LAUSR

Background Many anti-angiogenic agents have the potential to modulate the tumor microenvironment and improve immunotherapy. Anlotinib has demonstrated anti-tumor efficacy in non-small cell lung cancer (NSCLC) in third-line clinical trials. However, its roles in immune regulation and potentially synergistic anti-tumor effect in combination with immune checkpoint inhibition remain unclear. Methods Here, based on a syngeneic lung cancer mouse model, the intratumoral immunological changes post-anlotinib treatment in the model were assessed. Furthermore, it was tested whether anlotinib could enhance the anti-tumor effect of αPD-1 in vivo. Results This study shows that anlotinib increased infiltration of the innate immune cells, including natural killer (NK) cells, and antigen-presenting cells (APC), which include M1-like tumor-associated macrophages (TAM) and dendritic cells (DC), whereas the percentage of M2-like TAM was dramatically reduced. Subsequently, when combined with PD-1/PD-L1 (programmed cell death 1/PD-1 ligand 1) blockade, anlotinib conferred significantly synergistic therapeutic benefits. Conclusions Overall, these findings describe a role for anlotinib in the innate immune cells in the tumor microenvironment and a potentially synergistic anti-tumor combination with immune checkpoint inhibition.