CAR-redirected natural killer T cells demonstrate superior antitumor activity to CAR-T cells through multimodal CD1d-dependent mechanisms.

Human natural killer T (NKT) cells have been proposed as a promising cell platform for chimeric antigen receptor (CAR) therapy in solid tumors. Here we generated murine CAR-NKT cells and compared them with CAR-T cells in immune-competent mice. Both CAR-NKT cells and CAR-T cells showed similar antitumor effects in vitro, but CAR-NKT cells showed superior antitumor activity in vivo via CD1d-dependent immune responses in the tumor microenvironment. Specifically, we show that CAR-NKT cells eliminate CD1d-expressing M2-like macrophages. In addition, CAR-NKT cells promote epitope spreading and activation of endogenous T cell responses against tumor-associated neoantigens. Finally, we observed that CAR-NKT cells can co-express PD1 and TIM3 and show an exhaustion phenotype in a model of high tumor burden. PD1 blockade as well as vaccination augmented the antitumor activity of CAR-NKT cells. In summary, our results demonstrate the multimodal function of CAR-NKT cells in solid tumors, further supporting the rationale for developing CAR-NKT therapies in the clinic.