In situ reprogramming of tumor-associated macrophages enhances cancer immunotherapy

In situ reprogramming of tumor associated macrophages (TAMs) to resurge their phagocytic ability holds great potential in cancer treatment. However, most of currently existing TAMs-reshaping approaches fail to effectively reprogram TAMs due to low efficiency, poor specificity, and potential immune side effects. Herein, we report a strategy called molecularly imprinted lysosomal nanodegrader (MILND) for resurging the phagocytosis of macrophages and reversing the "don't eat me" CD47-SIRPα signal via degrading SIRPα in lysosomes. The MILND, which was rationally engineered by controllable molecular imprinting using the N-terminal epitope of SIRPα as template, could specifically bind SIPRα on TAMs. Upon being engulfed by TAMs via endocytosis, the MILND-SIRPα complex was transferred to lysosomes for degradation. The degradation of SIRPα induced a cascade reaction of the downstream PI3K signaling pathway to resurging the phagocytic and recognition capability of TAMs towards cancer cells. Ultimately, MILND resulted in a subsequent series of anti-tumor effects. Benefiting from this, MILND effectively sensitized the immune microenvironment and amplified CD8+ T cell responses, leading to substantial tumor growth inhibition in tumor-bearing mouse model. Thus, this work provides an efficient and versatile immunomodulatory strategy for enhanced antitumor immunotherapy.