BTG and Ortho Biotech’s Prostate Cancer Trial Unblinded

Significant survival benefits lead to establishment of early-access program for CYP17 inhibitor.

BTG and its licensee, the Johnson & Johnson business unit Ortho Biotech Oncology Research & Development, confirmed that a Phase III metastatic prostate cancer trial evaluating abiraterone acetate has been unblinded, and patients in the placebo arm will be offered the drug on the basis of positive interim data. The data is due for presentation in October at the “European Society of Medical Oncology Congress” in Milan. Ortho Biotech is part of Cougar Biotechnology. BTG granted Cougar an exclusive worldwide license to abiraterone acetate in 2004. The latter was acquired by Johnson & Johnson in a $1 billion cash deal during 2009.

Study COU-AA-301 included 1,195 patients with metastatic advanced prostate cancer who had progressed following one or two chemotherapy regimens, at least one of which included docetaxel. Trial participants were randomized to receive abiraterone acetate plus prednisone or placebo plus prednisone. Data from a prespecified interim analysis showed that abiraterone acetate treatment significantly lengthens overall survival. The firms say an early-access program for abiraterone acetate is also being initiated and will be opened in the U.S. next month, and subsequently sites outside the U.S.

Abiraterone acetate is Cougar’s lead product. The drug is an orally administered inhibitor of the steroidal enzyme CYP17 (17α-hydroxylase/C17,20 lyase), a cytochrome p450 complex involved in testosterone and estrogen production.

Abiraterone is currently being investigated in a number of clinical studies involving castration-resistant prostate cancer patients in North America, Europe, and Australia. Cougar says interim clinical trial results to date have shown the therapy leads to confirmed reductions in prostate specific antigen (PSA) levels by up to 90+%, as well as partial radiological responses (as measured by the RECIST criteria), regression in bone disease, improvements in pain, and reduced opioid use.

A Phase I/II clinical trial evaluating abiraterone acetate in advanced breast cancer patients is separately under way at the U.K.’s Institute of Cancer Research in London, with funding from Cancer Research U.K.