A novel oncolytic poxvirus carrying CD47 nanomabs in the treatment of pancreatic cancer by reshaping the immune microenvironment.

Pancreatic cancer remains a highly aggressive malignancy with limited treatment options. Recent advances have identified CD47 as a promising therapeutic target, though clinical translation faces challenges due to the complex immunosuppressive tumor microenvironment (TME). Here we developed an innovative oncolytic vaccinia virus platform expressing an anti-CD47 nanobody (OVV-aCD47nb), designed to simultaneously target tumor cells and modulate immune responses. Our in vitro studies demonstrated that OVV-aCD47nb effectively infected and replicated in pancreatic cancer cells while secreting functional aCD47nb that specifically bound to tumor cell surfaces. In vivo evaluation revealed remarkable therapeutic efficacy, with significant inhibition of primary tumor growth, suppression of contralateral and metastatic lesions, and substantial extension of survival in multiple pancreatic cancer models. Notably, the treatment induced robust and durable immune memory, providing protection against tumor rechallenge. At the mechanistic level, comprehensive analysis showed that OVV-aCD47nb induced profound remodeling of the TME, characterized by increased infiltration of cytotoxic CD8 T cells, NK cells, and tumor-suppressive M1 macrophages. Through detailed T cell activation assays, we elucidated that virus-activated macrophages secreted key chemokines (CXCL9), creating a pro-inflammatory microenvironment that enhanced T cell recruitment and activation. Furthermore, the treatment upregulated PD-L1 expression in the TME, and combination therapy with PD-L1 blockade demonstrated synergistic anti-tumor effects, significantly improving survival outcomes. These findings establish OVV-aCD47nb as a multifaceted immunotherapeutic that reprograms the TME through coordinated immune activation. The macrophage-mediated T cell activation via chemokine signaling, combined with PD-L1 blockade, presents a transformative approach for pancreatic cancer with strong clinical potential.