Treatment of Hairy Cell Leukaemia with 2'-Deoxycoformycin

The adenosine deaminase inhibitor 2'-deoxycoformycin (DCF) has been used to treat 40 patients with hairy cell leukaemia (HCL) who have been followed up for a minimum of 6 months. 21 patients had previously undergone splenectomy. 33 had received treatment with alpha-interferon (IFN), half of whom had relapsed and the remainder had either been partially treated due to intolerance or had an incomplete response. Deoxycoformycin was administered by slow intravenous injection at a dose of 4 mg/m(2) weekly for 4 consecutive weeks and then 2-weekly for 4 doses followed by 4-weekly injections until a complete remission was achieved. No maintenance therapy was given. The overall response rate was 97yi, with 82% complete remission (CR) and 15% partial remission (PR). CR have lasted from 3+ to 30+ months (median 12 +) with no relapses recorded so far. Only one evaluable patient, suffering from a variant form of HCL, failed to respond to DCF, whilst two other HCL-variant cases who had been resistant to alpha-IFN have achieved a PR and are still on treatment. DCF was generally well tolerated, the major toxicity being related to cytopenia and associated infection. Four patients developed severe infections, one of whom died of septicaemia before it was possible to evaluate the response to DCF. A group of 12 patients who had received alpha-IFN immediately prior to treatment with DCF and had obtained clinical and haematological benefit had fewer infections with DCF than the group who had either not received IFN immediately before or who had failed to respond to it. In view of the infections associated with DCF, we would now recommend initial therapy for HCL patients with alpha-IFN for 2-4 months to obtain clinical and haematological improvement, followed by DCF given 2-weekly, to eradicate residual disease. This approach may achieve a higher proportion of sustained CR with a short treatment time and minimal toxicity.