Effect of IGHV Gene Mutation Status and BCR Structure Stereotypy on Effectiveness of BR Regimen in First-Line Therapy of Chronic Lymphocytic Leukemia

Background & Aims. The IGHV gene mutation status is a constant biological feature of tumor cells in chronic lymphocytic leukemia (CLL). This parameter is an important predictor of the efficacy of immunochemotherapy. It was included into the CLL international prognostic index CLL-IPI developed recently. The aim is to evaluate the prognostic significance of the BR regimen in patients with different variants of the B-cell receptor (BCR) structure. Methods. The study examined immediate and delayed treatment outcomes for 183 CLL patients included in a Russian, prospective, observational BEN-001 trial (NCT02110394). The median age was 61 years (range: 35–79); 53/179 (29.6 %) patients were older than 65; and 14/179 (7.8 %) patients were older than 75. Prevalence of males (110/179, 61.5 %) in the male/female ratio (1.6:1.0) was observed. Most patients had advanced disease: Binet B 116/173 (67 %) or Binet C 38/173 (22 %). The patients received the first-line therapy according to the BR regimen at standard doses in 36 hematological institutions in the Russian Federation over the period from 2012 until 2015. The genome DNA isolated from mononuclear leukocytes in the peripheral blood was used to assess the mutation status of the IGHV-genes. Results. The study demonstrated that unmutated CLL (≥ 98 % of homology to germline gene) is associated with worsening of the event-free and overall survival rates most of all; at that, the complete remission rate and the MRD-free survival rate were the same. Conclusion. It is reasonable to analyze the IGHV mutation status in all patients prescribed with the BR regimen as the first-line therapy

Role of Superficial CD200 Marker in Differential Diagnosis of Malignant B-Cell Lymphoproliferative Diseases

Background & Aims. Flow cytometry is successfully used for diagnosis of malignant lymphoproliferative disorders. However, there are atypical cases that are difficult to interpret; thus, new markers relevant for the differential diagnosis are to be searched for. The aim is to analyze CD200 expression in patients with B-cell lymphoproliferative disorders. Materials & Methods. 187 patients with chronic lymphocytic leukemia (CLL), 14 patients with mantle cell lymphoma (MCL), 9 patients with marginal zone lymphoma (MZL), and 5 patients with hairy cell leukemia (HCL) were enrolled in the study. Neoplasm was not confirmed in 12 subjects. The patients underwent the following tests: CBC, immunophenotyping of peripheral blood or bone marrow lymphocytes, and a cytogenetic test. In some cases, an additional immunohistochemical test of bone marrow trepanobiopsy or lymph node biopsy samples was required. Results. In all cases of CLL and HCL, the CD200 expression was positive; mean fluorescence intensity was higher in these cases as compared to other groups. Negative expression of CD200 prevailed in MCL patients; however, at the same time 2 cases of intermediate and positive expression were reported, both showing moderate fluorescence intensity values. CD200 expression was heterogeneous in MZL patients. Conclusion. The CD200 negative expression excludes typical HCL and CLL. Additional cytogenetic and immunnohistoсhemical tests should be performed in such cases to verify the diagnosis, first of all, MCL or MZL

Minimal Residual Disease and IGHV-Genes Mutational Status as the Main Predictors of Response to Bendamustine-Rituximab Therapy in Previously Untreated Chronic Lymphocytic Leukemia

Background. In patients with chronic lymphocytic leukemia (CLL) the eradication of minimal residual disease (MRD) is a prognostic factor of overall survival (OS) and progression-free survival (PFS). IGHV mutational status has also independent prognostic value. Aim. To analyse the impact of mutational status and MRD eradication in CLL patients after first-line standard BR (bendamustine + rituximab) immunochemotherapy. Materials & Methods. The prospective study included patients with immunophenotypically confirmed CLL who had not previously received anticancer therapy. All patients were treated by BR combination from 2012 to 2015. MRD level was determined in 109 patients after completing the 3rd and the 6th treatment courses. IGHV mutational status data were available for 98 patients. IGHV mutational status was evaluated in accordance with ERIC recommendations. MRD was assessed by standardized method of 4-color flow cytometry. Results. MRD negativity was achieved in 37 (34 %) out of 109 patients. MRD eradication correlated with the best PFS (p = 0.04). IGHV mutational status had a statistically significant impact on PFS (p = 0.02). In patients with MRD-negative response and IGHV mutation no unfavorable events occurred during the period of monitoring. Conversely, PFS rates in MRD-negative patients having no IGHV mutation and in MRD-positive patients with mutation were significantly worse. MRD eradication resulted in statistically significant improvement of PFS rates after completing 3 treatment courses, compared with the cases with MRD persistence regardless of residual malignant clone level (p = 0.01). Conclusion. BR therapy as first-line treatment statistically improved PFS in patients who achieved MRD-negative remission after completing the 3rd treatment course. PFS was significantly higher in MRD-negative patients with IGHV mutation after 6 treatment courses. MRD negativity resulting from 6 BR therapies in patients having no IGHV mutation was not accompanied by PFS improvement. It follows that by itself MRD negativity cannot be considered to be a universal prognostic factor

Mechanical Strength of 17 134 Model Proteins and Cysteine Slipknots

A new theoretical survey of proteins' resistance to constant speed stretching is performed for a set of 17 134 proteins as described by a structure-based model. The proteins selected have no gaps in their structure determination and consist of no more than 250 amino acids. Our previous studies have dealt with 7510 proteins of no more than 150 amino acids. The proteins are ranked according to the strength of the resistance. Most of the predicted top-strength proteins have not yet been studied experimentally. Architectures and folds which are likely to yield large forces are identified. New types of potent force clamps are discovered. They involve disulphide bridges and, in particular, cysteine slipknots. An effective energy parameter of the model is estimated by comparing the theoretical data on characteristic forces to the corresponding experimental values combined with an extrapolation of the theoretical data to the experimental pulling speeds. These studies provide guidance for future experiments on single molecule manipulation and should lead to selection of proteins for applications. A new class of proteins, involving cystein slipknots, is identified as one that is expected to lead to the strongest force clamps known. This class is characterized through molecular dynamics simulations.Comment: 40 pages, 13 PostScript figure

Old wine in new bottles: reaction norms in salmonid fishes

Genetic variability in reaction norms reflects differences in the ability of individuals, populations and ultimately species to respond to environmental change. By increasing our understanding of how genotype × environment interactions influence evolution, studies of genetic variation in phenotypic plasticity serve to refine our capacity to predict how populations will respond to natural and anthropogenic environmental variability, including climate change. Given the extraordinary variability in morphology, behaviour and life history in salmonids, one might anticipate the research milieu on reaction norms in these fishes to be empirically rich and intellectually engaging. Here, I undertake a review of genetic variability in continuous and discontinuous (threshold) norms of reaction in salmonid fishes, as determined primarily (but not exclusively) by common-garden experiments. Although in its infancy from a numerical publication perspective, there is taxonomically broad evidence of genetic differentiation in continuous, threshold and bivariate reaction norms among individuals, families and populations (including inter-population hybrids and backcrosses) for traits as divergent as embryonic development, age and size at maturity, and gene expression. There is compelling inferential evidence that plasticity is heritable and that population differences in reaction norms can reflect adaptive responses, by natural selection, to local environments. As a stimulus for future work, a series of 20 research questions are identified that focus on reaction-norm variability, selection, costs and constraints, demographic and conservation consequences, and genetic markers and correlates of phenotypic plasticity