Boosting B Cell and Macrophage‐Mediated Humoral Immunity with Fusion Nanovesicles for Triple‐Negative Breast Cancer Combined Therapy

Abstract Cell‐derived nanovesicles are widely utilized as therapeutic agents for cancer therapy. Current research mostly focuses on their ability to activate antitumor cellular immunity. However, whether they can activate and participate in antitumor humoral immunity is rarely studied. Here, doxorubicin‐loaded hybrid cell nanovesicles (DNVs) are designed for boosting antitumor humoral and cellular immunity. The hybrid cell nanovesicles are generated through fusion of nanovesicles derived from M1‐type macrophages and 4T1 tumor cells. It is found that DNVs can accumulate at tumor tissues and draining lymph nodes effectively, which results in the activation of antitumor immune response and significant inhibition of tumor progression. During this process, dendritic cells are effectively activated, subsequently inducing cytotoxicity T lymphocytes‐mediated cellular immunity. Furthermore, DNVs elicit the antitumor humoral immunity through boosting T follicular helper cells and germinal center B cells. By analyzing the mechanism behind humoral immunity activation, it is found that M1‐type macrophages repolarized by DNVs play an important role. In general, besides antitumor cellular immunity, the proposed hybrid nanovesicles provide a promising strategy for enhancing antitumor humoral immunity by macrophages repolarization and germinal center B cells activation.