Ilex Oncology Inc announced that the US FDA would grant six months of extended market exclusivity to clofarabine under the Best Pharmaceuticals for Children Act. Clofarabine is currently under priority review by the FDA for the treatment of refractory or relapsed acute leukaemia in children. If approved by the FDA, clofarabine would be the first drug to be labelled initially for paediatric leukaemia in more than a decade, release from Ilex said.

"This is an important milestone for children with cancer and for the FDA because children are usually an afterthought in oncology drug development," said Children's Cause for Advocacy President, Susan L Weiner. "Hopefully this good news will set a precedent for other companies to make children with cancer a priority in their drug development plans," Susan added.

The Best Pharmaceuticals for Children Act offers extended market exclusivity to drug developers as an incentive to increase therapeutic research in children.

Clofarabine was previously granted orphan drug designation for the treatment of adult and paediatric acute lymphoblastic leukaemia and acute myeloid leukaemia. In the United States, orphan drug status provides for seven years of market exclusivity for the orphan drug indication following the FDA's marketing approval.

Clofarabine is a next generation of the drug class purine nucleoside analogs which all inhibit DNA production necessary for cancer cell growth.

Bioenvision Inc sub-licensed Ilex the right to develop and market clofarabine for human cancer indications in the United States and Canada. Bioenvision is entitled to milestone payments tied to the development of the compound and is entitled to royalties on North American sales. As is its exclusive right, Bioenvision is developing clofarabine in the rest of the world. Bioenvision originally obtained clofarabine development and commercialization rights under patents held by Southern Research Institute.

Ilex Oncology Inc is an oncology drug development company with a marketed product, Campath in the United States and Mabcampath in the European Union, as well as a pipeline of investigational compounds focused on the treatment of cancer.