Non-clinical evaluation of NT-112, an autologous T cell product engineered to express an HLA-C*08:02-restricted TCR targeting KRAS G12D and resistant to TGF-b inhibition.

e14533 Background: Adoptive transfer of T-cell receptor (TCR)-engineered T-cells to target shared cancer neoantigens is a promising new immunotherapy approach for patients harboring mutations in oncogenes such as KRAS. Activating mutations in KRAS are among the most prevalent oncogenic driver mutations in human cancers, with KRAS G12D being the most frequent KRAS mutation in colorectal carcinoma and pancreatic cancer. NT-112 is an autologous engineered T-cell product expressing an HLA-C*08:02-restricted TCR that specifically targets the KRAS G12D mutation. NT-112 is additionally engineered to lack TGF-β receptor II (TGFBR2) expression, rendering T-cells insensitive to TGF-b-mediated inhibition in the tumor microenvironment. Methods: For manufacturing of NT-112, CD4 and CD8 T-cells are enriched from leukapheresis material, activated in vitro and gene-edited to knock-out both endogenous TGFBR2 and TCR β constant 1/2 (TRBC1/2) and knock-in an HLA-C*08:02-restricted KRS G12D neoantigen-specific TCR at the TCR α constant (TRAC) locus using CRISPR-Cas9 technology. NT-112 product functionality was evaluated in both in vivo models and in vitro co-culture experiments with a panel of cell lines including those endogenously expressing the KRAS G12D mutation. T-cell reactivity was assessed by measuring cytotoxicity, proliferation, and cytokine production. For determination of NT-112 product safety, cross-reactivity and allo-reactivity assessments were carried out. A comprehensive analysis of potential off-target editing by CRISPR/Cas9 was performed to assess potential risk of genotoxicity in clinical grade NT-112. Results: High reactivity of the NT-112 TCR against KRAS G12D and HLA-C*08:02-expressing target cells was observed. T-cell activation and functionality was highly specific, as demonstrated by a lack of reactivity against KRAS WT, minimal cross-reactivity in Alanine and Glycine scans, and lack of T-cell activation in the absence of HLA-C*08:02. In vivo, NT-112 T-cells were able to induce tumor clearance in two independent models. Low frequency chromosomal translocation events (<0.1%) between on-target and off-target Cas9 cleavage sites were detectable in NT-112 T-cells. However importantly, these did not result in autonomous cytokine-independent growth. Conclusions: Non-clinical studies revealed a favorable safety and efficacy profile for NT-112 and supported further clinical development of a TGF-β-resistant TCR-edited T-cell product for mutant KRAS-targeted cancer immunotherapy.