New Targeted Therapy Combination Holds Promise to Untangle Hairy Cell Leukemia

Hairy cell leukemia (HCL) is an uncommon B-cell neoplasm uniquely characterized by a high prevalence of the BRAF^V600E mutation, which leads to constitutive activation of the mitogen-activated protein kinase (MAPK) pathway.¹ In fact, the BRAF^V600E point mutation is identified in nearly all cases of HCL; however, it is absent in HCL variant (vHCL) and rare in other B-cell neoplasms.^2,3 Notably, in contrast to melanoma or other BRAF mutant solid tumors, HCL exhibits very few other mutations, potentially explaining the high response rates observed in patients treated with mutant BRAF-targeted agents, such as vemurafenib.