SUCCESSFUL TREATMENT OF PATIENTS WITH HAIRY-CELL LEUKEMIA (HCL) USINGA SINGLE-CYCLE OF 2-CHLORO-2'-DEOXYADENOSINE (CDA)

2-Chloro-deoxyadenosine (CdA) is a new adenosine-deaminase (ADA) resis tent purine analogue with high specificity for lymphoid cells. It was shown that CdA is very effective in hairy cell leukemia (HCL), refract ory chronic lymphocytic leukemia and cutaneous T-cell lymphoma leading to lasting remissions in the majority of patients with HCL. We report the successful treatment of five patients with HCL at different stage s of their disease using CdA, who were either previously untreated or had received interferon, splenectomy and deoxycoformycin (dCF), an ADA -inhibitor with high therapeutic efficacy in HCL. After one 7-day cour se of treatment, all patients reached remission. CdA was well tolerate d and, only mild side effects such as skin lash, headache, fever, naus ea were observed. Aplasia was pronounced in all instances with a slow recovery. The type of histomorphological procedure in preparing and ev aluating bone marrow biopsies is emphazised to detect minimal residual infiltration by hairy cells.