Hairy cell leukemia: update and current therapeutic approach.

PURPOSE OF REVIEW: In this review, we discuss the pathogenesis and standard therapeutic approach to hairy cell leukaemia (HCL) as well as newer targeted therapies under investigation showing promising end-points in treating HCL. RECENT
FINDINGS: HCL is an indolent B-cell leukaemia. Historically, HCL patients have achieved excellent response to purine nucleoside analogues and single purine analogue treatment with pentostatin or cladribine is currently the standard of care for initial treatment. Most patients achieve complete remission with this form of therapy. However, long-term follow-up has demonstrated that a large number of patients eventually develop relapsed disease. Relapse disease tends to be more difficult to treat and refractory to the same purine analogues. Development of relapsing and refractory disease after initially achieving complete remission with purine analogue treatment has generated a need for alternative therapies.
SUMMARY: Identification of the BRAFV600E mutation in nearly 100% of HCL patients has provided rationale for inclusion of BRAF inhibitors into the therapeutic armamentarium to treat HCL. Clinical trials are currently underway measuring efficacy of vemurafenib in achieving clinical response in relapsed/refractory HCL and also toxicity. Other novel therapies with monoclonal and immunotoxin-conjugated antibodies have also shown promising response in recent investigational studies.