Introduction Nadir bone marrow biopsies (BM Bx) are routinely performed around day 14 to assess early response to AML intensive induction therapy. The presence of residual disease prompts initiation of reinduction therapy, often with another cycle of intensive chemotherapy. Whether there are characteristics of nadir BM Bx that predict for response to intensive reinduction is unknown. To evaluate this, we analyzed data from ECOG-ACRIN clinical trials in AML of intensive induction chemotherapy with nadir biopsy information available to determine predictors of outcomes after reinduction. Methods We included patients from ECOG-ACRIN E1900 (Fernandez NEJM 2009) and arm A of E2906 (Foran ASH 2015) who received induction therapy with daunorubicin and cytarabine (7+3), had residual disease (blasts ≥5% or cellularity ≥20%) at nadir BM Bx and received reinduction chemotherapy. Nadir BM Bx characteristics that were evaluated included blast percentage and cellularity as well as both absolute and relative (percentage change, e.g. 20% to 10% = -50%) differences calculated between diagnosis and nadir for each parameter. Complete remission (CR) after reinduction therapy, disease free survival (DFS) and overall survival (OS) were outcomes for all analyses. Logistic regression models were used to evaluate associations with CR, and Cox proportional hazards models were used for DFS and OS. For models evaluating changes in blast percentage or cellularity as predictors, baseline blast percentage or cellularity was included as a covariate, respectively. Results Of 1013 patients identified, 750 (74%) had a nadir biopsy, 233 (23%) had evidence of residual disease, received reinduction therapy, and were included in the primary analysis. The median age was 58 and 42% were female. Cytogenetic risk category (by ELN2017) was adverse in 31%, intermediate in 66% and favorable in 3%. The median nadir BM Bx blast was 30% (range 0 to +97%) and cellularity was 20% (0 to +100%). The median absolute difference in blast percentage between baseline and nadir BM Bx was -15% (-95% to +66%) with a median relative difference of -36% (-100% to +400%). After reinduction, 118 patients (52%) achieved a CR. Neither absolute difference in blast percentage (OR 0.99, 95%CI 0.98-1.00, p=0.20) nor relative difference (OR 1.00, 95%CI 0.99-1.00, p=0.33) predicted CR. There was similarly no association with DFS (HR = 1.00, 95%CI: 0.99-1.01, p=0.65) or OS (HR = 1.00, 95%CI 0.99-1.01, p=0.76). Blast reduction ≥50% similarly did not predict these outcomes. We also evaluated the impact of any reduction in blast percentage (responders) from baseline to nadir and again found no association with CR (OR 1.65, 95%CI 0.90-3.03, p=0.11). Similarly, there was no association with DFS (HR 0.74, 95%CI 0.51-1.09, p=0.13) or OS (HR 0.81, 95%CI 0.58-1.13, p=0.21) in responders vs nonresponders. No association with CR, DFS or OS were identified when performing the same analysis in intermediate and adverse cytogenetic subgroups. We found no association with CR when nadir cellularity was assessed as a continuous variable (OR 0.99, 95%CI 0.98-1.00, p=0.10) or by relative difference (OR 0.99, 95%CI 0.99-1.00, p=0.10). There was a trend towards association with absolute reduction in cellularity from baseline to nadir and CR (OR 0.99, 95%CI 0.98-1.00, p=0.06). No association was identified between relative difference in cellularity and DFS and OS, nor was there an association among cytogenetic risk subgroups with any outcome. Discussion In intensively treated patients with residual disease at nadir BM Bx (i.e. day 14) who received intensive reinduction, the likelihood of achieving a CR was not influenced by the magnitude of disease reduction nor the extent of disease at the time of nadir biopsy. Similarly, there were no nadir biopsy features that predicted DFS or OS after intensive reinduction therapy. Given alternative reinduction therapies such as hypomethylating agents and venetoclax are available, these results suggest that the decision to attempt a second intensive induction cycle following the unequivocal presence of residual disease should not be influenced by characteristics of the nadir BM Bx. Although patient-specific factors such as patient fitness may favor a switch to less intensive options, these results support consideration of intensive reinduction therapy in patients with residual disease at nadir biopsy, even without changes in blasts or cellularity.

Abstract Myelodysplastic syndromes (MDS) are clinically and biologically diverse disorders, emphasizing the need for personalized treatment approaches. The International Working Group for Prognostication of MDS (IWG_PM) recently introduced a molecular classification, referred to as the MDS taxonomy, that categorizes patients into 16 subgroups based on 21 gene mutations, 6 cytogenetic abnormalities, and loss of heterozygosity (LOH) at TP53 and TET2 loci. This study sought to validate and enhance the clinical relevance of the MDS taxonomy by analyzing a large retrospective cohort (n = 5136) and transcriptomic data from a prospective cohort (n = 477). The taxonomy successfully identified subgroups with distinct clinical characteristics and disease progression patterns. However, incorporating gene interactions from taxonomy subgroups did not improve the prognostic performance of the Molecular International Prognostic Scoring System (IPSS‐M). We further assessed whether the taxonomy could guide management in patients receiving disease‐modifying therapies. Except for the “TP53‐complex” subgroup, taxonomy classifications were not predictive of hypomethylating agent response or transplant outcomes. Nonetheless, they correlated with overall survival, suggesting that while both IPSS‐M and the taxonomy capture disease biology, other non‐genetic factors may influence treatment response. RNA sequencing confirmed the biological distinctiveness of the taxonomy groups. Transcriptomic profiling of CD34+ bone marrow cells revealed unique, homogeneous gene expression patterns, particularly within the AML‐like, biTET2, SF3B1, and TP53‐complex subgroups. Further integration of multi‐omics data may refine MDS classification, improving clinical decision‐making and guiding the development of targeted therapies.

Excessively restrictive inclusion and exclusion criteria in clinical trials are one of many barriers to clinical trial enrollment for patients with myelodysplastic syndromes/neoplasms (MDSs). Many organizations are developing efforts to increase clinical trial eligibility; yet, several recent publications focused on patients with MDS suggest that many patients with this disease may be excluded from clinical trials unnecessarily. Clinical trial eligibility should reflect the phase of the study and risks of the agent being studied. Phase 3 trials should be less restrictive than early-phase trials to represent the real-world population as closely as possible. We hypothesize that many clinical trials, particularly phase 3 trials, have unnecessarily restrictive eligibility criteria. This study aims to evaluate the most common eligibility criteria according to phase of trial and to determine whether criteria correspond with drug safety signals. We identified MDS clinical trials registered on ClinicalTrials.gov from 1 January 2000 to 1 September 2023 and analyzed the eligibility criteria of 191 therapeutic MDS trials. We found that categorical inclusion and exclusion criteria are remarkably similar in representation across trial phases. Additionally, only 13% of trials are concordant with drug safety signals, suggesting that the eligibility criteria are often arbitrary. On behalf of the icMDS (International Consortium for Myelodysplastic Syndromes), an association of international MDS experts, we provide a position statement on restrictive eligibility criteria for MDS clinical trials that should be avoided with the aim of removing barriers to clinical trial enrollment.

The NCCN Guidelines for Myelodysplastic Syndromes (MDS) provide recommendations for the evaluation, diagnosis, and comprehensive care of patients with MDS based on a review of recent clinical evidence that has led to important advances in treatment or has yielded new information on biologic factors that may have prognostic significance in MDS. The multidisciplinary panel of MDS experts is convened at least on an annual basis. During the annual meeting, the panel evaluates new and emerging data to inform their recommendations. These NCCN Guidelines Insights review the recent updates, including treatment recommendations both for lower-risk and higher-risk MDS, preference stratification of therapeutic agents, and emerging data on novel therapeutics.

The NCCN Guidelines for Myelodysplastic Syndromes (MDS) provide recommendations for the evaluation, diagnosis, and comprehensive care of patients with MDS based on a review of recent clinical evidence that has led to important advances in treatment or has yielded new information on biologic factors that may have prognostic significance in MDS. The multidisciplinary panel of MDS experts is convened at least on an annual basis. During the annual meeting, the panel evaluates new and emerging data to inform their recommendations. These NCCN Guidelines Insights review the recent updates, including treatment recommendations both for lower-risk and higher-risk MDS, preference stratification of therapeutic agents, and emerging data on novel therapeutics.

CONTEXT.—:Standardized bone marrow reporting specifically for myelodysplastic syndromes/neoplasms (MDS) is currently lacking in the literature and much needed in practice. OBJECTIVE.—:To propose a standardized approach to MDS evaluation in bone marrow specimens by (1) enhancing interinstitutional and intrainstitutional collaborations and clinical decision-making among hematopathologists and clinical hematologists and (2) allowing for efficient data extraction for clinical trials, institutional databases, and registry templates. This suggested approach is summarized in a modifiable, user-friendly template for hematopathologists to reference as they examine bone marrows (in the Supplemental Digital Content). DATA SOURCES.—:We built upon the bone marrow template reporting guideline outlined by the College of American Pathologists Pathology and Laboratory Quality Center for Evidence-Based Guidelines and gathered expert insight from hematopathologists and hematologists-oncologists who specialize in MDS. CONCLUSIONS.—:This proposed approach to MDS evaluation in the bone marrow standardizes reporting, which enhances communication among health care professionals and allows for efficient data extraction.

The year 2026 marks the semi-centennial of the first iteration of the classification schema for myeloid neoplasms, namely the 1976 French-American-British (FAB) classification created by John M. Bennett and colleagues. The FAB classification of acute leukemia formed the biological framework of our current understanding of myeloid neoplasia. Reflecting from this historical lens, we have seen remarkable advances in diagnostics, prognostication, and therapeutics over the decades. Concerted efforts from various consensus groups have paved the way for these advances. Herein, we perform a historical analysis of the evolution of the nosology of myeloid neoplasms over the past 50 years, beginning with the landmark 1976 FAB classification. We discuss how the new nosology of myeloid neoplasms has been inspired by the widespread availability of next-generation sequencing technology as a critical adjunct to classical morphological assessment. We discuss evidence in support of a conceptual framework for categorizing myeloid neoplasms based on ontogeny, beginning from clonal hematopoiesis of indeterminate potential (CHIP). We review the foundational definitions of CHIP, including parallels with Darwinism at the cellular level, and the relevance of incorporation of precursor conditions into the most recent disease classification of myeloid neoplasms. We shed light onto patient-focused practical implications of classification schema, with emphasis on mutation-adapted therapeutic strategies. Finally, we discuss how emerging techniques such as single-cell sequencing and multi-omics may integrate into future revisions.

Methods for introducing subtle modifications at the level of single atoms/bonds (“skeletal editing”) are highly desirable in organic and medicinal chemistry, owing to their potential for fine‐tuning the structure and biological activity of organic molecules. Here, we report a chemoenzymatic strategy for enabling the skeletal editing of organic frameworks via ring expansion at the level of one or more aliphatic (methylene) C─H sites, as achieved through the synergistic combination of P450‐mediated site‐selective oxidation with subsequent Baeyer–Villiger rearrangement or ketone homologation. Combining this approach with engineered P450 catalysts exhibiting divergent regioselectivity enabled the expeditious synthesis of a panel of ring‐expanded analogs of various complex natural product substrates. Importantly, the skeletal modification was found to drastically altered the anticancer activity of some of these compounds. By the direct targeting of aliphatic C─H sites with tunable site‐selectivity, this strategy provides a powerful tool to rapidly access skeletally edited derivatives of natural products and other bioactive molecules for applications in drug discovery and chemical biology.

Acute myeloid leukemia (AML) with RUNX1::RUNX1T1 fusion is well known to often demonstrate aberrant upregulation of CD19 expression. We studied the clinicopathologic and genetic features of 16 cases of AML with various RUNX1 lesions, including mutations, copy number gains, and translocations other than fusions with RUNX1T1. Most of these cases were classified as AML-myelodysplasia-related or AML-post-cytotoxic therapy based on the cytogenetic and molecular work-up. These neoplasms showed partial expression of one or more B-cell antigens by flow cytometry and/or immunohistochemistry, fulfilling the criteria for mixed-phenotype acute leukemia (MPAL)-B/myeloid (i.e., ≥20% blasts expressing B and myeloid lineage antigens) in most cases. These findings suggest that AML cases with RUNX1 lesions including mutations, copy number gains, and translocations other than RUNX1T1 fusion, also commonly express B-cell markers, imparting a “mixed-lineage-like” immunophenotype in cases of AML that otherwise fulfill the criteria for other defined subtypes. We present these cases as to caution regarding this potential diagnostic pitfall and favor a diagnosis of AML with RUNX1 lesion(s) in the setting of a case of AML with myeloid/B-cell antigen expression, a history of myelodysplasia or cytotoxic therapy, the demonstration of pDC differentiation by flow cytometry (generally associated with the presence of a RUNX1 mutation), and the presence of a RUNX1 lesion (mutation, copy number gain, and/or translocation exclusive of a rearrangement with RUNX1T1).

Follow-up of previously healthy patients surviving cryptococcal meningitis found that cryptococcal antigen could be detected for >1 year in serum from 38 of 44 (86%) patients and in cerebrospinal fluid (CSF) from 20 of 31 patients (67%), far beyond the time of culture conversion. The speed of titer decline, measured as the number of days for a 2-fold drop in titer to occur, was slower in serum than in CSF. The speed of decline of antigen titers was much slower in serum and CSF for patients infected with Cryptococcus gattii than Cryptococcus neoformans. The speed of decline in CSF and serum titers was also much slower in patients who had received a ventriculoperitoneal shunt for increased intracranial pressure. The variable and extraordinarily slow rate of clearance in our patients did not appear to reflect differences in disease control but rather differences in species and shunting for increased intracranial pressure.

Myelodysplastic neoplasms/syndromes (MDS) are a heterogeneous group of biologically distinct entities characterized by variable degrees of ineffective hematopoiesis. Recently, 2 classification systems (the 5th edition of the World Health Organization Classification of Haematolymphoid tTumours and the International Consensus Classification) further subcharacterized MDS into morphologically and genetically defined groups. Accurate diagnosis and subclassification of MDS require a multistep systemic approach. The International Consortium for MDS (icMDS) summarizes a contemporary, practical, and multimodal approach to MDS diagnosis and classification.

The guidelines for classification, prognostication, and response assessment of myelodysplastic syndromes/neoplasms (MDS) have all recently been updated. In this report on behalf of the International Consortium for MDS (icMDS) we summarize these developments. We first critically examine the updated World Health Organization (WHO) classification and the International Consensus Classification (ICC) of MDS. We then compare traditional and molecularly based risk MDS risk assessment tools. Lastly, we discuss limitations of criteria in measuring therapeutic benefit and highlight how the International Working Group (IWG) 2018 and 2023 response criteria addressed these deficiencies and are endorsed by the icMDS. We also address the importance of patient centered care by discussing the value of quality-of-life assessment. We hope that the reader of this review will have a better understanding of how to classify MDS, predict clinical outcomes and evaluate therapeutic outcomes.

Maximilian Stahl, Omar Abdel-Wahab, Andrew H. Wei, Michael R. Savona, Mina L. Xu, Zhuoer Xie, Justin Taylor, Daniel Starczynowski, Guillermo F. Sanz, David A. Sallman, Valeria Santini, Gail J. Roboz, Mrinal M. Patnaik, Eric Padron, Olatoyosi Odenike, Aziz Nazha, Stephen D. Nimer, Ravindra Majeti, Richard F. Little, Steven Gore, Alan F. List, Vijay Kutchroo, Rami S. Komrokji, Tae Kon Kim, Nina Kim, Christopher S. Hourigan, Robert P. Hasserjian, Stephanie Halene, Elizabeth A. Griffiths, Peter L. Greenberg, Maria Figueroa, Pierre Fenaux, Fabio Efficace, Amy E. DeZern, Matteo G. Della Porta, Naval G. Daver, Jane E. Churpek, Hetty E. Carraway, Andrew M. Brunner, Uma Borate, John M. Bennett, Rafael Bejar, Jacqueline Boultwood, Sanam Loghavi, Jan Philipp Bewersdorf, Uwe Platzbecker, David P. Steensma, Mikkael A. Sekeres, Rena J. Buckstein, and Amer M. Zeidan

Background: There are currently no commercially available tests to identify early stage breast cancer patients treated with breast conserving surgery (BCS) and systemic therapy at low risk of locoregional recurrence (LRR) for whom postoperative radiotherapy (RT) may be safely omitted. Profile for the Omission of Local Adjuvant Radiotherapy (POLAR) is a 16-gene molecular signature developed to identify invasive breast cancer patients who may be candidates for RT omission after BCS. In this work, we seek to validate POLAR in a meta-analysis of three RCTs of BCS +/- RT: SweBCG91RT, Scottish Conservation Trial (SCT) and Princess Margaret Hospital (PMH). Methods: A patient-level meta-analysis was performed in 623 node-negative breast cancer patients with ER+/HER2-negative tumors who were enrolled in the three RCTs and for whom primary tumor material was available for analysis. Contributions from each cohort were as follows: SweBCG91RT N=354 (57%), SCT N=137 (22%), and PMH N=132 (21%). Numbers of LRR events in each cohort were as follows: SweBCG91RT N=72 (20%), SCT N=28 (20%), and PMH N=16 (12%). There was a mix of systemic therapy used (no systemic therapy for SweBCG91RT, chemotherapy or adjuvant endocrine therapy, but not both, in SCT, and tamoxifen but no chemotherapy for PMH). Median follow-up time for the patients who did not have LRR was 13.3 years for SweBCG91RT, 21.1 years for SCT, and 8.6 years for PMH. A multivariable Cox proportional hazards model on time to LRR, including the continuous standardized POLAR score, RT, and interaction, stratified by cohort, was used to test the interaction between the continuous POLAR score and RT. Additional Cox models tested the association between treatment arms separately for patients with a low and high POLAR score using a pre-specified cut point. Cumulative incidences were computed, with distant metastasis and death without recurrence considered as competing events. Results: The test for interaction between RT treatment and POLAR was statistically significant (p = 0.022). Patients with a high POLAR score (N=429 [69%]) had a large benefit from RT (10-year cumulative incidence of LRR: 20% [15%-26%] for those not treated with RT vs 7% [4%-11%] for those treated with RT; hazard ratio for RT vs no RT: 0.37 [0.23-0.60], p < 0.001), whereas there was no evidence of benefit from RT for patients with a low POLAR score (N=194 [31%], 10-year cumulative incidence of LRR: 5% [2%-11%] for those not treated with RT vs 7% [3%-14%] for those treated with RT; hazard ratio for RT vs no RT: 0.92 [0.42-2.02], p = 0.832). Conclusions: To our knowledge, POLAR is the first genomic classifier that is not only prognostic for LRR but also predictive, showing a significant interaction between RT and the classifier. Patients with a high POLAR score should be recommended radiotherapy while patients with a low score may be candidates for omission of radiotherapy after breast conserving surgery. Citation Format: Per Karlsson, Anthony Fyles, S. Laura Chang, Bradley Arrick, Frederick Baehner, Per Malmström, Mårten Fernö, Erik Holmberg, Martin Sjöström, Fei-Fei Liu, David A. Cameron, Linda J. Williams, John MS Bartlett, Joanna Dunlop, Jacqueline Caldwell, Joseph F. Loane, Elizabeth Mallon, Tammy Piper, Wilma J. Jack, Ian Kunkler, Felix Y. Feng, Corey W. Speers, Lori Pierce, John Bennett, Karen J. Taylor. Validation of Profile for the Omission of Local Adjuvant Radiotherapy (POLAR) in a meta-analysis of three randomized controlled trials of breast conserving surgery +/- radiotherapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS4-03.

BackgroundObesity (body mass index [BMI] >= 30 kg/m(2)) is an important epidemiological risk factor for developing acute myeloid leukemia (AML). Therefore, the authors studied the association of obesity with clinical and genetic phenotype and its impact on outcome in adults with AML. MethodsThe authors analyzed BMI in 1088 adults who were receiving intensive remission induction and consolidation therapy in two prospective, randomized therapeutic clinical trials of the Eastern Cooperative Oncology Group-American College of Radiology Imaging Network: E1900 (ClinicalTrials.gov identifier NCT00049517; patients younger than 60 years) and E3999 (ClinicalTrials.gov identifier NCT00046930; patients aged 60 years or older). ResultsObesity was prevalent at diagnosis (33%) and, compared with nonobesity, was associated with intermediate-risk cytogenetics group (p = .008), poorer performance status (p = .01), and a trend toward older age (p = .06). Obesity was not associated with somatic mutations among a selected 18-gene panel that was tested in a subset of younger patients. Obesity was not associated with clinical outcome (including complete remission, early death, or overall survival), and the authors did not identify any patient subgroup that had inferior outcomes based on BMI. Obese patients were significantly more likely to receive <90% of the intended daunorubicin dose despite protocol specification, particularly in the E1900 high-dose (90 mg/m(2)) daunorubicin arm (p = .002); however, this did not correlate with inferior overall survival on multivariate analysis (hazard ratio, 1.39; 95% confidence interval, 0.90-2.13; p = .14). ConclusionsObesity is associated with unique clinical and disease-related phenotypic features in AML and may influence physician treatment decisions regarding daunorubicin dosing. However, the current study demonstrates that obesity is not a factor in survival, and strict adherence to body surface area-based dosing is not necessary because dose adjustments do not affect outcomes.

The patient is a 68-year-old man diagnosed with B-acute lymphoblastic leukemia/lymphoma (B-ALL) replacing the bone marrow, without evidence of myelofibrosis by morphology and reticulin stain (Figure 1A–C). By flow cytometry analysis, blasts were positive for CD10, CD19, CD20 (bright), CD22, CD34, cytoplasmic TdT, and cytoplasmic CD79a, while double-negative for both surface, and cytoplasmic, kappa and lambda light chain expression. Cytogenetic analysis revealed a diploid male karyotype. FISH analysis showed copy number gain of the BCR (22q11.2) locus; However, no evidence of BCR/ABL1 gene rearrangement or other cytogenetic lesions was detected. Lumbar puncture analysis was negative for central nervous system involvement by B-ALL. The patient was enrolled in a Phase III randomized trial of Blinatumomab for newly diagnosed BCR-ABL negative B-ALL in adults (ECOG-ACRIN clinical trial E1910). He received 2 cycles of induction therapy with Daunorubicin, Vincristine, Dexamethasone, Rituximab, Cytarabine, and Methotrexate, followed by maintenance with Methotrexate, Pegaspargase, and Leucovorin. He was then randomized to recieve 3 cycles of consolidation with Blinatumumab, followed by maintenance with Daunorubicin, Vincristine, Dexamethasone, Rituximab, Cytarabine, and Methotrexate. Throughout chemotherapy, patient's complete blood count values fluctuated: His white blood cell count averaged at 6 × 109/L (normal range (NR), 4.2–9.1); hemoglobin and mean corpuscular volume averaged at 11 g/dL (NR, 13.7–17.5) and 110 fL (NR, 79–92), respectively, while his platelets averaged at 70 × 109/L (NR, 150–330). Following cycle two, he was negative for minimal residual disease by flow cytometry analysis, with the following blood count values: white blood cell count of 5 × 109/L (normal range, NR, 4.2–9.1), hemoglobin and mean corpuscular volume of 10.8 g/dL (NR, 13.7–17.5) and 111.3 fL (NR, 79–92), respectively, with platelets of 71 × 109/L (NR, 150–330). A follow-up bone marrow biopsy showed regenerative trilineage hematopoiesis without evidence of myelofibrosis (Figure 1D–F). After completion of chemotherapy 2 years later, the patient was still in complete remission with negative minimal residual disease by flow cytometry analysis and the following complete blood count values: white blood cell count averaged of 1.9 × 109/L, hemoglobin and mean corpuscular volume of 7.3 g/dL and 103 fL, respectively, and platelets of 17 × 109/L. A concurrent bone marrow biopsy was remarkable for dense marrow fibrosis (myelofibrosis (MF)−3 by reticulin stain) with megakaryocytic hyperplasia and dysplasia (Figure 1G–I). Next-generation sequencing interrogating 35 myeloid unique genes with a limit of detection at 5% allele frequency at 500x coverage showed the following pathogenic mutations: DNMT3A c.2071dupA p.Thr691AsnfsTer22 and TP53 c.428T > C p.Val143Ala detected with similar variant allele frequency (VAFs) of 25% and 21%, respectively. In addition, the following mutation of unknown significance, EZH2 c.938G > A p.Arg313Gln was detected with a VAF of 19%. Cytogenetic analysis revealed a diploid karyotype. The patient was managed with supportive care only (transfusion with platelets and packed red blood cells) and was evaluated for potential allogeneic hematopoietic stem cell transplant in the future. The patient stayed in complete remission (negative minimal residual disease by flow cytometry analysis) 4 years after diagnosis of B-ALL, and 2 years after myelofibrosis, until he was found to be positive for minimal residual disease and was started on Blinatimumab. Following Blinatumumab, his blood count values averaged as follows: white blood cell count of 4.3 × 109/L (normal range, NR, 4.2–9.1), hemoglobin and mean corpuscular volume of 7.6 g/dL (NR, 13.7–17.5) and 88 fL (NR, 79–92), respectively, with platelets of 23 × 109/L (NR, 150–330). Acute myelofibrosis is a distinct clinicopathological entity characterized by the sudden onset of pancytopenia, extensive bone marrow (BM) fibrosis, megakaryocytic hyperplasia with or without dysplasia, leucoerythroblastic blood picture, absence of hepatosplenomegaly (HSM), and no tear drop cells. Myelofibrosis, preceding [1-5] or coexisting [6-9] with B-ALL, have been reported before. However, to our knowledge, this is the first report of acute myelofibrosis superseding B-ALL, 2 years after remission. In the case we illustrate, signs pointing at marrow failure included inexplicable and persistent decreased blood counts. A bone marrow core biopsy was helpful in unraveling underlying fibrosis and dysplastic megakaryocytes, findings that were absent in the bone marrow biopsy after cycle 2 chemotherapy, arguing against the possibility of evolution of B-ALL from an established (pre B-ALL) or concurrent myeloproliferative neoplasm with fibrosis (namely, primary myelofibrosis). A question that may be raised is whether the evolving myelofibrosis with pathogenic mutations in DNMT3A and TP53 during complete remission could have started in clonal hematopoiesis to support homeostasis in a regenerative marrow. Another question that remains unclear is whether the myelofibrosis constituted an early sign of B-ALL relapse (which occurred 2 years after the morphologic and molecular diagnosis of myelofibrosis). The relationship between these 2 processes remains to be determined, although we favor that these are 2 unrelated diseases with divergent pathobiology. Nevertheless, this case highlights the possibility of acquired myelofibrosis as a rare cause of decreasing blood counts in cases of B-ALL in remission, in the setting of treatment with Blinatumumab. Furthermore, it argues in favor of performing bone marrow biopsies in similar scenarios to assess for the presence of an evolving new hematologic process. SEH conceptualized and wrote the initial draft of the manuscript with valuable comments from JMB and KMO. None of the authors declares conflict of interest. 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Background: As reported in our preliminary work (Blood (2022) 140 (Supplement 1): 9142-9143) myeloid neoplasms (MN) with MYC-positive double minutes (dmin) are mostly AML and often show a cytomorphological proximity to APL. We here now present detailed genotypical and phenotypical characteristics to address the question if MN with MYC dmin might represent a distinct hematologic entity. Aim: In-depth characterization of cytomorphological, mutational, transcriptional and clinical features of 76 MN with MYC dmin and analysis of the amplified chromosomal region and its effect on gene expression (GE). Methods: We analyzed 60 bone marrow (BM) and 16 peripheral blood (PB) samples of 76 pts with MN and MYC dmin (36 female, 40 male; median age 75 yrs, range 44-89 yrs). The diagnosis was established following WHO guidelines. Dmin and MYC amplification were assessed by chromosome banding analysis and FISH. Cytomorphologic examination included assessment of APL-like features, i.e. high number of atypical hypergranulated promyelocytes, high number of Auer rods, faggot(-like) cells and pseudo Chediak-Higashi (PCH) granules. Molecular genetic analyses comprised a targeted NGS panel (all pts, median coverage 1500x), WGS (16 pts, median coverage 100x) and WTS (40 pts, 50 Mio reads). Mut frequencies and GE levels were compared to AML cases without MYC dmin (“non dmin” AML). Survival data were available for 41 pts (median follow-up: 12 months). Results: According to WHO 2022 most of the 76 cases were AML-MR (myelodysplasia-related) (55/76, 72 %, 9 of these post MDS or post MDS/MPN). Three (4 %) cases each were classified as AML with maturation or without maturation, while one case with AML was not further classifiable due to insufficient material quality and lack of defining markers. Other diagnoses comprised MDS with biallelic TP53 inactivation (4/76, 5 %), MDS-IB1 (1/76, 1 %), CMML-2 (4/76, 5 %), CMML-1 (1/76, 1 %), MDS/MPN (3/76, 4 %) and MPN in blast phase (1/76, 1 %). BM blast count was ≥10 % in 52/60 (87 %) pts, likely underestimated in the remaining 8 samples due to lack of particles, and all 16 pts where only PB was available showed >2 % blasts. Out of 50 pts with fully assessable cytomorphology 48 (96 %) presented with a highly dysplastic granulopoiesis, often including severe dysplasia in other myeloid lineages, independent of myelodysplasia-related genetic markers. Twenty-nine of 50 (58 %) pts were APL-like (≥2 APL-like features), but with a higher degree of maturation than APL. A complex karyotype (ck, ≥3 aberrations in addition to MYC dmin) was present in 25/76 pts (33 %), whereas 21/76 (28 %) pts presented with MYC dmin as the only cytogenetic aberration. TET2 mut, which represented the most frequent mut in MYC dmin pts (55/76, 72 %), often were biallelic events (36/55 pts, 65 %). TET2 mut were strikingly overrepresentated compared to “non dmin” AML (19 %) (p<0.001) (Figure A) and often accompanied by trisomy 4, representing the most frequent chromosomal gain (12/76, 16 %). TP53 mut (24/75, 32 %) and U2AF1 mut (20/75, 27 %) were almost always mutually exclusive (except for 2 pts). While TP53 mut were strongly associated with ck (84 % vs. 6 % in non ck, p<0.001), U2AF1 mut were associated with APL-like cytomorphology (48 % vs. 5 % (1 case) in non APL-like cases, p=0.001). Both mut were highly overrepresented in MYC dmin pts compared to “non dmin” AML ( TP53: 32 % vs. 11 %, p<0.001; U2AF1: 27 % vs. 4 %, p<0.001) (Figure A). WGS analysis revealed an amplified chromosomal region with a size varying from 4.3 - 5.6 Mb and a commonly amplified region of 4.3 Mb (Chr 8:126,422,001-130,697,000). This region encompasses 6 protein coding genes ASAP1, CYRIB, GSMDC, LRATD2, POU5F1B and MYC as well as several non-coding RNAs including the long non-coding RNA PVT1. An effect of the amplified region on GE was confirmed by overexpression of MYC (p<0.001) and PVT1 (p<0.001) compared to “non dmin” AML (Figure B). The median overall survival of 41 evaluable pts was 16 months. Only TP53 mut was independently associated with inferior survival (HR: 11.0, p=0.001). Conclusion: MN with MYC dmin are often AML-MR according to WHO 2022 definition, but even if not, show consistent features of severe dysplasia. They exhibit characteristic mutational patterns and distinct GE profiles, which are affected by a commonly amplified chromosomal region. Thus, we suggest MN with MYC dmin as a distinct genetically defined entity.

Background. The inclusion of gene mutations and chromosomal abnormalities in the 2022 WHO and ICC Classifications of MDS has enhanced diagnostic precision and is expected to improve clinical decision-making process. Although these two systems share similarities, clinically relevant discrepancies still exist and potentially cause inconsistency in their adoption in a clinical setting. In this study on behalf of the International Consortium for MDS (icMDS), we adopted a data-driven approach to provide a harmonization roadmap between the 2022 WHO and ICC classification for MDS. A modified Delphi Process consensus approach is currently ongoing among icMDS experts to finalize a harmonized MDS classification scheme. Methods. We analyzed retrospective international cohorts of patients with a diagnosis of MDS (n=7017) and AML (n=1002) according to WHO 2016 criteria. Hierarchical Dirichlet Processes were applied to define clusters capturing broad dependencies among all gene mutations and cytogenetic abnormalities. To investigate the features of importance and their impact on the clustering process, we employed the SHapley Additive exPlanations approach (SHAP). This allowed to define harmonized labels for each clinical entity. The clinical relevance of the unsupervised clustering was assessed through the analysis of phenotypic features and outcomes among each group. ( Blood 2022;140: 9828-9830) Results. Patients' characteristics are summarized in Table 1. We identified 9 clusters, defined by specific genomic features. The cluster of highest hierarchical importance was characterized by biallelic inactivation of TP53 (biTP53). According to SHAP analysis, bi TP53 was defined as 2 or more TP53 mutations, or 1 mutation with copy number loss or cnLOH. Most patients assigned to bi TP53 cluster had TP53 VAF>10% (77.9%) and complex karyotype (70.1%). Assignment to bi TP53 cluster was irrespective of blast count. Patients with monoallelic TP53 mutation segregated into other clusters. Hierarchically, the second cluster included patients with del(5q). SHAP analysis highlighted 5q deletion alone, or with one other chromosomal abnormality other than -7, and absence of bi TP53, as the most relevant features. Most of these patients had blast counts <5% (88.1%). The third distinct cluster included patients with SF3B1 mutations (in the absence of concurrent del(7q), abn3q26.2, complex karyotype or RUNX1 mutation). Most patients with MDS and SF3B1 mutation had <5% blasts (94.2%). Common co-mutated variants in the SF3B1 cluster included mutant DNMT3A (25.2%) and TET2 (38.3%). Morphologically defined MDS cases (i.e., not meeting criteria for bi TP53, del(5q) or SF3B1) were preferentially assigned to the following additional clusters: SF3B1 and concurrent higher-risk mutations (e.g., RUNX1 and ASXL1); SRSF2 and concomitant TET2 mutations; U2AF1 mutations with del(20q), del(7q) or -7; SRSF2 with TET2 mutations and co-mutational patterns including RUNX1 and ASXL1; and AML-like genomic signatures. Our analyses suggest that morphologically defined MDS is characterized by a large heterogeneity in terms of mutation profiles, not entirely captured by the presence of unilineage versus multilineage dysplasia, percentage of bone marrow blasts, and presence of hypocellularity and fibrosis. To better investigate the continuum between high risk MDS (i.e., patients with ≥10% blasts) and AML, an exploratory comparison was made using a cohort of AML (defined according to WHO 2016) patients analyzed using the same statistical methods. Only a partial overlap in genetic signatures was observed between MDS with ≥10% blasts and AML. However, similarities were observed between the AML-like MDS clusters (characterized by mutant NPM1, bZIP CEBPA, and Core Binding Factor abnormalities) and AML clusters defined by the same genetic signature, thus supporting the classification of these entities as AML, irrespective of blast count. Conclusion. Our study demonstrated the utility of a data-driven approach based on advanced statistical methods to generate a harmonized classification for MDS. Table 2 shows a provisional, hierarchical classification algorithm. Further refinement of entity labels and classification criteria is the subject of the ongoing modified Delphi Process consensus approach among icMDS experts.