Mechanistic insights and potential therapeutic approaches for NUP98-rearranged hematologic malignancies

Off-pore Nup98 condensates mobilize heterochromatic breaks and exclude Rad51

Phase separation forms membraneless compartments, including heterochromatin "domains" and repair foci. Pericentromeric heterochromatin mostly comprises repeated sequences prone to aberrant recombination. In Drosophila cells, "safe" homologous recombination (HR) repair of these sequences requires their relocalization to the nuclear periphery before Rad51 recruitment and strand invasion. How this mobilization initiates is unknown, and the contribution of phase separation is unclear. Here, we show that Nup98 nucleoporin is recruited to repair sites before relocalization by Sec13 or Nup88, and downstream of the Smc5/6 complex and heterochromatin protein 1 (HP1). Remarkably, Nup98 condensates are immiscible with HP1 condensates, and they are required and sufficient to mobilize repair sites and exclude Rad51, thus preventing aberrant recombination while promoting HR repair. Disrupting this pathway results in heterochromatin repair defects and widespread chromosome rearrangements, revealing an "off-pore" role for nucleoporins and phase separation in nuclear dynamics and genome integrity in a multicellular eukaryote.

Clinicopathologic and Molecular Characterization of NUP98-Rearranged Acute Leukemias

INTRODUCTION

NUP98 rearrangements are rare in acute leukemias and portend a poor prognosis.

METHODS

This study explored clinicopathologic and molecular features of five patients with NUP98 rearranged (NUP98-r) acute leukemias, including three females and two males with a median age of 34 years.

RESULTS

NUP98 fusion partners were associated with distinctive leukemia characteristics and biology. Three patients had NUP98::NSD1-r acute myeloid leukemia (AML, all cytogenetically cryptic and with concomitant FLT3-ITD) and unfavorable prognoses (in two patients), one patient had NUP98::HOXA9-r AML with morphologic and immunophenotypic features resembling acute promyelocytic leukemia, and lastly, one patient had previously underreported NUP98::MLLT1-r B/T mixed phenotype acute leukemia. After a median follow-up of 24.7 months, median overall survival was 30 months and three of five patients (60%) remained in complete remission at the last follow-up.

CONCLUSION

Our study expands the clinical and molecular spectrum of NUP98-r acute leukemias and recommends FISH testing for NUP98 rearrangement on those leukemia cases without recurrent gene rearrangements and/or normal karyotype followed by molecular confirmation to improve timely diagnosis and clinical management.

Phase Separation in Chromatin Organization and Human Diseases

Understanding how the genome is organized into multi-level chromatin structures within cells and how these chromatin structures regulate gene transcription influencing animal development and human diseases has long been a major goal in genetics and cell biology. Recent evidence suggests that chromatin structure formation and remodeling is regulated not only by chromatin loop extrusion but also by phase-separated condensates. Here, we discuss recent findings on the mechanisms of chromatin organization mediated by phase separation, with a focus on the roles of phase-separated condensates in chromatin structural dysregulation in human diseases. Indeed, these mechanistic revelations herald promising therapeutic strategies targeting phase-separated condensates-leveraging their intrinsic biophysical susceptibilities to restore chromatin structure dysregulated by aberrant phase separation.

Transcriptional and epigenetic rewiring by the NUP98::KDM5A fusion oncoprotein directly activates CDK12

Nucleoporin 98 (NUP98) fusion oncoproteins are strong drivers of pediatric acute myeloid leukemia (AML) with poor prognosis. Here we show that NUP98 fusion-expressing AML harbors an epigenetic signature that is characterized by increased accessibility of hematopoietic stem cell genes and enrichment of activating histone marks. We employ an AML model for ligand-induced degradation of the NUP98::KDM5A fusion oncoprotein to identify epigenetic programs and transcriptional targets that are directly regulated by NUP98::KDM5A through CUT&Tag and nascent RNA-seq. Orthogonal genome-wide CRISPR/Cas9 screening identifies 12 direct NUP98::KDM5A target genes, which are essential for AML cell growth. Among these, we validate cyclin-dependent kinase 12 (CDK12) as a druggable vulnerability in NUP98::KDM5A-expressing AML. In line with its role in the transcription of DNA damage repair genes, small-molecule-mediated CDK12 inactivation causes increased DNA damage, leading to AML cell death. Altogether, we show that NUP98::KDM5A directly regulates a core set of essential target genes and reveal CDK12 as an actionable vulnerability in AML with oncogenic NUP98 fusions.

Liquid-liquid phase separation in normal hematopoiesis and hematological diseases

Liquid-liquid phase separation (LLPS) is an emerging research field in cellular biology. LLPS-driven biomolecular condensates act as reaction chambers and regulatory hubs for critical processes, including chromatin architecture, gene expression, and metabolism. The dysregulation of these processes frequently impedes the proper execution of physiological functions. Current research indicates that abnormal phase separation plays a significant role in the pathogenesis of diseases and aging. This review briefly overviews the fundamental concepts and research methods related to phase separation. We also summarize studies concerning its physiological functions, particularly emphasizing its role in hematopoiesis. We further discuss how abnormal phase separation can lead to hematological disorders, specifically summarizing its involvement in the pathogenesis of leukemia. Despite recent advancements, elucidating LLPS mechanisms in hematopoiesis remains challenging due to the intricate interplay between biomolecular condensates and cellular function. Future research efforts aiming to reveal the role of LLPS in hematological diseases hold promise for novel therapeutic interventions and a deeper understanding of hematopoietic processes.

Pharmacologic degradation of WDR5 suppresses oncogenic activities of SS18::SSX and provides a therapeutic of synovial sarcoma

Cancer-causing aberrations recurrently target the chromatic-regulatory factors, leading to epigenetic dysregulation. Almost all patients with synovial sarcoma (SS) carry a characteristic gene fusion, SS18::SSX, which produces a disease-specific oncoprotein that is incorporated into the switch/sucrose non-fermentable (SWI/SNF) chromatin-remodeling complexes and profoundly alters their functionalities. Targeting epigenetic dependency in cancers holds promise for improving current treatment. Leveraging on cancer cell dependency dataset, pharmacological tools, and genomic profiling, we find WDR5, a factor critical for depositing histone H3 lysine 4 (H3K4) methylation, to be an unexplored vulnerability in SS. Mechanistically, WDR5 and SS18::SSX interact and colocalize at oncogenes where WDR5 promotes H3K4 methylation and the chromatin association of SS18::SSX-containing chromatin-remodeling complexes. WDR5 degradation by proteolysis-targeting chimera (PROTAC) not only suppresses the SS18::SSX-related oncogenic programs but additionally causes the ribosomal protein deregulations leading to p53 activation. WDR5-targeted PROTAC suppresses SS growth in vitro and in vivo, providing a promising strategy for the SS treatment.

Landscape of somatic mutations and clonal evolution in NUP98-rearranged adult acute myeloid leukaemia

Acute myeloid leukaemia with NUP98 rearrangement (AML-NUP98) has been previously described in paediatric patients, and the clinical significance in adult AML patients remains largely unexplored. In this study, we identified specific partner fusion genes and examined somatic co-mutations and clonal evolution longitudinally in adult AML-NUP98 patients. Our comprehensive analysis provides an understanding of NUP98 rearrangement and co-mutations influencing clonal evolution and disease progression and offers valuable insights into potential therapeutic strategies. Further multiple centre studies are needed to investigate this entity in adult patients and improve treatment strategy.

HoxBlinc: a key driver of chromatin dynamics in NUP98 fusion-driven leukemia

Nucleoporin 98 (NUP98) fusion oncogenes are known to promote aggressive pediatric leukemia by disrupting chromatin structure and modulating the expression of homeobox (HOX) genes, yet the precise molecular events are unclear. In this issue of the JCI, K. Hamamoto et al. explore the mechanistic underpinnings of NUP98 fusion-driven pediatric leukemia, with a focus on aberrant activation of the Hoxb-associated long, noncoding RNA (lncRNA) HoxBlinc. The authors provide compelling evidence that HoxBlinc plays a central role in the oncogenic transformation associated with NUP98 fusion protein. The study underscores a CTCF-independent role of HoxBlinc in the regulation of topologically associated domains (TADs) and chromatin accessibility, which has not been fully appreciated in previous research on the NUP98 fusion oncogenes. The discovery of HoxBlinc lncRNA as a downstream regulator of NUP98 fusion oncoproteins offers a potential target for therapeutic intervention in pediatric leukemia.

False positive NUP98 fluorescence in situ hybridization rearrangements in B-acute lymphoblastic leukemia

Gene fusions involving NUP98 have been reported in several hematologic malignancies yet have been very rarely reported in B-acute lymphoblastic leukemia (B-ALL). Two cases of B-ALL for which chromosome banding analysis (CBA) and fluorescence in situ hybridization (FISH) suggested apparent NUP98 rearrangements were further investigated with next-generation sequencing-based methodologies to verify the findings obtained with traditional cytogenetic methodologies. In the first case, CBA revealed a hyperdiploid karyotype with multiple structural abnormalities including additional material of unknown origin at 11p15; subsequent break-apart probe (BAP) FISH for NUP98 demonstrated 2 intact fusion signals and a single separate 5'NUP98 signal. However, whole-genome sequencing found no evidence of a NUP98 gene fusion. The results obtained with conventional cytogenetic methodologies were in fact attributable to structural variants (SV) with breakpoints not within NUP98 but within the 5'NUP98 BAP probe-binding sequence. In the second case, CBA revealed several structural and numeric abnormalities including a complex translocation between chromosomes 11 (at 11p15.4) and 19 (at 19p13.3) and an insertion of unknown material at 11p15.4. BAP FISH demonstrated a typical FISH signal pattern consistent with an apparent NUP98 rearrangement. However, no evidence of a NUP98 fusion was found on RNA sequencing. In conclusion, the two cases thus presented with clinical false positive NUP98 rearrangements by FISH. In the clinical laboratory, SVs in the vicinity of genes involved in recurrent rearrangements in hematologic malignancies may result in misleading results with conventional chromosome methodologies. This may preclude an accurate definition of the genetic attributes of malignancies with ensuing impacts on risk stratification and management. Higher-resolution testing methodologies such as whole-genome sequencing and RNA sequencing may be helpful in resolving unexpected results with conventional chromosome methodologies and enhancing the accuracy of genetic characterization of hematological malignancies in the clinical laboratory.

Functional specificity in biomolecular condensates revealed by genetic complementation

Biomolecular condensates are thought to create subcellular microenvironments that regulate specific biochemical activities. Extensive in vitro work has helped link condensate formation to a wide range of cellular processes, including gene expression, nuclear transport, signalling and stress responses. However, testing the relationship between condensate formation and function in cells is more challenging. In particular, the extent to which the cellular functions of condensates depend on the nature of the molecular interactions through which the condensates form is a major outstanding question. Here, we review results from recent genetic complementation experiments in cells, and highlight how genetic complementation provides important insights into cellular functions and functional specificity of biomolecular condensates. Combined with observations from human genetic disease, these experiments suggest that diverse condensate-promoting regions within cellular proteins confer different condensate compositions, biophysical properties and functions.

Promising activity of Selinexor in the treatment of a patient with refractory NUP98-NSD1+/FLT3-ITD + acute myeloid leukemia

Nucleoporin 98 (NUP98) fusion oncoproteins are associated with various hematologic malignancies. Acute myeloid leukemia (AML) with NUP98-NSD1 typically co-occurs with FLT3-ITD mutations, exhibiting poor initial responses to traditional chemotherapy. This case report describes a relapsed and refractory AML case co-expressing NUP98/NSD1 and FLT3/ITD after matched sibling haplo-identical allogeneic hematopoietic stem cell transplantation, achieving molecular remission with a salvage therapy combining selinexor, venetoclax, and azacitidine. To our knowledge, this is the first report demonstrating the effectiveness of this combination therapy for relapsed/refractory NUP98-NSD1+/FLT3-ITD + AML. This report highlights the potential synergy between selinexor and established AML therapies, suggesting a promising approach to improve outcomes for refractory AML patients.

From low remission to hope: the efficacy of targeted therapies in NUP98-R positive pediatric acute myeloid leukemia

BACKGROUND

Treating pediatric acute myeloid leukemia (AML) with NUP98 rearrangement (NUP98-R) is challenging. Standard chemotherapy results in low remission rates. This study aimed to evaluate different induction regimens and explore alternative therapies to improve outcomes.

METHODS

This retrospective study included 111 pediatric patients with AML treated at our institution from March 2012 to March 2023. Patients were classified into two groups: NUP98-R-positive (n = 10) and NUP98-R-negative (n = 101). We compared their clinical characteristics, treatment responses, and prognoses. Additionally, we presented three cases of NUP98-R-positive patients to elaborate on the role of targeted therapies during induction in treatment outcomes and prognosis.

RESULTS

Patients with NUP98-R fusion genes had a complete remission (CR) rate of 20% after the first induction, which was significantly lower than the 64.3% reported in those without NUP98-R fusion genes (P < 0.05). The 3-year event-free survival (EFS) rate was also lower, with only 30% for NUP98-R patients and 55.3% for non-NUP98-R patients (P < 0.05). The prognosis of NUP98-R patients improved with targeted therapies during induction. For example, Patient 1 achieved CR with FLT3 and BCL-2 inhibitors plus conventional chemotherapy. Patient 2, who was treated with a CDK6 inhibitor, a BCL-2 inhibitor, azacitidine, and an FLT3 inhibitor, also achieved CR and underwent successful stem cell transplantation. Conversely, Patient 3, who received only standard chemotherapy, did not achieve remission and died from a severe infection.

CONCLUSIONS

This study demonstrated that using targeted drugs for the induction in NUP98-R pediatric AML improved treatment outcomes. BCL-2, FLT3, and CDK6 inhibitors available at our institution are promising options for this phase of treatment.

The phenylalanine-and-glycine repeats of NUP98 oncofusions form condensates that selectively partition transcriptional coactivators

Recurrent cancer-causing fusions of NUP98 produce higher-order assemblies known as condensates. How NUP98 oncofusion-driven condensates activate oncogenes remains poorly understood. Here, we investigate NUP98-PHF23, a leukemogenic chimera of the disordered phenylalanine-and-glycine (FG)-repeat-rich region of NUP98 and the H3K4me3/2-binding plant homeodomain (PHD) finger domain of PHF23. Our integrated analyses using mutagenesis, proteomics, genomics, and condensate reconstitution demonstrate that the PHD domain targets condensate to the H3K4me3/2-demarcated developmental genes, while FG repeats determine the condensate composition and gene activation. FG repeats are necessary to form condensates that partition a specific set of transcriptional regulators, notably the KMT2/MLL H3K4 methyltransferases, histone acetyltransferases, and BRD4. FG repeats are sufficient to partition transcriptional regulators and activate a reporter when tethered to a genomic locus. NUP98-PHF23 assembles the chromatin-bound condensates that partition multiple positive regulators, initiating a feedforward loop of reading-and-writing the active histone modifications. This network of interactions enforces an open chromatin landscape at proto-oncogenes, thereby driving cancerous transcriptional programs.

Biomolecular condensation of human IDRs initiates endogenous transcription via intrachromosomal looping or high-density promoter localization

Protein intrinsically disordered regions (IDRs) are critical gene-regulatory components and aberrant fusions between IDRs and DNA-binding/chromatin-associating domains cause diverse human cancers. Despite this importance, how IDRs influence gene expression, and how aberrant IDR fusion proteins provoke oncogenesis, remains incompletely understood. Here we develop a series of synthetic dCas9-IDR fusions to establish that locus-specific recruitment of IDRs can be sufficient to stimulate endogenous gene expression. Using dCas9 fused to the paradigmatic leukemogenic NUP98 IDR, we also demonstrate that IDRs can activate transcription via localized biomolecular condensation and in a manner that is dependent upon overall IDR concentration, local binding density, and amino acid composition. To better clarify the oncogenic role of IDRs, we construct clinically observed NUP98 IDR fusions and show that, while generally non-overlapping, oncogenic NUP98-IDR fusions convergently drive a core leukemogenic gene expression program in donor-derived human hematopoietic stem cells. Interestingly, we find that this leukemic program arises through differing mechanistic routes based upon IDR fusion partner; either distributed intragenic binding and intrachromosomal looping, or dense binding at promoters. Altogether, our studies clarify the gene-regulatory roles of IDRs and, for the NUP98 IDR, connect this capacity to pathological cellular programs, creating potential opportunities for generalized and mechanistically tailored therapies.

Acute myeloid leukemia with NUP98::RARG rearrangement: a case report and review of the relevant literature

We herein report a rare case of acute myeloid leukemia (AML) with t(11;12)(p15;q13) and NUP98::RARG, which seems to be involved in the development of AML. The morphological features were similar to those of classic acute promyelocytic leukemia (APL), but unlike classic APL, this leukemia was resistant to treatment with all-trans retinoic acid (ATRA). We decided to use standard chemotherapy for AML with monitoring of minimal residual disease (MRD) by qualitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis for NUP98::RARG mRNA. Although MRD disappeared after induction chemotherapy, it later reappeared, and hematological relapse occurred during subsequent chemotherapies. The patient received haploidentical hematopoietic stem cell transplantation while not in remission and achieved a second molecular remission. However, relapse occurred 4 months after transplantation. The specific mechanism of ATRA resistance in this unique case of AML remains unclear, and no standard treatment has been determined. This is the first case report of AML with NUP98::RARG rearrangement in Japan. Qualitative RT-PCR analysis for NUP98::RARG mRNA was helpful for the accurate diagnosis and evaluation of MRD to choose an adequate treatment for this type of AML.

HoxBlinc lncRNA reprograms CTCF-independent TADs to drive leukemic transcription and HSC dysregulation in NUP98-rearranged leukemia

Although nucleoporin 98 (NUP98) fusion oncogenes often drive aggressive pediatric leukemia by altering chromatin structure and expression of homeobox (HOX) genes, underlying mechanisms remain elusive. Here, we report that the Hoxb-associated lncRNA HoxBlinc was aberrantly activated in NUP98-PHF23 fusion-driven leukemias. HoxBlinc chromatin occupancies led to elevated mixed-lineage leukemia 1 (MLL1) recruitment and aberrant homeotic topologically associated domains (TADs) that enhanced chromatin accessibilities and activated homeotic/hematopoietic oncogenes. HoxBlinc depletion in NUP98 fusion-driven leukemia impaired HoxBlinc binding, TAD integrity, MLL1 recruitment, and the MLL1-driven chromatin signature within HoxBlinc-defined TADs in a CCCTC-binding factor-independent (CTCF-independent) manner, leading to inhibited homeotic/leukemic oncogenes that mitigated NUP98 fusion-driven leukemogenesis in xenografted mouse models. Mechanistically, HoxBlinc overexpression in the mouse hematopoietic compartment induced leukemias resembling those in NUP98-PHF23-knockin (KI) mice via enhancement of HoxBlinc chromatin binding, TAD formation, and Hox gene aberration, leading to expansion of hematopoietic stem and progenitor cell and myeloid/lymphoid cell subpopulations. Thus, our studies reveal a CTCF-independent role of HoxBlinc in leukemic TAD organization and oncogene-regulatory networks.

Biomolecular condensates in immune cell fate

Fate decisions during immune cell development require temporally precise changes in gene expression. Evidence suggests that the dynamic modulation of these changes is associated with the formation of diverse, membrane-less nucleoprotein assemblies that are termed biomolecular condensates. These condensates are thought to orchestrate fate-determining transcriptional and post-transcriptional processes by locally and transiently concentrating DNA or RNA molecules alongside their regulatory proteins. Findings have established a link between condensate formation and the gene regulatory networks that ensure the proper development of immune cells. Conversely, condensate dysregulation has been linked to impaired immune cell fates, including ageing and malignant transformation. This Review explores the putative mechanistic links between condensate assembly and the gene regulatory frameworks that govern normal and pathological development in the immune system.

Fusion oncoproteins and cooperating mutations define disease phenotypes in NUP98-rearranged leukemia

Leukemias with NUP98 rearrangements exhibit heterogeneous phenotypes correlated to fusion partners, whereas the mechanism responsible for this heterogeneity is poorly understood. Through genome-wide mutational and transcriptional analyses of 177 NUP98-rearranged leukemias, we show that cooperating alterations are associated with differentiation status even among leukemias sharing the same NUP98 fusions, such as NUP98::KDM5A acute megakaryocytic leukemia with RB1 loss or T-cell acute lymphoblastic leukemia with NOTCH1 mutations. CUT&RUN profiling reveals that NUP98 fusion oncoproteins directly regulate differentiation-related genes, with binding patterns also influenced by differentiation stage. Using in vitro models, we show RB1 loss cooperates with NUP98::KDM5A by blocking terminal differentiation toward platelets and expanding megakaryocyte-like cells, whereas WT1 frameshifts skew differentiation toward dormant lympho-myeloid primed progenitor cells and cycling granulocyte-monocyte progenitor cells. NUP98::KDM5A models with RB1 or WT1 alterations have different sensitivities to menin inhibition, suggesting cellular differentiation stage-specific resistant mechanism against menin inhibitors with clinical implications for NUP98-rearranged leukemia.

Targeting Protein-Protein Interactions in Hematologic Malignancies

Over the last two decades, there have been extensive efforts to develop small-molecule inhibitors of protein-protein interactions (PPIs) as novel therapeutics for cancer, including hematologic malignancies. Despite the numerous challenges associated with developing PPI inhibitors, a significant number of them have advanced to clinical studies in hematologic patients in recent years. The US Food and Drug Administration approval of the very first PPI inhibitor, venetoclax, demonstrated the real clinical value of blocking protein-protein interfaces. In this review, we discuss the most successful examples of PPI inhibitors that have reached clinical studies in patients with hematologic malignancies. We also describe the challenges of blocking PPIs with small molecules, clinical resistance to such compounds, and the lessons learned from the development of successful PPI inhibitors. Overall, this review highlights the remarkable success and substantial promise of blocking PPIs in hematologic malignancies.

Structural Variant Analysis of Complex Karyotype Myelodysplastic Neoplasia Through Optical Genome Mapping

Myelodysplastic neoplasia with complex karyotype (CK-MDS) poses significant clinical challenges and is associated with poor survival. Detection of structural variants (SVs) is crucial for diagnosis, prognostication, and treatment decision-making in MDS. However, the current standard-of-care (SOC) cytogenetic testing, relying on karyotyping, often yields ambiguous results in cases with CK. Here, SV detection by novel optical genome mapping (OGM) technique was explored in 15 CK-MDS cases, which collectively harbored 85 chromosomes with abnormalities reported by SOC. Additionally, OGM was utilized in the discovery of novel SVs. Altogether, OGM detected corresponding > 5 Mbp alterations for 73 out of 85 SOC reported abnormalities, resulting in an 86% concordance rate. OGM provided further specification of these abnormalities, revealing that 64% of the altered chromosomes were affected by multiple SVs or chromoanagenesis. Prominently, only 5% of missing chromosomes reported by SOC were true monosomies. In addition, OGM detected alterations in chromosomes not reported as abnormal by karyotyping in 93% of cases and provided clinically relevant gene-level information, such as SVs in TP53, MECOM, NUP98, IKZF1, and ETV6. Analysis of novel SVs revealed two previously unreported gene-fusions (SCFD1::ZNF592 and VPS8::LRBA), both confirmed by transcriptome sequencing. Furthermore, the repositioning of CCDC26 (8q24.21) was identified as a potential cause of inappropriate gene activation in two cases, affecting MECOM and SOX7, respectively. This study shows that OGM can significantly enhance the diagnostic analysis of SVs in CK-MDS and highlights the utility of OGM identifying novel SVs in complex cancer genomes.

Monitoring measurable residual disease in NUP98::NSD1-positive acute myeloid leukemia

BACKGROUND

NUP98 fusion genes are detected in acute myeloid leukemia (AML) subgroups that have a poor prognosis. An appropriate therapeutic approach should therefore be established. Treatment intensification according to the minimal residual disease (MRD) level can lead to a better prognosis in patients with acute lymphoblastic leukemia (ALL). However, the importance of MRD monitoring in the patient with NUP98-positive AML is unclear.

METHODS

This study aimed to develop a digital droplet polymerase chain reaction (ddPCR) method for monitoring NUP98::NSD1-positive leukemic cells and to report its utility compared with the results of NUP98 split fluorescence in situ hybridization (FISH).

RESULTS

The results of NUP98::NSD1 ddPCR correlated with those of NUP98 split FISH and were more sensitive than NUP98 split FISH. The sensitivity of ddPCR was 0.001%, equivalent to 1 in 1 × 105 cells. The MRD level of NUP98::NSD1, measured by ddPCR, correlated well with relapse.

CONCLUSION

The use of ddPCR to target NUP98::NSD1 chimera mRNA for MRD monitoring would be beneficial for NUP98::NSD1 AML treatment.

Therapeutic approaches targeting oncogenic proteins in myeloid leukemia: challenges and perspectives

INTRODUCTION

Leukemia is typically categorized into myeloid leukemia and lymphoblastic leukemia based on the origins of leukemic cells. Myeloid leukemia is a group of clonal malignancies characterized by the presence of increased immature myeloid cells in both the bone marrow and peripheral blood. Of note, the aberrant expression of specific proteins or the generation of fusion proteins due to chromosomal abnormalities are well established drivers in various forms of myeloid leukemia. Therefore, these oncoproteins represent promising targets for drug development.

AREAS COVERED

In this review, we comprehensively discussed the pathogenesis of typical leukemia oncoproteins and the current landscape of small molecule drugs targeting these oncogenic proteins. Additionally, we elucidated novel strategies, including proteolysis-targeting chimeras (PROTACs), hyperthermia, and genomic editing, which specifically degrade oncogenic proteins in myeloid malignancies.

EXPERT OPINION

Although small molecule drugs have significantly improved the prognosis of oncoprotein-driven myeloid leukemia patients, drug resistance due to the mutations in oncoproteins is still a great challenge in the clinic. New approaches such as PROTACs, hyperthermia, and genomic editing are considered promising approaches for the treatment of oncoprotein-driven leukemia, especially for drug-resistant mutants.

NUP98 fusion proteins and KMT2A-MENIN antagonize PRC1.1 to drive gene expression in AML

Control of stem cell-associated genes by Trithorax group (TrxG) and Polycomb group (PcG) proteins is frequently misregulated in cancer. In leukemia, oncogenic fusion proteins hijack the TrxG homolog KMT2A and disrupt PcG activity to maintain pro-leukemogenic gene expression, though the mechanisms by which oncofusion proteins antagonize PcG proteins remain unclear. Here, we define the relationship between NUP98 oncofusion proteins and the non-canonical polycomb repressive complex 1.1 (PRC1.1) in leukemia using Menin-KMT2A inhibitors and targeted degradation of NUP98 fusion proteins. Eviction of the NUP98 fusion-Menin-KMT2A complex from chromatin is not sufficient to silence pro-leukemogenic genes. In the absence of PRC1.1, key oncogenes remain transcriptionally active. Transition to a repressed chromatin state requires the accumulation of PRC1.1 and repressive histone modifications. We show that PRC1.1 loss leads to resistance to small-molecule Menin-KMT2A inhibitors in vivo. Therefore, a critical function of oncofusion proteins that hijack Menin-KMT2A activity is antagonizing repressive chromatin complexes.

RNA and condensates: Disease implications and therapeutic opportunities

Biomolecular condensates are dynamic membraneless organelles that compartmentalize proteins and RNA molecules to regulate key cellular processes. Diverse RNA species exert their effects on the cell by their roles in condensate formation and function. RNA abnormalities such as overexpression, modification, and mislocalization can lead to pathological condensate behaviors that drive various diseases, including cancer, neurological disorders, and infections. Here, we review RNA's role in condensate biology, describe the mechanisms of RNA-induced condensate dysregulation, note the implications for disease pathogenesis, and discuss novel therapeutic strategies. Emerging approaches to targeting RNA within condensates, including small molecules and RNA-based therapies that leverage the unique properties of condensates, may revolutionize treatment for complex diseases.

Case report: NUP98::LEDGF fusion gene drives malignant hematological tumor with mixed immunological phenotype

This is the first report of NUP98::LEDGF positive malignant hematological tumor expressing T cell and myeloid lineage antigens. Patients carrying this fusion gene have a high relapse rate and a poor prognosis, allo-HSCT may be an option to cure this disease. This patient underwent allo-HSCT, a relapse occurred three months post-transplantation. Subsequent screening at our hospital confirmed the presence of the NUP98::LEDGF fusion gene, salvage therapy was administered, followed by a successful second allo-HSCT. Furthermore, we included eight previously reported cases from the literature for analysis and discuss.

Targeted gene sequencing and transcriptome sequencing reveal characteristics of NUP98 rearrangement in pediatric acute myeloid leukemia

BACKGROUND

NUP98 rearrangements (NUP98-r) are rare but overrepresented mutations in pediatric acute myeloid leukemia (AML) patients. NUP98-r is often associated with chemotherapy resistance and a particularly poor prognosis. Therefore, characterizing pediatric AML with NUP98-r to identify aberrations is critically important.

METHODS

Here, we retrospectively analyzed the clinicopathological features, genomic and transcriptomic landscapes, treatments, and outcomes of pediatric patients with AML.

RESULTS

Nine patients with NUP98-r mutations were identified in our cohort of 142 patients. Ten mutated genes were detected in patients with NUP98-r. The frequency of FLT3-ITD mutations differed significantly between the groups harboring NUP98-r and those without NUP98-r (P = 0.035). Unsupervised hierarchical clustering via RNA sequencing data from 21 AML patients revealed that NUP98-r samples clustered together, strongly suggesting a distinct subtype. Compared with that in the non-NUP98-r fusion and no fusion groups, CMAHP expression was significantly upregulated in the NUP98-r samples (P < 0.001 and P = 0.001, respectively). Multivariate Cox regression analyses demonstrated that patients harboring NUP98-r (P < 0.001) and WT1 mutations (P = 0.030) had worse relapse-free survival, and patients harboring NUP98-r (P < 0.008) presented lower overall survival.

CONCLUSIONS

These investigations contribute to the understanding of the molecular characteristics, risk stratification, and prognostic evaluation of pediatric AML patients.

NUP98 oncofusions in myeloid malignancies: An update on molecular mechanisms and therapeutic opportunities

Acute myeloid leukemia (AML) is an aggressive hematological malignancy with a heterogeneous molecular landscape. In the pediatric context, the NUP98 gene is a frequent target of chromosomal rearrangements that are linked to poor prognosis and unfavorable treatment outcomes in different AML subtypes. The translocations fuse NUP98 to a diverse array of partner genes, resulting in fusion proteins with novel functions. NUP98 fusion oncoproteins induce aberrant biomolecular condensation, abnormal gene expression programs, and re-wired protein interactions which ultimately cause alterations in the cell cycle and changes in cellular structures, all of which contribute to leukemia development. The extent of these effects is steered by the functional domains of the fusion partners and the influence of concomitant somatic mutations. In this review, we discuss the complex characteristics of NUP98 fusion proteins and potential novel therapeutic approaches for NUP98 fusion-driven AML.

Interdependence between Nuclear Pore Gatekeepers and Genome Caretakers: Cues from Genome Instability Syndromes

This review starts off with the first germline homozygous variants of the Nucleoporin 98 gene (NUP98) in siblings whose clinical presentation recalls Rothmund-Thomson (RTS) and Werner (WS) syndromes. The progeroid phenotype caused by a gene associated with haematological malignancies and neurodegenerative disorders primed the search for interplay between caretakers involved in genome instability syndromes and Nuclear Pore Complex (NPC) components. In the context of basic information on NPC architecture and functions, we discuss the studies on the interdependence of caretakers and gatekeepers in WS and Hereditary Fibrosing Poikiloderma (POIKTMP), both entering in differential diagnosis with RTS. In WS, the WRN/WRNIP complex interacts with nucleoporins of the Y-complex and NDC1 altering NPC architecture. In POIKTMP, the mutated FAM111B, recruited by the Y-complex's SEC13 and NUP96, interacts with several Nups safeguarding NPC structure. The linkage of both defective caretakers to the NPC highlights the attempt to activate a repair hub at the nuclear periphery to restore the DNA damage. The two separate WS and POIKTMP syndromes are drawn close by the interaction of their damage sensors with the NPC and by the shared hallmark of short fragile telomeres disclosing a major role of both caretakers in telomere maintenance.

NUP98::NSD1 and FLT3/ITD co-expression is an independent predictor of poor prognosis in pediatric AML patients

OBJECTIVE

Patients who carry NUP98::NSD1 or FLT3/ITD mutations are reported to have poor prognosis. Previous studies have confidently reported that the poor outcome in younger AML patients is owning to dual NUP98::NSD1 and FLT3/ITD positivity, with a high overlap for those two genetic lesions. In this study, we assessed the prognostic value of the presence of both NUP98::NSD1 and FLT3/ITD in pediatric AML patients.

METHODS

We screened a large cohort of 885 pediatric cases from the COG-National Cancer Institute (NCI) TARGET AML cohort and found 57 AML patients with NUP98 rearrangements.

RESULTS

The frequency of NUP98 gene fusion was 10.8% in 529 patients. NUP98::NSD1 fusion was the most common NUP98 rearrangement, with a frequency of 59.6%(34 of 57). NUP98::NSD1 -positive patients who carried FLT3/ITD mutations had a decreased CR1 or CR2 rate than those patients carried FLT3/ITD mutation alone (P = 0.0001). Moreover, patients harboring both NUP98::NSD1 fusion and FLT3/ITD mutation exhibited inferior event-free survival (EFS, P < 0.001) and overall survival (OS, P = 0.004) than patients who were dual negative for these two genetic lesions. The presence of only NUP98::NSD1 fusion had no significant impact on EFS or OS. We also found that cases with high FLT3/ITD AR levels ( > = 0.5) with or without NUP98::NSD1 had inferior prognosis. Multivariate analysis demonstrated that the presence of both NUP98::NSD1 and FLT3/ITD was an independent prognostic factors for EFS (hazard ratio: 3.2, P = 0.001) in patients with pediatric AML. However, there was no obvious correlation with OS (hazard ratio: 1.3, P = 0.618). Stem cell transplantation did not improve the survival rate of cases with NUP98 fusion or NUP98::NSD1 AML in terms of EFS or OS.

CONCLUSION

Presence of both NUP98::NSD1 and FLT3/ITD was found to be an independent factor for dismal prognosis in pediatric AML patients. Notably, lack of FLT3/ITD mutations in NUP98::NSD1 -positive patients did not retain its prognostic value.

Clinical features and prognosis of patients with myeloid neoplasms harboring t(7;11)(p15;p15) translocation: a single-center retrospective study

BACKGROUND

For myeloid neoplasms with t(7;11)(p15;p15) translocation, the prognosis is quite dismal. Because these tumors are rare, most occurrences are reported as single cases. Clinical results and optimal treatment approaches remain elusive. This study endeavors to elucidate the clinical implications and prognosis of this cytogenetic aberration.

METHODS

This study retrospectively analyzed 23 cases of myeloid neoplasm with t(7;11)(p15;p15). Clinicopathological characteristics, genetic alterations, and outcomes were evaluated, and the Kaplan-Meier method was employed to construct survival curves.

RESULTS

Of these, nine cases were newly diagnosed acute myeloid leukemia (ND AML), seven presented with relapsed refractory AML (R/R AML), four had myelodysplastic syndrome (MDS), two had secondary AML, and one exhibited a mixed germinoma associated with MDS. Patients with t(7;11)(p15;p15) in AML were primarily younger females who preferred subtype M2. Interestingly, these patients had decreased hemoglobin and red blood cell counts, along with markedly elevated levels of lactic dehydrogenase and interleukin-6, and exhibited the expression of CD117. R/R AML patients exhibited a higher likelihood of additional chromosome abnormalities (ACAs) besides t(7;11). WT1 and FLT3-ITD were the most commonly found mutated genes, and 10 of those instances showed evidence of the NUP98::HOXA9 fusion gene. The composite complete remission rate was 66.7% (12/18), while the cumulative graft survival rate was 100% (4/4). However, the survival outcomes were dismal. Interestingly, the median overall survival for R/R AML patients was 4.0 months (95% CI: 1.7-6.4). Additionally, the type of AML diagnosis or the presence of ACAs or molecular prognostic stratification did not significantly influence clinical outcomes (p = 0.066, p = 0.585, p = 0.570, respectively).

CONCLUSION

Myeloid leukemia with t(7;11) exhibits unique clinical features, cytogenetic properties, and molecular genetic characteristics. These survival outcomes were dismal. R/R AML patients have a limited lifespan. For myeloid patients with t(7;11), targeted therapy or transplantation may be an effective course of treatment.

Combination of menin and kinase inhibitors as an effective treatment for leukemia with NUP98 translocations

Chromosomal translocations of the nucleoporin 98 (NUP98) gene are found in acute myeloid leukemia (AML) patients leading to very poor outcomes. The oncogenic activity of NUP98 fusion proteins is dependent on the interaction between Mixed Lineage Leukemia 1 and menin. NUP98-rearranged (NUP98-r) leukemia cells also rely on specific kinases, including CDK6 and/or FLT3, suggesting that simultaneous targeting of these kinases and menin could overcome limited sensitivity to single agents. Here, we found that combinations of menin inhibitor, MI-3454, with kinase inhibitors targeting either CDK6 (Palbociclib) or FLT3 (Gilteritinib) strongly enhance the anti-leukemic effect of menin inhibition in NUP98-r leukemia models. We found strong synergistic effects of both combinations on cell growth, colony formation and differentiation in patient samples with NUP98 translocations. These combinations also markedly augmented anti-leukemic efficacy of menin inhibitor in Patient Derived Xenograft models of NUP98-r leukemia. Despite inhibiting two unrelated kinases, when Palbociclib or Gilteritinib were combined with the menin inhibitor, they affected similar pathways relevant to leukemogenesis, including cell cycle regulation, cell proliferation and differentiation. This study provides strong rationale for clinical translation of the combination of menin and kinase inhibitors as novel treatments for NUP98-r leukemia, supporting the unexplored combinations of epigenetic drugs with kinase inhibitors.

Advances in the understanding of nuclear pore complexes in human diseases

BACKGROUND

Nuclear pore complexes (NPCs) are sophisticated and dynamic protein structures that straddle the nuclear envelope and act as gatekeepers for transporting molecules between the nucleus and the cytoplasm. NPCs comprise up to 30 different proteins known as nucleoporins (NUPs). However, a growing body of research has suggested that NPCs play important roles in gene regulation, viral infections, cancer, mitosis, genetic diseases, kidney diseases, immune system diseases, and degenerative neurological and muscular pathologies.

PURPOSE

In this review, we introduce the structure and function of NPCs. Then We described the physiological and pathological effects of each component of NPCs which provide a direction for future clinical applications.

METHODS

The literatures from PubMed have been reviewed for this article.

CONCLUSION

This review summarizes current studies on the implications of NPCs in human physiology and pathology, highlighting the mechanistic underpinnings of NPC-associated diseases.

Treatment of three pediatric AML co-expressing NUP98-NSD1, FLT3-ITD, and WT1

During the treatment of 89 pediatric patients with Acute Myeloid Leukemia (AML) at the Hematology Department of Kunming Medical University's Children's Hospital from 2020 to 2023, three patients were identified to co-express the NUP98-NSD1, FLT3-ITD, and WT1 gene mutations. The bone marrow of these three patients was screened for high-risk genetic mutations using NGS and qPCR at the time of diagnosis. The treatment was administered following the China Children's Leukemia Group (CCLG)-AML-2019 protocol. All three patients exhibited a fusion of the NUP98 exon 12 with the NSD1 exon 6 and co-expressed the FLT3-ITD and WT1 mutations; two of the patients displayed normal karyotypes, while one presented chromosomal abnormalities. During the induction phase of the CCLG-AML-2019 treatment protocol, the DAH (Daunorubicin, Cytarabine, and Homoharringtonine) and IAH (Idarubicin, Cytarabine, and Homoharringtonine) regimens, in conjunction with targeted drug therapy, did not achieve remission. Subsequently, the patients were shifted to the relapsed/refractory chemotherapy regimen C + HAG (Cladribine, Homoharringtonine, Cytarabine, and G-CSF) for two cycles, which also failed to induce remission. One patient underwent Haploidentical Hematopoietic Stem Cell Transplantation (Haplo-HSCT) and achieved complete molecular remission during a 12-month follow-up period. Regrettably, the other two patients, who did not receive transplantation, passed away. The therapeutic conclusion is that pediatric AML patients with the aforementioned co-expression do not respond to chemotherapy. Non-remission transplantation, supplemented with tailor-made pre- and post-transplant strategies, may enhance treatment outcomes.

"Off-pore" nucleoporins relocalize heterochromatic breaks through phase separation

Phase separation forms membraneless compartments in the nuclei, including by establishing heterochromatin "domains" and repair foci. Pericentromeric heterochromatin mostly comprises repeated sequences prone to aberrant recombination, and "safe" homologous recombination (HR) repair of these sequences requires the movement of repair sites to the nuclear periphery before Rad51 recruitment and strand invasion. How this mobilization initiates is unknown, and the contribution of phase separation to these dynamics is unclear. Here, we show that Nup98 nucleoporin is recruited to heterochromatic repair sites before relocalization through Sec13 or Nup88 nucleoporins, and downstream from the Smc5/6 complex and SUMOylation. Remarkably, the phase separation properties of Nup98 are required and sufficient to mobilize repair sites and exclude Rad51, thus preventing aberrant recombination while promoting HR repair. Disrupting this pathway results in heterochromatin repair defects and widespread chromosome rearrangements, revealing a novel "off-pore" role for nucleoporins and phase separation in nuclear dynamics and genome integrity in a multicellular eukaryote.

Phase separation is regulated by post-translational modifications and participates in the developments of human diseases

Liquid-liquid phase separation (LLPS) of intracellular proteins has emerged as a hot research topic in recent years. Membrane-less and liquid-like condensates provide dense spaces that ensure cells to high efficiently regulate genes transcription and rapidly respond to burst changes from the environment. The fomation and activity of LLPS are not only modulated by the cytosol conditions including but not limited to salt concentration and temperture. Interestingly, recent studies have shown that phase separation is also regulated by various post-translational modifications (PTMs) through modulating proteins multivalency, such as solubility and charge interactions. The regulation mechanism is crucial for normal functioning of cells, as aberrant protein aggregates are often closely related with the occurrence and development of human diseases including cancer and nurodegenerative diseases. Therefore, studying phase separation in the perspective of protein PTMs has long-term significance for human health. In this review, we summarized the properties and cellular physiological functions of LLPS, particularly its relationships with PTMs in human diseases according to recent researches.

NUP98-BPTF promotes oncogenic transformation through PIM1 upregulation

INTRODUCTION

Nucleoporin 98 (NUP98) fusion proteins are recurrently found in leukemia and are associated with unfavorable clinical outcomes. They are distributed to the nucleus and contribute to leukemogenesis via aberrant transcriptional regulation. We previously identified NUP98-BPTF (NB) fusion in patients with T-cell acute lymphoblastic leukemia (T-ALL) using next-generation sequencing. The FG-repeat of NUP98 and the PHD finger and bromodomain of bromodomain PHD finger transcription factor (BPTF) are retained in the fusion. Like other NUP98 fusion proteins, NB is considered to regulate genes that are essential for leukemogenesis. However, its target genes or pathways remain unknown.

MATERIALS AND METHODS

To investigate the potential oncogenic properties of the NB fusion protein, we lentivirally transduced a doxycycline-inducible NB expression vector into mouse NIH3T3 fibroblasts and human Jurkat T-ALL cells.

RESULTS

NB promoted the transformation of mouse NIH3T3 fibroblasts by upregulating the proto-oncogene Pim1, which encodes a serine/threonine kinase. NB transcriptionally regulated Pim1 expression by binding to its promoter and activated MYC and mTORC1 signaling. PIM1 knockdown or pharmacological inhibition of mTORC1 signaling suppressed NB-induced NIH3T3 cell transformation. Furthermore, NB enhanced the survival of human Jurkat T-ALL cells by inactivating the pro-apoptotic protein BCL2-associated agonist of cell death (BAD).

CONCLUSION

We demonstrated the pivotal role of NB in cell transformation and survival and identified PIM1as a key downstream target of NB. These findings propose a promising therapeutic strategy for patients with NB fusion-positive leukemia.

Rare NUP98::PRRX1 fusion transcript in a therapy-related acute myeloid leukemia associated with del(7q) following chemotherapy for diffuse large B-cell lymphoma

BACKGROUND

Therapy-related acute myeloid leukemia (t-AML) is increasingly recognized as a treatment complication in patients receiving chemotherapy, radiotherapy, or immunosuppressive agents for primary neoplasms. NUP98::PRRX1 fusion gene, caused by t(1;11)(q23;p15), is a rare recurrent cytogenetic alteration in leukemia, and only seven cases with NUP98::PRRX1 were reported so far.

METHODS

A 53-year-old female patient was diagnosed with t-AML after 20 months of complete remission (CR) from diffuse large B-cell lymphoma (DLBCL). Conventional karyotype, fluorescence in situ hybridization (FISH), and DNA/RNA next-generation sequence (NGS) were used to detect genetic abnormalities.

RESULTS

Abnormal karyotype of 46, XX, t(1;11)(q25;p15), del(7)(q22) was revealed. NUP98 gene rearrangement and del(7)(q22) were verified by FISH. Further, RNA NGS detected NUP98::PRRX1 fusion transcript, and DNA NGS detected KRAS gene mutation. The patient achieved CR after a combined chemotherapy regimen containing BCL-2 inhibitor and underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT), but she died of leukemia recurrence 14 months later.

CONCLUSIONS

Novel targeted drugs may provide opportunities for patients with NUP98::PRRX1 to undergo allo-HSCT. However, since the cases of carrying the NUP98::PRRX1 are limited, more patients with this genetic change need to be investigated to elucidate the prognostic significance.

The ETO2 transcriptional cofactor maintains acute leukemia by driving a MYB/EP300-dependent stemness program

Transcriptional cofactors of the ETO family are recurrent fusion partners in acute leukemia. We characterized the ETO2 regulome by integrating transcriptomic and chromatin binding analyses in human erythroleukemia xenografts and controlled ETO2 depletion models. We demonstrate that beyond its well-established repressive activity, ETO2 directly activates transcription of MYB, among other genes. The ETO2-activated signature is associated with a poorer prognosis in erythroleukemia but also in other acute myeloid and lymphoid leukemia subtypes. Mechanistically, ETO2 colocalizes with EP300 and MYB at enhancers supporting the existence of an ETO2/MYB feedforward transcription activation loop (e.g., on MYB itself). Both small-molecule and PROTAC-mediated inhibition of EP300 acetyltransferases strongly reduced ETO2 protein, chromatin binding, and ETO2-activated transcripts. Taken together, our data show that ETO2 positively enforces a leukemia maintenance program that is mediated in part by the MYB transcription factor and that relies on acetyltransferase cofactors to stabilize ETO2 scaffolding activity.

Acute myeloid leukemia with rare recurring translocations-an overview of the entities included in the international consensus classification

Two different systems exist for subclassification of acute myeloid leukemia (AML); the World Health Organization (WHO) Classification and the International Consensus Classification (ICC) of myeloid malignancies. The two systems differ in their classification of AML defined by recurrent chromosomal abnormalities. One difference is that the ICC classification defines an AML subset that includes 12 different genetic abnormalities that occur in less than 4% of AML patients. These subtypes exhibit distinct clinical traits and are associated with treatment outcomes, but detailed description of these entities is not easily available and is not described in detail even in the ICC. We searched in the PubMed database to identify scientific publications describing AML patients with the recurrent chromosomal abnormalities/translocations included in this ICC defined patient subset. This patient subset includes AML with t(1;3)(p36.3;q21.3), t(3;5)(q25.3;q35.1), t(8;16)(p11.2;p13.3), t(1;22)(p13.3;q13.1), t(5;11)(q35.2;p15.4), t(11;12)(p15.4;p13.3) (involving NUP98), translocation involving NUP98 and other partner, t(7;12)(q36.3;p13.2), t(10;11)(p12.3;q14.2), t(16;21)(p11.2;q22.2), inv(16)(p13.3q24.3) and t(16;21)(q24.3;q22.1). In this updated review we describe the available information with regard to frequency, biological functions of the involved genes and the fusion proteins, morphology/immunophenotype, required diagnostic procedures, clinical characteristics (including age distribution) and prognostic impact for each of these 12 genetic abnormalities.

Clinical whole-genome sequencing and FISH identify two different fusion partners for NUP98 in a patient with acute myeloid leukemia: A case report

BACKGROUND

Only rare cases of acute myeloid leukemia (AML) have been shown to harbor a t(8;11)(p11.2;p15.4). This translocation is believed to involve the fusion of NSD3 or FGFR1 with NUP98; however, apart from targeted mRNA quantitative PCR analysis, no molecular approaches have been utilized to define the chimeric fusions present in these rare cases.

CASE PRESENTATION

Here we present the case of a 51-year-old female with AML with myelodysplastic-related morphologic changes, 13q deletion and t(8;11), where initial fluorescence in situ hybridization (FISH) assays were consistent with the presence of NUP98 and FGFR1 rearrangements, and suggestive of NUP98/FGFR1 fusion. Using a streamlined clinical whole-genome sequencing approach, we resolved the breakpoints of this translocation to intron 4 of NSD3 and intron 12 of NUP98, indicating NUP98/NSD3 rearrangement as the likely underlying aberration. Furthermore, our approach identified small variants in WT1 and STAG2, as well as an interstitial deletion on the short arm of chromosome 12, which were cryptic in G-banded chromosomes.

CONCLUSIONS

NUP98 fusions in acute leukemia are predictive of poor prognosis. The associated fusion partner and the presence of co-occurring mutations, such as WT1, further refine this prognosis with potential clinical implications. Using a clinical whole-genome sequencing analysis, we resolved t(8;11) breakpoints to NSD3 and NUP98, ruling out the involvement of FGFR1 suggested by FISH while also identifying multiple chromosomal and sequence level aberrations.