MYB rearrangements and over-expression in T-cell acute lymphoblastic leukemia.

We investigated MYB rearrangements (MYB-R) and the levels of MYB expression, in 331 pediatric and adult patients with T-cell acute lymphoblastic leukemia (T-ALL). MYB-R were detected in 17 cases and consisted of MYB tandem duplication (tdup) (= 14) or T cell receptor beta locus (TRB)-MYB (= 3). As previously reported, TRB-MYB was found only in children (1.6%) while MYB tdup occurred in both age groups, although it was slightly more frequent in children (5.2% vs 2.8%). Shared features of MYB-R T-ALL were a non-early T-cell precursor (ETP) phenotype, a high incidence of NOTCH1/FBXW7 mutations (81%) and CDKN2AB deletions (70.5%). Moreover, they mainly belonged to HOXA (=8), NKX2-1/2-2/TLX1 (=4), and TLX3 (=3) homeobox-related subgroups. Overall, MYB-R cases had significantly higher levels of MYB expression than MYB wild type (MYB-wt) cases, although high levels of MYB were detected in ~ 30% of MYB-wt T-ALL. Consistent with the transcriptional regulatory networks, cases with high MYB expression were significantly enriched within the TAL/LMO subgroup (P = .017). Interestingly, analysis of paired diagnosis/remission samples demonstrated that a high MYB expression was restricted to the leukemic clone. Our study has indicated that different mechanisms underlie MYB deregulation in 30%-40% of T-ALL and highlighted that, MYB has potential as predictive/prognostic marker and/or target for tailored therapy.

Molecular Cytogenetics Detect an Unbalanced t(2;13)(q36;q14) and PAX3-FOXO1 Fusion in Rhabdomyosarcoma With Mixed Embryonal/Alveolar Features.

Distinguishing between alveolar rhabdomyosarcoma (ARMS) and embryonal rhabdomyosarcoma (ERMS) is crucial because treatment and prognosis are different. We describe a case of paratesticular rhabdomyosarcoma (RMS), which was classified as mixed ERMS/ARMS. Fluorescence in situ hybridization (FISH) detected losses of 3'PAX3 and 5'FOXO1, suggesting they had undergone an unbalanced rearrangement that probably produced the PAX3-FOXO1 fusion. Double-color FISH and reverse transcription-polymerase chain reaction (RT-PCR) revealed PAX3-FOXO1, which is characteristic of high-risk RMS. This finding highlights the importance of supplementing histology with genetics so that atypical RMS is appropriately classified and patients are correctly stratified and treated.

Optimizing the risk stratification of astrocytic tumors by applying the cIMPACT-NOW Update 3 signature: real-word single center experience.

Our work reports implementation of a useful genetic diagnosis for the clinical managment of patients with astrocytic tumors. We investigated 313 prospectively recruited diffuse astrocytic tumours by applying the cIMPACT-NOW Update 3 signature. The cIMPACT-NOW Update 3 (cIMPACT-NOW 3) markers, i.e., alterations of TERT promoter, EGFR, and/or chromosome 7 and 10, characterized 96.4% of IDHwt cases. Interestingly, it was also found in 48,5% of IDHmut cases. According to the genomic profile, four genetic subgroups could be distinguished: (1) IDwt/cIMPACT-NOW 3 (n = 270); (2) IDHwt/cIMPACT-NOW 3 negative (= 10); (3) IDHmut/cIMPACT-NOW 3 (n = 16); and 4) IDHmut/cIMPACT-NOW 3 negative (n = 17). Multivariate analysis confirmed that IDH1/2 mutations confer a favorable prognosis (IDHwt, HR 2.91 95% CI 1.39-6.06), and validated the prognostic value of the cIMPACT-NOW 3 signature (cIMPACT-NOW 3, HR 2.15 95% CI 1.15-4.03). To accurately identify relevant prognostic categories, overcoming the limitations of histopathology and immunohistochemistry, molecular-cytogenetic analyses must be fully integrated into the diagnostic work-up of astrocytic tumors.

T-Cell Acute Lymphoblastic Leukemia: Biomarkers and Their Clinical Usefulness.

T-cell acute lymphoblastic leukemias (T-ALL) are immature lymphoid tumors localizing in the bone marrow, mediastinum, central nervous system, and lymphoid organs. They account for 10-15% of pediatric and about 25% of adult acute lymphoblastic leukemia (ALL) cases. It is a widely heterogeneous disease that is caused by the co-occurrence of multiple genetic abnormalities, which are acquired over time, and once accumulated, lead to full-blown leukemia. Recurrently affected genes deregulate pivotal cell processes, such as cycling (CDKN1B, RB1, TP53), signaling transduction (RAS pathway, IL7R/JAK/STAT, PI3K/AKT), epigenetics (PRC2 members, PHF6), and protein translation (RPL10, CNOT3). A remarkable role is played by NOTCH1 and CDKN2A, as they are altered in more than half of the cases. The activation of the NOTCH1 signaling affects thymocyte specification and development, while CDKN2A haploinsufficiency/inactivation, promotes cell cycle progression. Among recurrently involved oncogenes, a major role is exerted by T-cell-specific transcription factors, whose deregulated expression interferes with normal thymocyte development and causes a stage-specific differentiation arrest. Hence, TAL and/or LMO deregulation is typical of T-ALL with a mature phenotype (sCD3 positive) that of TLX1, NKX2-1, or TLX3, of cortical T-ALL (CD1a positive); HOXA and MEF2C are instead over-expressed in subsets of Early T-cell Precursor (ETP; immature phenotype) and early T-ALL. Among immature T-ALL, genomic alterations, that cause BCL11B transcriptional deregulation, identify a specific genetic subgroup. Although comprehensive cytogenetic and molecular studies have shed light on the genetic background of T-ALL, biomarkers are not currently adopted in the diagnostic workup of T-ALL, and only a limited number of studies have assessed their clinical implications. In this review, we will focus on recurrent T-ALL abnormalities that define specific leukemogenic pathways and on oncogenes/oncosuppressors that can serve as diagnostic biomarkers. Moreover, we will discuss how the complex genomic profile of T-ALL can be used to address and test innovative/targeted therapeutic options.

New somatic TERT promoter variants enhance the Telomerase activity in Glioblastoma.

The catalytic activity of human Telomerase Reverse Transcriptase (TERT) compensates for the loss of telomere length, eroded during each cell cycle, to ensure a correct division of stem and germinal cells. In human tumors, ectopic TERT reactivation, most frequently due to hotspot mutations in the promoter region (TERTp), i.e. c.1-124 C > T, c.1-146 C > T, confers a proliferative advantage to neoplastic cells. In gliomas, TERTp mutations (TERTpmut) mainly occur in oligodendroglioma and glioblastoma. We screened, for TERTp hotspot mutations, 301 adult patients with gliomas and identified heterozygous mutations in 239 cases: 94% of oligodendroglioma, 85% of glioblastoma, and 37.5% of diffuse/anaplastic astrocytoma. Besides the recurrent c.1-124 C > T and c.1-146 C > T, two cases of glioblastoma harbored novel somatic TERTp variants, which consisted of a tandem duplications of 22 nucleotides, i.e. a TERTp c.1-100_1-79dup and TERTp c.1-110_1-89, both located downstream c.1-124 C > T and c.1-146 C > T. In silico analysis predicted the formation of 119 and 108 new transcription factor's recognition sites for TERTp c.1-100_1-79dup and TERTp c.1-110_1-89, respectively. TERTp duplications (TERTpdup) mainly affected the binding capacity of two transcription factors' families, i.e. the members of the E-twenty-six and the Specificity Protein/Krüppel-Like Factor groups. In fact, these new TERTpdup significantly enhanced the E-twenty-six transcription factors' binding capacity, which is also typically increased by the two c.1-124 C > T/c.1-146 C > T hotspot TERTpmut. On the other hand, they were distinguished by enhanced affinity for the Krüppel proteins. The luciferase assay confirmed that TERTpdup behaved as gain-of-function mutations causing a 2,3-2,5 fold increase of TERT transcription. The present study provides new insights into TERTp mutational spectrum occurring in central nervous system tumors, with the identification of new recurrent somatic gain-of-function mutations, occurring in 0.8% of glioblastoma IDH-wildtype.

Design of a Comprehensive Fluorescence in Situ Hybridization Assay for Genetic Classification of T-Cell Acute Lymphoblastic Leukemia.

T-cell acute lymphoblastic leukemia (T-ALL) results from deregulation of a number of genes via multiple genomic mechanisms. We designed a comprehensive fluorescence in situ hybridization (CI-FISH) assay that consists of genomic probes to simultaneously investigate oncogenes and oncosuppressors recurrently involved in chromosome rearrangements in T-ALL, which was applied to 338 T-ALL cases. CI-FISH provided genetic classification into one of the well-defined genetic subgroups (ie, TAL/LMO, HOXA, TLX3, TLX1, NKX2-1/2-2, or MEF2C) in 80% of cases. Two patients with translocations of the LMO3 transcription factor were identified, suggesting that LMO3 activation may serve as an alternative to LMO1/LMO2 activation in the pathogenesis of this disease. Moreover, intrachromosomal rearrangements that involved the 10q24 locus were found as a new mechanism of TLX1 activation. An unequal distribution of cooperating genetic defects was found among the six genetic subgroups. Interestingly, deletions that targeted TCF7 or TP53 were exclusively found in HOXA T-ALL, LEF1 defects were prevalent in NKX2-1 rearranged patients, CASP8AP2 and PTEN alterations were significantly enriched in TAL/LMO leukemias, and PTPN2 and NUP214-ABL1 abnormalities occurred in TLX1/TLX3. This work convincingly shows that CI-FISH is a powerful tool to define genetic heterogeneity of T-ALL, which may be applied as a rapid and accurate diagnostic test.

Cytogenetic/mutation profile of chronic lymphocytic leukemia/malignant melanoma collision tumors of the skin.

BACKGROUND: Collision tumors are rare entities that consist of two histologically distinct tumor types arising in the same anatomic site. An association between chronic lymphocytic leukemia (CLL) and malignant melanoma (MM) has been already described. Up to now, they have been documented only at positive regional lymph nodes while we focused on collision tumor in a skin lesion. CASE PRESENTATION: We characterized the genomic profile of a skin CLL/MM collision tumor in a patient with a 9-years story of CLL. Typical high-grade genomic biomarkers featured the CLL: the immunoglobulin heavy variable genes were unmutated; a clonal del(11q), involving ATM and BIRC3, was present in the peripheral blood (PB) and skin lesion, while a subclonal large del(13q)/D13S319-RB1 was detected only in the PB. Interestingly, the del(13q) clone, increased from 10% to 46% from diagnosis to relapse. NOTCH1, SF3B1, and TP53 were wild type. The MM lesion carried a BRAFV600E and a TERT promoter mutation.As the family story was consistent with a genetic predisposition to cancer, we performed mutational analysis of genes involved in familial melanoma and CLL, and of BRCA1 and BRCA2. No germinal mutation known to predispose to CLL, MM, or breast cancer was found. Interestingly, conventional cytogenetic detected a constitutional t(12;17)(p13;p13). CONCLUSIONS: Our data are consistent with distinct genetic landscape of the two tumors which were characterized by specific disease-related abnormalities. CLL cells carried poor prognostic imbalances, i.e. large deletions of the long arm of chromosomes 11 and 13, while in MM cells two functionally linked mutations, i.e. BRAFV600E and a TERT promoter occurred. Although, known germline variations predisposing to MM and/or CLL were ruled out, genetic counseling suggested the proband family was at high risk for MM.

MYB deregulation from a EWSR1-MYB fusion at leukemic evolution of a JAK2 (V617F) positive primary myelofibrosis.

BACKGROUND: Although Philadelphia-negative myeloproliferative neoplasms (Ph-MPN) are usually not aggressive, the type and the number of molecular lesions impact greatly on leukemic transformation. Indeed, the molecular background underlying progression is still largely unexplored even though ASXL1, IDH1/2, SRSF2, and TP53 mutations, together with adverse karyotypic changes, place the patient at high risk of leukemic transformation. CASE PRESENTATION: Our patient, a 64-year old man with a diagnosis of JAK2 (V617F) primary myelofibrosis (PMF) had an unusually rapid leukemic transformation. Genomic profiling showed that TET2 and SRSF2 mutations were also present. At leukemic transformation, the patient developed a complex chromosome rearrangement producing a EWSR1-MYB fusion. Remarkably, the expression of MYB and of its target BCL2 was, respectively, ≥4.7 and ≥2.8 fold higher at leukemic transformation than after chemotherapy, when the patient obtained the hematological remission. At this time point, the EWSR1-MYB fusion disappeared while JAK2 (V617F), TET2, and SRSF2 mutations, as well as PMF morphological features persisted. CONCLUSIONS: Rapid leukemic transformation of JAK2 (V617F) PMF was closely linked to a previously undescribed putative EWSR1-MYB transcription factor which was detected only at disease evolution. We hypothesize that the EWSR1-MYB contributed to leukemia transformation through at least two mechanisms: 1) it sustained MYB expression, and consequently deregulated its target BCL2, a putative onco-suppressor gene; and 2) ectopic EWSR1-MYB expression probably fulfilled its own oncogenic potential as demonstrated for other MYB-fusions. As our study confirmed that MYB is recurrently involved in chronic as well as leukemic transformation of PMF, it appears to be a valid molecular marker for tailored treatments.

Metachronous cardiac and cerebral sarcomas: case report with focus on molecular findings and review of the literature.

Although multiple primary malignancies are relatively rare, they have increased in frequency over the last decades, partly because of advances in diagnosis and therapy. This report describes for the first time the case of a patient with past occupational exposure to asbestos and no family history of cancer who developed 2 rare primary malignancies: a cardiac sarcoma and a gliosarcoma 11 months later. Molecular-cytogenetic studies did not identify common lesions to these 2 rare metachronous sarcomas. The gliosarcoma was associated with monosomy 10 and underlying PTEN monoallelic loss, which has been recurrently observed. In the cardiac sarcoma, MDM2 amplification and CDKN2AB/9p21 biallelic deletion suggested intimal sarcoma. No causal relationship was found between cardiac sarcoma and asbestos exposure, although MDM2 abnormalities were linked to malignant mesothelioma.

The GNAS1 gene in myelodysplastic syndromes (MDS).

GNAS1 gene is located at the long arm of chromosome 20 (q13.32). GNAS1 gene deletion has never been investigated in MDS. A GNAS1 activating mutation (R201) was recently found in MDS. We applied FISH and DHPLC plus sequencing to investigate GNAS1 gene in MDS cases with and without del(20q) at karyotype.

Multiple EWSR1-WT1 and WT1-EWSR1 copies in two cases of desmoplastic round cell tumor.

To provide new insights into the genomic profile of desmoplastic round cell tumors (DSRCT), we applied fluorescence in situ hybridization (FISH) and metaphase comparative genomic hybridization (M-CGH) to two newly diagnosed cases. FISH detected multiple subclones bearing one to three copies of der(11)t(11;22)(p13;q12) and/or der(22)t(11;22)(p13;q12) in both patients. This peculiar genomic imbalance might result from derivative chromosome duplication due to non-disjunction and/or mitotic recombination between normal and derivative chromosomes 11 and 22. Concomitant loss of normal chromosomes (i.e., 11 in patient 1 and 22 in patient 2) caused loss of the WT1 or EWSR1 wild-type allele. M-CGH identified other genomic imbalances: gain at chromosome 3 in both cases and chromosome 5 polysomy in patient 1. Common genomic events (i.e., trisomy 3 and extra EWSR1-WT1 and WT1-EWSR1 copies) probably contributed to disease pathogenesis and/or evolution of DSRCT. Our study demonstrated that an integrated molecular cytogenetic approach identified EWSR1-WT1 cooperating molecular events and genetic markers for prognosis. Thus, FISH and M-CGH might well be applied in a large series of patients to elucidate the genomic background of DSRCT.