Engineered bacteria with inserted CAR cell membranes for enhanced tumor targeting and biotherapy

Although bacteria have been widely applied in treating various tumors, their inadequate tumor-specific targeting and in vivo controllability often result in suboptimal therapeutic outcomes and inevitable side effects post-administration. Here, we develop an acid-responsive engineered bacteria system (CARM-Bac^ClyA) with inserted chimeric antigen receptor (CAR) cell membranes (M) for enhanced tumor targeting and biotherapy. Specifically, we genetically engineer attenuated Escherichia coli to construct acid-responsive therapeutic bacteria (Bac^ClyA) that express cytotoxic cytolysin A (ClyA) proteins. Simultaneously, we genetically engineer cells to construct cells that express CARs specifically targeting tumor antigens. Subsequently, CARM fragments are inserted into Bac^ClyA during plasmolysis and deplasmolysis (P/deP) to obtain CARM-Bac^ClyA. As a proof-of-concept study, in the mouse solid B-cell lymphoma model, the enrichment of CARM-Bac^ClyA at tumor sites is significantly increased to 2.5-fold that of naked Bac^ClyA after systemic administration. Furthermore, the acidic pH triggers Bac^ClyA to express ClyA proteins, leading to perforation-induced tumor cell death, thereby inhibiting tumor growth. This work introduces a strategy for manipulating engineered bacterial behaviors, and proves the potential of CARM-inserted engineered bacteria for enhanced tumor targeting and biotherapy.