Bortezomib in the treatment of refractory thrombotic thrombocytopenic purpura.

Acquired thrombotic thrombocytopenic purpura (TTP) is a rare, life-threatening condition caused by autoantibody-mediated inhibition of ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type-1 motif, 13). Therapeutic plasma exchange (TPE) improves survival, but disease may be refractory despite therapy. Management and treatment response of refractory TTP is variable, with rituximab and other immunosuppression often being used. Case reports have suggested a benefit of the proteasome inhibitor, bortezomib, possibly due to elimination of the autoreactive plasma cells producing anti-ADAMTS13 antibodies. We evaluated the effect of bortezomib in a series of primary refractory TTP patients unresponsive to intensive therapy. Bortezomib-treated patients were identified from consecutive cases managed at two UK referral centres. Demographic and clinical data were extracted from hospital records. ADAMTS13 activity was measured using a fluorescence resonance energy transfer VWF73 assay, and anti-ADAMTS13 IgG using enzyme-linked immunosorbent asssay. We identified six bortezomib-treated patients out of 51 consecutive cases of acute, acquired TTP. All patients received TPE, methylprednisolone and rituximab. Five of the six achieved complete remission with bortezomib, and one died of cardiac arrest due to underlying disease. No treatment-related adverse events were observed. Mean follow-up time after hospital discharge was 17 months (range: 3-33). Bortezomib appears effective in the treatment of a subgroup of cases with severe, refractory TTP. Prospective trials are required to further investigate this effect.

The molecular pathogenesis of B-cell non-Hodgkin lymphoma.

The B-cell non-Hodgkin lymphomas (B-NHL) are a diverse group of haematological malignancies which arise from the mature B-lymphocyte compartment. Recently, our understanding of the molecular pathogenesis of these disorders has greatly increased due to technological advances such as high-throughput DNA sequencing techniques. A paradigm of B-NHL pathogenesis has emerged where the normal genetic processes that are central to generating B-cell receptor diversity (somatic hypermutation and class switch/VDJ recombination) also drive the genesis of large-scale, chromosomal-level genetic lesions and smaller-scale gene-level mutations to produce the malignant phenotypes observed. Whilst a significant degree of genetic heterogeneity exists within each B-NHL subtype, the genetic lesions present within each subtype show a degree of convergence on common intracellular signalling, epigenetic and cell cycle pathways. This convergence gives an insight into the key oncogenic drivers of specific B-NHL subtypes and potential targets for therapeutic intervention. This review covers the current understanding of the causative genetic processes of B-NHL, the associated driving molecular lesions and the implications of these findings for the treatment of this group of disorders.

Detection of BRAF mutations in patients with hairy cell leukemia and related lymphoproliferative disorders.

Hairy cell leukemia has been shown to be strongly associated with the BRAF V600E mutation. We screened 59 unenriched archived bone marrow aspirate and peripheral blood samples from 51 patients with hairy cell leukemia using high resolution melting analysis and confirmatory Sanger sequencing. The BRAF V600E mutation was detected in 38 samples (from 36 patients). The BRAF V600E mutation was detected in all samples with disease involvement above the limit of sensitivity of the techniques used. Thirty-three of 34 samples from other hematologic malignancies were negative for BRAF mutations. A BRAF K601E mutation was detected in a patient with splenic marginal zone lymphoma. Our data support the recent finding of a disease defining point mutation in hairy cell leukemia. 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.

Molecular lesions in B-cell lymphoproliferative disorders: recent contributions from studies utilizing high-throughput sequencing techniques.

Next-generation sequencing techniques are powerful high-throughput methods that have enabled the comprehensive documentation of genetic lesions in numerous hematological malignancies. In recent times, the genomes of multiple different B-cell lymphoproliferative disorders including chronic lymphocytic leukemia, diffuse large B-cell lymphoma, Burkitt lymphoma, splenic marginal zone lymphoma, mantle cell lymphoma, hairy cell leukemia and Waldenström macroglobulinemia have been documented. Between them, these studies have reinforced and provided insight into the mechanisms for the dysregulation of known pathways (e.g. nuclear factor-κB [NF-κB]), uncovered the importance of new pathways for oncogenesis (e.g. mRNA processing), identified disease-defining mutations and provided meaningful new targets which are already being translated into therapeutic interventions. This review summarizes the molecular lesions that have been discovered in B-cell lymphoproliferative disorders thus far by studies utilizing high-throughput sequencing techniques and the aberrations in the numerous intracellular pathways that have been shown to be involved.