INTERFERON TREATMENT FOR HAIRY-CELL LEUKEMIA - AN UPDATE ON A COHORT OF 69 PATIENTS TREATED FROM 1983 TO 1986

We report follow-up information on 69 hairy cell leukemia (HCL) patien ts treated with interferon alfa-2b (IFN) as primary treatment from 198 3 to 1986. Follow-up through April, 1993 shows that only 14 patients h ave expired. Forty-seven of the 61 patients completing the intended 12 or more months of initial IFN treatment were eventually considered IF N failures. Forty-three required retreatment (41 received a second cou rse of IFN and 2 received pentostatin). Four patients died without fur ther therapy for HCL. The median time to interferon failure was 31.3 m onths. Fourteen patients are alive and have not required further treat ment after completing their initial 12 or more months of interferon. F ifteen patients underwent a third course of interferon therapy at a me dian time after completion of a second course of IFN of 1.0 year. Eigh teen patients were eventually treated with pentostatin and ten with 2- chlorodeoxyadenosine (2-CdA). Thirteen patients developed a second mal ignancy; six of these patients developed a hematologic malignancy betw een 44.6 months and 99.1 months after initiation of interferon therapy . We conclude that although interferon provides excellent palliation, that most patients will eventually require further treatment with inte rferon or chemotherapy. Future trials in HCL must be aware of the risk of second malignancies.