Tandem CAR-T cells targeting MUC1 and PSCA combined with anti-PD-1 antibody exhibit potent preclinical activity against non-small cell lung cancer.

Chimeric antigen receptor (CAR)-T cells encounter many issues when treating solid tumors, including tumor antigen heterogeneity and immunosuppression. United targeting of two tumor-associated antigens (TAAs) and blocking of PD-1 may solve this problem and enhance the function of CAR-T. Mucin 1 (MUC1) and prostate stem cell antigen (PSCA) are overexpressed in non-small cell lung cancer (NSCLC). Here, we constructed a bivalent tandem CAR-T (Tan CAR-T), which can simultaneously target MUC1 and PSCA and evaluated its effects of inhibiting non-small cell lung cancer (NSCLC) in vitro and in vivo. Results indicated that the tumor killing effect of these Tan CAR-T was more effective than that of single-target CAR-T, its antitumor efficacy could be further strengthened by anti-PD-1 antibody. Our study reported a previously unstudied therapeutic effect of a Tan CAR-T in NSCLC, providing a preclinical rationale for anti-PD-1 antibody combined with Tan CAR-T targeting MUC1 and PSCA in the treatment of NSCLC.

FEN1 inhibitor SC13 promotes CAR-T cells infiltration into solid tumours through cGAS-STING signalling pathway.

It is well known that chimeric antigen receptor T-cell immunotherapy (CAR-T-cell immunotherapy) has excellent therapeutic effect in haematological tumours, but it still faces great challenges in solid tumours, including inefficient T-cell tumour infiltration and poor functional persistence. Flap structure-specific endonuclease 1 (FEN1), highly expressed in a variety of cancer cells, plays an important role in both DNA replication and repair. Previous studies have reported that FEN1 inhibition is an effective strategy for cancer treatment. Therefore, we hypothesized whether FEN1 inhibitors combined with CAR-T-cell immunotherapy would have a stronger killing effect on solid tumours. The results showed that low dose of FEN1 inhibitors SC13 could induce an increase of double-stranded broken DNA (dsDNA) in the cytoplasm. Cytosolic dsDNA can activate the cyclic GMP-AMP synthase-stimulator of interferon gene signalling pathway and increase the secretion of chemokines. In vivo, under the action of FEN1 inhibitor SC13, more chemokines were produced at solid tumour sites, which promoted the infiltration of CAR-T cells and improved anti-tumour immunity. These findings suggest that FEN1 inhibitors could enable CAR-T cells to overcome poor T-cell infiltration and improve the treatment of solid tumours.

DC vaccine enhances CAR-T cell antitumor activity by overcoming T cell exhaustion and promoting T cell infiltration in solid tumors.

OBJECTIVE: Great success has been achieved in CAR-T cell immunotherapy in the treatment of hematological tumors. However, it is particularly difficult in solid tumors, because CAR-T is difficult to enter interior and exert long-term stable immune effects. Dendritic cells (DCs) can not only present tumor antigens but also promote the infiltration of T cells. Therefore, CAR-T cells with the help of DC vaccines are a reliable approach to treat solid tumors. METHODS: To test whether DC vaccine could promote CAR-T cell therapy in solid tumors, DC vaccine was co-cultured with MSLN CAR-T cells. The in vitro effects of DC vaccine on CAR-T were assessed by measuring cell proliferation, cell differentiation, and cytokine secretion. Effects of DC vaccine on CAR-T were evaluated using mice with subcutaneous tumors in vivo. The infiltration of CAR-T was analyzed using immunofluorescence. The persistence of CAR-T in mouse blood was analyzed using real-time quantitative PCR. RESULTS: The results showed that DC vaccine significantly enhanced the proliferation potential of MSLN CAR-T cells in vitro. DC vaccines not only promoted the infiltration of CAR-T cells, but also significantly improved the persistence of CAR-T in solid tumors in vivo. CONCLUSION: In conclusion, this study has demonstrated that DC vaccine can promote CAR-T therapy in solid tumors, which provides the possibility of widespread clinical application of CAR-T cells in the future.