The complex karyotype in hematological malignancies: a comprehensive overview by the Francophone Group of Hematological Cytogenetics (GFCH).

Karyotype complexity has major prognostic value in many malignancies. There is no consensus on the definition of a complex karyotype, and the prognostic impact of karyotype complexity differs from one disease to another. Due to the importance of the complex karyotype in the prognosis and treatment of several hematological diseases, the Francophone Group of Hematological Cytogenetics (Groupe Francophone de Cytogénétique Hématologique, GFCH) has developed an up-to-date, practical document for helping cytogeneticists to assess complex karyotypes in these hematological disorders. The evaluation of karyotype complexity is challenging, and it would be useful to have a consensus method for counting the number of chromosomal abnormalities (CAs). Although it is not possible to establish a single prognostic threshold for the number of CAs in all malignancies, a specific consensus prognostic cut-off must be defined for each individual disease. In order to standardize current cytogenetic practices and apply a single denomination, we suggest defining a low complex karyotype as having 3 CAs, an intermediate complex karyotype as having 4 CAs, and a highly complex karyotype as having 5 or more CAs.

Is Acute Myeloblastic Leukemia in Children Under 2 Years of Age a Specific Entity? A Report from the FRENCH ELAM02 Study Group.

The clinical and biological characteristics of children under 2 years (infants) with acute myeloid leukemia (AML) are different from those of older children. We aimed to describe the specific characteristics of this population and the potential factors that influence the prognosis. We analyzed data concerning 438 children with newly-diagnosed AML treated in the ELAM02 protocol between March 2005 and December 2011, of which 103 were under 2 years old at diagnosis. The evaluation criteria were overall survival (OS) and event-free survival (EFS) of infants vs older children. The clinical and biological features were secondary criteria. Infants presented more frequent extra-medullary presentation than older children. They had a significantly higher proportion of skin lesions and central nervous system involvement (15% vs 3%, p < 0.0001 and 26% vs 12%, p = 0.0005, respectively). The global incidence of KMT2A rearrangements was nearly 55% for infants vs 11% for older children (p < 0.0001). Median 5-year OS was 70.4% for infants vs 71.4% for older children (p = 0.83). Five-year EFS was 67% for infants vs 58% for older children (p = 0.27). Infants with AML represent a cohort of patients with specific clinical and biological features. These remarkable differences had no significant impact on their outcome in the ELAM02 protocol.

NUP98 is rearranged in 3.8% of pediatric AML forming a clinical and molecular homogenous group with a poor prognosis.

Pediatric acute myeloid leukemia (AML) is a rare disease whose prognosis is highly variable according to factors such as chromosomal abnormalities. Recurrent genomic rearrangements are detected in half of pediatric AML by karyotype. NUcleoPorin 98 (NUP98) gene is rearranged with 31 different fusion partner genes. These rearrangements are frequently undetected by conventional cytogenetics, as the NUP98 gene is located at the end of the chromosome 11 short arm (11p15). By screening a series of 574 pediatric AML, we detected a NUP98 rearrangement in 22 cases (3.8%), a frequency similar to CBFB-MYH11 fusion gene (4.0%). The most frequent NUP98 fusion gene partner is NSD1. These cases are homogeneous regarding their biological and clinical characteristics, and associated with bad prognosis only improved by bone marrow transplantation. We detailed the biological characteristics of these AML by exome sequencing which demonstrated few recurrent mutations (FLT3 ITD, WT1, CEBPA, NBPF14, BCR and ODF1). The analysis of the clonal structure in these cases suggests that the mutation order in the NUP98-rearranged pediatric AML begins with the NUP98 rearrangement leading to epigenetic dysregulations then followed by mutations of critical hematopoietic transcription factors and finally, activation of the FLT3 signaling pathway.

Cytogenetics and outcome of allogeneic transplantation in first remission of acute myeloid leukemia: the French pediatric experience.

We analyzed the impact of cytogenetics on 193 children enrolled in two successive French trials (LAME89/91 and ELAM02), who received hematopoietic stem cell transplantation during CR1. Detailed karyotype was available for 66/74 (89%) in LAME89/91 and 118/119 (99%) in ELAM02. Several karyotype and transplant characteristics differed according to therapeutic protocol: unfavorable karyotypes were more frequent in ELAM02 (36% vs 18%), pretransplant chemotherapy included high-dose cytarabine in ELAM02 and not in LAME89/91, IV replaced oral busulfan in the conditioning regimen, methotrexate was removed from post-transplant immunosuppression, and matched unrelated donor and cord blood transplantation were introduced. Five-year overall survival (OS) was 78.2% in LAME89 and 81.4% in ELAM02. OS was significantly lower for the unfavorable cytogenetic risk group in LAME89/91 when compared with intermediate and favorable groups (50% vs 90.6 and 86.4%, P=0.001). This difference was no longer apparent in ELAM02 (80.9% vs 71.3% and 5/5, respectively). Survival improvement for children with unfavorable karyotype was statistically significant (P=0.026) and was due to decrease in relapse risk. Five-year transplantation-related mortality was 6.75% in LAME89/91. In ELAM02, it was 3.2% for patients with a sibling donor and 10.9% with an unrelated donor or cord blood. We conclude that the outcome of children with unfavorable karyotype transplanted in CR1 has improved.

Tissue factor up-regulation in proinflammatory conditions confers thrombin generation capacity to endothelial colony-forming cells without influencing non-coagulant properties in vitro.

BACKGROUND: Endothelial progenitor cells (EPC) are good candidates for cell-based therapy in cardiovascular diseases. However, concerns have been raised about the potential risks of EPC-based cell therapy, in terms of thrombogenicity particularly in inflammatory conditions, currently observed in such patients. Tissue factor (TF) can trigger coagulation and may support thrombogenicity. TF is also a key receptor in angiogenesis. OBJECTIVE: The present study was designed to (i) evaluate the capacity of resting and tumour necrosis factor-alpha (TNF)-α-stimulated late-outgrowth endothelial colony-forming cells (ECFCs) to express TF and (ii) investigate the effect of TF/FVII(a) interaction on procoagulant and non-procoagulant activities of ECFCs in vitro. METHODS: ECFCs from cord blood (cb) and adult peripheral blood (ab) were analyzed for TF expression and activity using reverse transcription-polymerase chain reaction (RT-PCR), flow cytometry, Western blot and a thrombin generation assay. Non-procoagulant properties of TF-expressing ECFCs were investigated in vitro using wound-healing, cell proliferation, tube formation and spheroid-based assays. RESULTS: ECFCs expressed TF in response to TNF-α. The up-regulation of TF conferred to ECFCs a FVII(a)-dependent thrombin generation activity. Compared with cb-ECFC, ab-ECFCs can display a higher level of constitutive TF expression and activity, with a notable heterogeneity among donors. TF/FVIIa interaction did not modify non-procoagulant properties of TNF-α stimulated cb-ECFCs in vitro. CONCLUSIONS: Proinflammatory conditions up-regulate TF expression in ECFCs. This expression confers to ECFCs a strong thrombin generation capacity without influencing their non-coagulant properties. Our results suggest that EPC-based cell therapy may be associated with prothrombotic risk which could be limited by inhibiting TF without affecting the proangiogenic capacity of the cells.

Cyclin D2 dysregulation by chromosomal translocations to TCR loci in T-cell acute lymphoblastic leukemias.

Strong expression of at least one of the three D-type cyclins is common in human cancers. While the cyclin D1 and D3 genes (CCND1 and CCND3) are recurrently involved in genomic rearrangements, especially in B-cell lymphoid neoplasias, no clear involvement of the cyclin D2 gene (CCND2) has been reported to date. Here, we identified chromosomal translocations targeting the CCND2 locus at 12p13, and the T-cell receptor beta (TCRB) or the TCRA/D loci in T-cell acute lymphoblastic leukemias (T-ALLs). Expression analysis demonstrated dramatic cyclin D2 overexpression in the translocated cases (n=3) compared to other T-ALLs (total, n=89). In order to evaluate dysregulation in T-ALL with respect to normal T-cell differentiation, we analyzed CCND2 expression in normal purified human thymic subpopulations. CCND2 levels were downregulated through progression from the early stages of human T-cell differentiation, further suggesting that the massive and sustained expression in the CCND2-rearranged T-ALL cases was oncogenic. Association with other oncogene expression (TAL1, HOXAs, or TLX3/HOX11L2), NOTCH1 activating mutations, and/or CDKN2A/p16/ARF deletion, showed that cyclin D2 dysregulation could contribute to multi-event oncogenesis in various T-ALL groups. This report is the first clear evidence of a direct involvement of cyclin D2 in human cancer due to recurrent somatic genetic alterations.