Cladribine in the treatment of hairy cell leukemia: initial and subsequent results.

Hairy cell leukemia (HCL) is a chronic B-cell lymphoproliferative disorder associated with pancytopenia, splenomegaly, and recurrent infections. Although interferon alpha and pentostatin were initially found to be effective in this disease, cladribine has emerged as the preferred initial therapy. Cladribine given as a single continuous intravenous seven-day infusion is the dosing schedule with the most durable complete remissions and evaluated in the greatest number of patients with HCL. Patients who relapse after purine analogue therapy, whether it be cladribine or pentostatin, can be successfully retreated with cladribine. Patients with HCL may develop complications of recurrent infection and second malignancies. Although both complications are postulated to be related to therapy, they may also be due to the duration and burden of the disease. Minimal residual disease detected on bone marrow biopsy is thought to predict for future relapse. We will review the initial and subsequent results of cladribine in the management of HCL.