Hairy cell leukemia: short review, today’s recommendations and outlook

Abstract

Hairy cell leukemia (HCL) is part of the low-grade non-Hodgkin lymphoma family and represents approximately 2% of all leukemias. Treatment with splenectomy and interferon-α historically belonged to the first steps of therapeutic options, achieving partial responses/remissions (PR) in most cases with a median survival between 4 and 6 years in the 1980s. The introduction of the purine analogs (PA) pentostatin and cladribine made HCL a well-treatable disease: overall complete response rates (CRR) range from 76 to 98%, with a median disease-free survival (DFS) of 16 years a normal lifespan can be reached and HCL-related deaths are rare. However, insufficient response to PA with poorer prognosis and relapse rates of 30–40% after 5–10 years of follow-up may require alternative strategies. Minimal residual disease can be detected by additional examinations of bone marrow specimens after treatment with PA. The use of immunotherapeutic monoclonal antibodies (mAB) like rituximab as a single agent or in combination with a PA or more recently clinical trials with recombinant immunotoxins (RIT) show promising results to restrict these problems. Recently, the identification of the possible disease-defining BRAF V600E mutation may allow the development of new therapeutic targets.

Biomarkers in Lung Adenocarcinoma: A Decade of Progress

“…118 In fact, BRAFactivating mutations, namely, the p.Val600Gly (V600E) mutation, is a diagnostic feature of some entities, such as hairy cell leukemia. 119 BRAF is a critical member of the RAS/ RAF/MAPK growth and proliferation signaling pathway, acting downstream of RAS family members. In melanoma, in which BRAF V600E occurs in upwards of 50% of cases, it is a critical biomarker of response to BRAF-targeted inhibitors such as vemurafenib.…”

Characteristics and treatment patterns among US patients with hairy cell leukemia: a retrospective claims analysis

“…While HCL is not curable, it is responsive to available therapies and the goal is to achieve complete remission [1,2]. Over the last few decades, the treatment strategy for HCL has shifted from the use of splenectomy and interferon-alfa to use of a singleagent purine nucleoside analog (PNA), either pentostatin or cladribine [3]. The CD20-targeting monoclonal antibody, rituximab, may be considered in patients with relapse or refractory following initial PNA therapy [4].…”

“…Overall survival rates have ranged from 80 to 90% with pentostatin at 10 years, and 97% with cladribine at 9 years [9]. However, relapse occurs in 30-40% of patients after 5-10 years of follow-up [3]. Response may vary by age, and long-term follow-up is needed for this rare malignancy to determine overall survival versus competing mortalities associated with aging [2].…”

Diagnosis and management of craniopharyngiomas in the era of genomics and targeted therapy

“…Mutations in BRAF V600E have been observed and effectively targeted in other tumor types, including melanoma, 15,16 ameloblastoma, 20,27,42 hairy cell leukemia, 12,13,17,23,33,38 Erdheim-Chester disease, 21,23 and pleomorphic xanthoastrocytoma. 11,23,29,32 We recently achieved a clinically significant response in a patient with a recurrent BRAF V600E mutant PCP using targeted BRAF and MEK inhibitors 5 ( Fig.…”