JAK2 Alterations in Acute Lymphoblastic Leukemia: Molecular Insights for Superior Precision Medicine Strategies

The Role of the JAK-STAT Pathway in Childhood B-Cell Acute Lymphoblastic Leukemia

B-cell lymphoblastic leukemia is a hematologic neoplasm that poses a serious health concern in childhood. Genetic aberrations, such as mutations in the genes IL-7, IL7R, JAK1, JAK2, TLSP, CRLF2, and KTM2A or gene fusions involving BCR::ABL1, ETV6::RUNX1, and PAX5::JAK2, often correlate with the onset of this disease. These aberrations can lead to malfunction of the JAK-STAT signaling pathway, which is implicated in various important biological processes, including those related to immunology. Understanding the mechanisms underlying the malfunction of the JAK-STAT pathway holds potential for research on drugs targeting its components. Available drugs that interfere with the JAK-STAT pathway include fludarabine, ruxolitinib, and fedratinib.

Transcriptome analysis of primary adult B-cell lineage acute lymphoblastic leukemia identifies pathogenic variants and gene fusions, and predicts subtypes for in depth molecular diagnosis

BACKGROUND

B-cell acute lymphoblastic leukemia (B-ALL) is classified into subgroups based on known driver oncogenes and molecular lesions, including translocations and recurrent mutations. However, the current diagnostic tests do not identify subtypes or oncogenic lesions for all B-ALL samples, creating a heterogeneous B-ALL group of unknown subtypes.

METHODS

We sorted primary adult B-ALL cells and performed transcriptome analysis by bulk RNA sequencing (RNA-seq).

RESULTS

Transcriptomic analysis of an adult B-ALL cohort allowed the classification of four patient samples with subtypes that were not previously revealed by standard gene panels. The leukemia of two patients were of the DUX4 subtype and two were CRLF2+ Ph-like B-ALL. Furthermore, single nucleotide variant analysis detected the oncogenic NRAS-G12D, KRAS-G12D, and KRAS-G13D mutations in three of the patient samples, presenting targetable mutations. Additional oncogenic variants and gene fusions were uncovered, as well as multiple variants in the PDE4DIP gene across five of the patient samples.

CONCLUSION

We demonstrate that RNA-seq is an effective tool for precision medicine in B-ALL by providing comprehensive molecular profiling of leukemia cells, identifying subtype and oncogenic lesions, and stratifying patients for appropriate therapy.

Mechanisms and therapeutic prospect of the JAK-STAT signaling pathway in liver cancer

Liver cancer (LC) poses a significant global health challenge due to its high incidence and poor prognosis. Current systemic treatment options, such as surgery, chemotherapy, radiofrequency ablation, and immunotherapy, have shown limited effectiveness for advanced LC patients. Moreover, owing to the heterogeneous nature of LC, it is crucial to uncover more in-depth pathogenic mechanisms and develop effective treatments to address the limitations of the existing therapeutic modalities. Increasing evidence has revealed the crucial role of the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway in the pathogenesis of LC. The specific mechanisms driving the JAK-STAT pathway activation in LC, participate in a variety of malignant biological processes, including cell differentiation, evasion, anti-apoptosis, immune escape, and treatment resistance. Both preclinical and clinical investigations on the JAK-STAT pathway inhibitors have exhibited potential in LC treatment, thereby opening up avenues for the development of more targeted therapeutic strategies for LC. In this study, we provide an overview of the JAK-STAT pathway, delving into the composition, activation, and dynamic interplay within the pathway. Additionally, we focus on the molecular mechanisms driving the aberrant activation of the JAK-STAT pathway in LC. Furthermore, we summarize the latest advancements in targeting the JAK-STAT pathway for LC treatment. The insights presented in this review aim to underscore the necessity of research into the JAK-STAT signaling pathway as a promising avenue for LC therapy.

Non-coding RNAs: Emerging biomarkers and therapeutic targets in ulcerative colitis

Ulcerative colitis (UC) is a persistent inflammatory condition affecting the colon's mucosal lining, leading to chronic bowel inflammation. Despite extensive research, the precise molecular mechanisms underlying UC pathogenesis remain elusive. NcRNAs form a category of functional RNA molecules devoid of protein-coding capacity. They have recently surfaced as pivotal modulators of gene expression and integral participants in various pathological processes, particularly those related to inflammatory disorders. The diverse classes of ncRNAs, encompassing miRNAs, circRNAs, and lncRNAs, have been implicated in UC. It highlights their involvement in key UC-related processes, such as immune cell activation, epithelial barrier integrity, and the production of pro-inflammatory mediators. ncRNAs have been identified as potential biomarkers for UC diagnosis and monitoring disease progression, offering promising avenues for personalized medicine. This approach may pave the way for novel, more specific treatments with reduced side effects, addressing the current limitations of conventional therapies. A comprehensive understanding of the interplay between ncRNAs and UC will advance our knowledge of the disease, potentially leading to more effective and personalized treatments for patients suffering from this debilitating condition. This review explores the pivotal role of ncRNAs in the context of UC, shedding light on their possible targets for diagnosis, prognosis, and therapeutic interventions.

Clinical features and prognosis of pediatric acute lymphocytic leukemia with JAK-STAT pathway genetic abnormalities: a case series

The objective of this study is to explore the clinical features and outcomes of pediatric patients with acute lymphoblastic leukemia (ALL) harboring JAK-STAT signaling pathway genetic abnormalities. This retrospective case series examined the clinical data of pediatric patients diagnosed with ALL harboring JAK-STAT pathway genetic abnormality at the Children's Hospital of the Capital Institute of Pediatrics between January 2016 and January 2022. Bone marrow next-generation sequencing was used to reveal the JAK pathway abnormalities. Descriptive statistics were used. From 432 children with ALL during the study period, eight had JAK-STAT pathway genetic abnormalities. Regarding immunotyping, there were four patients with common-B cell types and one with pre-B cell type. The three patients with T-ALL had early T-cell precursor(ETP) type, pre-T cell type, and T cell type. Gene mutations were more common than fusion genes. There was no central nervous system involvement in eight patients. All patients were considered at least at intermediate risk before treatments. Four patients underwent hematopoietic stem cell transplantation (HSCT). One child had a comprehensive relapse and died. The child had a severe infection and could not tolerate high-intensity chemotherapy. Another child relapsed 2 years after HSCT and died. Disease-free survival was achieved in six children. JAK-STAT pathway genetic abnormalities in pediatric Ph-like ALL are rare. Special attention should be paid to treatment-related complications, such as infection and combination therapy (chemotherapy, small molecule targeted drugs, immunotherapy, etc.) to reduce treatment-related death and improve long-term quality of life.

New scaffolds for type II JAK2 inhibitors overcome the acquired G993A resistance mutation

Recurrent JAK2 alterations are observed in myeloproliferative neoplasms, B-cell acute lymphoblastic leukemia, and other hematologic malignancies. Currently available type I JAK2 inhibitors have limited activity in these diseases. Preclinical data support the improved efficacy of type II JAK2 inhibitors, which lock the kinase in the inactive conformation. By screening small molecule libraries, we identified a lead compound with JAK2 selectivity. We highlight analogs with on-target biochemical and cellular activity and demonstrate in vivo activity using a mouse model of polycythemia vera. We present a co-crystal structure that confirms the type II binding mode of our compounds with the "DFG-out" conformation of the JAK2 activation loop. Finally, we identify a JAK2 G993A mutation that confers resistance to the type II JAK2 inhibitor CHZ868 but not to our analogs. These data provide a template for identifying novel type II kinase inhibitors and inform further development of agents targeting JAK2 that overcome resistance.

PAX5 fusion genes in acute lymphoblastic leukemia: A literature review

Acute lymphoblastic leukemia (ALL) is a common cancer affecting children worldwide. The development of ALL is driven by several genes, some of which can be targeted for treatment by inhibiting gene fusions. PAX5 is frequently mutated in ALL and is involved in chromosomal rearrangements and translocations. Mutations in PAX5 interact with other genes, such as ETV6 and FOXP1, which influence B-cell development. PAX5/ETV6 has been observed in both B-ALL patients and a mouse model. The interaction between PAX5 and FOXP1 negatively suppresses the Pax5 gene in B-ALL patients. Additionally, ELN and PML genes have been found to fuse with PAX5, leading to adverse effects on B-cell differentiation. ELN-PAX5 interaction results in the decreased expression of LEF1, MB1, and BLNK, while PML-PAX5 is critical in the early stages of leukemia. PAX5 fusion genes prevent the transcription of the PAX5 gene, making it an essential target gene for the study of leukemia progression and the diagnosis of B-ALL.

Clinicopathologic characteristics, genetic features, and treatment options for acute lymphoblastic leukemia with JAK2 rearrangement-A 10-case study and literature review

JAK2 rearrangement (JAK2-R) in acute lymphoblastic leukemia (ALL) is rare and often categorized as B-ALL with BCR::ABL1-like features based on the World Health Organization classification. We report 10 patients with JAK2-R ALL, 9 males and 1 female, with a median age 40.5 years. Eight patients presented with marked leukocytosis (median WBC, 63 × 10 ⁹/L) and hypercellular (>95%) bone marrow with increased lymphoblasts (72%-95%). There was no evidence of bone marrow fibrosis or hypereosinophilia. Immunophenotypic analysis showed 9 B-cell and 1 T-cell neoplasms. Using fluorescence in situ hybridization (FISH) and RNA sequencing analysis, JAK2 partners were identified for 7 cases and included PCM1 (n=4), ETV6 (n=2) and BCR (n=1). All patients received upfront polychemotherapy. Additionally, 2 patients received ruxolitinib, 2 received allogeneic stem cell transplant, and 1 received CAR-T therapy. The 1- and 3-year overall survival rates were 55.6% and 22.2%, respectively. A literature review identified 24 B-ALL and 4 T-ALL cases with JAK2-R reported, including 16 males, 6 females and 6 gender not stated. Many JAK2 partner-genes were reported with the most common being PAX5 (n=7), ETV6 (n=4), BCR (n=3) and PCM1 (n=2). Survival data or 13 reported cases showed 1- and 3-year overall survival rates of 41.7% and 41.7%, respectively. In summary, JAK2-R ALL occurs more often in adult males, are mostly of B-cell lineage, and associated with an aggressive clinical course. Absence of eosinophilia and bone marrow fibrosis and no evidence of preexisting/concurrent JAK2-R myeloid neoplasms distinguish JAK2-R ALL from other myeloid/lymphoid neoplasms with eosinophilia and JAK2-R.

Clonal heamatopoiesis and associated cardiovascular diseases

Cancer and cardiovascular disease share several risk factors. Clonal heamatopoiesis, a novel risk factor associated with both diseases, has received increasing attention in the fields of cardiology, heamatology and oncology. Clonal heamatopoiesis of indeterminate potential refers to the presence of at least one driver mutation in the heamatopoietic cells of peripheral blood without heamatological malignancy. Clonal heamatopoiesis of indeterminate potential is a common age-related condition that affects up to 60% of individuals aged > 80 years. Importantly, clonal heamatopoiesis of indeterminate potential carriers have a 2- to 4-fold higher risk of developing cardiovascular disease than non-carriers. Therefore, we performed an up-to-date review of clonal heamatopoiesis and its association with various forms of cardiovascular disease, including atherosclerotic disease, heart failure, aortic stenosis and pulmonary hypertension. In addition, we reviewed experimental studies that examined the causality and directionality between clonal heamatopoiesis and cardiovascular disease. Lastly, we discussed future research directions that will aid in the design of personalized therapies and preventive strategies for individuals with clonal heamatopoiesis. This review showed that clonal heamatopoiesis of indeterminate potential is a common condition, especially in older patients, and is associated with an increased risk of cardiovascular disease and worse prognosis. However, further research is needed to determine whether anti-inflammatory therapies or therapies that can reduce or eliminate clone size are effective in preventing cardiovascular disease in patients with clonal heamatopoiesis of indeterminate potential.

TSLP as a Potential Therapy in the Treatment of CRLF2 B Cell Acute Lymphoblastic Leukemia

Cytokine receptor-like factor 2 B-cell acute lymphoblastic leukemia (CRLF2 B-ALL) is a high-risk subtype characterized by CRLF2 overexpression with poor survival rates in children and adults. CRLF2 and interleukin-7 receptor alpha (IL-7Rα) form a receptor for the cytokine thymic stromal lymphopoietin (TSLP), which induces JAK/STAT and PI3K/AKT/mTOR pathway signals. Previous studies from our group showed that low TSLP doses increased STAT5, AKT, and S6 phosphorylation and contributed to CRLF2 B-ALL cell survival. Here we investigated the role of TSLP in the survival and proliferation of CRLF2 B-ALL cells in vitro and in vivo. We hypothesized that high doses of TSLP increase CRLF2 signals and contribute to increased proliferation of CRLF2 B-ALL cells in vitro and in vivo. Interestingly, we observed the opposite effect. Specifically, high doses of TSLP induced apoptosis in human CRLF2 B-ALL cell lines in vitro, prevented engraftment of CRLF2 B-ALL cells, and prolonged the survival of +TSLP patient-derived-xenograft mice. Mechanistically, we showed that high doses of TSLP induced loss of its receptor and loss of CRLF2 signals in vitro. These results suggest that high doses of TSLP could be further investigated as a potential therapy for the treatment of CRLF2 B-ALL.

Case Report: Whole genome sequencing identifies CCDC88C as a novel JAK2 fusion partner in pediatric T-cell acute lymphoblastic leukemia

In the present report, we applied whole genome sequencing (WGS) to genetically characterize a case of pediatric T-cell acute lymphoblastic leukemia (ALL) refractory to standard therapy. WGS identified a novel JAK2 fusion, with CCDC88C as a partner. CCDC88C encodes a protein part of the Wnt signaling pathway and has previously been described in hematological malignancies as fusion partner to FLT3 and PDGFRB. The novel CCDC88C::JAK2 fusion gene results in a fusion transcript, predicted to produce a hybrid protein, which retains the kinase domain of JAK2 and is expected to respond to JAK2 inhibitors. This report illustrates the potential of WGS in the diagnostic setting of ALL.