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.

Automated summary

Chimeric antigen receptor T-cell immunotherapy (CAR-T-cell immunotherapy) is effective in haematological tumours but faces challenges in solid tumours, such as poor T-cell infiltration and functional persistence. Flap structure-specific endonuclease 1 (FEN1), highly expressed in cancer cells, is involved in DNA replication and repair. Inhibiting FEN1 has been shown to be an effective strategy for cancer treatment. This study suggests that combining FEN1 inhibitors with CAR-T-cell immunotherapy can enhance the killing effect on solid tumours by promoting T-cell infiltration and improving anti-tumour immunity.