Population-based survival and demographic disparities in acute megakaryoblastic leukemia with t(1;22)(p13;q13); RBM15–MKL1: A SEER analysis (2000–2021).

Abstract

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 <50 years (HR 3.01; 95% CI, 1.14–7.92); p = 0.026. Patients ≥80 years showed an elevated risk (HR 1.93) that did not reach statistical significance (p = 0.3), likely due to small sample size. Receipt of chemotherapy was associated with markedly improved survival, reducing the hazard of death by approximately 83% (HR 0.17; 95% CI, 0.07–0.43); p < 0.001 (Table). No significant differences were observed by sex (HR 1.00; p > 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: <50 years)  50–79 years 3.01 (1.14–7.92) 0.026  ≥80 years 1.93 (0.52–7.14) 0.30 Sex (ref: female)  Male 1.00 (0.55–1.81) >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