NPM1-mutated myeloid neoplasms are a unique entity not defined by bone marrow blast percentage.

INTRODUCTION: NPM1-mutated (NPM1mut) myeloid neoplasms (MNs) with <20% bone marrow (BM) blasts (NPM1mut MNs<20) are uncommon, and their classification remains inconsistent. METHODS: The clinicopathologic features of 54 patients with NPM1mut MNs <20 were evaluated and compared with wild-type NPM1 MNs <20 and NPM1mut MNs≥20, respectively. RESULTS: NPM1mut MNs had similar features regardless of blast percentage, except for higher IDH2 (29% vs 7%, p = .023) and FLT3 (70% vs 11%, p < .001) frequency in patients with ≥20% BM blasts. Thirty-three (61%) patients with NPM1mut MNs <20 received low-intensity chemotherapy (LIC) and 12 (22%) received intensive chemotherapy (IC). Higher complete remission rates (75% vs 27%, p = .006) and median overall survival (mOS) (not reached vs 30.4 months, p = .06) were observed with IC compared to LIC. Young patients (age <60 years) did not reach mOS either when treated with LIC or IC. Stem cell transplant was associated with increased survival only in patients treated with LIC (HR, 0.24; p = .025). No differences in mOS were observed by BM blast strata (32.2 months, not reached and 46.9 months for <10%, 10%-19%, and ≥20% blasts, p = .700) regardless of treatment modality (LIC: p = .900; IC: p = .360). Twenty-three patients (43%) with NPM1mut MNs <20 had marrow blast progression to ≥20%. CONCLUSIONS: Overall, NPM1mut MNs define a unique entity independent of BM blast percentage.

Overlapping Stromal Alterations in Myeloid and Lymphoid Neoplasms.

Myeloid and lymphoid neoplasms share the characteristics of potential bone marrow infiltration as a primary or secondary effect, which readily leads to hematopoietic insufficiency. The mechanisms by which clonal malignant cells inhibit normal hematopoietic stem and progenitor cells (HSPCs) in the bone marrow (BM) have not been unraveled so far. Given the pivotal role of mesenchymal stromal cells (MSCs) in the regulation of hematopoiesis in the BM niche it is assumed that MSCs also play a relevant role in the pathogenesis of hematological neoplasms. We aimed to identify overlapping mechanisms in MSCs derived from myeloid and lymphoid neoplasms contributing to disease progression and suppression of HSPCs to develop interventions that target these mechanisms. MSCs derived from healthy donors (n = 44) and patients diagnosed with myeloproliferative neoplasia (n = 11), myelodysplastic syndromes (n = 16), or acute myeloid leukemia (n = 25) and B-Non-Hodgkin lymphoma (n = 9) with BM infiltration and acute lymphoblastic leukemia (n = 9) were analyzed for their functionality and by RNA sequencing. A reduced growth and differentiation capacity of MSCs was found in all entities. RNA sequencing distinguished both groups but clearly showed overlapping differentially expressed genes, including major players in the BMP/TGF and WNT-signaling pathway which are crucial for growth, osteogenesis, and hematopoiesis. Functional alterations in healthy MSCs were inducible by exposure to supernatants from malignant cells, implicating the involvement of these factors in disease progression. Overall, we were able to identify overlapping factors that pose potential future therapeutic targets.

Acute Erythroid Leukemia: From Molecular Biology to Clinical Outcomes.

Acute Erythroid Leukemia (AEL) is a rare and aggressive subtype of Acute Myeloid Leukemia (AML). In 2022, the World Health Organization (WHO) defined AEL as a biopsy with ≥30% proerythroblasts and erythroid precursors that account for ≥80% of cellularity. The International Consensus Classification refers to this neoplasm as "AML with mutated TP53". Classification entails ≥20% blasts in blood or bone marrow biopsy and a somatic TP53 mutation (VAF > 10%). This type of leukemia is typically associated with biallelic TP53 mutations and a complex karyotype, specifically 5q and 7q deletions. Transgenic mouse models have implicated several molecules in the pathogenesis of AEL, including transcriptional master regulator GATA1 (involved in erythroid differentiation), master oncogenes, and CDX4. Recent studies have also characterized AEL by epigenetic regulator mutations and transcriptome subgroups. AEL patients have overall poor clinical outcomes, mostly related to their poor response to the standard therapies, which include hypomethylating agents and intensive chemotherapy. Allogeneic bone marrow transplantation (AlloBMT) is the only potentially curative approach but requires deep remission, which is very challenging for these patients. Age, AlloBMT, and a history of antecedent myeloid neoplasms further affect the outcomes of these patients. In this review, we will summarize the diagnostic criteria of AEL, review the current insights into the biology of AEL, and describe the treatment options and outcomes of patients with this disease.

CSF3R mutated myeloid neoplasms: Beyond chronic neutrophilic leukemia.

CSF3R activating mutation is a genetic hallmark of chronic neutrophilic leukemia (CNL), and is also present in a subset of atypical chronic myeloid leukemia (aCML), but infrequent in other myeloid neoplasms. However, the occurrence of CSF3R mutations in various myeloid neoplasms is not well studied. Here we evaluate the spectrum of CSF3R mutations and the clinicopathologic features of CSF3R mutated myeloid neoplasms. We retrospectively identified CSF3R mutations in a variety of myeloid neoplasms: two CNL, three atypical chronic myeloid leukemia (aCML), nine acute myeloid leukemia (AML), one chronic myelomonocytic leukemia, and one myeloproliferative neoplasm. The prototypic T618I mutation was found in 50% of cases: CNL (2/2), aCML (2/3) and AML (4/9). We observed a new recurrent CSF3R mutation Q776* in 25% of cases, and a potential-germline mutation in a 20-year-old patient. Co-occurring mutations were often in epigenetic modifier and spliceosome. IDH/RUNX1 and tumor suppressor mutations were frequent in AML but absent in CNL/aCML. All CNL/aCML patients succumbed within 2-years of diagnosis. We demonstrate that CSF3R mutations are not restricted to CNL. CNL and aCML show similar clinicopathologic and molecular features, suggesting that CNL may be best classified as myelodysplastic/myeloproliferative neoplasm rather than myeloproliferative neoplasm.

Updates on germline predisposition in pediatric hematologic malignancies: What is the role of flow cytometry?

Hematologic neoplasms with germline predisposition have been increasingly recognized as a distinct category of tumors over the last few years. As such, this category was added to the World Health Organization (WHO) 4th edition as well as maintained in the WHO 5th edition and International Consensus Classification (ICC) 2022 classification systems. In practice, these tumors require a high index of suspicion and confirmation by molecular testing. Flow cytometry is a cost-effective diagnostic tool that is routinely performed on peripheral blood and bone marrow samples. In this review, we sought to summarize the current body of research correlating flow cytometric immunophenotype to assess its utility in diagnosis of and clinical decision making in germline hematologic neoplasms. We also illustrate these findings using cases mostly from our own institution. We review some of the more commonly mutated genes, including CEBPA, DDX41, RUNX1, ANKRD26, GATA2, Fanconi anemia, Noonan syndrome, and Down syndrome. We highlight that flow cytometry may have a role in the diagnosis (GATA2, Down syndrome) and screening (CEBPA) of some germline predisposition syndromes, although appears to show nonspecific findings in others (DDX41, RUNX1). In many of the others, such as ANKRD26, Fanconi anemia, and Noonan syndrome, further studies are needed to better understand whether specific flow cytometric patterns are observed. Ultimately, we conclude that further studies such as large case series and organized data pipelines are needed in most germline settings to better understand the flow cytometric immunophenotype of these neoplasms.

BRAF Mutations in Patients with Myeloid Neoplasms: A Cancer Center Multigene Next-Generation Sequencing Analysis Experience.

BRAF mutations are rare in myeloid neoplasms and are reported to be associated with poor treatment outcomes. The purpose of our study is to characterize BRAF mutations in myeloid neoplasms using a next-generation sequencing (NGS) panel based on the experiences of a single cancer center. We conducted a retrospective review of patients with myeloid neoplasms who underwent the HopeSeq studies between January 2018 and September 2023. A total of 14 patients with myeloid neoplasms carrying BRAF mutations were included in our cohort. The clinical, pathological, and molecular features of these patients were investigated. Our study indicates that BRAF mutations are rare in myeloid neoplasms, constituting only 0.53% (14/2632) of all myeloid neoplasm cases, with the most common BRAF mutation being BRAF V600E (4/14; 28.6%). Interestingly, we observed that six out of seven patients with acute myeloid leukemia (AML) exhibited AML with monocytic differentiation, and all the patients with AML exhibited an extremely poor prognosis compared to those without BRAF mutations. TET2 (5/14; 35.7%), ASXL1 (4/14; 28.6%), and JAK2 (4/14; 28.6%) were the three most frequently co-mutated genes in these patients. Moreover, we noted concurrent KMT2A gene rearrangement with BRAF mutations in three patients with AML (3/7; 42.9%). Our study suggests that although BRAF mutations are rare in myeloid neoplasms, they play a crucial role in the pathogenesis of specific AML subtypes. Furthermore, RAS pathway alterations, including BRAF mutations, are associated with KMT2A gene rearrangement in AML. However, these findings warrant further validation in larger studies.

Intensive Reinduction Chemotherapy Followed by Early Allogeneic Hematopoietic Cell Transplantation for Relapsed/Refractory High-Grade Myeloid Neoplasms.

Outcomes for adults with relapsed/refractory (R/R) high-grade myeloid neoplasms remain poor, with allogeneic hematopoietic cell transplantation (HCT) the sole therapy likely to result in cure. We conducted the present study to determine the feasibility of early HCT-within 60 days of beginning reinduction chemotherapy-to see whether getting patients to HCT in an expeditious manner would expand the number of patients being offered this curative option. In this proof-of-principle feasibility study, we included adults age 18 to 75 years with R/R myeloid malignancies with ≥10% blood/marrow blasts at diagnosis who were eligible for a reduced-intensity HCT. Subjects received reinduction chemotherapy with cladribine, cytarabine, mitoxantrone, and filgrastim (CLAG-M) and proceeded to HCT with reduced-intensity conditioning (fludarabine/ melphalan). We enrolled 30 subjects, all of whom received CLAG-M reinduction, although only 9 underwent HCT within 60 days (<15, the predetermined threshold for feasibility "success"), with a median time to HCT of 48 days (range, 42 to 60 days). Eleven additional subjects received HCT beyond the target 60 days (off-study), with a median time to transplantation of 83 days (range, 53 to 367 days). Barriers to early HCT included infection, physician preference, lack of an HLA-matched donor, logistical delays, and disease progression, all of which may limit the real-world uptake of such early-to-transplantation protocols.

Eosinophilia During Lenalidomide Therapy in Myelodysplastic Syndrome.

BACKGROUND: Lenalidomide is an immunomodulatory therapy used to treat multiple hematologic malignancies. The incidence of eosinophilia and hypereosinophilia during lenalidomide therapy, and the requirement for high-dose steroids are not well-defined PATIENTS AND METHODS: We retrospectively reviewed 44 patients with myelodysplastic syndromes who were treated with lenalidomide therapy from August 2006 and March 2023. RESULTS: Eosinophilia (0.5-1.5 × 109/L) and hypereosinophilia (>1.5 × 109/L) were observed in 6 patients (14%) and 4 patients (9%), respectively. The median duration of lenalidomide therapy was 6.5 months. Backward multivariate ordinary logistic regression identified higher absolute eosinophil count (OR, 4759.986; 95% CI, 11.223-2018772.073; P = .006) and longer duration of lenalidomide therapy (OR, 1.148; 95% CI, 1.012-1.302; P = .032) as independent prognostic factors for the incidence of eosinophilia and hypereosinophilia. There was a trend for a higher use of high-dose steroids with hypereosinophilia. The median time to develop the first occurrence hypereosinophilia was 0.5 months. Steroids were used in 40% of patients with eosinophilia or hypereosinophilia. All events resolved with discontinuation of lenalidomide and/or use of steroids. No long-tern lasting adverse effects were recorded. CONCLUSION: Lenalidomide may induce or worsen existing eosinophilia which may lead to the need for steroids within a month of therapy.

CUX1 regulates human hematopoietic stem cell chromatin accessibility via the BAF complex.

CUX1 is a homeodomain-containing transcription factor that is essential for the development and differentiation of multiple tissues. CUX1 is recurrently mutated or deleted in cancer, particularly in myeloid malignancies. However, the mechanism by which CUX1 regulates gene expression and differentiation remains poorly understood, creating a barrier to understanding the tumor-suppressive functions of CUX1. Here, we demonstrate that CUX1 directs the BAF chromatin remodeling complex to DNA to increase chromatin accessibility in hematopoietic cells. CUX1 preferentially regulates lineage-specific enhancers, and CUX1 target genes are predictive of cell fate in vivo. These data indicate that CUX1 regulates hematopoietic lineage commitment and homeostasis via pioneer factor activity, and CUX1 deficiency disrupts these processes in stem and progenitor cells, facilitating transformation.

Molecular Pathology of Myeloid Neoplasms: Molecular Pattern Recognition.

Despite the apparent complexity of the molecular genetic underpinnings of myeloid neoplasms, most myeloid mutational profiles can be understood within a simple framework. Somatic mutations accumulate in hematopoietic stem cells with aging and toxic insults, termed clonal hematopoiesis. These "old stem cells" mutations, predominantly in the epigenetic and RNA spliceosome pathways, act as "founding" driver mutations leading to a clonal myeloid neoplasm when sufficient in number and clone size. Subsequent mutations can create the genetic flavor of the myeloid neoplasm ("backseat" drivers) due to their enrichment in certain entities or act as progression events ("aggressive" drivers) during clonal evolution.

Myeloid neoplasms post cytotoxic therapy: epidemiology, pathogenesis outcomes, prognostic factors, and treatment options.

Myeloid neoplasms post cytotoxic therapy (MN-pCT) are a category includes AML, MDS, and MDS/MPN arising in patients exposed to cytotoxic (DNA-damaging) therapy for an unrelated condition in 2022 version World Health Organization (WHO) classification. With improved survival of patients with tumors, the incidence of MN-pCT after chemotherapy and/or radiation therapy among patients with tumors has gradually risen. However, the outcome of MN-pCT is poorer than that of primary myeloid neoplasms. This review summarizes the current understanding based on existing research, as a foundation for further research on MN-pCT.

Germline assessment for alloHSCT candidates over 50 years: A 'Fast-Track' screening in myeloid neoplasms.

Patients aged 50 or above diagnosed with myeloid neoplasms (MNs) are typically not candidates for germline testing. However, approximately 8% carry pathogenic germline variants. Allogeneic haematopoietic stem cell transplantation (alloHSCT) remains an option for those aged over 50; neglecting germline testing could mask the risk for relative donor cell-derived MN. We propose a germline-augmented somatic panel (GASP), combining MN predisposition genes with a myeloid somatic panel for timely germline variant identification when initial testing is not indicated. Out of our 133 whole-exome-sequenced MN cases aged over 50 years, 9% had pathogenic/likely variants. GASP detected 92%, compared to 50% with somatic-only panel. Our study highlights the relevance of germline screening in MN, particularly for alloHSCT candidates without established germline-testing recommendations.

Role of the STING pathway in myeloid neoplasms: a prospero-registered systematic review of principal hurdles of STING on the road to the clinical practice.

Myeloid neoplasms are a group of bone marrow diseases distinguished by disruptions in the molecular pathways that regulate the balance between hematopoietic stem cell (HSC) self-renewal and the generation of specialized cells. Cytokines and chemokines, two important components of the inflammatory process, also influence hematological differentiation. In this scenario, immunological dysregulation plays a pivotal role in the pathogenesis of bone marrow neoplasms. The STING pathway recognizes DNA fragments in the cell cytoplasm and triggers an immune response by type I interferons. The role of STING in cancer has not yet been established; however, both actions, as an oncogene or tumor suppressor, have been documented in other types of cancer. Therefore, we performed a systematic review (registered in PROSPERO database #CRD42023407512) to discuss the role of STING pathway in the advancement of pathogenesis and/or prognosis for different myeloid neoplasms. In brief, scientific evidence supports investigations that primarily use cell lines from myeloid neoplasms, such as leukemia. More high-quality research and clinical trials are needed to understand the role of the STING pathway in the pathology of hematological malignancies. Finally, the STING pathway suggests being a promising therapeutic molecular target, particularly when combined with current drug therapies.

Germline predisposition to myeloid neoplasms: Characteristics and management of high versus variable penetrance disorders.

Myeloid neoplasms with germline predisposition have been recognized increasingly over the past decade with numerous newly described disorders. Penetrance, age of onset, phenotypic heterogeneity, and somatic driver events differ widely among these conditions and sometimes even within family members with the same variant, making risk assessment and counseling of these individuals inherently difficult. In this review, we will shed light on high malignant penetrance (e.g., CEBPA, GATA2, SAMD9/SAMD9L, and TP53) versus variable malignant penetrance syndromes (e.g., ANKRD26, DDX41, ETV6, RUNX1, and various bone marrow failure syndromes) and their clinical features, such as variant type and location, course of disease, and prognostic markers. We further discuss the recommended management of these syndromes based on penetrance with an emphasis on somatic aberrations consistent with disease progression/transformation and suggested timing of allogeneic hematopoietic stem cell transplant. This review will thereby provide important data that can help to individualize and improve the management for these patients.

Genomic testing for germline predisposition to hematologic malignancies.

Germline predisposition (GPD) to hematological malignancies has gained interest because of the increased use of genetic testing in this field. Recent studies have suggested that GPD is underrecognized and requires appropriate genomic testing for an accurate diagnosis. Identification of GPD significantly affects patient management and has diverse implications for family members. This review discusses the reasons for testing GPD in hematologic malignancies and explores the considerations necessary for appropriate genomic testing. The aim is to provide insights into how these genetic insights can inform treatment strategies and genetic counseling, ultimately enhancing patient care.

Successful management of acute graft-versus-host disease with ibrutinib during cord blood transplantation for germline DDX41-mutated acute myeloid leukemia.

Background: Acute graft-versus-host disease (GVHD) is a major complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT) with significant morbidity and mortality, and efficacy of currently available therapeutics are limited. Acute and chronic GVHD are similar in that both are initiated by antigen presenting cells and activation of alloreactive B-cells and T-cells, subsequently leading to inflammation, tissue damage, and organ failure. One difference is that acute GVHD is mostly attributed to T-cell activation and cytokine release, whereas B-cells are the key players in chronic GVHD. Ibrutinib is an irreversible inhibitor of the Bruton's tyrosine kinase (BTK), which is part of B-cell receptor signaling. Ibrutinib is currently used for treating chronic GVHD, but its efficacy towards acute GVHD is unknown. Besides BTK, ibrutinib also inhibits interleukin-2 inducible T-cell kinase (ITK), which is predominantly expressed in T-cells and a crucial enzyme for activating the downstream pathway of TCR signaling. ITK activates PLCγ2 and facilitates signaling through NF-κB, NFAT, and MAPK, leading to activation and proliferation of T-cells and enhanced cytokine production. Therefore, the TCR signaling pathway is indispensable for development of acute GVHD, and ITK inhibition by ibrutinib would be a rational therapeutic approach. Case presentation: A 56-year-old male acute myeloid leukemia patient with Myeloid neoplasms with germline DEAD-box RNA helicase 41 (DDX41) mutation underwent cord blood transplantation and developed severe gastrointestinal (GI) acute GVHD which was refractory to steroids and mesenchymal stem cell therapy. While acute GVHD accommodated by multiple life-threatening GI bleeding events persisted, chronic cutaneous GVHD developed, and ibrutinib 420 mg/day was initiated from day 147 of transplant. Although ibrutinib was commenced targeting the chronic GVHD, unexpected and abrupt remission of acute GVHD along with remission of chronic GVHD was observed. Conclusion: Ibrutinib is a promising therapeutic for treating acute GVHD, and further studies are warranted.

The crossroads of cancer therapies and clonal hematopoiesis.

The intricate interplay between Clonal Hematopoiesis (CH) and the repercussions of cancer therapies has garnered significant research focus in recent years. Previously perceived as an age-related phenomenon, CH is now closely linked to inflammation ("Inflammaging") and cancer, impacting leukemogenesis, cancer progression, and treatment responses. This review explores the complex interplay between CH and diverse cancer therapies, including chemotherapy, targeted treatments, radiation, stem cell transplants, CAR-T cell therapy, and immunotherapy, like immune checkpoint inhibitors. Notably, knowledge about post-chemotherapy CH mutation/acquisition has evolved from a de novo incident to more of a clonal selection process. Chemotherapy and radiation exposure, whether therapeutic or environmental, increases CH risk, particularly in genes like TP53 and PPM1D. Environmental toxins, especially in high-risk environments like post-disaster sites or space exploration, are associated with CH. CH affects clinical outcomes in stem cell transplant scenarios, including engraftment, survival, and t-MN development. The presence of CH also alters CAR-T cell therapy responses and impacts the efficacy and toxicity of immunotherapies. Furthermore, specific mutations like DNMT3A and TET2 thrive under inflammatory stress, influencing therapy outcomes and justifying the ongoing tailored interventions in clinical trials. This review underscores the critical need to integrate CH analysis into personalized medicine, enhancing risk assessments and refining treatment strategies. As we progress, multidisciplinary collaboration and comprehensive studies are imperative. Understanding CH's impact, especially concerning genotoxic stressors, will inform screening, surveillance, and early detection strategies, decreasing the risk of therapy-related myeloid neoplasms and revolutionizing cancer treatment paradigms.

Immunohistochemistry screening for TP53 mutation in myeloid neoplasms in AZF-fixed bone marrow biopsies.

TP53 mutational status in myeloid neoplasms is prognostic and in acute myeloid leukaemia (AML) may lead to alternative induction therapy; therefore, rapid assessment is necessary for precision treatment. Assessment of multiple prognostic genes by next generation sequencing in AML is standard of care, but the turn-around time often cannot support rapid clinical decision making. Studies in haematological neoplasms suggest p53 immunohistochemistry (IHC) correlates with TP53 mutational status, but they have used variable criteria to define TP53 overexpression. p53 IHC was performed and interpreted on AZF-fixed, acid decalcified bone marrow biopsies on 47 cases of clonal myeloid neoplasms with TP53 mutations between 2016 and 2019 and 16 control samples. Results were scored by manual and digital analysis. Most TP53-mutated cases (81%) overexpressed p53 by digital analysis and manual analysis gave similar results. Among the nine TP53-mutated IHC-negative cases, seven (78%) were truncating mutations and two (22%) were single-hit missense mutations. Using a digital cut-off of at least 3% ≥1+ positive nuclei, the sensitivity and specificity are 81% and 100%; cases with loss-of-function mutations were more likely to be negative. In this cohort, p53 immunopositivity correlated with TP53 mutational status, especially missense mutations, with excellent specificity. Truncating TP53 mutations explain most IHC-negative cases, impacting the sensitivity. We demonstrate that p53 IHC can screen for TP53 mutations allowing quicker treatment decisions for most patients. However, not all patients will be identified, so molecular studies are required. Furthermore, cut-offs for positivity vary in the literature, consequently laboratories should independently validate their processes before adopting p53 IHC for clinical use. p53 IHC performs well to screen for TP53 mutations in AZF-fixed bone marrow. Performance in our setting differs from the literature, which shows variability of pre-analytic factors and cut-offs used to screen for TP53 mutations. Each laboratory should validate p53 IHC to screen for TP53 mutations in their unique setting.