Treatment of hairy cell leukemia with 2-chlorodeoxyadenosine (2-CdA): long-term follow-up of the Northwestern University experience.

2-Chlorodeoxyadenosine (2-CdA), a purine analog, has become universally accepted as the agent of choice in treating hairy cell leukemia (HCL). However, few studies have reported long-term outcomes after 2-CdA treatment. Between January 1990 and June 2003, 86 consecutive patients with HCL were treated with a single 7-day course of 2-CdA by continuous infusion at a dose of 0.1 mg/kg per day. Of the 86 patients (mean age: 49 years), 67 patients (79%) achieved a complete remission (CR); 18 patients (21%) achieved a partial remission (PR); and 1 patient's response was unable to be assessed. The progression-free survival (PFS) for initial relapse after 12 years was 54%. At a median follow-up of 9.7 years (range, 0.3-13.8 years), 31 (36%) of 85 patients relapsed. There were 23 relapsed patients treated with a second cycle of 2-CdA; 2 patients were treated with alternative agents; and 6 patients were observed. Of the 23 relapsed patients retreated with 2-CdA, 12 (52%) achieved a CR and 7 (30%) patients achieved a PR (overall response rate: 83%). The overall survival (OS) rate after 12 years was 87%. There were 15 patients (17%) who developed other malignancies. Long-term follow-up of up to 14 years (median: 9.7 years) showed an excellent PFS and OS for HCL patients after 2-CdA treatment.