2-CHLORODEOXYADENOSINE IN THE TREATMENT OF HAIRY-CELL LEUKEMIA AND CHRONIC LYMPHOCYTIC-LEUKEMIA

More than 450 patients with hairy cell leukemia have been treated at the Scripps Clinic. Of 144 patients followed for a median of 14.2 months (range, 8.1-70 months), 123 (85%) obtained complete responses, 17 (12%) partial responses, 3 (2%) did not respond, and 1 patient was unevaluable. So far, 4 patients have relapsed at a median of 36 months (range, 12-48 months). Fever was the principal toxicity occurring in 43% of patients. Five patients resistant (3 patients) or intolerant (2 patients) to deoxycoformycin were also treated. Of these 5 patients, 4 obtained complete responses, including 2 patients resistant to deoxycoformycin, and 1 patient a partial response, suggesting a possible lack of cross-resistance between deoxycoformycin and 2-CdA in hairy cell leukemia. Other single-institution studies have documented similar response rates and toxicities. Ninety patients with advanced chronic lymphocytic leukemia were treated with 2-CdA administered either as a 0.1 mg/kg/day 7-day continuous intravenous infusion or as a 0.0280.14 mg/kg/day 2-hour bolus for 5 consecutive days. Four patients (4%) obtained complete responses and 36 patients (40%) partial responses, using NCI-sponsored Working Group guidelines. Of the 50 patients who were non-responders, 27 (54%) had a greater than or equal to 50% sustained reduction in the absolute lymphocyte count. The ratio of deoxycytidine kinase to cytoplasmic 5'-nucleotidase was predictive of 2-CdA responsiveness. Fourteen patients with fludarabine-failed chronic lymphocytic leukemia were also treated. No responses were achieved and 2 patients had progressive disease. Six patients had a greater than or equal to 50% reduction in the absolute lymphocyte count. The efficacy and safety of 2-CdA in fludarabine-failed chronic lymphocytic leukemia patients remains to be evaluated in larger numbers of patients.