Enhanced antitumor efficacy through combined chimeric antigen receptor T cell therapy and CD40 stimulation in syngeneic solid tumor models.

BACKGROUND

Solid tumors present unique barriers to treatment with chimeric antigen receptor (CAR) T cells, including poor tumor infiltration into a highly immunosuppressive and metabolically challenging tumor microenvironment (TME).

OBJECTIVES

To enhance both CAR T cell efficacy and the overall immune response against solid tumors, this study explored the therapeutic potential of combining CAR T cells with CD40 stimulation via an agonistic CD40 antibody (αCD40). We hypothesized that CAR T cells could serve as targeted vaccines, promoting antigen release and cooperating with αCD40 to activate and mobilize the endogenous immune cells, thus "heating up" the TME and potentially rendering it more receptive to subsequent therapies.

METHODS

We used a syngeneic mouse model of pancreatic ductal adenocarcinoma and further validated our findings in a triple-negative breast cancer mouse model

RESULTS

This combined strategy was associated with enhanced antitumor activity over CAR T cells alone. This included rapid and sustained tumor necrosis, increased immune cell activation both systemically and within the TME, as well as an overall improvement in survival rates. Comprehensive immune profiling at early time points revealed mechanistic insights into the enhanced antitumor effects of CAR T cell therapy and αCD40 treatment.

CONCLUSIONS

These findings set the stage for future clinical applications of CAR T cells in combination with CD40 agonists for the treatment of challenging solid tumors.