The RTK-RAS signaling pathway is enriched in patients with rare acute myeloid leukemia harboring t(16;21)(p11;q22)/FUS::ERG.

Acute myeloid leukemia (AML) with t(16;21)(p11;q22)/FUS::ERG is a rare AML subtype associated with poor prognosis. However, its clinical and molecular features remain poorly defined. We determined the clinicopathological, genomic, and transcriptomic characteristics and outcomes of patients with AML harboring FUS::ERG at our center. Thirty-six AML patients harboring FUS::ERG were identified, with an incidence rate of 0.3%. These patients were characterized by high lactate dehydrogenase levels (median: 838.5 U/L), elevated bone marrow blast counts (median: 71.5%), and a CD56-positive immunophenotype (94.3%). Notably, we found that RTK-RAS GTPase (RAS) pathway genes, including NRAS (33%) and PTPN11 (24%), were frequently mutated in this subtype. Transcriptome analysis revealed enrichment of the phosphatidylinositol-3-kinase-Akt (PI3K-Akt), mitogen-activated protein kinase (MAPK), and RAS signaling pathways and upregulation of BCL2, the target of venetoclax, in FUS::ERG AML compared to RUNX1::RUNX1T1 AML, a more common AML subtype with good prognosis. The median event-free survival in patients with FUS::ERG AML was 11.9 (95% confidence interval [CI]: 9.0-not available [NA]) months and the median overall survival was 18.2 (95% CI: 12.4-NA) months. Allogeneic hematopoietic stem cell transplantation failed to improve outcomes. Overall, the high incidence of RTK-RAS pathway mutations and high expression of BCL2 may indicate promising therapeutic targets in this high-risk AML subset.

TLS/FUS-ERG fusion gene in acute leukemia and myelodysplastic syndrome evolved to acute leukemia: report of six cases and a literature review.

To investigate the pathogenesis and the refractory/relapse mechanisms in patients with t(16;21)(p11;q22), we retrospectively analyzed the clinical data of six cases in our hospital and sixty-two cases reported in the literature. Among the patients in our hospital, five cases were diagnosed as acute leukemia, and one was myelodysplastic syndrome evolved to acute myeloid leukemia, harboring TLS/FUS-ERG fusion gene; all the cases were detected t(16;21)(p11;q22) translocation, and five cases showed additional chromosomal abnormalities. We firstly report a novel three-way translocation t(11;16;21)(q13;p11;q22), which may affect the prognosis of leukemia with TLS-ERG fusion gene because this patient shows a more satisfactory treatment effect and deeper remission. And we found patients with TLS-ERG are more likely to have bone and arthrosis pain. Besides, CD56 and CD123 were positive in these cases, which are related to poor prognosis and the character of refractory. Moreover, some gene mutations are involved, and GATA2 and SMAD4 mutations were identified when the disease progressed from myelodysplastic syndrome to leukemia. Among sixty-two patients reported in the literature, valid positive percent of CD56 and CD123 were 81% and 14.3%, respectively. Mutation of the RUNX1 gene was detected in four cases, and one patient had multiple mutations, including BCOR, PLCG1, DIS3, BRAF, JAK2, and JAK3. The prominent feature of leukemia carrying the TLS/FUS-ERG gene is its poor prognosis. The relevant mechanism includes new mutation, jumping translocation, different transcripts, and so on. The mechanism still acquaints scarcely, which requires further study.

Salvage therapy with azacitidine for pediatric acute myeloid leukemia with t(16;21)(p11;q22)/FUS-ERG and early relapse after allogeneic blood stem cell transplantation: A case report.

Acute myeloid leukemia (AML) with FUS-ERG has a poor prognosis regardless of allo-hematopoietic stem cell transplantation (HSCT). Maintenance therapy such as azacitidine after allo-HSCT for AML with FUS-ERG may be clinically meaningful.

Acute basophilic leukemia associated with the t(16;21)(p11;q22)/FUS-ERG fusion gene.

We herein report a rare case of acute basophilic leukemia with t(16;21)(p11;q22) generating the FUS-ERG fusion gene. The basophilic nature of leukemia blasts was demonstrated by cytomorphology, toluidine blue metachromasia, mature basophil-associated antigen expression, and characteristic granules under electron microscopy. The molecular link between t(16;21)/FUS-ERG and basophilic differentiation remains unclear.

A genomic approach to study down syndrome and cancer inverse comorbidity: untangling the chromosome 21.

Down syndrome (DS), one of the most common birth defects and the most widespread genetic cause of intellectual disabilities, is caused by extra genetic material on chromosome 21 (HSA21). The increased genomic dosage of trisomy 21 is thought to be responsible for the distinct DS phenotypes, including an increased risk of developing some types of childhood leukemia and germ cell tumors. Patients with DS, however, have a strikingly lower incidence of many other solid tumors. We hypothesized that the third copy of genes located in HSA21 may have an important role on the protective effect that DS patients show against most types of solid tumors. Focusing on Copy Number Variation (CNV) array data, we have generated frequencies of deleted regions in HSA21 in four different tumor types from which DS patients have been reported to be protected. We describe three different regions of deletion pointing to a set of candidate genes that could explain the inverse comorbidity phenomenon between DS and solid tumors. In particular we found RCAN1 gene in Wilms tumors and a miRNA cluster containing miR-99A, miR-125B2 and miR-LET7C in lung, breast, and melanoma tumors as the main candidates for explaining the inverse comorbidity observed between solid tumors and DS.

Two Cases of Acute Myeloid Leukemia with t(16;21)(p11;q22) and TLS/FUS-ERG Fusion Transcripts / 대한진단검사의학회지

Many AML-associated chromosomal abnormalities, such as t(8;21), t(15;17), inv(16), t(9;11), t(9;22) and t(6;9) are well known. The chromosomal aberration of t(16;21)(p11;q22) in AML is rare and it is known to be associated with poor prognosis, young age (median age, 22 yr), and involvement of various subtypes of the French-American-British classification. We report here 2 AML patients with t(16;21)(p11;q22), proved by conventional cytogenetics and/or reverse transcription (RT)-PCR. Erythrophagocytosis by leukemic blasts was observed in both of the cases. One patient was a 24 yr-old male with acute myelomonocytic leukemia. His karyotype was 46,XY,t(16;21)(p11;q22),del(18)(p11.2) and RT-PCR revealed the TLS/FUS-ERG fusion transcripts. Although he received allogeneic peripheral blood stem cell transplantation after the first remission, he died 9 months after the initial diagnosis due to relapse of the disease and graft-versus-host disease. The other patient was a 72 yr-old male with acute myeloid leukemia without maturation. His karyotype was 45,XY,-16,add(21)(q22) and the presence of t(16;21)(p11;q22) was detected by RT-PCR. He was transferred to another hospital with no more follow-up. We suggest that the presence of t(16;21)(p11;q22) and/or TLS/FUS-ERG fusion transcripts has to be considered in cases of AML with erythrophagocytosis.