* Patients showed rise in overall survival and survival without cancer worsening
* Independent panel recommends patients on placebo shift to the drug
* Medivation shares rises 10 percent before the bell (Adds details, stock movement)
Oct 22 (Reuters) - Medivation Inc and its Japanese partner Astellas Pharma Inc said their prostate cancer treatment improved patient survival in a late-stage trial testing the drug for use in a wider population.
Medivation shares rose 10 percent before the bell after the companies said the treatment, Xtandi, met both the main goals of the study.
Xtandi is currently approved for treating patients with advanced prostate cancer who have previously received a chemotherapy.
Patients treated with Xtandi in the latest trial showed a statistically significant increase in their overall survival, as well as survival without the cancer worsening, compared with those on placebo.
The late-stage study, named Prevail, tested the drug in more than 1,700 men with advanced prostate cancer that progressed despite hormone therapy and who have not yet received chemotherapy.
Patients in the study treated with the drug, also known as enzalutamide, had a median overall survival of 32.4 months, compared with 30.2 months for those on placebo.
An independent safety committee monitoring the trial recommended that the study be stopped and all patients be treated with enzalutamide, the companies said in a joint statement.
"To my knowledge, the benefits in overall survival and radiographic progression-free survival reported ... are unprecedented in this patient population," said Tomasz Beer, a deputy director of Knight Cancer Institute at the Oregon Health & Science University and an investigator for the study.
Medivation and Astellas will initiate regulatory meetings beginning in early 2014.
Medivation shares rose 10 percent to $54.97 in premarket trade. They closed at $49.82 on the Nasdaq on Monday. (Reporting by Esha Dey in Bangalore; Editing by Sriraj Kalluvila)