Sequential administration of recombinant interferon alpha and deoxycoformycin in the treatment of hairy cell leukaemia

Summary Both recombinant interferon alpha and deoxycoformycin (dCF) are effective in the treatment of hairy cell leukaemia. In an attempt to reduce the complications from dCF therapy, a pilot study of the Eastern Cooperative Oncology Group (ECOG) first treated patients with interferon to improve peripheral blood cell counts before dCF treatment began. Thirty‐four patients were treated for 3 months with recombinant interferon alpha‐2a (rIFN alpha‐2a), 3 × 10⁶ IU subcutaneously three times a week for 3 months, and then by dCF, 4 mg/m² intravenously every 2 weeks for a maximum of 12 months. The overall response rate was 94% (32/34); 76% of patients (26/34) had complete response (CR) (90% confidence interval, 62–88%) and 18% (6/34) partial response. One patient was found to have a Mycobacterium avium infection while receiving rIFN alpha‐2a. Without specific antimycobacterial therapy and with continued administration of rIFN alpha‐2a and dCF, the infection resolved and he achieved CR. Three patients had culture‐negative febrile episodes during the dCF phase of treatment. Non‐disseminated herpes zoster developed in four patients, but three of the episodes occurred only after treatment was discontinued. Sequential administration of rIFN alpha‐2a and dCF resulted in fewer infections (P=0.027) than in ECOG's previous study of dCF used alone. Two patients died, one of combined hairy cell leukaemia and non‐Hodgkin's lymphoma of intermediate histologic type 17 months after entry into the study and the other of cardiac arrest 20 months after entry. Thirty‐two patients were alive with a median follow‐up of 21 months (range 13–31 months). This combination produces durable CRs with a low incidence of infection.