Modern Strategies for Hairy Cell Leukemia

Abstract

Enormous progress in the treatment of hairy cell leukemia over the last five decades has emerged as a result of organized clinical investigations. Although interferon represented one of the initial major therapeutic advances in the management of this disease in 1984, the subsequent introduction of purine nucleoside analogs (pentostatin and cladribine) changed the natural history of this rare disease by achieving a high rate of complete and durable remissions. The disease-free survival after effective therapy has not reached a plateau, suggesting control but not cure of the disease. Identification of minimal residual disease in patients achieving a complete hematologic remission provides insight into the potential source for predicting eventual relapse. Modern strategies of targeted therapies directed against immunophenotypic markers on the leukemic cells provide hope that improved long-term control of the disease is possible. Combined chemoimmunotherapy may hold the highest promise for disease eradication, but the optimal strategy for using this approach is under active investigation. Despite the perception by hematologists that this disease has already been conquered, there are critically important unanswered questions that remain. Investigation of the bone marrow microenvironment and its impact on minimal residual disease may ultimately prevent relapse. Consideration of the median age of patients at diagnosis combined with a substantial relapse rate mandates continued pursuit of improved therapy. The ultimate goal will be to achieve cure rather than simple control of the disease.

Consensus guidelines for the diagnosis and management of patients with classic hairy cell leukemia

“…50 Both agents administered on 1 of these schedules appear to be equally effective. 3,15,51 The choice is determined by physician preference or patient convenience with no benefit to support one over the other.…”

“…[14][15][16][17][18][19][20][21] Nevertheless, patients relapse and require additional therapy. Substantial variability has been introduced into how these agents are administered.…”

Advances in the Treatment of Hairy Cell Leukemia

“…The adenosine deaminase (ADA) inhibitor, Pentostatin (2'-deoxycoformycin), was developed in the 1970s and was introduced to treat HCL in late 1980s [5]. It was proved to induce high response rates and long-lasting responses [6].…”

Orphan drugs for the treatment of hairy cell leukemia

“…These treatments are commonly used in the small proportion of patients who are refractory to the purine analogs or who experience only partial responses (PR) or multiple relapses. An excellent review on the efficacy of the various treatments in HCL has been published by Grever and Lozanski [4]. Such progress has not been taken place in the variant form of HCL (HCL-variant), a disease that will not be discussed here since, although it shares some pathological features with HCL, it is at present considered biologically unrelated to the classical form [5][6][7].…”