e18550 Background: Acute megakaryoblastic leukemia (AMKL) with t(1;22)(p13;q13); RBM15–MKL1 is a rare, genetically defined AML subtype, predominantly affecting infants and young children. Prior literature consists largely of case reports and small series, with no population-based studies describing survival patterns or demographic disparities. Understanding national-level outcomes is critical to guide treatment strategies and improve health equity. Methods: SEER data (2000–2021) were queried for patients with AMKL harboring t(1;22); RBM15–MKL1. Overall survival (OS) was estimated using Kaplan–Meier methods. A multivariable Cox proportional hazards model assessed the impact of age at diagnosis, sex, race, year of diagnosis, and receipt of chemotherapy on OS. Results: Among 79 patients, 55 deaths occurred during follow-up. Increasing age was associated with inferior OS: patients aged 50–79 years had significantly higher mortality compared with those 0.9), race/ethnicity, or year of diagnosis, although power was limited for subgroup analyses. Conclusions: This population-based analysis provides the first national-level survival estimates for AMKL with t(1;22); RBM15–MKL1. Age at diagnosis is a key prognostic factor, while chemotherapy confers substantial survival benefit. No clear disparities by sex or race/ethnicity were observed, but small numbers limit interpretation. These findings reinforce the importance of systemic therapy and provide a benchmark for future clinical and translational studies in AMKL. Multivariable Cox regression for overall survival in t(1;22) acute megakaryoblastic leukemia. Characteristic Hazard ratio (95% CI) P value Age at diagnosis (ref: 0.90 Year of diagnosis (continuous) 1.00 (0.93–1.09) >0.90 Chemotherapy (ref: no/unknown) Yes 0.17 (0.07–0.43) <0.001
Sadurski et al. (Thu,) studied this question.