Johnson & Johnson took a knocking yesterday after an accelerated approval for its investigational drug to treat leukaemia, Zarnestra (tipifarnib), was given the thumbs down by a US Food and Drug Administration advisory panel. The panel has requested Phase III data be included in the regulatory dossier, saying without this “it’s not at all clear that the overall survival of patients is higher” for Zarnestra than best supportive care.

J&J was hoping to win a nod using data from a single arm, Phase II study of Zarnestra in elderly patients with poor-risk acute myeloid leukaemia. However, the panel voted 7-4 against recommending such an approval, saying only a small number of patients seemed to benefit from the drug with just a 15% complete remission rate as determined by J&J. The FDA said it was just 11%.

The committee also voiced its concern that it was difficult to assess which patients would respond to therapy and member Bruce Cheson (Georgetown University Hospital) said: “I don’t know when patients are going to respond, when patients aren’t going to respond.” For that reason, the panel concluded that it would be difficult to identify an appropriate patient population for labeling.

Cheson also put a question mark over Zarnestra in the wake of the FDA’s handling of the first drug in the compound class – AstraZeneca’s Iressa (genti) – which received accelerated approval on the back of Phase II data but failed to show a survival benefit in a confirmatory study. “It makes me much less comfortable” in supporting Zarnestra’s approval, Cheson said, adding he had “no faith” the drug would not continue to be sold if the Phase III data were negative.

The news is a major setback for J&J, which although it has now initiated a Phase III study, does not expect to be able to present it to the FDA until 2007.