New approach could expand the success of immunotherapy from blood cancers to solid tumors.

Bacteria play an important role in human health. “Good” bacteria on human skin and in the gut help prevent diseases and maintain proper digestive function. Now researches are using bacteria to help fight cancers that involve solid tumors –– cancers that have only seen limited benefits from the wave of new immunotherapy drugs.

Scientists at Columbia University’s School of Engineering and Irving Medical Center have engineered a non-pathogenic strain of Escherichia coli that, when injected into mouse tumors, release cancer-killing drugs locally within the tumors and even in distant tumors, reducing metastasis of the cancers. The bacteria are designed to colonize solid tumors, replicate and eventually die, releasing the active drug substance into the tumor. A limited number survive to allow further delivery of the drug.

In one particular example, the active drug was a small antibody that targets CD47, a protein that normally shields cancer cells from immune attack and is found in many solid tumors. The challenge in the past with targeting this protein is its presence in many locations in the body, leading to high toxicity for systemic treatments.

The researchers have established a company to develop a treatment for humans based on this technology. They are conducting further studies to demonstrate the effectiveness of the strategy and are planning safety studies in a range of solid tumors intending to eventually move into the clinic.

Many other companies, both emerging biotech and big pharma, are exploring ways in which the human microbiome can be leveraged to fight cancer.