Hairy cell leukemia: towards a curative strategy

Although not all patients who have HCL require therapy at diagnosis, most eventually need treatment. Historically, splenectomy and interferon-alpha resulted in hematologic responses; however, responses tend to be short. The introduction of purine analogs dramatically changed the prognosis for most patients who hae HCL. It is now considered standard of care to use a purine analog, such as 2-CdA or 2'-DCF, as first-line therapy. This approach results in a high CR rate and prolong DFS. Although both agents yield the same rates of CR and survival, 2-CdA seems easier to administer and my be associated with less toxicity. Despite the excellent results with purine analogs, most patients have MRD detected by sensitive techniques; 30% to 40% of patients eventually relapse and most require further therapy. A repeat course of 2-CdA (or 2'-DCF) will result in CR in approximately 70% of patients. For patients who have relapsed or refractory disease, monoclonal antibody-based therapies are emerging options. Rituximab and BL22 are highly active in this setting. Until BL22 becomes widely available, rituximab is a reasonable choice for salvage therapy; however, the dosing schedule needs to be denied further. The roles of rituximab and BL22 as initial therapy for patients who have previously untreated HCL have not been investigated. Fig. 1 is a suggested algorithm for the treatment of HCL. With the introduction of effective new agents, further studies will determine whether the now achievable prolonged survival will translate into cure.