Role of focused ultrasound in CD40 mediated anti-tumor immunity

Abstract

Advanced stage melanoma tumors are chemo- and radio-resistant, demonstrate poor antigenicity and defective antigen presentation mechanisms, and low tumor specific cytotoxic T cell population, resulting in poor survival rates in patients. Novel therapeutic approaches that can reprogram the tumor immune microenvironment and improve outcomes against refractory and aggressive melanoma is urgently needed. We hypothesized that focused ultrasound (FUS) and its combination with anti-CD40 agonistic antibody (CD40) will improve the melanoma therapy outcomes by activating the innate and adaptive immune cells in the tumors. Prior research has shown that FUS has an immunomodulatory effect in solid tumors, and CD40 is a known enhancer of antigen presenting cell (APC) function. To investigate our hypothesis, we exposed B16F10 murine melanoma to various FUS parameters (thermal and histotripsy [HT]) in the presence and absence of CD40 stimulation. We found that CD40 and FUS combination increased the anti-tumoral M1 macrophages and granzyme B+ cytotoxic T cell population in murine melanoma and suppressed both treated and untreated tumors. In particular, HT plus CD40 (HT40) caused a significant increase in the expression of immune checkpoints, namely CTLA4 and PD-L1, to aid the anti-CTLA4 and PD-L1 therapy (ICI), thereby prolonging the mice survival rates in HT40+ICI group compared to ICI therapy alone group. In conclusion, our data suggest that focused ultrasound and anti-CD40 agonistic antibody combination enhances the anti-tumor immunity and sensitization to checkpoint inhibitor therapy in advanced stages.