Roche says study shows Viracept poses no cancer risk

Roche has presented new studies that show Viracept patients" exposure to the impurity EMS is well below the toxicity threshold and so the drug does not pose an increased risk of cancer.

EMS (ethyl methanesulfonate) is a potential by-product of the manufacturing of mesylate salts, which are contained in over 40 drugs currently available worldwide.

Following the discovery of elevated levels of EMS in some batches of Viracept, Roche in June 2007 undertook a total global recall in areas of the world where it supplies the drug. This was followed by the suspension of Viracept's license in August 2007. In agreement with the European health authority, Roche undertook a comprehensive review and correction of its manufacturing procedures, which led to Viracept's licence being reinstated by the European Commission in October 2007. Since then, the product has been made available again in the EU.

The latest studies were designed to determine the impact of elevated EMS levels in some batches of Roche's Viracept (nelfinavir mesylate) and demonstrated a clear threshold response at which DNA damage, the underlying mechanism for the carcinogenesis of EMS, occurs.

Presented at the XVII International AIDS Conference in Mexico City, the results of the animal studies can be translated to humans with high confidence, says Roche, and they confirm that Viracept patients exposed to the EMS impurity at levels well below this threshold are not at an increased risk of cancer.

'These data provide unprecedented insight into the toxicity of EMS for humans. They will change the long held perceptions of the hazards posed by low doses of some genotoxic carcinogens', said professor David Tweats, Department of Medicine and Genetics, University of Wales Swansea, UK.