Chemo-immunotherapy for hairy cell leukemia.

With the introduction of the nucleoside analogs cladribine and pentostatin the treatment of patients with hairy cell leukemia (HCL) has been revolutionized, and the majority of patients achieve a long-lasting complete remission with rare patients ever needing the traditional treatment strategies such as splenectomy. However, in the studies employing either of these nucleoside analogs, a proportion of patients do not respond to the initial therapy and the event-free survival curve does not reach a plateau, with up to 40% of patients relapsing within a few years. New therapeutic modalities including monoclonal antibodies such as rituximab and immunotoxins such as BL22 are now available. Furthermore, progress in the identification of minimal residual disease (MRD) using consensus primer or patient specific polymerase chain reaction for the immunoglobulin heavy chain variable region gene (IGHV), as well as multiparameter flow cytometry, allows for the detection and eradication of MRD. Whether this will translate to a reduction in the rate of relapse will require large prospective randomized trials. Alternatively, it may be possible to identify patients who are more likely to relapse using pretreatment characteristics such as the mutational status of IGHV and apply these strategies solely to them.