Earlier this week, Medivation, Inc. MDVN and Astellas Pharma Inc. ALPMY jointly announced new data from a randomized, double-blind phase II study (TERRAIN) on Xtandi. The study compared the efficacy and safety of Xtandi to AstraZeneca’s AZN Casodex for the treatment of metastatic castration-resistant prostate cancer (CRPC) in patients whose disease progressed following a luteinizing hormone-releasing hormone (LHRH) analogue therapy or after surgical castration.
In the TERRAIN study, Xtandi showed an improvement over the standard practice of the adding Casodex to a LHRH therapy. The study successfully met its primary objective of a statistically significant increase in progression-free survival (PFS) under treatment with Xtandi compared to Casodex. The median PFS in the Xtandi arm (15.7 months) was 9.9 months longer than that in the Casodex arm (5.8 months). Median time on treatment was longer for Xtandi (11.7 months) compared to Casodex (5.8 months).
However, a higher proportion of patients (31.1%) in the Xtandi arm reported serious adverse events compared to those in the Casodex arm (23.3%). Moreover, common adverse events were reported by a higher percentage of Xtandi-treated patients versus patients administered with Casodex.
Meanwhile, Medivation also provided results from the final overall survival (OS) analysis of a placebo-controlled phase III study (PREVAIL) on Xtandi for the treatment of chemotherapy-naive metastatic CRPC patients whose disease progressed on androgen deprivation therapy. The co-primary endpoints of the study were OS and radiographic PFS. The analysis showed that Xtandi led to a statistically significant OS benefit with a 23% reduction in risk of death and a 4-month improvement in median survival over placebo.
The above data were presented at the European Association of Urology Congress held at Madrid, Spain.
We note that Xtandi is already approved for the treatment of CRPC. We are pleased with the company’s label expansion efforts for the drug. With partner Astellas, Medivation is conducting several studies on Xtandi for prostate cancer and advanced breast cancer. As per their agreement, both companies equally share profits (or losses) related to the U.S. net sales of Xtandi. Additionally, Medivation receives royalties in the range of low teens to low twenties on the ex-U.S. net sales of the drug, apart from milestone payments upon the achievement of certain development and sales events.