. PFS is a measure of how long a patient takes their treatment without their cancer become progressively worse. The results showed that Xtandi achieved a PFS of 19.4 months versus Casodex achieving a PFS of 5.7 months. Both drugs showed a similar effect in adverse events in the trial but these adverse events were not life threatening. Some of these adverse events experienced by patients were: fatigue, back pain, decreased appetite, and dizziness. Medivation and Astellas will still have to run a phase 3 clinical trial to determine additional efficacy of the drug in a larger group of patients which could take a few years to see. Still, the efficacy shown in this phase 2 clinical trial with Xtandi is encouraging and we will just have to wait and see how it goes fares against its other competitor Johnson & Johnson (JNJ) Zytiga drug.