The role of new technologies in myeloproliferative neoplasms: Application of next-generation sequencing in myelofibrosis.

INTRODUCTION: Driver mutations in Philadelphia chromosome-negative myeloproliferative neoplasms are well known. In the past, whole-genome sequencing identified nondriver mutations in other genes, potentially contributing to evolution of malignant clones. METHODS: Next-generation sequencing was used to assess the presence of any mutations in 14 candidate genes at the point of diagnosis and the resultant impact on the clinical course of the disease. RESULTS: The study analysed 63 patients with myelofibrosis (MF). Nondriver mutations were detected in 44% of them. The most frequently affected genes were ASXL1 (27%), TET2 (11%) and SF3B1 (6%). The frequency of such mutations was highest in primary MF (59%) and lowest in the prefibrotic phase of primary MF (21%). Patients with prognostically unfavourable sequence variants in genes had significantly worse overall survival (53 vs 71 months; HR = 2.77; 95% CI 1.17-6.56; P = .017). CONCLUSION: In our study, multivariate analysis proved DIPSS to be the only significant factor to predict patient survival. DIPSS contains all of the important clinical and laboratory factors except genetic changes. Stratification of patients according to DIPSS is still beneficial although there are newer and improved scoring systems like GIPSS or MIPSS70. Assessing subclonal mutations in candidate genes during diagnosis may aid in the identification of high-risk MF patients and is therefore relevant for making a prediction for overall survival more accurate.

Recurrent breakpoints in 14q32.13/TCL1A region in mature B-cell neoplasms with villous lymphocytes.

The genetic background of mature B-cell neoplasms with villous lymphocytes is poorly understood. We identified a novel breakpoint region at 14q32.13 that was rearranged together with IGH/14q32.33 in four cases of BRAF/V600E-negative leukemia/lymphoma with villous lymphocytes carrying either t(14;14)(q32.13;q32.33) (three patients) or del(14)(q32.13q32.33) (one patient). The 14q32.13 breakpoints were mapped by fluorescence in situ hybridization (FISH) in the region harboring the TCL1A/TCL1B/TCL6 genes, known to be affected by TCRA/D-mediated t(14;14)(q11;q32)/inv(14)(q11q32) occurring in T-cell leukemia/lymphoma. To identify the target of t(14;14)(q32.13; q32.33) and del(14)(q32.13q32.33), quantitative real-time polymerase chain reaction (qRT-PCR) analysis of 25 candidate genes located centromerically and telomerically to the 14q32.13 breakpoint was performed. Any of the analyzed genes was commonly overexpressed in the presented cases. Of note, up-regulated transcription of TCL1A was observed in two cases. In summary, we provide evidence that IGH-mediated chromosomal aberrations affecting the 14q32.13/TCL1A-TCL6 region are recurrent in mature B-cell neoplasms with villous lymphocytes. Despite extensive qRT-PCR studies, molecular consequences of these novel aberrations remain elusive.

Identification of e6a2 BCR-ABL fusion in a Philadelphia-positive CML with marked basophilia: implications for treatment strategy.

AIM: This is a case report of a 51 year old male with marked splenomegaly, basophilia, severe thrombocytopenia, anemia and high SFKL phosphorylation downstream of Bcr-Abl, investigated for association of the e6a2 BCR-ABL fusion gene and marked basophilia. The treatment strategy implications in patients with Philadelphia positive CML are described. METHODS: RT-PCR and sequencing were carried out on the peripheral blood leukocytes to detect the type of BCR-ABL transcript. The BCR-ABL mutational status was assessed using sequencing of the RT-PCR products. The in vitro test of sensitivity to TKIs was based on detecting inhibited phosphorylation of the Crkl and Phospho-Src family kinases (SFK, Tyr416) using immunodetection. RESULTS: The cytogenetics revealed 90% of Ph+ (Philadelphia) cells in the bone marrow aspirate with no additional clonal chromosomal abnormalities at diagnosis. This correlated with an accelerated phase of the CML. Sequencing analysis of reverse transcribed and PCR amplified BCR-ABL transcript revealed a rare e6a2 fusion, with no evidence for Bcr-Abl kinase domain mutation. Western blot analysis showed high phosphorylation (activation) of Crkl and the Src family of kinases (P-SFK). In vitro test of sensitivity of the patients' leukemic cells to imatinib demonstrated sensitivity of Bcr-Abl tyrosine kinase to imatinib, as assessed by a decrease in phosphorylated Crkl and the disappearance of P-SFK, suggesting that P-Src reflects only the Bcr-Abl-dependent Src activity. The initial treatment strategy was reduced imatinib and search for an unrelated hematopoietic stem cell donor (according to the ELN recommendations). The patient was allografted with peripheral stem cells from an HLA- identical male donor but on day +70 graft failure occurred. He was allografted again with the peripheral stem cells from an HLA-identical female donor, engrafted on day +15 and showed 100% donor chimerism with no evidence of the e6a2 BCR-ABL fusion transcript on day +30. CONCLUSION: The clinical disease course in patients with the rare e6a2 BCR-ABL transcript variant is aggressive. This may be the result of increased kinase activity due to partial loss of the guanine exchange factor/dbl-like domain which mediates the interaction with several Ras-like G-proteins involved in cell proliferation, signal transduction, and cytoskeletal organization. For the above reasons, these patients should receive stem cell transplant immediately after a short course of treatment with imatinib/ dual Src/Abl kinase inhibitor or they should be registered in clinical trials with experimental agents.

Comparison of new flu-bu12-tg conditioning with the standard bu-cy myeloablative regimen in patients undergoing allogeneic stem cell transplantation for acute myeloid leukemia.

AIMS: This study compares the outcomes of patients with high-risk acute myeloid leukemia (AML) who underwent allogeneic stem cell transplantation (SCT) after conditioning combining busulfan (16 mg/kg orally) and cyclophosphamide (120 mg/kg intravenously) (BU-CY) with those allografted after administration of fludarabine (150 mg/m(2) intravenously), busulfan (12 mg/kg orally) and thymoglobulin (6 mg/kg intravenously) (FLU-BU12-TG). MATERIAL AND METHODS: SCT after BU-CY and FLU-BU12-TG was performed in 21 and 10 AML patients. There were no significant differences between groups in number of patients treated in complete disease remission, gender, age, donors, CD34+, mononuclear cell (MNC) count in the graft and follow-up period. However, significantly more SCTs from unrelated (90% vs. 19%; p=0.00018) and HLA-mismatched donors (50% vs. 0%; p=0.0004) were performed in the FLU-BU12-TG group. The Cox proportional hazards model was used to assess the risk of post-transplant AML relapse and non-relapse mortality (NRM). The probability of post-transplant 2-year event-free survival (EFS) and overall survival (OS) were calculated using the Kaplan-Meier method. RESULTS: No significant differences were found between the FLU-BU12-TG and BU-CY groups in risk of AML relapse (HR=1.036; 95% CI [0.102 - 10.47]; p=0.9), post-transplant NRM (HR=0.25; 95% CI [0.031 - 1.96]; p=0.18), 2-year EFS (89% vs. 43%; p=0.19) or OS (79% vs. 57%; p=0.23). CONCLUSION: These pilot results demonstrate the efficacy of the new FLU-BU12-TG conditioning regimen in patients allografted for high-risk AML. This conditioning might become an alternative approach in patients at high risk of severe post-transplant complications after the standard BU-CY myeloablative regimen.

Imatinib dose escalation in two patients with chronic myeloid leukemia, with low trough imatinib plasma levels measured at various intervals from the beginning of therapy and with suboptimal treatment response, leads to the achievement of higher plasma levels and major molecular response.

Despite the prognostic value of trough imatinib plasma levels (IPL) identified in some studies, no recommendations for the use of IPL results in routine management of CML patients have been issued. We report two patients in whom daily imatinib dose was increased from 400 to 600 or 800 mg because of low IPL found at various intervals from the beginning of treatment (7 measurements; mean IPL values = 616.33 and 764.5 ng/mL, respectively). Both patients achieved suboptimal response according to the European LeukemiaNet criteria (complete cytogenetic response was not achieved after 1 year of treatment in patient 1 and major molecular response after 47 months of standard-dose imatinib therapy in patient 2). In addition, we have demonstrated low hOCT-1 expression at diagnosis in both patients, retrospectively. Escalation of imatinib daily dose resulted in a significant increase of IPL (6 measurements; mean = 1790 and 1416.66 ng/mL, respectively) and in the achievement of complete cytogenetic response in patient 1 after 3 months and major molecular response within 15 and 6 months in both patients. Our cases demonstrate that low IPL identified at various non-predefined intervals from the beginning of therapy may be used for deciding on dose escalation in selected CML patients in the routine clinical setting, especially in cases with suboptimal treatment response.

Methylation analysis of the imprinted DLK1-GTL2 domain supports the random parental origin of the IGH-involving del(14q) in B-cell malignancies.

Leukemias/lymphomas with IGH-involving del(14q)(1) commonly lose the DLK1-GTL2 imprinted domain that comprises several paternally and maternally expressed genes, including a cluster of microRNAs. Given that deletion of this region could lead to inactivation of a monoallelically expressed tumor suppressor gene, our study aimed at determination of the parental origin of del(14q/IGH). The designed allele-specific methylation study of the DLK1/GTL2 intergenic differentially methylated region allowed us to determine the parental origin of del(14q/IGH) in 9/20 analyzed cases. In six cases del(14q/IGH) was of the paternal origin and in three cases of the maternal origin. These findings argue against the concept that a TSG/anti-oncomir located in the imprinted region is systematically inactivated by a targeted deletion of its functional allele.