received a non-approvable letter for its cancer drug Xinlay (atrasentan) from a US Food and Drug Administration advisory panel, saying it “warrants further study.”

When it filed for approval of Xinlay, Abbott had originally hoped to garner approval for use in patients with hormone refractory prostate cancer. However, following a failed Phase III trial, it limited the proposed labelling to men with confirmed bone metastases [[15/12/04d]]. “I do think that the drug has some activity,” said committee consultant Otis Brawley. “I, however, think that the company needs to look at the subsets for where that activity was, try to better define and do clinical trials in that population that is highly likely to benefit.” Ronald, Bukowski, another panel member, added: “There are subsets clearly where there is going to be activity. They don’t have the exact mechanism nailed down yet. They need to refine their groups: they need to refine their patient selection so that they enrich their population to show the differences they want to show.”

Aside from the efficacy issues, the FDA panel had other concerns about the potential for Xinlay to cause serious cardiovascular events, after eight deaths in the trial versus two amongst placebo receivers. Further trials should be designed to clearly characterize any cardiovascular risk, concluded the FDA panel, which voted unanimously not to recommend approval of the drug.

Abbott is currently conducting a trial of Xinlay in earlier-stage prostate cancer patients who are refractory to hormone therapy but who have not developed metastases. Although not expected to complete until 2006, the US biotechnology firm has highlighted this study as a back-up option should the FDA reject its application. 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.