Therapeutic Outcomes in VEXAS Syndrome: A Multicenter Comparative Cohort of Allogeneic Hematopoietic Stem Cell Transplantation and Hypomethylating Agents.

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.