Callisto Pharmaceuticals, Inc., a biopharmaceutical company primarily focused on the development of drugs to treat cancer, has been granted orphan drug designation by the Office of Orphan Products Development of the United States Food and Drug Administration (FDA) to its drug candidate Annamycin for the treatment of acute lymphoblastic leukaemia (ALL).

Annamycin, a second-generation anthracycline developed at M.D. Anderson Cancer Centre, is being developed by Callisto to treat relapsed acute leukaemia patients. Callisto plans to begin a clinical trial in adult relapsed acute lymphoblastic leukaemia patients in the near future, according to a company release.

Callisto chief executive officer Dr. Gary S. Jacob says, "Callisto is planning an ambitious programme of clinical development of Annamycin starting this year, and the designation of orphan drug status to treat ALL gives additional assurance to both the company and our investors that we are well protected against any potential competition."

Orphan drug designation, along with approval by the FDA for commercialization of Annamycin, entitles Callisto to seven years of market exclusivity in the United States, provided Callisto continues to meet certain conditions established by the FDA. During the seven-year exclusivity period, the FDA will not accept or approve other applications to market the same medicinal product for the same therapeutic indication.

Annamycin, a drug from the anthracycline family, earlier completed a Phase I/IIa trial in refractory leukaemia patients. The drug was developed to address limitations associated with other anthracyclines. Annamycin circumvents multiple drug resistance, shows decreased cardiotoxicity, and achieves greater than 95 per cent incorporation into liposomes, providing a favourable means of drug administration, the release added.