Pfizer Inc discontinued a phase III clinical trial (A3671009), of single-agent tremelimumab (CP-675,206) in patients with advanced melanoma, after the review of interim data showed that the trial would not demonstrate superiority to standard chemotherapy.

Pfizer said it has communicated with worldwide regulatory authorities and investigators regarding the discontinuation of the trial. Investigators will work with their patients to determine if they are benefiting from treatment and therefore should continue treatment with tremelimumab, the company said.

"Although this outcome is disappointing, Pfizer remains committed to investigating new treatment options for patients with melanoma, a high risk area of research with significant unmet medical need. We continue to focus on additional studies involving tremelimumab alone and in combination with other therapies which are currently ongoing in patients with several types of cancer," said Charles Baum, M.D., Ph.D., vice president and head, Oncology Therapeutic Area, Pfizer Global Research and Development. "We will continue to assess the study data to understand the clinical benefit seen in some patients who received tremelimumab."

The full data set from study A3671009 is being analysed, and more details are expected to be available at the upcoming American Society for Clinical Oncology Annual Meeting in June 2008.

"We have a robust pipeline within Pfizer Oncology and we remain committed to the discovery and development of novel cancer treatments which hold promise for patients with cancer," said Dr. Baum. "We are extremely grateful for the strong support we have received for this clinical trial from the physicians, study staff, and most importantly from the patients."

Pfizer is developing several classes of agents in its Immuno-Oncology pipeline including CD40 agonists, toll-like receptor (TLR) agonists and vaccines.