Kosan Biosciences Incorporated has commenced its multi-centre Phase II clinical trial to evaluate the safety and efficacy of KOS-862 (Epothilone D) as monotherapy for prostate cancer. KOS-862 is a polyketide that inhibits cancer cells by the same mechanism as paclitaxel, and preclinical models have shown the compound to be effective against paclitaxel-resistant tumours.

"Based on encouraging data from preclinical and clinical trials, we are initiating a Phase II monotherapy trial to evaluate the anti-tumour activity and clinical benefit of KOS-862 in prostate cancer patients," said Robert G. Johnson, chief medical officer, Kosan Biosciences.

According to the Phase II trial design, KOS-862 will be administered weekly by intravenous administration for three of four weeks at a dose of 100 mg/m2. The trial is expected to enrol between 20 and 50 patients in hormone refractory patients who have progressed following treatment with a docetaxel-based regimen. Changes in Prostate Specific Antigen (PSA) and tumour response will be assessed to determine clinical activity.

Under a global development and commercialization agreement between Roche and Kosan, Roche has the worldwide exclusive right to market and sell KOS-862 and epothilone analogs owned by or licensed to Kosan for the treatment of cancer; Kosan will co-develop and has the right to co-promote Kosan/Roche epothilone products in the US for the treatment of cancer. The Roche-Kosan partnership's clinical plans include evaluating KOS-862 in ongoing Phase Ib combination studies with Gemzar, Paraplatin and Herceptin and a Phase II monotherapy trial in metastatic breast cancer.