TGFbeta inhibition via CRISPR promotes the long-term efficacy of CAR-T cells against solid tumors

In recent years, CAR-T cell therapy has proven to be a promising approach against cancer. Nonetheless, this approach still faces multiple challenges in eliminating solid tumors, one of which being the immunosuppressive tumor microenvironment (TME). Here we demonstrated that by knocking out the endogenous TGFbeta receptor II (TGFBR II) in CAR-T cells with CRISPR/Cas9 technology, we could reduce the induced regulatory T-cell (iTreg) conversion and prevent the exhaustion of CAR-T cells. Meanwhile, TGFBR II edited CAR-T cells had better in vivo tumor elimination efficacy, both in cell line derived xenograft (CDX) and patient derived xenograft (PDX) solid tumor models, whether administered locally or systemically. In addition, the edited CAR-T cells could eliminate contralaterally re-inoculated xenografts in mice effectively with an increased proportion of central memory and effector memory subsets. In conclusion, we greatly improved the in vitro and in vivo function of CAR-T cells in TGFbeta-rich tumor environments by knocking out endogenous TGFBR II, proposing a new method to improve the efficacy of CAR-T cell therapy for treating solid tumors.