Project description:ETV6-ABL1 is a rare gene fusion with oncogenic properties, reported so far in 28 patients presenting a variety of haematological malignancies associated with clinical outcome, including chronic myeloid leukaemia (CML), acute myeloid leukaemia (AML), acute lymphoblastic leukaemia (ALL) and chronic myeloproliferative neoplasm (cMPN). Here we report on a 46-year-old female who presented with Philadelphia negative CML, positive for the ETV6-ABL1 fusion. Whole genome screening carried out with oligonucleotide arrays showed a subtle loss at 12p13 and cryptic imbalances within the 9q34.3 region in a highly unstable genome. FISH mapping with custom BAC probes identified two breakpoints 5 Mb apart within the 9q34 region, together with a break at 12p13. While FISH with commercial BCR-ABL1 probes failed to detect any ABL1 changes, the ETV6 break-apart probe conclusively identified the ETV6-ABL1 fusion thus determining the probe's role as the primary diagnostic FISH test for this chimeric oncogene. In addition, we confirm the association of the ETV6-ABL1 fusion with imatinib resistance reported so far in three other patients, while recording excellent response to the 2nd generation tyrosine kinase inhibitor (TKI) nilotinib. In summary, we highlight the value of ETV6 FISH as a diagnostic test and the therapy resistance of ETV6-ABL1 positive disorders to imatinib.
Project description:ETV6::ABL1 rearranged neoplasms are rare hematological diseases. To date, about 80 cases have been reported, including myeloid and lymphoid leukemias. The ETV6 gene codes for an ETS family transcription factor and several fusion partners have been described. When translocated, ETV6 causes the constitutive activation of the partner genes. Here, we report the case of a 54-year-old woman with a cryptic insertion of the 3' region of ABL1 in the ETV6 gene. The patient was first diagnosed with idiopathic hypereosinophilic syndrome, according to the clinical history, conventional cytogenetics, standard molecular analyses and pathologist description. Next generation sequencing of diagnosis samples unexpectedly detected both ETV6::ABL1 type A and B fusion transcripts, which were then confirmed by FISH. The diagnosis was Myeloid/Lymphoid neoplasm with ETV6::ABL1 fusion, and the patient received imatinib mesylate treatment. In a follow-up after more than one year, the patient still maintained the molecular and complete hematological responses. This case highlights the importance of timely and proper diagnostics and prompt tyrosine kinase inhibitor treatment.
Project description:ETV6-ABL1 gene fusion is a rare genetic rearrangement in a variety of malignancies, including myeloproliferative neoplasms (MPN), acute lymphoblastic leukemia (ALL), and acute myeloid leukemia (AML). Here, we report the case of a 16-year-old male diagnosed with a MPN, 7 months post-completion of treatment for Burkitt leukaemia. RNA sequencing analysis confirmed the presence of an ETV6-ABL1 fusion transcript, with an intact, in-frame ABL tyrosine-kinase domain. Of note, secondary ETV6-ABL1-rearranged neoplastic diseases have not been reported to date. The patient was started on a tyrosine kinase inhibitor (TKI; imatinib) and, subsequently, underwent a 10/10 matched unrelated haematopoietic stem cell transplant. He is disease-free five years post-transplant. Definitive evidence of the prognostic influence of the ETV6-ABL1 fusion in haematological neoplasms is lacking; however, overall data suggest that it is a poor prognostic factor, particularly in patients with ALL and AML. The presence of this ETV6-ABL1 fusion should be more routinely investigated, especially in patients with a CML-like picture. More routine use of whole-genome and RNA sequencing analyses in clinical diagnostic care, in conjunction with conventional cytogenetics, will facilitate these investigations.
Project description:FIP1L1-RARA-a ssociated neoplasm is a very rare and aggressive disease, with only 3 previously reported cases in the literature. Here, we describe a 9-month-old boy who presented with a FIP1L1-RARA fusion-associated myelodysplastic/myeloproliferative neoplasm-like overlap syndrome, with similarities and distinct features to both acute promyelocytic leukemia and juvenile myelomonocytic leukemia. Using a combined approach of chemotherapy, differentiating agents, and allogeneic hematopoietic stem cell transplant (allo-HCT), this patient remains in remission 20 months after allo-HCT. To our knowledge, this is only the second published pediatric case involving this condition and the only case with a favorable long-term outcome. Given the aggressive disease described in the previously published case report, as well as the successful treatment course described, the combinatorial use of chemotherapy, differentiation therapy, and allo-HCT for treatment of FIP1L1-RARA fusion-associated myeloid neoplasms should be considered.
Project description:Myeloproliferative neoplasms (MPN), a group of haematopoietic stem cell (HSC) disorders, are often accompanied by myelofibrosis. We previously identified the fusion of the ETV6 gene to the LYN gene (ETV6-LYN) in idiopathic myelofibrosis with ins(12;8)(p13;q11q21). The introduction of ETV6-LYN into HSCs resulted in fatal MPN with massive myelofibrosis in mice, implicating the rearranged LYN kinase in the pathogenesis of MPN with myelofibrosis. However, the signalling molecules directly downstream from and activated by ETV6-LYN remain unknown. In this study, we demonstrated that the direct activation of STAT5 by ETV6-LYN is crucial for the development of MPN. ETV6-LYN was constitutively active as a kinase through autophosphorylation. ETV6-LYN, but not its kinase-dead mutant, supported cytokine-free proliferation of haematopoietic cells. STAT5 was activated in a JAK2-independent manner in ETV6-LYN-expressing cells. ETV6-LYN interacted with STAT5 and directly activated STAT5 both in vitro and in vivo. Of note, ETV6-LYN did not support the formation of colonies by Stat5-deficient HSCs under cytokine-free conditions and the capacity of ETV6-LYN to induce MPN with myelofibrosis was profoundly attenuated in a Stat5-null background. These findings define STAT5 as a direct target of ETV6-LYN and unveil the LYN-STAT5 axis as a novel pathway to augment proliferative signals in MPN and leukaemia.
Project description:Despite extensive research into the genetic underpinnings of neurodevelopmental disorders (NDD), many clinical cases remain unresolved. We studied a female proband with a NDD, mildly dysmorphic facial features, and brain stem hypoplasia on neuroimaging. Comprehensive genomic analyses revealed a terminal 5p loss and a terminal 18q gain in the proband while a diploid copy number for chromosomes 5 and 18 in both parents. Genomic investigations in the proband identified an unbalanced translocation t(5;18) with additional genetic material from chromosome 2 (2q31.3) inserted at the breakpoint, pointing to a complex chromosomal rearrangement (CCR) involving 5p15.2, 2q31.3, and 18q21.32. Breakpoint junction analyses enabled by long-read genome sequencing unveiled the presence of four distinct junctions in the father, who is a carrier of a balanced CCR. The proband inherited from the father both the abnormal chromosome 5 resulting in segmental aneusomies of chr5 (loss) and chr18 (gain) and a der(2) homologue. Evidences suggest a chromoplexy mechanism for this CCR derivation, involving double-strand breaks (DSBs) repaired by non-homologous end joining (NHEJ) or alternative end joining (alt-EJ). The complexity of the CCR and the segregation of homologues elucidate the genetic model for this family. This study demonstrates the importance of combining multiple genomic technologies to uncover genetic causes of complex neurodevelopmental syndromes and to better understand genetic disease mechanisms.
Project description:Despite extensive research into the genetic underpinnings of neurodevelopmental disorders (NDD), many clinical cases remain unresolved. We studied a female proband with a NDD, mildly dysmorphic facial features, and brain stem hypoplasia on neuroimaging. Comprehensive genomic analyses revealed a terminal 5p loss and terminal 18q gain in the proband while a diploid copy number for chromosomes 5 and 18 in both parents. Genomic investigations in the proband identified an unbalanced translocation t(5;18) with additional genetic material from chromosome 2 (2q31.3) inserted at the breakpoint, pointing to a complex chromosomal rearrangement (CCR) involving 5p15.2, 2q31.3, and 18q21.32. Breakpoint junction analyses enabled by long read genome sequencing unveiled the presence of four distinct junctions in the father, who is carrier of a balanced CCR. The proband inherited from the father both the abnormal chromosome 5 resulting in segmental aneusomies of chr5 (loss) and chr18 (gain) and a der(2) homologue. Evidences suggest a chromoplexy mechanism for this CCR derivation, involving double-strand breaks (DSBs) repaired by non-homologous end joining (NHEJ) or alternative end joining (alt-EJ). The complexity of the CCR and the segregation of homologues elucidate the genetic model for this family. This study demonstrates the importance of combining multiple genomic technologies to uncover genetic causes of complex neurodevelopmental syndrome and to better understand genetic disease mechanisms.
Project description:Myeloid/lymphoid neoplasm with eosinophilia (MLN-Eo) is a World Health Organization (WHO) established category of hematologic malignancies primarily arising in adults. We discuss an 8-month-old infant who presented with clinical features similar to those of juvenile myelomonocytic leukemia (JMML) but who was diagnosed with MLN-Eo driven by an ETV6-FLT3 fusion. Results of patient-derived leukemia ex vivo studies demonstrated increased sensitivity to type I FLT3 inhibitors as compared with type II inhibitors. Treatment with the type I inhibitor gilteritinib resulted in complete immunophenotypic and cytogenetic remission. This patient subsequently underwent a hematopoietic stem cell transplant and remains in complete remission 1 year later. This is the youngest patient reported with an ETV6-FLT3 fusion and adds to the mounting reports of FLT3-rearranged MLN-Eo, supporting its addition to the WHO classification. Furthermore, this case highlights the clinical utility of ex vivo drug testing of targeted therapies.