- Observed Dose-Response Trends Suggest Improved Efficacy with Higher Doses -

- Dose Escalation Ongoing -

SAN FRANCISCO and CHICAGO, June 2 /PRNewswire-FirstCall/ -- Medivation,Inc. (Nasdaq: MDVN) today announced that data from an ongoing Phase 1-2clinical trial of the Company's novel androgen receptor antagonist, MDV3100,showed encouraging anti-tumor activity as measured by declining serum levelsof prostate specific antigen (PSA) and circulating tumor cells (CTC), as wellas radiographic disease stabilization, after three months of treatment. Anincreased number of androgen receptors present on prostate cancer cells isbelieved to play a major role in the growth of castration-resistant prostatecancer, also known as hormone-refractory prostate cancer. The observedclinical effects of MDV3100 on PSA levels, CTC counts and radiographic diseaseare consistent with blockade of androgen receptor signaling and inhibition oftumor growth. To date, 90 patients have been enrolled in the trial withenrollment completed at doses up to 240 mg/day. MDV3100 has been welltolerated and dose escalation at 360 mg/day is in progress.

The data were presented at the American Society of Clinical Oncology 2008Annual Meeting in Chicago in an oral presentation entitled 'Phase 1-2 study ofMDV3100 in patients (pts) with progressive Castration-Resistant ProstateCancer (CRPC)' by principal investigator, Howard Scher, M.D., chief of theGenitourinary Oncology Service and the D. Wayne Calloway Chair in UrologicOncology at Memorial Sloan-Kettering Cancer Center in New York.

The ongoing Phase 1-2 trial is an open-label U.S. dose-escalation studyenrolling prostate cancer patients who have failed standard hormonaltherapies. The dose-expansion study has enrolled 84 patients in three cohorts(60, 150, 240 mg/day) to date. Dr. Scher's presentation covered PSA data fromall patients who have been followed for at least 12 weeks, the standardminimum duration of observation used to assess the treatment effects ofprostate cancer drugs. Of the 42 chemo-naive and 31 post-chemotherapyevaluable patients across the three dose levels, 23 patients (55 percent) and13 patients (42 percent) showed PSA declines greater than 50 percent at week12 compared to baseline, respectively.