Nelfinavir’s contamination with ethyl methanesulfonate (EMS) in the spring of 2007 was not of a level to involve any risk of cancer, evidence gathered by the drug’s manufacturer, Roche, shows.
Between March and May of 2007 batches of nelfinavir (Viracept) were accidentally contaminated with EMS during the drug’s manufacture. European drug regulatory authorities were informed once this problem became known, leading to a near-global recall of nelfinavir and the temporary suspension of nelfinavir’s licence.
Roche has undertaken studies to try and determine the risk to patients of exposure to EMS. Because EMS is a potentially cancer-causing substance it is not possible to conduct studies in humans to see what level of exposure involves a substantial cancer risk. Therefore the drug company looked at a number of studies involving animals.
An independent, ad hoc panel of toxicology experts consulted by Roche agreed that these studies had been well conducted and that it was appropriate to use them to assess the risk in humans.
The studies lasted up to 28 days and the panel of toxicologists concluded that this was long enough to allow an assessment of the longest possible period of exposure to contaminated nelfinavir in humans.
Roche’s studies also assessed the level of EMS exposure needed to have a potentially cancer-causing effect. They also assumed that any resulting from exposure to EMS would be because of damage to the DNA in cells. The toxicologists agreed that these were appropriate questions for Roche to be asking.
A very cautious interpretation of the findings of these studies suggested that patients who took contaminated nelfinavir were exposed to levels of EMS far below those that could potentially lead to cancer. Toxicologists agreed with this conclusion.
Roche is consulting community groups and leading HIV doctors from around the world about these findings. They were presented to a panel of non-governmental organisations (NGOs) and treatment activists in London on June 2nd and will be considered by an ad hoc independent panel of HIV physicians in London on June 10th.
All the results have been provided to European drug regulatory authorities who will review the information at their June meeting.