2'-Chlorodeoxyadenosine Effectively Induces Complete Remission in Hairy Cell Leukaemia

Hairy cell leukaemia, previously known as leukaemic reticuloendotheliosis, is an indolent lymphoproliferative disorder of unknown etiology. It typically affects males, causes marked splenomegaly and moderate enlargement of the liver, whilst lymphadenopathy is inconspicuous. Pancytopenia is characteristic with unusually profound monocytopenia, variable reduction in platelets, and the presence in the peripheral blood and marrow of abnormal small lymphocytes having irregular cytoplasmic margins. Ultrastructure, combined with cytochemistry and flow cytometry, have refined diagnosis. A variant exists between this classical entity and B prolymphocytic leukaemia, where blastic transformation or massive lymph node enlargement are found, and this is of ominous significance. In all these patients with this entity conventional chemotherapy is ineffective and shortens survival. Our previous experience with splenectomy results in excellent clinical control for long periods of time, but without disease eradication. There followed a vogue for the use of interferon but this is limited by high cost and dose-dependent side-effects. Contemporary management centres on the purine analogues, where durable responses are possible with fludarabine and deoxycoformycin, but best with 2'chlorodeoxyadenosine (2-CDA). To document the efficacy of the latter agent, we analysed the outcome in seventeen consecutive patients treated over the last five years. Four were ineligible for analysis, although two had 2-CDA. The other thirteen, managed on a standard seven-day course of 0.1 mg/kg 2-CDA given as a continuous intravenous infusion, all responded promptly. Apart from transient leucopenia complications have been minimal, and oral co-trimoxazole prophylaxis for pneumocystis carinii was maintained during the first one year. In all thirteen there was a rapid return to normal of peripheral blood count and marrow on aspiration and trephine biopsy. Even in the longest follow-up clinical and haematologic remission has been maintained and no patients have required retreatment. One individual has relapsed in the marrow at two years. Despite the relative expense of the agent the excellent treatment outcome and patient acceptability, coupled with its safety, leads to the recommendation that in South Africa-as elsewhere in the world-this be regarded as the first line of treatment.