The US Food and Drug Administration has rejected Abbott Laboratories marketing application of its prostate cancer drug, Xinlay (atrasentan), as recommended by the agency’s advisory panel for cancer drugs last month [[14/09/05c]].

The panel unanimously voted to reject Xinlay for the treatment of hormone-refractory prostate cancer that had spread to the bone - an indication already scaled back by Abbott because of disappointing trial results [[15/12/04d]] - after concluding that the two trials submitted by Abbott in its application failed to slow down the progression of the disease. It also asked for more data on the cardiovascular safety of the drug.

Abbott had decided to press ahead with the application anyway, as Xinlay was being reviewed under the fast-track mechanism at the FDA - which allows additional data to be submitted post-marketing to support the application - and the drug had shown some benefits in easing the symptoms of sufferers, including relieving pain.

The FDA’s ‘not approvable’ letter came as no surprise in light of the advisory committee vote, but Abbott emphasised that Xinlay is still in development as a treatment for men with hormone-refractory prostate cancer that has not spread. The company has a 1,000-patient study already ongoing in the latter indication, and results are expected in the first half of next year.

It is also planning a trial of Xinlay in combination with Sanofi-Aventis' Taxotere (docetaxel) for treating hormone refractory prostate cancer patients with bone metastases.