Bacteria genetically engineered to seek and destroy tumors

Cancer tumors are particularly adept at evading the body’s immune response, making treatment difficult. A new study has genetically engineered a common gut bacteria, enabling it to seek out and destroy cancer tumors from the inside.

The chemokine CXCL16 recruits T cells, the white blood cells that help fight infection and cancer, to infiltrate cells. CXCL16 and its receptor, CXCR6 have been shown to improve survival rates in patients with colon and lung cancers. And recent studies suggest that CXCL16 and CXCR6 together generate anti-tumor immunity. However, no one has discovered a method to deliver CXCL16 into the tumor’s cellular environment.

Scientists have known for some time that some species of bacteria can survive inside tumors. A new study by researchers at Columbia University has used that knowledge, combining it with genetic engineering to create a way of targeting and destroying tumors by recruiting the body’s own immune cells.

Crucial to the study was the introduction of an engineered, probiotic strain of Escherichia coli (E. coli), a bacterium common to the human gut. The E. coli was engineered to contain a synchronized lysis circuit, a way of exploiting the innate ability of some bacteria to invade disease sites in the body.

When the bacteria enter a tumor, the circuit is triggered, causing them to break apart, or lyse. Lysis enables the repeated localized delivery of chemokines, which recruit T cells and augment anti-tumor immunity.