The open-label, US Phase I-II study evaluated prostate cancer patients who had failed standard hormonal therapies, including men who had also failed standard chemotherapy regimens. A total of 140 men were enrolled in the trial, which evaluated doses between 30 and 600mg/day. Patients are being followed and may remain on treatment for as long as they continue to tolerate the drug and their disease does not progress.
Preliminary results of this trial, covering 73 treated patients in the 60, 150 and 240mg/day dose groups showed encouraging and durable anti-tumor activity as measured by prostate specific antigen (PSA) declines, radiographic findings, circulating tumor cell (CTC) changes and time on treatment.
These data also suggested a dose-response trend, with a higher percentage of patients in the 240mg/day dose group experiencing 90% reduction in PSA levels, radiographic partial responses and conversions to favorable CTC counts of less than five post-treatment.
The company expects to move into Phase III trials with either the 240 or the 360mg/day dose, both of which have been generally well tolerated. The 480mg/day dose did not have acceptable tolerability due to side effects, primarily fatigue. Efficacy data from the 360mg/day dose group are under analysis and will be reported later, along with additional efficacy data from the 240mg/day and lower dose groups. Final selection of the Phase III dose will be made following completion of data analyses.
Lynn Seely, chief medical officer of Medivation, said: We are pleased to have reached another development milestone in our prostate cancer program by successfully completing enrollment in our Phase I-II clinical trial in castration-resistant prostate cancer patients with limited treatment options. We look forward to presenting additional data from this trial and to advancing this program into Phase III development in 2009, as we have previously guided.