biostudies-literatureJen WYNCI NIH HHSNIH HHS2451-2461https://www.ebi.ac.uk/biostudies/studies/S-EPMC12490727biostudies-literatureUnknown207(6)MECOM rearrangements (MECOM-r) are acute myeloid leukaemia (AML)-defining, regardless of blast percentage or MECOM fusion partner. We sought to investigate if blast percentage or MECOM-r partner was associated with overall survival (OS). We included 152 adult patients with newly diagnosed MECOM-r and classified blast percentage into <20% or ≥20% and MECOM-r partner into classic (GATA2::MECOM) or variant (others). Thirty-one per cent had <20% blasts, with 69% having ≥20%; 57% had classic and 43% variant MECOM-r. Treatment was with intensive chemotherapy (IC) in 41% and low-intensity therapy (LIT) in 59%. Composite complete remission rates were similar between IC (50%) and LIT (48%, p = 0.99). The median OS was 17 months (95% confidence interval [CI], 12-not estimable [NE]) for <20% blasts, British journal of haematologyMECOM fusion partner and bone marrow blast percentage influence outcomes of patients with MECOM rearranged acute myeloid leukaemia.PMC12490727P30 CA016672P50 CA100632CA100632Sasaki KIssa GCPierce SMontalban-Bravo GTang GGarcia-Manero GKantarjian HMKugler EBataller ALoghavi SDaver NGKadia TMToruner GAJen WYBazinet APopat UShort NJJabbour EBhalla KDiNardo CDPemmaraju NCroden JBouligny IMBorthakur GRavandi FfalseMECOM fusion partner and bone marrow blast percentage influence outcomes of patients with MECOM rearranged acute myeloid leukaemia.MECOM rearrangements (MECOM-r) are acute myeloid leukaemia (AML)-defining, regardless of blast percentage or MECOM fusion partner. We sought to investigate if blast percentage or MECOM-r partner was associated with overall survival (OS). We included 152 adult patients with newly diagnosed MECOM-r and classified blast percentage into <20% or ≥20% and MECOM-r partner into classic (GATA2::MECOM) or variant (others). Thirty-one per cent had <20% blasts, with 69% having ≥20%; 57% had classic and 43% variant MECOM-r. Treatment was with intensive chemotherapy (IC) in 41% and low-intensity therapy (LIT) in 59%. Composite complete remission rates were similar between IC (50%) and LIT (48%, p = 0.99). The median OS was 17 months (95% confidence interval [CI], 12-not estimable [NE]) for <20% blasts, 2025-01-01T00:00:00Z2025 Dec2026-06-06T13:36:26.558Z2026-05-31T03:07:50.884ZS-EPMC124907274098356710.1111/bjh.70171