Many such genetic events have already demonstrated clinical utility, such as BRAFV600E that confers sensitivity to vemurafenib in patients with hairy cell leukemia.
Besides confirming the constant presence of BRAF-V600E in all patients with hairy cell leukemia, we observed ubiquitous phospho-ERK expression in this malignancy.
Diagnosis of HCL is based on morphological evidence of hairy cells, an HCL immunologic score of 3 or 4 based on the CD11C, CD103, CD123, and CD25 expression, the trephine biopsy which makes it possible to specify the degree of tumoral medullary infiltration and the presence of BRAFV600E somatic mutation.
Diagnostically, the BRAF(V600E) mutation is a powerful molecular marker for papillary thyroid carcinoma and, quite possibly, hairy cell leukemia as well.
Hairy cell leukemia (HCL) is a rare, low-grade mature B-cell neoplasm with a characteristic clinical, morphological, immunophenotypic, and more recently described molecular (BRAFp.V600E mutation) profile.
Importantly, SkE resensitized the PLX-4032-resistant 451Lu melanoma cell line (451Lu-R) and was more efficient than U0126, a MEK inhibitor, and PLX-4032 (PLX) at inducing the apoptosis of two hairy cell leukemia (HCL) patient samples carrying the B-Raf-V600E mutation.
Unearthing of the BRAF mutation in self-renewing hematopoietic stem cells reveals an unexpected origin for hairy cell leukemia-a mature B cell malignancy-and a potential new therapeutic target (Chung et al., this issue).
In this issue of Blood, Pettirossi et al, including Drs Tiacci and Falini, who led the effort in 2011 defining the BRAF-V600E driving mutation in hairy cell leukemia (HCL),provide extensive laboratory studies showing that inhibitors of BRAF-V600E and/or mitogen-activated protein kinase kinase (MEK) reach their targets and cause HCL cell death
In this study we investigated the application of a BRAFV600E mutation-specific antibody (clone VE1) to differentiate HCL from HCL mimics, such as HCL variant and splenic marginal zone lymphoma.
The discovery of the BRAFV600E mutation in most cases of classical hairy cell leukemia opens up unique opportunities for tumor specific treatment of HCL targeting the MEK/ERK signaling pathway.
In order to investigate the suitability of MinION sequencing on formalin-fixed paraffin-embedded samples, the presence and frequency of BRAF c.1799T > A mutation was investigated in two archival tissue specimens of Hairy cell leukemia and Hairy cell leukemia Variant.
Using this BRAFV600E mutation specific antibody, this immunohistochemical study has 100% sensitivity and 100% specificity for the diagnosis of HCL in our cohort.
As mutant BRAF alone is insufficient to drive malignant transformation in other histological cancers, it suggests that individual tumours utilise largely differing patterns of genetic somatic mutations to coalesce with BRAF V(600)E to drive pathogenesis of malignant HCLc disease.
We investigated BRAF mutations in 36 subjects with different forms of SM, but could not detect BRAF mutation in any of the cases, not even in the mast cell lineage of a patient with V600EBRAF-positive HCL.
Furthermore, high resolution melting with confirmatory Sanger sequencing are useful methods that can be employed in routine diagnostic laboratories to detect BRAF mutations in patients with hairy cell leukemia and related lymphoproliferative disorders.
Identification of the BRAF-V600E kinase mutation as the genetic cause of HCL has opened the way, in the relapsed/refractory experimental setting, to targeted and non-myelotoxic effective strategies that are based on inhibition of BRAF with vemurafenib, co-inhibition of BRAF and its target MEK with dabrafenib and trametinib, and BRAF inhibition with vemurafenib combined with anti-CD20 immunotherapy.
The thymidine kinase inhibitor vemurafenib, which inhibits the V600E mutant of BRAF, was reported to induce a CR in multiply relapsed and refractory HCL, with nearly complete clearing of MRD.
We compared the ability of Sanger sequencing, fluorescent single-strand conformational polymorphism (F-SSCP) and high resolution melting (HRM) analysis to detect BRAF mutations in 20 cases of HCL consisting of four archival Romanowsky stained air-dried peripheral blood and bone marrow aspirate smears, 12 mercury fixed decalcified bone marrow trephine biopsies, three formalin fixed, paraffin embedded (FFPE) splenectomy samples and one fresh peripheral blood sample.