Journal Article

Hairy Cell Leukaemia

Dearden, Claire, Cross, Matthew

2020

Overview

Purpose of ReviewTo summarise diagnostic clinical/laboratory findings and highlight differences between classical hairy cell leukaemia (HCLc) and hairy cell leukaemia variant (HCLv). Discussion of prognosis and current treatment indications including novel therapies, linked to understanding of the underlying molecular pathogenesis.Recent FindingsImproved understanding of the underlying pathogenesis of HCLc, particularly the causative mutation BRAF V600E, leading to constitutive activation of the MEK/ERK signalling pathway and increased cell proliferation.SummaryHCLc is caused by BRAF V600E mutation in most cases. Purine nucleoside analogue (PNA) therapy is the mainstay of treatment, with the addition of rituximab, improving response and minimal residual disease (MRD) clearance. Despite excellent responses to PNAs, many patients will eventually relapse, requiring further therapy. Rarely, patients are refractory to PNA therapy. In relapsed/refractory patients, novel targeted therapies include BRAF inhibitors (BRAFi), anti-CD22 immunoconjugate moxetumomab and Bruton tyrosine kinase inhibitors (BTKi). HCLv has a worse prognosis with median overall survival (OS), only 7–9 years, despite the combination of PNA/rituximab improving front-line response. Moxetumomab or ibrutinib may be a viable treatment but lacks substantial evidence.

• Publisher: Springer Nature B.V
• Subject: CD22 antigen / Cell proliferation / Extracellular signal-regulated kinase / Immunotherapy / Inhibitor drugs / Leukemia / Medical prognosis / Minimal residual disease / Monoclonal antibodies / Mutation / Nucleoside analogs / Pathogenesis / Patients / Prognosis / Protein-tyrosine kinase / Rituximab / Signal transduction / Targeted cancer therapy