Researchers at the University of Chicago announced on July 24 a new strategy to enhance immune response against pancreatic cancer using engineered probiotic bacteria. The approach involves BifidoSumIL-2, a modified strain of Bifidobacterium longum, which is naturally found in the gut and delivers an immune-stimulating therapy directly inside tumors.
The study, published in Science Advances, reports that this treatment suppressed pancreatic tumor growth by selectively activating cancer-fighting T cells. When combined with chemotherapy, radiotherapy, or immunotherapy, the effects were further enhanced. "A big unmet medical need has been pancreatic cancer, and so that was going to be our mountain to climb," said Ralph Weichselbaum, MD, Daniel K. Ludwig Distinguished Service Professor and Chair of Radiation and Cellular Oncology at the University of Chicago.
BifidoSumIL-2 releases a modified form of interleukin-2 (IL-2) inside tumors. IL-2 is known for activating T cells but can cause harmful side effects when used traditionally. The engineered version aims to stimulate only cancer-fighting T cells while limiting activation of regulatory T cells that might suppress the antitumor response.
Mark Mimee, PhD, Assistant Professor of Microbiology at the University of Chicago, said: "This was a highly interdisciplinary effort. We had to bring together people who understand bacteria, people who understand tumors, and people who understand the immune system to make something like this possible." He added that Bifidobacterium was chosen as it thrives in low-oxygen environments typical of solid tumors but not healthy tissues.
In animal models tested by researchers, BifidoSumIL-2 accumulated in tumors and activated immune responses leading to slowed tumor growth. The combination with standard treatments such as chemotherapy or anti-PD-L1 immunotherapy improved tumor control compared with single treatments alone. "This combination potential is one of the study's most important findings; BifidoSumIL-2 not only works by itself—it works with radiotherapy, chemotherapy, and immunotherapy," Weichselbaum said.
The therapy has not yet been tested in humans; future studies will focus on evaluating safety over time and exploring oral delivery options instead of injection.
