2-chlorodeoxyadenosine administration to patients with the myeloid blast phase of chronic myelogenous leukemia.

Three patients with chronic myelogenous leukemia (CML) in myeloid blast phase received 2-chlorodeoxyadenosine (2-CdA) at 0.7 mg/kg per course over 5 days every 2-4 weeks for 7, 2 and 5 courses. Each patient had a decrement in their white blood cell count, and in the absolute number and percentage of circulating immature cells following 2-CdA administration. Two patients achieved hematologic responses of 14 and 3 months and survived 19 and 6 months, respectively, while the non-responder died 2 months later. 2-CdA-induced anemia and thrombocytopenia, generally mild and reversible, were observed in all patients. Given the dismal results and considerable toxicities that follow multiagent induction chemotherapy for CML in myeloid blast phase, 2-CdA therapy may represent a reasonable therapeutic alternative, although confirmation is required in larger numbers of patients.