Recipient and donor JAK2 46/1 haplotypes are associated with acute graft-versus-host disease following allogeneic hematopoietic stem cell transplantation.

Several genetic polymorphisms have been implicated to affect the outcome of allogeneic hematopoietic stem cell transplantation (allo-HSCT). The role of cytokines in acute graft-versus-host disease (aGvHD) is well established and many of the involved cytokines signal through the Janus kinase (JAK) pathways. In this study, we assessed the association of recipient and donor JAK2 46/1 haplotypes and allo-HSCT outcome in a cohort of 124 acute myeloid leukemia patients. Both, recipient and donor 46/1 haplotypes significantly affected aGvHD grades II-IV development (p = 0.006 and p = 0.031, respectively), furthermore the influence of the haplotypes seemed to be additive. In multivariate analyses the recipient haplotype remained independently related (p = 0.012) to aGvHD, while the donor not (p = 0.08). We observed significantly less relapses among haplotype carriers (p = 0.004), but overall survival did not differ (p = 0.732). Our findings suggest that recipient and donor JAK2 46/1 haplotypes might be involved in the regulation of aGvHD.

Co-occurrence of Myeloproliferative Neoplasms and Solid Tumors Is Attributed to a Synergism Between Cytoreductive Therapy and the Common TERT Polymorphism rs2736100.

BACKGROUND: The germline telomerase reverse transcriptase (TERT) rs2736100_C variant was identified as a susceptibility factor for a variety of solid tumors and recently for myeloproliferative neoplasms (MPN). METHODS: LightCycler melting curve analysis was applied to detect risk alleles of TERT rs2736100_C and Janus kinase 2 (JAK2) rs12343867_C tagging 46/1 haplotype in 584 BCR-ABL1-negative MPN, 308 acute, and 86 chronic myeloid leukemia (AML and CML) patients and 400 healthy individuals. RESULTS: TERT rs2736100_C showed an increased allele frequency in BCR-ABL1-negative MPN patients compared with controls (62.7%±2.8% vs. 48.8%±3.5%, P < 0.0001) regardless of molecular background or disease type, but not in CML or AML. Combined TERT and JAK2 hetero- or homozygosity conferred even higher risk for classic MPN. Common complications (thrombosis, myelofibrosis, or leukemia) were not associated with the TERT variant; however, adverse survival was noted in TERT variant carrier polycythemia vera patients. MPN patients with the TERT CC genotype had a higher probability (44.4%) to die from solid tumors compared with TERT AC/AA individuals (5.3%; P = 0.004). TERT rs2736100_C carriers had increased risk of solid tumors independently from cytoreductive treatment [3.08 (1.03-9.26), P = 0.045]. CONCLUSIONS: TERT rs2736100_C polymorphism predisposes to the development of BCR-ABL1-negative MPN with the co-occurrence of solid tumors, especially with the usage of cytoreductive treatment. IMPACT: The high frequency of TERT variant in the classic MPN population highlights the importance of the avoidance of long-term cytoreductive treatment in MPN patients.

[Complex molecular genetic algorithm in the diagnosis of myeloproliferative neoplasms]. / Komplex molekuláris genetikai vizsgálati algoritmus myeloproliferativ neoplasiák diagnosztikájában.

INTRODUCTION: Mutations in Janus kinase 2, calreticulin and thrombopoietin receptor genes have been identified in the genetic background of Philadelphia chromosome negative, "classic" myeloproliferative neoplasms. AIM: The aim of the authors was to identify driver mutations in a large myeloproliferative cohort of 949 patients. METHOD: A complex array of molecular techniques (qualitative and quantitative allele-specific polymerase chain reactions, fragment analyzes, high resolution melting and Sanger sequencing) was applied. RESULTS: All 354 patients with polycythemia vera carried Janus kinase 2 mutations (V617F 98.6%, exon 12: 1.4%). In essential thrombocythemia (n = 468), the frequency of V617F was 61.3% (n = 287), that of calreticulin 25.2% (n = 118), and that of thrombopoietin receptor mutations 2.1% (n = 10), while 11.3% (n = 53) were triple-negative. Similar distribution was observed in primary myelofibrosis (n = 127): 58.3% (n = 74) V617F, 23.6% (n = 30) calreticulin, 6.3% (n = 8) thrombopoietin receptor mutation positive and 11.8% (n = 15) triple-negative. CONCLUSIONS: The recent discovery of calreticulin gene mutations led to definite molecular diagnostics in around 90% of clonal myeloproliferative cases.

Distinct clinical characteristics of myeloproliferative neoplasms with calreticulin mutations.

Somatic insertions/deletions in the calreticulin gene have recently been discovered to be causative alterations in myeloproliferative neoplasms. A combination of qualitative and quantitative allele-specific polymerase chain reaction, fragment-sizing, high resolution melting and Sanger-sequencing was applied for the detection of three driver mutations (in Janus kinase 2, calreticulin and myeloproliferative leukemia virus oncogene genes) in 289 cases of essential thrombocythemia and 99 cases of primary myelofibrosis. In essential thrombocythemia, 154 (53%) Janus kinase 2 V617F, 96 (33%) calreticulin, 9 (3%) myeloproliferative leukemia virus oncogene gene mutation-positive and 30 triple-negative (11%) cases were identified, while in primary myelofibrosis 56 (57%) Janus kinase 2 V617F, 25 (25%) calreticulin, 7 (7%) myeloproliferative leukemia virus oncogene gene mutation-positive and 11 (11%) triple-negative cases were identified. Patients positive for the calreticulin mutation were younger and had higher platelet counts compared to Janus kinase 2 mutation-positive counterparts. Calreticulin mutation-positive patients with essential thrombocythemia showed a lower risk of developing venous thrombosis, but no difference in overall survival. Calreticulin mutation-positive patients with primary myelofibrosis had a better overall survival compared to that of the Janus kinase 2 mutation-positive (P=0.04) or triple-negative cases (P=0.01). Type 2 calreticulin mutation occurred more frequently in essential thrombocythemia than in primary myelofibrosis (P=0.049). In essential thrombocythemia, the calreticulin mutational load was higher than the Janus kinase 2 mutational load (P<0.001), and increased gradually in advanced stages. Calreticulin mutational load influenced blood counts even at the time point of diagnosis in essential thrombocythemia. We confirm that calreticulin mutation is associated with distinct clinical characteristics and explored relationships between mutation type, load and clinical outcome.

Medium-sized FLT3 internal tandem duplications confer worse prognosis than short and long duplications in a non-elderly acute myeloid leukemia cohort.

Internal tandem duplications (ITDs) of the fms-like tyrosine kinase 3 (FLT3) gene occur in about 25% of patients with adult acute myeloid leukemia (AML). The aim of our study was to investigate the frequency of FLT3-ITD mutations followed by a detailed analysis of the mutational load and size of ITD insertions in a cohort consisting of 324 patients younger than 60 years old and treated with curative intention. FLT3-ITD alone did not influence overall survival (OS) or disease-free survival (DFS). We observed worse OS and DFS for patients with high mutational load indicative for loss of the FLT3 wild type allele (p = 0.010, p = 0.038, respectively). In multivariate analyses, patients with FLT3-ITD(48-60bp) showed worse OS and DFS compared to other groups (FLT3-ITD(neg), FLT3-ITD (< 48b), FLT3-ITD (> 60bp); p = 0.014, p = 0.019, respectively). Our novel observation suggested that not only high FLT3-ITD load, but also medium-sized ITD insertions (48-60 bp) represented an adverse prognostic subgroup of patients with AML.