Although CAR-T cells are widely used to treat cancer, efficiency of CAR-T cell cytolytic responses has not been carefully examined. We engineered CAR specific for HMW-MAA (highmolecular- weight melanoma-associated antigen) and evaluated potency of CD8+ CAR-T cells to release cytolytic granules and to kill tissue-derived melanoma cells, which express different levels of HMW-MAA. CAR-T cells efficiently killed melanoma cells expressing high level of HMW-MAA, but not melanoma cells with lower levels of HMW-MAA. The same melanoma cells presenting significantly lower level of stimulatory peptide- MHC ligand were readily lysed by T cells transduced with genes encoding α,β-TCR specific for the peptide-MHC ligand. The data suggest that higher level of targeted molecules is required to engage a larger number of CARs than TCRs to induce efficient cytolytic granule release and destruction of melanoma cells. Understanding the difference in molecular mechanisms controlling activation thresholds of CAR- versus TCR-mediated responses will contribute to improving efficiency of CAR T cells required to eliminate solid tumors presenting low levels of targeted molecules.
Recommended CitationAnikeeva, Nadia; Panteleev, Sergey; Mazzanti, Nicholas W; Terai, Mizue; Sato, Takami; and Sykulev, Yuri, "Efficient killing of tumor cells by CAR-T cells requires greater number of engaged CARs than TCRs" (2021). Department of Microbiology and Immunology Faculty Papers. Paper 134.
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