Advancing a multi-dimension KRAS mutation-specific T cell receptor (TCR) library with a 3S TCR targeting the G12D mutation to address large global patient populations

BackgroundKirsten rat sarcoma (KRAS) gene is one of the most commonly mutated oncogenes in numerous tumor types. High prevalence of KRAS mutations (mKRAS) is found in difficult-to-treat indications such as pancreatic, colorectal and non-small cell lung cancer. mKRAS was long considered to be ‘undruggable’. A breakthrough occurred in 2021 with FDA approval of the first G12C inhibitor. Nevertheless, monotherapy with mKRAS inhibitors shows a significant proportion of non-response and accumulated resistance, confirming that additional mKRAS-specific modalities are needed. We describe the expansion of a mKRAS-specific TCR library by addition of highly specific, sensitive and safe (3S) TCRs targeting the G12D KRAS mutation. 3S TCRs when combined with the costimulatory switch protein (CSP) PD1-41BB generate advanced TCR-T therapies, that are armored and enhanced to overcome immunosuppressive tumor microenvironments with potential for improved safety and efficacy.MethodsT cells of multiple healthy donors were primed with mKRAS antigen-loaded dendritic cells and tested in high-throughput functional screens, providing diverse TCR sequences for comparison. Specific TCRs were co-expressed with the PD1-41BB CSP in recipient T cells and assessed for IFN-γ secretion and cytotoxic activity against tumor cells, peptide sensitivity, HLA-allogeneic cross-recognition and off-target toxicity.ResultsmKRAS G12D-specific TCRs showed exquisite specificity for mKRAS G12D across various HLA-A*11 subtypes, high peptide sensitivity with strong tumor recognition as well as an excellent safety profile. These features correspond to those of previously presented mKRAS G12V-specific TCRs in the library. Impact of PD1-41BB CSP on armoring and enhancement of TCR-T functionality is also investigated.ConclusionsOur growing library of mKRAS-specific TCRs is designed to cover different mutations and multiple HLA allotypes, aiming to expand the patient population suitable for treatment. Dual armoring and enhancement of TCR-T cells with PD1-41BB CSP may be particularly effective to improve TCR-T cell activity in hostile tumor microenvironments.Legal entity responsible for the studyThe authors.FundingHas not received any funding.DisclosureAll authors have declared no conflicts of interest.