Subcutaneous injections of 2-chlorodeoxyadenosine for symptomatic hairy cell leukemia

To evaluate the clinical efficacy and safety of 2-chlorodeoxyadenosine (CdA) when administered by subcutaneous injection to patients with symptomatic hairy cell leukemia (HCL), and to evaluate predictive factors for response.

Seventy-three patients were given CdA as a subcutaneous injection once daily for 7 days. Complete remission (CR) required normalized blood counts and the absence of B-ly 7-positive bone marrow cells by flow cytometry. CdA concentrations in plasma following the first injection were analyzed by high-pressure liquid chromatography.

Fifty-nine patients (81%) achieved a durable CR after one (n = 55) or two courses, and 10 had a partial remission (PR). With a median follow-up duration of 20 months, no patient had a clinical relapse. Neutropenic fever that required intravenous antibiotics occurred in 28 patients (38%). No toxicity at injection sites was observed. Incomplete response was predicted by an elevated lymphocyte count and serum beta 2-microglobulin level, and by a high percentage of hairy cells in the bone marrow. Plasma CdA levels were similar to those achieved from intravenous administration.

Subcutaneous injection of CdA is safe and as effective as continuous infusion without problems associated with the mode of administration. Our schedule simplifies CdA treatment and can be generally recommended.