Mis-splicing-derived neoantigens and cognate TCRs in splicing factor mutant leukemias

Mis-splicing-derived neoantigens and cognate TCRs in splicing factor mutant leukemias

Mis-splicing-derived neoantigens and cognate TCRs in splicing factor mutant leukemias

Cell. 2025 Jun 26;188(13):3422-3440.e24.

Won Jun Kim, Edie I Crosse, Emma De Neef, Inaki Etxeberria, Erich Y Sabio, Eric Wang, Jan Philipp Bewersdorf, Kuan-Ting Lin, Sydney X Lu, Andrea Belleville, Nina Fox, Cynthia Castro, Pu Zhang, Takeshi Fujino, Jennifer Lewis, Jahan Rahman, Beatrice Zhang, Jacob H Winick, Alexander M Lewis, Robert F Stanley, Susan DeWolf, Brigita Meškauskaitė Urben, Meril Takizawa, Tobias Krause, Henrik Molina, Ronan Chaligne, Priya Koppikar, Jeffrey Molldrem, Mathieu Gigoux, Taha Merghoub, Anthony Daniyan, Smita S Chandran, Benjamin D Greenbaum, Christopher A Klebanoff, Robert K Bradley, Omar Abdel-Wahab

Mutations in RNA splicing factors are prevalent across cancers and generate recurrently mis-spliced mRNA isoforms. Here, we identified a series of bona fide neoantigens translated from highly stereotyped splicing alterations promoted by neomorphic, leukemia-associated somatic splicing machinery mutations. We utilized feature-barcoded peptide-major histocompatibility complex (MHC) dextramers to isolate neoantigen-reactive T cell receptors (TCRs) from healthy donors, patients with active myeloid malignancy, and following curative allogeneic stem cell transplant. Neoantigen-reactive CD8+ T cells were present in the blood of patients with active cancer and had a distinct phenotype from virus-reactive T cells with evidence of impaired cytotoxic function. T cells engineered with TCRs recognizing SRSF2 mutant-induced neoantigens arising from mis-splicing events in CLK3 and RHOT2 resulted in specific recognition and cytotoxicity of SRSF2-mutant leukemia. These data identify recurrent RNA mis-splicing events as sources of actionable public neoantigens in myeloid leukemias and provide proof of concept for genetically redirecting T cells to recognize these targets.