Pfizer won the backing of a US Food and Drug Administration advisory panel yesterday to extend the use of its anti-clotting drug Fragmin to include the prevention of venous thromboembolism (VTE) in patients with cancer.

Fragmin (dalteparin sodium) is already approved to prevent clots in patients undergoing surgeries, as well as use alongside aspirin for the prevention of ischaemic complications resulting from cardiovascular diseases such as unstable angina and myocardial infarction.

The panel voted 12 to 0 to back Pfizer’s application and, if the FDA concurs with their view, Fragmin could become the first drug in the low-molecular weight heparin class of drugs to win approval for this indication, although its premium pricing over currently-used drugs in this setting, such as warfarin, could limit its use.

Earlier, the FDA had raised questions about whether Fragmin’s uses should be expanded to include cancer patients, who can be at increased risk of clots caused by their disease, chemotherapy or the intravenous lines used to deliver treatment.

The main point of contention was the death rate seen in patients receiving Fragmin in the clinical trial – called CLOT – that supported Pfizer’s application. This showed that Fragmin was 52% more effective than warfarin in reducing blood clots, but the FDA was concerned by data showing that, among patients who did not complete the study, 17% of the Fragmin group did so because they died, compared to 7% of the warfarin group.

However, the panel was encouraged by the overall mortality data from the study, which showed no statistically-significant difference between the groups, with 39% of Fragmin-treated patients dying versus 41% of the warfarin group. The overall view was that the difference could be down to the way patients were classified in the study.

A year ago Japanese drugmaker Eisai signed a deal with Pfizer giving it exclusive rights to promote Fragmin in the USA.