CALLISTO BEGINS DOSING IN PEDIATRIC LEUKEMIA TRIAL

Callisto Pharmaceuticals has begun dosing patients in a Phase I clinical trial of L-Annamycin in children and young adults with refractory or relapsed acute lymphocytic leukemia (ALL) or acute myelogenous leukemia (AML).

The primary objectives of the Phase I clinical trial are to evaluate safety and identify the maximum tolerated dose (MTD) of L-Annamycin, starting at 130 mg/m2/day, given over three consecutive days and to evaluate the antileukemia activity of L-Annamycin in children and young adults with refractory or relapsed ALL or AML. The secondary objective is to measure the pharmacokinetics of annamycin and its metabolite, annamycinol. L-Annamycin is administered by infusion using a patented liposomal formulation.

L-Annamycin is in the anthracycline family of drugs. In animal and in vivo studies, L-Annamycin overcomes multidrug resistance and shows decreased cardiotoxicity. An earlier Phase I clinical trial of L-Annamycin in relapsed or refractory acute leukemia patients showed the drug's potential to treat this disease and was the basis for the initiation by Callisto in December 2005 of a Phase I trial of L-Annamycin in adult relapsed or refractory ALL patients. In June that same year the FDA granted L- Annamycin orphan drug designation for treating ALL and AML.