Kusne, Yael N

ABSTRACT Hypomethylating agents (HMA) and allogeneic hematopoietic stem cell transplantation (alloHSCT) have both demonstrated remissions in VEXAS; however, comparative data is lacking. We conducted a multicenter, retrospective analysis of 66 patients diagnosed with VEXAS syndrome treated with HMA ( n = 35) or alloHSCT ( n = 31). Baseline characteristics such as genetics, co‐morbidities, and performance status were balanced between the groups, except older age in the HMA group. Median follow‐up from therapy initiation was 18 months (95% CI: 11–26), and 14 (21%) deaths were reported (alloHSCT n = 3; HMA n = 11). Among all evaluable patients within the alloHSCT cohort, all patients achieved molecular remission, and a substantial proportion of patients discontinued glucocorticoids (58%). In contrast, HMA therapy was associated with lower but meaningful rates of molecular remission (22%) and glucocorticoid discontinuation (6%). In a real‐world setting, HMA therapy was associated with a high discontinuation rate related to toxicity or lack of response. On multivariable analysis adjusted for age and Charlson Comorbidity Index, alloHSCT was associated with improved overall survival (HR = 0.20, 95% CI: 0.05–0.81; p = 0.024). This association remained consistent across multiple ancillary sensitivity analyses, including restriction to transplant‐eligible patients, patients aged ≤ 75 years, 1:1 matching, and propensity score‐based weighted analyses. Although limited by retrospective design, these findings suggest that alloHSCT remains an attractive and potentially curative strategy in selected patients with VEXAS. Prospective validation of these findings is warranted.

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.