O12.03 Menin inhibition following allo-HCT enhances graft-versus-leukemia effects through endogenous retrovirus induction in AML and T-cell activation

Background Acute myeloid leukemia (AML) with chromosomal rearrangements involving the lysine methyltransferase 2A (KMT2A) gene and mutations in the nucleophosmin (NPM1) gene often relapse following allogeneic hematopoietic cell transplantation (allo-HCT). Targeting the interaction between menin and KMT2A with pharmacological menin-inhibitors disrupts oncogenic KMT2A chromatin complexes, impairing abnormal self-renewal and promoting myeloid differentiation. However, its impact on post-transplant immune surveillance and graft-versus-leukemia (GVL) activity has not been defined. We investigated whether menin inhibition modulates leukemia immunogenicity and donor T-cell function to enhance GVL effects.Methods Human AML cell lines and primary samples were treated with menin inhibitors. MHC expression, cytokines, and cytolytic markers were analyzed by flow cytometry. Human endogenous retrovirus (HERV) and interferon-stimulated gene (ISG) expression were assessed by qRT-PCR and RNA-seq, while chromatin accessibility and menin/KMT2A occupancy were examined by ATAC-seq and ChIP-seq. Primary human T-cells were activated in the presence or absence of menin-inhibitors, and activation, exhaustion, cytokine secretion, and cytotoxicity were evaluated by (high-dimensional) flow cytometry, ELISA, and killing assays. GVL activity was assessed in allogeneic and xenogeneic AML transplantation models, and GVHD was evaluated by histopathology and inflammatory marker analysis.Results Menin inhibition consistently induced CIITA and MHC class II expression in KMT2A-rearranged and NPM1-mutated AML cell lines and primary patient samples, both in vitro and in vivo. Increased MHC-II expression significantly enhanced susceptibility of AML cells to allogeneic T-cell–mediated cytotoxicity. This effect was preserved in xenograft models using primary human AML, resulting in improved leukemia control and prolonged survival after T-cell transfer.Mechanistically, menin inhibition derepressed multiple families of human endogenous retroviruses, leading to accumulation of double-stranded RNA and activation of a type I interferon response. This was accompanied by robust upregulation of interferon-stimulated genes and increased chromatin accessibility at immune-related loci. Pharmacologic inhibition of the cGAS-STING pathway reversed ISG induction and MHC-II upregulation, demonstrating that this signaling pathway is required for menin inhibitor–mediated immunogenic remodeling.In parallel, menin inhibition directly enhanced donor T-cell effector function. Treated T-cells showed increased production of TNF-α, IFN-γ, perforin, and granzyme A/B, alongside reduced expression of inhibitory receptors and exhaustion-associated markers. Chromatin immunoprecipitation and transcriptional profiling revealed reduced menin-KMT2A occupancy at genes encoding negative regulators of T-cell activation. Functionally, menin-treated T-cells exhibited increased cytolytic activity against AML targets in vitro and in vivo.Importantly, enhanced GVL activity did not translate into increased GVHD. Histopathological analysis, inflammatory cytokine expression in target organs, and body weight monitoring showed no exacerbation of acute GVHD in menin inhibitor–treated mice.Conclusion Menin inhibition amplifies GVL through two converging mechanisms: induction of leukemia immunogenicity via a HERV–interferon–MHC-II axis and direct enhancement of donor T-cell cytotoxicity. These findings support menin inhibition as a rational post-transplant maintenance strategy to prevent AML relapse without increasing GVHD risk. V.Fetsch: none, L.Schwöbel: none, E.Ozyerli-Goknar: none, A.Stell: none, M.Punta: none, T.Plenge: none, T.Klaus: none, M.K.Gupta: none, G.Andrieux: none, K.Shoumariyeh: none, S.Pfeiffer: none, E.Corrales: none, L.Schlenke: none, H.Baniadam: none, S.M.Brandl: none, M.Andreis: none, M.Remen: none, A.Hartmann: none, K.Grueter: none, M.Zwick: none, N.Köhler: none, M.Kuban: none, E.Metzger: none, C.Rummelt: none, J.Duyster: none, M.Boerries: none, M.Hofmann: none, J.Färber: none, L.Braun: none, A.J.Zähringer: none, M.Lübbert: none, C.Toffalori: none, L.Vago: none, F.H.Heidel: Merck, Janssen, Kartos, GSK, Abbvie, Silence Therapeutics, Prelude Therapeutics, AOP Health, BMS/Celgene, Novartis: modest, S.Minguet: none, P.Apostolova: none, T.Feuchtinger: none, K.Maas-Bauer: none, F.Blaeschke: none, M.W.M.Kühn: AbbVie, Bristol Myers Squibb/Celgene, Gilead, Johnson & Johnson, Jazz, Pfizer, Servier, Kura Oncology, Syndax Pharmaceuticals Inc: modest, H.Th.M.Timmers: none, T.Wertheimer: none, F.Perner: Syndax Pharmaceuticals, CHARM Therapeutics: modest, R.Zeiser: Novartis, Incyte, Sanofi, Medac, Neovii, Mallinckrodt: modest.