Abstract LB073: Adoptive transfer of one CD4TCR and one CD8TCR targeting autochthonous neoantigens are essential and sufficient for eradication of naturally heterogeneous solid tumors

Abstract Despite advances in checkpoint blockade therapy or adoptive transfer of tumor-infiltrating lymphocytes (TILs), achieving cure remains challenging, but success of immunotherapy seems to depend on recognition of tumor-specific antigens (neoantigens). We aimed to determine how many neoantigens need to be recognized by how many different TCRs for eradication of solid tumors. Unmanipulated, naturally expressed (autochthonous) neoantigens were targeted with adoptively transferred TCR-engineered autologous T cells (TCR-therapy). Investigated were effects of TCR-engineered CD8+ T cells, TCR-engineered CD4+ T cells or a combination of both. The targeted tumors were established for at least three weeks and derived from primary autochthonous cancer cell cultures, resembling natural solid tumors and their heterogeneity as found in humans. CD8TCR-therapy was only effective against homogenous tumors and relapse was common in heterogeneous tumors, even when targeting multiple different autochthonous neoantigens. By contrast, a combination of CD8TCR-therapy with CD4TCR-therapy, each targeting an independent neoantigen, eradicated large and established solid tumors of natural heterogeneity. CD4TCR-therapy targeted a mutant neoantigen on tumor stroma while direct cancer cell recognition by CD8TCR-therapy was essential for cure. Thus, two cancer-specific TCRs can be essential and sufficient to eradicate heterogeneous solid tumors expressing unmanipulated, autochthonous neoantigens. Citation Format: Steven Wolf, Vasiliki Anastasopoulou, Kimberley Drousch, Markus Diehl, Boris Engels, Poh Yin Yew, Kazuma Kiyotani, Yusuke Nakamura, Karin Schreiber, Hans Schreiber, Matthias Leisegang. Adoptive transfer of one CD4TCR and one CD8TCR targeting autochthonous neoantigens are essential and sufficient for eradication of naturally heterogeneous solid tumors abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (7Suppl): Abstract nr LB073.