Citations

6588 Background: TET2 is the most frequently mutated gene in chronic myelomonocytic leukemia (CMML) and has been associated with favorable outcome, with recent studies suggesting a more pronounced prognostic impact in the presence of ≥2 TET2 mutations ( Csizmar et al. leukemia 2025;39:2030; Kynning et al. Br J Haematol. 2025 Nov 25. doi: 10.1111/bjh.70264 ). We sought to determine if this particular observation extended to patients with ≥3 TET2 mutations ( TET2 MUT ) and also held true in the context of recently reiterated genetic risk factors. Methods: The current study was conducted under institutional review board approved minimum risk protocols allowing retrospective patient data collection and analysis. Diagnostic criteria were according to the International Consensus Classification (Arber et al. Blood 2022. 140:1200). All statistical analyses were conducted using JMP 18 software. Results: 536 CMML patients who underwent CLIA-approved NGS testing were stratified according to the number of TET2 MUT : 221 (41%) wild-type, 148 (28%) with one, 153 (29%) 2, and 14 (2%) ≥3 TET2 MUT . Co-mutation frequencies with significant differences between one vs. two TET2 MUT included ASXL1 (46% vs. 29%; p<0.01), KRAS (7% vs. 14%; p=0.02) and SETBP1 (5% vs. 0.6%; p=0.02). Phenotypic comparisons revealed preponderance of prognostically favorable traits associated with wild-type TET2 but no significant differences between one vs. two TET2 MUT . In age-adjusted univariate analysis, transplant-censored overall survival (TCOS), calculated from the time of mutation detection, was superior in patients with one (p<0.01; HR 0.7) or 2 (p<0.01; HR 0.4) but not ≥3 (p=0.4) TET2 MUT , vs. those with wild-type TET2 . TCOS was also superior with 2 vs. 1 (p=0.02; HR 0.7) but not with ≥3 vs. 1 (p=0.7) TET2 MUT ; the results were similar when TCOS was calculated from the time of diagnosis. Multivariable analysis confirmed the survival advantage of exactly two TET2 MUT vs. wild-type TET2 (p<0.01; HR 0.5), one TET2 MUT (p<0.01; HR 0.6), or ≥3 TET2 MUT (p<0.01; HR 0.4), after adjusting for age, sex, anemia, circulating blasts ≥2%, and leukocyte count ≥13×10⁹/L. The favorable impact of exactly two TET2 MUT persisted in CMML-MD and CMML-MP and remained independent of TET2 VAF, mutation type, karyotype, and other prognostically relevant mutations. This association was sustained in the BLAST (p<0.01; HR 0.5) and CPSS-mol (p=0.02; HR 0.7) models, but not in BLAST-mol model (p=0.12). Conclusions: Mechanistic explanation for this novel observation includes the possibility that TET2 mutational categories based on mutation count reflect distinct biological states rather than having a simple linear effect. The persistence of this signal despite adjustment for established molecular and genetic risk factors supports its consideration in the development of future CMML prognostic models.

6525 Background: Venetoclax plus hypomethylating agent (Ven-HMA) is the standard treatment for unfit patients with newly diagnosed acute myeloid leukemia (ND-AML), with Ven typically administered for 28 days (d) per cycle (DiNardo NEJM 2020) . However, the optimal duration of Ven across risk groups remains unclear. We examined survival outcomes with Ven 7, 14, 21, and 28d in ND-AML, in the context of European LeukemiaNet (ELN) and Mayo Genetic risk models. Methods: ND-AML patients receiving Ven-HMA at the Mayo Clinic were retrospectively studied. Patients were stratified by ELN 2024 (Döhner Blood 2024) and Mayo Genetic risk (Gangat Am J Hematol 2025) , and analyzed using standard statistical methods. Results: 540 patients (median age 75 years, 52% de novo) received HMA with Ven for 7d ( n =33), 14d ( n =117), 21d ( n =96), or 28d ( n =294). ELN and Mayo risk distributions were 22%/35% high, 18%/56% intermediate, 60%/9% low risk, respectively. Baseline characteristics were comparable. CR/CRi rates were comparable across Ven durations, with the exception of lower CR/CRi with 7d vs 21d (p=0.04). Risk-stratified CR/CRi showed variations across Mayo and ELN groups but without significant differences based on Ven duration (Table). Allogeneic transplant rates were 15%, 18%, 18%, 20% for 7, 14, 21, 28d (p=0.86). At a median followup of 37.7 months, median overall survival (OS) differed by ELN risk (6.6, 11.9, 20 months) and Mayo genetic risk (7.8, 17.4 months, not reached (NR)), for high, intermediate, low risk (p<0.01), respectively. Median OS was comparable across Ven 7, 14, 21, 28 d (13, 13, 17, 14 months; p=0.84), with corresponding 1/3/5-year survival rates (Table). 30/60d mortality differed by Ven duration; 7d 10%/20%, 14d 7%/15%, 21d 4%/13%, 28d 4%/6%. Compared with 28d, 30d mortality was higher with 7d and 14d (p=0.07/0.03), and 60d mortality was higher with 7d, 14d, and 21d (p=0.02/0.01/0.05). OS was comparable across Ven durations within ELN intermediate/low risk and all Mayo risk groups, except among ELN high risk, patients receiving 14d Ven had inferior OS compared with 21d and 28d (p<0.01). Cumulative incidence of relapse at 1 year was similar among patients receiving 14, 21, 28d Ven (16%, 18%, 18%;p >0.1). Conclusions: Survival outcomes were comparable across Ven 7, 14, 21, 28 d in ND-AML, with outcomes driven by Mayo Genetic and ELN risk. Despite differences by Ven duration in high-risk groups, higher early mortality with 7d and 14d likely reflects treatment selection. Prospective trials are needed to establish risk adapted Ven dosing strategies. 7 (N=33) 14 (N=117) 21 (N=96) 28 (N=294) P-value CR/CRi (%) 52 63 72 65 0.19 7≠21 Mayo Risk High 33 49 58 55 0.53 - Intermediate 55 69 80 69 0.17 7≠21 Low 100 85 80 84 0.84 - ELN Risk High 33 30 57 53 0.21 - Intermediate 33 59 64 56 0.63 - Low 62 74 80 73 0.46 - Median OS (months) 13 13 17 14 0.84 - 1/3/5-year survival (%) 53/NR/NR 51/25/22 56/23/20 55/27/20 >0.1 -

6530 Background: Venetoclax (Ven) plus hypomethylating agents (HMA) is standard frontline therapy for newly diagnosed AML (ND-AML) patients unfit for intensive chemotherapy and is also being considered in younger and fit patients (Fathi, Blood 2025). However, consolidation with allogeneic stem cell transplant (ASCT) is often required to secure durable remission. The current study examines predictors of post-transplant survival (PTS) in the particular scenario. Methods: ND-AML patients who received upfront Ven+HMA and underwent ASCT were retrospectively studied. PTS, relapse rate, and non-relapse mortality (NRM) were evaluated. Results: 111 ND-AML patients (58% male, 60% secondary/therapy-related, median age 70 [37-80 years]) received median 3 cycles of Ven-HMA. 22% had complex karyotype. Mutations at diagnosis included RUNX1 (18%), SRSF2 (17%), TP53 (16%), ASXL1 , IDH2 , K/NRAS and TET2 (14% each), STAG2 (11%), DNMT3A (8%) and at time of ASCT (N=78 evaluable); RUNX1 (8%), NPM1 (6%), TP53 and ASXL1 (5% each), and SRSF2 and TET2 (4% each). At ASCT, all patients were in CR/CRi; 88% after Ven-HMA and 12% after additional bridging therapy. MRD by flow cytometry was detected in 18 (24%) of 76 evaluable patients and complex karyotype in 8 (9%) of 94. Donors were mostly HLA-matched unrelated (75%), with 51% receiving fludarabine/melphalan conditioning and 67% post-transplant cyclophosphamide (PTCy). At a median follow-up of 30 months, 42 patients (38%) have died including 18 (40%) from relapse. Median PTS was not reached (NR) with 1-2-3-year survival of 69%/60%57%. On multivariate analysis, age ≥65 years (median NR vs 10 months p<0.01), STAG2 (NR vs 44 months; p=0.04), and DNMT3A mutations (NR vs.NR p=0.05) were associated with superior PTS. In analysis limited to variables at time of ASCT, age ≥65 years remained significant (p<0.01) while TP53 mutations, donor type, and MRD status were not (p>0.1). Patients <65 years more often received bridging therapy compared to ≥65 years (23% vs 7%; p<0.05); excluding salvage-treated patients did not change survival results. 18 patients (16%) experienced post-ASCT relapse with median RFS of 7 months. Relapse rates at 1/2/3 years were 22%, 30% and 31% and NRM 13%, 24%, 46%, respectively. Patients <65 years had a higher 1 yr relapse incidence than those ≥65 years (36% vs 18%; p=0.01), with similar NRM (p=0.58). PTCy was not associated with relapse (p=0.66) but showed a borderline association with higher NRM (1-/2-/3-year 17%/31%/58% vs 4%/7%/16% in non-PTCy recipients; p=0.06). GVHD rate was 44% (50% ≥grade 2) with no association with relapse (p=0.43) or NRM (p=0.99). Conclusions: In the current study, older age (>65 years), including >75 years, was independently associated with superior PTS in ND-AML patients receiving Ven-HMA. By contrast, PTS was not affected by genetic profile at the time of ASCT, donor type, conditioning regimen, or GVHD prophylaxis.

6501 Background: Hepcidin, a central regulator of iron homeostasis, is pathologically elevated in patients with myelofibrosis (MF) and anemia. Chronic hepcidin elevation limits iron availability for red blood cell (RBC) production and contributes to anemia onset and severity. DISC-0974 is an investigational, first-in-class, monoclonal antibody that blocks hemojuvelin, a co-receptor in the bone morphogenetic protein-signaling pathway driving hepcidin expression. Methods: RALLY-MF (NCT05320198) is an ongoing Phase 2, open-label study conducted in the US. The primary aim is to evaluate DISC-0974 efficacy in participants with MF and anemia. Secondary aims include evaluating safety, pharmacokinetics (PK), and pharmacodynamics (PD). Eligible participants are ≥18 years of age with primary or secondary MF and hemoglobin (Hgb) <10 g/dL or RBC transfusion requirement. Participants enroll into 3 cohorts based on RBC units transfused in the 84 days prior to screening: non-transfusion dependent (nTD, 0 units and Hgb <10 g/dL), low transfusion burden (TD low, 1-2 units), high transfusion burden (TD high, 3-12 units). Stable dose of concomitant Janus kinase inhibitor (JAKi) is allowed. DISC-0974 is administered subcutaneously at 50 mg monthly for up to 6 doses, with escalation to 75 mg for inadequate or lost response. Primary endpoints include major hematologic response defined as transfusion independence (TI) during any consecutive 16 weeks (TD low) or 12 weeks (TD high), or a mean Hgb increase of ≥1.5 g/dL from baseline for ≥12 weeks (nTD). Secondary endpoints include PK/PD markers of iron regulation and safety assessments. Data were summarized using descriptive statistics. Results: At data cut (16 Oct 2025), 47 participants enrolled in the nTD (n=30), TD low (n=10), and TD high (n=7) cohorts, with 53% on concomitant JAKi therapy. DISC-0974 led to sustained hepcidin reduction and iron mobilization across cohorts. DISC-0974 resulted in meaningful hematologic responses among evaluable participants: 50% of nTD participants achieved a mean Hgb increase of ≥1.5 g/dL for ≥12 weeks, 71% of TD low participants achieved TI for ≥16 weeks, and 67% of TD high participants experienced a ≥50% reduction in transfusion burden, with follow-up ongoing. Major hematologic response rates were 50% for participants on and off concomitant JAKi therapy (n=18 and n=16, respectively). DISC-0974 was associated with meaningful improvement in FACIT-Fatigue scores for nTD and TD low participants. Serious adverse events (AEs, n=9) and ≥Grade 3 AEs (n=16) were considered unrelated to DISC-0974. There were no early withdrawals due to AEs. Conclusions: DISC-0974 was well tolerated and shows a favorable safety profile. Anemia response and fatigue scores improved across patients with MF and anemia, including those receiving JAKi therapy. These data validate hepcidin reduction as a promising approach to treating anemia in MF. Clinical trial information: NCT05320198 .

Abstract Recent updates to monocyte count thresholds recognize oligomonocytic chronic myelomonocytic leukemia (OM-CMML) as an early form of CMML. However, the clinical validity of these changes remains uncertain without incorporating biological and genomic factors. In this study, we analyzed a cohort of 911 patients (249 with OM-CMML, 359 with overt CMML, and 303 with myelodysplastic syndromes) using unsupervised clustering to evaluate the role of genomic determinants in refining CMML diagnosis. Our findings show that CMML molecular signatures (biallelic TET2 mutations or SRSF2-TET2 comutations) are linked to a distinct transcriptome, monocytic bias, classical monocytosis, and a higher risk of progression to overt CMML in OM-CMML cases. We developed a weighted genomic model and diagnostic workflow showing that combining genomic signatures with bone marrow monocyte frequencies in OM-CMML more accurately predicts progression to overt CMML. These findings support integrating genomic determinants and our clinic-ready diagnostic workflow into the CMML diagnostic framework to improve accuracy. Significance: Through comprehensive clinical and genomic profiling of a large patient cohort, alongside immunophenotypic and transcriptional cellular analyses, this study provides evidence that incorporating genomic determinants into the diagnostic criteria for OM-CMML improves diagnostic accuracy and refines the identification of early-stage CMML, thereby preventing misclassification.

Abstract TP53 and PPM1D are key regulators of DNA damage response and repair, and somatic mutations in these genes often co-occur in hematopoietic cells, expanding under genotoxic stress. Unlike TP53 mutations, where mechanisms of progression are defined, pathways underlying clonal fitness and transformation in PPM1D mutant cells remain unclear. In collaboration with 5 academic institutions, we analyzed the clinical and molecular landscape of 337 patients with clonal hematopoiesis (CH) and clonal cytopenia of undetermined significance (CCUS) across 4 genotypes: PPM1Dmt/TP53wt (n = 170 [50%]), PPM1Dmt/TP53mt (n = 25 [7%]), TP53mt/PPM1Dwt (n = 17 [5%]), and TP53wt/PPM1Dwt (n = 125 [38%]). All PPM1D variants were truncating, located in exon 6 of the gene, with a median variant allele frequency (VAF) of 6% (range, 0.3%-64%). The PPM1Dmt/TP53mt genotype was most frequently encountered in therapy-related CH/CCUS (t-CH/t-CCUS; 80%, 66.5%, 76.5%, and 19%; P ≤ .001) and had a shorter time interval to detection from last genotoxic exposure (6.2, 5.9, 11.25, and 24.5 months; P ≤ .001) compared with PPM1Dmt/TP53wt, TP53mt/PPM1Dwt, and TP53wt/PPM1Dwt genotypes, respectively. Acknowledging the short follow-up duration, rates of malignant transformation were lower in the PPM1Dmt/TP53wt (2%) and PPM1Dmt/TP53mt (4%) groups compared with PPM1Dwt/TP53wt (12%) and PPM1Dwt/TP53mt (17%) groups (P ≤ .001), respectively. In summary, PPM1D mutations are frequently observed in t-CH/t-CCUS, with low median VAFs, and are associated with low rates of progression, even when comutated with TP53.