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Abstract Introduction Pronounced disparities in pediatric B-lymphoblastic leukemia (B-ALL) outcomes by race and ethnicity persist in the contemporary era. Gaps in overall survival (OS) from initial diagnosis are wider than event-free survival, suggesting that post-relapse mechanisms may contribute. However, data on treatment and outcomes after relapse are lacking. In a large, multicenter, real-world cohort of children and young adults with high-risk 1st relapse of B-ALL, we sought to (1) define survival outcomes by race/ethnicity and (2) explore if differences in therapy utilization drive outcomes. Methods We conducted an analysis within the Retrospective Study of Contemporary Approaches to 1st Relapse in B-ALL (ReCALL-1) cohort, which includes patients <30 years who initiated 1st relapse therapy between 2018-2022. This analysis was restricted to patients treated at US centers for “high-risk” 1st relapse, defined as relapse for which hematopoietic cell transplant (HCT) is generally standard-of-care: Early relapse (medullary <36m; isolated extramedullary <18m), late relapse with persistent end of reinduction disease, Ph+ B-ALL or age ≥18 years. Patients with Trisomy 21, those who received cell therapy before relapse and those who died during reinduction were excluded. The primary exposure was race/ethnicity categorized as Hispanic, non-Hispanic Black (NHB), non-Hispanic White (NHW), and other/unknown. The primary outcome was OS from relapse. Multivariable Cox regression models were constructed to include other social drivers of health (SDOH; health insurance, preferred language) and disease characteristics. Results Of 479 patients in ReCALL-1, 311 from 31 centers met inclusion for this analysis (41% Hispanic, 7% NHB, 46% NHW, 5% NH-other/unknown). With a median follow-up of 47m, OS differed by race/ethnicity (log-rank p=0.017): Hispanic, 4y OS 59%; NHB, 37%; NHW, 68%. Compared to NHW patients, NHB patients had an increased hazard of death (HR 2.3, 95% CI 1.3-4.3, p=0.006), while Hispanic patients were more similar to NHW patients (HR 1.3, 95% CI 0.9-2.0, p=0.16). Adjustment for SDOH only marginally attenuated the risk for NHB patients (aHR 2.0, 95% CI, 1.1-3.7, p=0.031) and led to equivalent outcomes for Hispanic patients (aHR 0.9, 95% CI, 0.5-1.5, p=0.66). Adjusting for disease characteristics that differed by race/ethnicity at p<0.2 (time to relapse, Ph+, Ph-like, KMT2Ar, age ≥18, or relapsed infant ALL) did not diminish the risk for NHB patients (aHR 2.0, 95% CI, 1.1-3.7, p=0.032) while outcomes remained equivalent for Hispanic patients (aHR 1.2, 95% CI, 0.8-1.8, p=0.40). Point estimates of cumulative incidence of non-relapse mortality (NRM) were highest in NHB patients (Hispanic, 4y NRM 13%, NHB 22%, NHW 11%), but this trend was not statistically significant (Gray’s p=0.52). Only 17% of patients initiated therapy for relapse on a clinical trial with no differences observed by race/ethnicity. Most patients received definitive treatment for relapse with either CAR T cell therapy (CART) or HCT: 79% overall, 74% Hispanic, 91% NHB, and 83% NHW. CART and HCT were utilized equally (39% and 40%, respectively) and the proportion that received each therapy did not vary by race/ethnicity. Time to CART/HCT, external referral for treatment, receipt of investigational v commercial CART, and use of post-CART consolidative HCT revealed no differences by race/ethnicity. Of the 66 patients (21%) who did not receive cell therapy, 26 had planned for CART or HCT, but did not receive due to disease progression or NRM (n=24; 12 Hispanic, 10 NHW), or insurance barriers (n=2, both Hispanic). After HCT, OS was worse for NHB patients (log-rank p=0.03) with 4y OS of 42% v 85% for NHW and 75% for Hispanic. Post-CART, 4y OS was 40% for NHB v 59% for NHW and 51% for Hispanic, but this difference was not statistically significant. Conclusion In a large real-world cohort of children with high-risk 1st relapse of B-ALL, we found a two-fold increased hazard of death for NHB patients compared to NHW patients, even after adjustment for other SDOH factors and high-risk disease features. In contrast to previous studies of adult patients, children appeared to have equal access to cell therapies across races/ethnicities. We found that Hispanic patients, who comprised >40% of the cohort, had similar survival to NHW children, suggesting that availability of cellular and immunotherapies may be mitigating historically observed disparities for children with relapsed B-ALL.

Abstract Background: Partial tandem duplications of the histone methyltransferase KMT2Agene(KMT2A-PTD) are the most common KMT2A-aberration in adult acute myeloid leukemia (AML). KMT2A-PTD AML represents a high-risk disease subset with a poor prognosis. However, KMT2A-PTD leukemia is under studied, likely due to a lack of experimental models, and therefore the underlying mechanisms of leukemogenesis remain elusive. Since KMT2A-PTD leukemias possess high-level expression of HOXAgenes, similar to KMT2A-rearranged (KMT2A-r) and NPM1c AML, patients with this type of AML are currently enrolled into several phase I/II trials assessing menin inhibitors (MIs). However, mechanistic or clinical evidence for treatment response is lacking. To date, no targeted therapeutic approaches for KMT2A-PTD leukemia are available. Results: To better understand KMT2A-PTD mediated leukemogenesis, we endogenously tagged the KMT2A-PTD or KMT2A-wildtype (WT) allele in EOL-1 cells with a dTAG that can be degraded with PROTACs. Targeted protein degradation showed that the KMT2A-PTD, but not the KMT2A-WT protein, is critical to maintain leukemia cell growth. We identified KMT2A-PTD specific genome-wide chromatin binding sites and direct target genes as assessed by changes in nascent RNA production that started to occur within 30 minutes of KMT2A-PTD degradation. KMT2A-PTD target genes identified in this study included HOXA9, HMX2, HMX3, CDKN2C, MYC and CDK6 among others. Having defined the KMT2A-PTD target gene program, we assessed the effect of MI on KMT2A-PTD function. In KMT2A-PTD cell lines, PDXs and cells from a published murine KMT2A-PTD/FLT3-ITD knockin model, we observed intrinsic resistance to revumenib characterized by retained chromatin binding of KMT2A-PTD, but not KMT2A-WT after MI treatment. We next defined critical domains for KMT2A-PTD function via a KMT2A domain scan. This revealed the CXXC domain and AT hooks as critical dependencies in EOL-1 cells. Overexpression of KMT2A or mutants with duplicated domains in 293T cells showed that a duplication of the CXXC domain or the AT hooks is sufficient to mediate retained KMT2A chromatin binding under MI. Therefore, the resistance to MIs is likely due to the duplicated protein of KMT2A subverting menin function at critical target loci. Given that KMT2A-PTD remains chromatin-bound upon menin inhibition, we focused on ENL as a potential regulator of leukemia gene expression programs. In KMT2A-r and NPM1c leukemia, the ENL protein has been shown to be a critical dependency as it associates with acetyl lysine via its YEATS domain. ENL/AF9 YEATS inhibitors reverse ENL-dependent gene expression including HOXA9 and MYC. Using the small molecules TDI-11055 and TM-7, we show that YEATS inhibition leads to loss of members of the super-elongation complex and DOT1L from KMT2A-PTD driven loci and downregulation of target gene expression. Treatment of KMT2A-PTD PDXs with YEATS inhibitors induced differentiation and significantly reduced leukemia burden in vivo. Interestingly, we show that in contrast to previous findings in KMT2A-r leukemia, loss of ENL alone is insufficient to abrogate leukemic proliferation of EOL-1 cells. Instead, by combining ENL degradation with CRISPR-Cas9 mediated knockdown of AF9, we find that both YEATS proteins, ENL and its paralogue AF9, support aberrant gene expression in KMT2A-PTD leukemia. Finally, we show that the novel combination of MI and YEATS inhibition (revumenib plus TDI-11055) synergistically affects proliferation and induces differentiation in cell line and PDX models of KMT2A-PTD leukemia, which in turn prolongs survival of mice with KMT2A-PTD leukemia. Conclusions: KMT2A-PTD leukemia is dependent on the mutated, but not the WT KMT2A allele. It is characterized by a relative, intrinsic resistance to MI monotherapy, which is mediated by a duplication of the CXXC domain and AT hooks of KMT2A. Targeting both, the ENL and AF9 YEATS domain, is a possible treatment strategy and when combined with revumenib, YEATS inhibition has synergistic effects and overcomes intrinsic MI resistance. However, based on our studies, MI monotherapy may not be effective for most patients with KMT2A-PTD leukemia. Given that numerous compounds targeting the ENL (and AF9) YEATS domain are under study and MIs have recently obtained FDA approval, the combination of MI and YEATS inhibition could be translated into clinical trials for patients with KMT2A-PTD leukemia in the relatively near future.

Abstract Background Accurate reconstruction of electronic health record (EHR) treatment sequences is essential for leveraging real-world data (RWD) in clinical research and trial-eligibility platforms in multiple myeloma (MM). However, inconsistencies in RWD treatment documentation and the complexity of line-of-treatment (LOT) assignments in MM hinder reproducibility and limit comparisons against published trials. To address these limitations, we developed HEAL-MM, an automated rule-based algorithm that systematically parses structured medication data to calculate LOTs and segment treatment into standardized, clinically meaningful phases. The algorithm is designed to be interpretable, adaptable to evolving therapeutic frameworks, and compatible with widely adopted EHR data standards. Here, we report its real-world validation against expert-adjudicated treatment sequences to assess concordance, identify edge-case failure points, and support RWD integration. Methods A stratified cohort of 100 MM patients (9,136 structured treatment events) was curated from 114 unique healthcare systems compiled from the multi-institutional HealthTree Foundation harmonized registry. Cohort selection was randomized to ensure coverage across diagnostic eras (pre-2010, 2015–2020, 2022–2025) and treatment exposures, including CAR T-cell therapies, bispecific antibodies, and anti-CD38-based regimens. HEAL-MM sequenced MM regimens chronologically and applied predefined logic rules to identify LOT transitions, the initiation of a new therapeutic course based on drug changes, treatment gaps, and procedural anchors such as stem cell transplant or CAR T. Within each LOT, the algorithm segments and labels therapy into phases, clinically distinct intervals (e.g., induction and maintenance) using rule-based clinical logic. Outputs were benchmarked against expert-labeled adjudications. Concordance was evaluated using concordance index (C-index), stratified by patient, LOT depth and diagnostic era. Results: HEAL-MM demonstrated high concordance with expert-labeled treatment sequences: 0.94 for LOT identification, 0.98 for treatment phase segmentation, and 0.96 for phase label assignment. Achieving complete agreement with all expert annotations in 90% of patients for LOT assignment, 94% for the number of treatment phases identified, 77% for the specific labels applied to each phase, and 75% across all three dimensions simultaneously. Among discordant patients, the absolute difference in final LOT count was 0.5 ± 0.9. Performance was highest in early lines (LOTs 1–3; C-index: 0.97), with seven patients showing discrepancies at this stage. Concordance declined in later lines (LOT ≥4; C-index: 0.87), where 50% of the discordant cases (n=4) were attributable to misclassifications in earlier LOTs, such as medication restarts following >3-month gaps, demonstrating the compounding effect of early errors on longitudinal accuracy. Temporal stratification revealed improved accuracy in post-2020 cases (C-index: 0.94) compared to 2015–2020 cohorts (0.91), reflecting the increasing adoption of structured treatment standards and EHR data quality improvements. To assess HEAL-MM performance at clinically significant junctures, we analyzed treatment transitions that initiated a new LOT or marked a change in phase, achieving C-indices of 0.97 for LOT transitions, 0.97 for treatment phase shifts, and 0.94 for phase label assignment. Conclusions: HEAL-MM provides a validated, scalable solution for standardizing MM treatment structures in RWD environments, as it accurately detects the exact treatment entry of a new LOT 97% of the time. This rule-based framework enables reproducible LOT and phase assignment across heterogeneous EHR systems, supporting real-time cohort identification across institutions and EHR platforms. The algorithm's modular design allows for continuous integration of novel therapeutic categories and evolving treatment logic. While the algorithm maintained high fidelity overall, early-stage misclassifications consistent with increased heterogeneity and documentation ambiguity occasionally propagated downstream, underscoring the compounding effect of upstream errors in longitudinal reconstruction. With its generalizable structure and compatibility with industry-standard data models, HEAL-MM lays the foundation for structured treatment reconstruction in MM across RWD infrastructure and serves as a transferable blueprint for other hematologic malignancies.

Abstract Background: For LS-DLBCL, clinical trials (FLYER, LYSA/GOELAMS 02-03, LYSA LNH09-1B, S1001) have shown that 4 cycles of rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (RCHOP4) without radiation (RT) leads to durable remissions in >90% of cases. However, only patients (pts) with non-bulky disease and/or international prognostic index (IPI) of 0 and complete metabolic response (CMR) on interim positron emission tomography (PET) scan, if performed, were eligible for RCHOP4 alone in these studies. Outcomes in trial-ineligible LS-DLBCL and the appropriate real-world candidates for RCHOP4 are still undefined. Methods: We conducted a multicenter retrospective study of adult pts with stage I/II DLBCL of any tumor bulk, IPI and with or without B-symptoms diagnosed after 2011 and treated with RCHOP4 +/- 2 cycles R from 21 U.S. centers. Pts with PMBCL, PTLD or receiving non-standard dose RCHOP for cycle (C) 1 or planned consolidative RT were excluded. The primary endpoint was PFS from C1 by Kaplan-Meier method, not counting indolent lymphoma relapse. Event free survival (EFS) was time to next therapy without progression (including unplanned RT for non-CR), progression or death. A competing risks analysis of non-relapse mortality (NRM) vs. DLBCL progression was performed. Results: The characteristics of the 428 pts were: median age 60 (18-88), 60% male, 11% Hispanic and 4% non-Hispanic Black, 62% stage I, 15% elevated LDH, 3% ECOG PS>1, 5% tumor bulk >7cm, 9% had B-symptoms and median Charlson Comorbidity Index (CCI) was 4 (2-12). IPI was 0, 1 and 2-3 in 42%, 46% and 12% and stage-modified IPI (smIPI) was 0, 1, 2 and 3-4 in 25%, 48%, 21% and 6% of pts. 66% had nodal (59% head/neck, 11% pelvic, 9% multiple above diaphragm, 7% abdominal) and 46% extranodal sites (37% head/neck, 20% gastric/intestinal, 9% spleen, 8% skin/soft tissue); 6% had transformed/concurrent FL/MZL or grade 3B FL, 33% (138/408) were non-GCB cell of origin (COO), 25% (90/357) double expressor (DEL) and 0.5% (2/379) double-hit. 13% had completely resected disease, 97% staging PET and 47% bone marrow biopsy. Median diagnosis to treatment interval was 30 days (IQR 20-43), 6% had dose reductions after C1, 77% had an interim PET (iPET) after C2 (33%) or C3 (67%), 15% received 2 additional cycles R and 4% CNS prophylaxis. CMR rates by iPET were 83% after C2 and 94% after C3, and 95% by end-of-treatment PET. iPET PMR was more likely if smIPI>2 or bulky disease. Median follow-up time was 2.7 years. There were 32 progression events: 14 occurred at the primary site and 17 at distant sites (1 unknown), and 12 occurred after 2 years. Another 11 pts received unplanned RT after RCHOP4 for non-CR. There were 24 deaths, 12 without prior progression. Cause of death was DLBCL in 7 and non-DLBCL in 17 cases (6 infection, 2 ILD, 2 heart failure, 2 second cancer, 1 seizure, 4 unknown). EFS, PFS and OS rates were 88%, 90% and 96% at 3 years. By univariable Cox regression, Black race, elevated LDH, smIPI>2, DEL, increasing CCI, multiple subdiaphragmatic nodal sites and iPET PMR were associated with worse PFS. Non-significant variables of note included COO, extranodal sites, complete resection, missing bone marrow biopsy, missing iPET and additional cycles R. By multivariable analysis (including age>60, stage, ECOG PS>1, elevated LDH, bulky disease, CCI, B-symptoms and DEL), ECOG PS>1 (HR 3.95 p=0.050), CCI (HR 1.29 p=0.003) and DEL (HR 2.02 p=0.069) were associated with worse PFS. Cumulative incidence of DLBCL progression and NRM were 8% and 2% at 3 years. Competing risk analysis by univariable models found that age>60, ECOG PS>1, smIPI>2, elevated LDH, CCI and bulky disease were associated with NRM, while DEL and B-symptoms were associated with DLBCL progression.Conclusion: Presented is the largest retrospective cohort of LS-DLBCL treated uniformly with RCHOP4 to date. Despite modest follow-up time and lack of an “intention-to-treat“ population, this study shows that abbreviated RCHOP4 leads to excellent outcomes in the real-world, albeit with continuous risk of late relapse. smIPI risk factors were associated with worse PFS, though this may in part be driven by risk of non-lymphoma death. As pts with advanced age, poor performance status or comorbidities may benefit from reduced treatment exposure, RCHOP4 should still be considered for these and other “trial-ineligible” pts, particularly if other high-risk features (iPET PMR, DEL or B-symptoms) are absent.

Abstract Marginal zone lymphoma (MZL) is an uncommon non-Hodgkin B-cell lymphoma accounting for 7-10% of lymphoma diagnoses. Extranodal MZL (EMZL) of mucosa-associated lymphoid tissue (MALT) is the most common subtype (61%) of MZL. While the mutational landscape, chromosomal aberrations and transcriptome of nodal and splenic MZL have been extensively evaluated, the mutational landscape of EMZL has only been evaluated in a small number of patients and mainly by targeted sequencing. Consequently, the comprehensive genomic landscape of EMZL remains largely uncharacterized. Herein, we performed whole exome sequencing followed by targeted sequencing of potential tumor driver genes, copy number and/or RNA transcriptome analyses in 165 patients with pretreatment EMZL tumors involving 16 anatomic locations. All samples were collected and underwent expert review as part of the Atlas of Blood Cancer Genomes consortium. The most common anatomic locations were ocular adnexa (OAMZL) (n=35), gastric (n=25, including 6 positive for Helicobacter pylori), salivary glands (n=25), and lungs (n=24). Using common criteria for variant mutation calling and significant focal copy number (CN), we identified 1218 variants (1030 missense and 188 truncation mutations) across 174 genes and 2837 CN focal alterations (1614 copy gains and 1223 copy number losses). Of these genes, 44 and 11 were mutated in >5% and >10% of specimens, respectively. We detected variants identified previously by targeted sequencing in EMZL from different locations (e.g. TNFAIP3 (A20) (12%), TBL1XR1 (13%), SPEN (10%), CARD11 (7%), TET2 (7%) and CREBBP (6%)). We detected mutations in KLF2 (10 mutations in 8 EMZL patients) and PTPRD (7 mutations in 7 EMZL patients) that were previously suggested to be specific for splenic and nodal MZL, respectively. We also detected variants not previously reported in EMZL, including a transcriptional factor ZEB2, LRP1B,and others. The most frequently mutated gene in our study (25% of tumors) was IGLL5. Some mutations were limited to specific locations (e.g. ZEB2 mutations seen exclusively in gastric and salivary gland EMZL), while most were observed across all anatomic locations. There was no association between specific mutations and clonal IGHV, in contrast to previous reports. Using Enrichr tool, we observed enrichment of mutations in genes belonging to the B cell receptor activation, NOTCH signaling, Wnt-beta catenin signaling, NF-kB signaling , PI3K AKT signaling, DNA repair and other pathways. Chromosomal and copy number changes were also commonly observed including previously reported trisomy of chromosomes 3 and 18. Combining DNA mutations and CN alterations, the number of genetic lesions per tumor sample in the 174 mutated genes ranged from 0 to 95, with an average load of 17 lesions per case. RNA sequencing was successful in 159 EMZL tumors from 16 distinct anatomic locations. Unsupervised clustering using all genes with a median log2-normalized gene expression value greater than 5 and a standard deviation greater than 1 (1323 genes) demonstrated that the majority of gastric EMZL with and without H. pylori infections clustered together on 2 dendrograms as did most of the samples of OAMZL. Since the clustering could be forced by organ-specific and not tumor-specific gene expression, we next focused on the expression of the 345 genes from the LM22 matrix that passed our transcriptomic row filtering. Unsupervised clustering resulted in clustering of most gastric EMZL irrespective of H. pylori positivity together in the same dendrogram branch, accompanied by few additional EMZL from other anatomic locations. Most of the EMZL samples from other locations did not show preferential co-clustering together. On comparison of gene expression between gastric and OAMZL, there was enrichment of the B-cell receptor signaling pathway, B-cell activation, B-cell naïve and B-cell memory cells, B-cell proliferation and NF-kB signaling in the latter. Immune microenvironment analysis showed a statistically significant increase in resting mast cells and decrease in M1 macrophages in gastric EMZL and increase in regulatory T cells in salivary EMZL. The broad genomic studies reported here underscore the biological similarity of EMZL across anatomical sites with the potential exceptions of gastric EMZL (regardless of H. Pylori status). These data provide valuable genomic and transcriptomic resources to inform future diagnostic and therapeutic strategies.

Abstract Background: JAK2-unmutated erythrocytosis constitutes a spectrum of hereditary and acquired entities. We assessed the diagnostic yield and utility of next generation sequencing panel for hereditary erythrocytosis (NGS-HEP) in adults with JAK2-unmutated and otherwise unexplained erythrocytosis (OUE). Additionally, we describe the clinical phenotype, genetic findings, treatment approaches, and thrombotic outcomes in this cohort. Methods: Adults (≥18 years) withOUE, defined as hemoglobin (Hgb) >16.5 g/dL or hematocrit (Hct) >49% in males and Hgb >16 g/dL or Hct > 48% in females, negative for JAK2 exon 12-15mutations, absence of acquired cause, and high-oxygen affinity variants, underwent NGS-HEP; the gene panel included ACO1, ANKRD26, BHLHE41, BPGM, CYB5A, CYB5R3, EGLN1, EGLN2, EGLN3, EPAS1, EPO, EPOR, GFI1B, HIF1A, HIF1AN, HIF3A, JAK2, KDM6A, PFKM, PIEZO1, PKLR, SH2B3, SOCS3 and VHL, including deletion/duplication analysis.Variant curation was performed using ACMG-AMP guidelines and classified as pathogenic or variants of uncertain significance (VUS). Family and thrombosis history, and symptoms were recorded. Results: A total of 44 adult patients with JAK2-unmutated OUE (median age 48 years, range 21–79; 34 males [77%]) underwent NGS-HEP at the Mayo Clinic between March 2023 and June 2025. Variants were identified in 27 patients (61%), with a single variant detected in 19 (70%) and two distinct variants in 8 (30%). 26 variants (96%) were classified as heterozygous VUS and involved PIEZO1 (n=9, 20%; median variant allele frequency [VAF] 47.1%), HIF1A (n=8, 18%;46.2%), ANKRD26 (n=4, 9%;43.7%), SH2B3 (n=3, 7%; 49.9%), HIF3A (n=3, 7%;51.4%), EGLN2 (n=2, 5%;47.9%), BPGM (n=1, 2%; 50.4%), VHL (n=1, 2%; 41.8%), EPO (n=1, 2%; 45.4%) and BHLHE41 (n=1, 2%; 54.2%), while a pathogenic mutation in PKLR was detected in one patient. Presenting median Hgb/Hct values for males and females, respectively were 18.3 g/dL/53.5% and 16.9 g/dl/51.2% in variant- positive cases, and 17.8 g/dl/53.1% and 16.1 g/dl/49.3% in variant-negative cases (p>0.05). Median serum erythropoietin (sEpo) levels were 8.35 mIU/mL (range: <1-52.9) vs 8.8 mIU/mL (range: 1.6-54.7), respectively (p=0.67). Notably, sEpo was < 1 mIU/mL in a patient with ANKRD26/HIF3A VUS. Family history of erythrocytosis was documented in 5 patients (11%). Hyperviscosity-related symptoms were reported in 24 patients (55%), with no significant difference in prevalence between variant-positive and variant-negative cases (59% vs 47% p=0.42). Also, there was no significant association between the presence of symptoms and Hgb or Hct levels (p>0.05). Eight thrombotic events occurred in 7 patients (16%; median age 44 years; 71% males; 4 arterial and 4 venous; 3 provoked deep venous thromboses). Five (71%) of the 7 patients harbored VUS in PIEZO1, PIEZO1/HIF1A, ANKRD26, SH2B3, or BHLHE41. Notably, two younger male patients experienced arterial events in the absence of identifiable risk factors: a 32-year-old with PIEZO1/HIF1A VUS (VAF 46.2%/47.6%; sEpo 10.3 mIU/mL) suffered a myocardial infarction, and a 35-year-old with SH2B3 VUS (VAF 50.2%; sEpo 3.7 mIU/mL) had recurrent cerebrovascular accident despite phlebotomy, aspirin and apixaban. Overall, there was no significant association between thrombosis and the presence of a variant (19% in variant-positive vs 12% in variant-negative, p=0.54). Active therapies included phlebotomy in 22 patients (50%), antiplatelet agents in 23 (52%), systemic anticoagulation in 5 (11%), and hydroxyurea in one patient (2%). Among those who received phlebotomy, 10 patients (45%) reported improvement in symptoms, however, symptom relief did not correlate with Hgb or Hct levels (p>0.05). A separate analysis of 9 patients with heterozygous PIEZO1 VUS, none of whom had undergone splenectomy, showed a numerically higher incidence of symptoms (67% vs 51%) and thrombosis (22% vs 14%) compared to those without PEIZO1 variants, although the differences were not statistically significant (p>0.05). Conclusion: NGS-HEP yielded a molecular diagnosis in 61% of adults with JAK2-unmutated and OUE with heterozygous PIEZO1 variants being the most frequent. No consistent association was observed between variant status and presence of hyperviscosity-related symptoms or thrombotic events. These findings underscore the importance of NGS-HEP testing in the diagnostic workup of JAK2-unmutated and OUE and continued investigation into novel candidate genes.

Abstract Background: Systemic mastocytosis (SM) comprises a spectrum of subtypes characterized by neoplastic mast cell (MC) infiltration of tissues and release of MC mediators. Non-advanced SM (NonAdvSM), including indolent SM (ISM), smoldering SM (SSM), and bone marrow mastocytosis (BMM) subtypes, is the most prevalent form of SM. NonAdvSM can be associated with debilitating symptomology which can significantly impair quality of life. The gain-of-function somatic KIT c.2447 C>T (p.D816V) mutation is found in up to 95% of patients with SM. Bezuclastinib (CGT9486) is an oral, potent, and selective type 1 tyrosine kinase inhibitor with activity against KIT D816V. Results from Summit (NCT05186753) Part 1 informed the recommended phase 2 dose (100 mg QD bezuclastinib) for Part 2. We report topline results from the 24-week assessment of Summit Part 2. Methods: Summit is a multi-center, randomized, double-blind, placebo (PBO)-controlled Phase 2 trial of bezuclastinib in patients with NonAdvSM who had inadequate symptom control despite best supportive care (BSC) medications. The primary endpoint was 24-week mean change from baseline in Mastocytosis Symptom Severity Daily Diary (MS2D2) total symptom score (TSS) (range 0–110), which is a fit-for-purpose patient-reported outcome measure of NonAdvSM symptom severity. Key secondary endpoints included the proportion of patients with ≥50% reduction in serum tryptase, KIT p.D816V variant allele frequency (VAF), bone marrow (BM) MC burden, and MS2D2 TSS, ≥30% TSS reduction. Patients were randomized 2:1 to receive 100mg QD bezuclastinib + BSC or PBO + BSC. Results: As of May 22, 2025, 179 patients were enrolled in Part 2: 119 were randomized to receive bezuclastinib and 60 to placebo. Patients enrolled were representative of the NonAdvSM population with moderate to severe symptoms. Median age (range) was 51 (23-78) years; 65.9% female; mean (SD) baseline MS2D2 TSS 55.6 (19.8); 82% of patients had ISM, 11% had BMM, and 7% had smoldering SSM. At baseline, median (range) KIT p.D816V VAF in whole blood, BM MC burden, and serum tryptase was 0.25% (0-34%), 10% (1-75%), and 40 (6-692) ng/mL, respectively. Bezuclastinib demonstrated statistically significant superiority to placebo on all primary and key secondary endpoints. At Week 24, bezuclastinib led to significantly greater symptom improvement vs placebo (LS mean [95% CI] MS2D2 TSS change: –24.3 [–27.6 to –21.1] vs –15.4 [–19.6 to –11.2]; placebo-adjusted difference: –8.9 points; P=0.0002). A ≥50% reduction in serum tryptase was achieved in 87.4% of bezuclastinib-treated patients vs 0% on placebo (P<0.0001). Significantly more patients receiving bezuclastinib achieved ≥50% reductions in KIT D816V VAF, serum tryptase, BM MCs (P<0.0001), MS2D2 TSS (P=0.01), and ≥30% reduction in MS2D2 TSS (P=0.0004). Most treatment-emergent adverse events (TEAEs) were low grade (gr; 70% Gr 1) and reversible. The most common TEAEs (≥10%) in any treatment group and occurring in greater frequency in the bezuclastinib arm were hair color changes (69.5% vs 5.0%), altered taste (23.7% vs 0%), nausea (22.0% vs 13.3%), increased ALT/AST (22.0% vs 6.6%), headache (17.8% vs 11.7%), alopecia (11.9% vs 3.3%), and increased ALP (10.2% vs 3.3%). TEAEs (≥10%) that occurred more often in the placebo group were diarrhea (13% vs 18%), dizziness (10% vs 12%), fatigue (7% vs 12%), and arthralgia (6% vs 15%). ALT/AST elevations ≥Gr 3 were experienced by 5.9% of patients. The only hepatic adverse events (AEs) reported were transient lab abnormalities; none required hospitalization. Treatment-related AEs requiring dose reductions occurred in 11% of patients receiving bezuclastinib. All discontinuations (5.9%) due to treatment-related AEs were due to transaminase elevations; all fully resolved. Conclusions: At 24-weeks, bezuclastinib 100 mg QD demonstrated statistically and clinically significant improvements in symptom burden and biomarkers of disease vs placebo in patients with NonAdvSM. The treatment was generally well-tolerated and effective across a population that is representative of the real-world NonAdvSM population, including SSM. These results support the use of bezuclastinib to reduce SM burden and symptoms in pts with NonAdvSM, and a potentially disease-modifying impact.

Abstract This publication represents the first part of an update to the clinical practice guideline on the diagnosis and management of group A streptococcal (Streptococcus pyogenes or GAS) pharyngitis, developed by the Infectious Diseases Society of America (IDSA). Diagnosis of GAS pharyngitis by clinician judgment alone is unreliable, and unselective testing incurs cost and inconvenience for individuals at low risk of having GAS infection. Clinical scoring systems have been used to quantify the probability of a positive GAS throat culture based on standardized criteria such as the presence of fever; tonsillar enlargement or exudate; tender and enlarged anterior cervical lymph nodes; and the absence of cough. The goal of this article is to determine whether a scoring system should be used to decide which patients should have a diagnostic test performed by rapid antigen detection test, molecular methods, and/or throat culture. We performed a systematic review of randomized and nonrandomized studies that compared the use of a clinical scoring system to clinician judgment alone in predicting the outcome of a throat culture. Evidence from studies in children and adults suggests the diagnostic accuracy of a clinical scoring system is comparable to or slightly higher than clinician judgment alone. However, the studies are limited due to small size, lack of uniformity in outcome measures, and incomplete data. The consensus of the panel is that the balance of benefits and harms favors use of a clinical scoring system as part of the evaluation of patients with sore throat. The principal utility of using a scoring system is to identify patients with low probability of GAS pharyngitis and to reduce unnecessary testing.