Kosan Biosciences Incorporated has presented at the American Society of Clinical Oncology (ASCO) Annual Meeting in Orlando, favourable interim data from two Phase Ib clinical trials evaluating KOS-862 (Epothilone D) in combination with carboplatin (Paraplatin) and gemcitabine (Gemzar) in patients with advanced solid tumours.

Both trials were open-label, dose-escalation, two-centre studies designed to determine the maximum tolerated dose, toxicity profile, pharmacokinetics, and recommended Phase II dose of the combination therapies.

KOS-862 is a polyketide that inhibits cancer cell growth in vitro by a mechanism similar to paclitaxel, and preclinical models have shown the compound to be effective against paclitaxel-resistant tumors. KOS-862 continues to be evaluated in Phase II monotherapy trials in breast and prostate cancer, as well as Phase Ib combination trials with Gemzar, Paraplatin, and Herceptin.

Of the 12 patients treated with the KOS-862/carboplatin combination therapy, one patient with ovarian cancer experienced a complete response, and one patient with hepatocellular carcinoma demonstrated a 41 per cent decrease in aFP (alpha feto-protein) and stable disease for 21 weeks, providing preliminary evidence of anti-tumour activity.
Pharmacokinetic data revealed no apparent drug-drug interactions between the two agents.

Of the 14 patients treated with the KOS-862/gemcitabine combination therapy, one patient was observed to have a partial response, and two patients had disease stabilization for more than three months, suggesting evidence of anti-cancer activity. Pharmacokinetic data revealed no apparent drug-drug interactions between the two agents.

"These results confirm the findings of preclinical combination studies suggesting the potential for clinical benefit, low potential for drug-drug interactions, and showing non-overlapping toxicities," said Robert G. Johnson, Jr., Kosan Executive Vice President, Development, and Chief Medical Officer.

Under a global development and commercialization agreement between Kosan and Roche, 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.