Cladribine in the treatment of relapsed or refractory chronic lymphocytic leukemia

Purpose: Cladribine (2-CdA), a purine analog resistant to adenosine deaminase, has significant activity in a variety of lymphoproliferative diseases. This study was designed to determine the efficacy of 2-CdA in patients with relapsed or refractory chronic lymphocytic leukemia (CLL). Patients and Methods: Twenty-six patients aged 40 to 88 years (median, 64) who either had relapsed after an initial response or were refractory to conventional chemotherapy with at least an alkylating agent were treated with 2-CdA 0.1 mg/kg/d by continuous intravenous infusion for either 5 or 7 days every 28 days for a maximum of six cycles. Results: No complete remissions (CRs) occurred. Eight of 26 patients (31%) achieved a partial remission (PR). The actuarial median time to progression (TTF) in responding patients is 16 months (range, 6 to 22). The actuarial median survival duration of the responding patients is 12 months (range, 8 to 28). Eight of 26 patients (31%) sustained early toxicity. Seven of these eight patients died before the first reevaluation of infection (n = 3), pericardial tamponade (n = 1), Stevens- Johnson syndrome (n = 1), and stroke (n = 2). No nausea, emesis, alopecia, or renal, hepatic, or cardiac toxicity was observed. Conclusion: 2-CdA has activity in patients with relapsed or refractory CLL. However, patients who have received multiple prior regimens that included fludarabine are less likely to respond, and there can be significant morbidity. Treatment of patients with less prior therapy earlier in the natural history of the disease may lead to improved and more durable responses.