Bristol-Myers Squibb’s investigational cancer drug Sprycel (dasatinib) has received the thumbs up for the treatment of certain rare leukaemias from a US Food and Drug Administration advisory panel, which has recommended accelerated approval for the product on the back of robust clinical data.

The committee's decision was based on a review of Phase II study results, which demonstrated Sprycel’s strength in treating certain types of chronic myeloid leukaemia and acute lymphoblastic leukemia in patients intolerant or unresponsive to previous therapies, such Novartis’ Gleevec (imatinib mesylate).

This is a particularly important benefit as there is presently no other approved option – aside from a bone-marrow transplant - for patients resistant to Gleevec, the current gold standard of treatment.

B-MS believes Sprycel has a greater preclinical potency than Gleevec and estimates that 15%-20% of patients treated for CML do not achieve major cytogenetic responses to Gleevec within the first 12 months and that 5%-10% develop resistance.

The agent could find a ready market in the roughly 30% of patients who do not respond to Novartis' drug, according to analysts, who suggest the compound could see peak sales in excess of $500 million.

Sprycel is already under priority review with the FDA, and the agency is expected to reach a decision by the end of June.

US drug giant Pfizer is also developing a drug for patients resistant to Gleevec, but currently only for those with gastrointestinal stromal tumours (GIST). Sutent (sunitinib malate) received backing for approval by Europe's Committee for Medicinal Products for Human Use for this indication last month.