Probiotic Bacteria Engineered to Fight Pancreatic Tumors — SkimNews
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- University of Chicago researchers published in Science Advances that BifidoSumIL-2, an engineered strain of Bifidobacterium longum, infiltrated pancreatic tumors in animal models and slowed tumor growth by selectively activating cancer-fighting T cells.
- BifidoSumIL-2 was designed to release SumIL-2, a modified interleukin-2 molecule, directly inside tumors to activate cancer-fighting T cells while reducing stimulation of regulatory T cells that can dampen the antitumor response.
- Bifidobacterium longum functions as a targeted drug factory because it is an obligate anaerobe — it thrives in the low-oxygen core of solid tumors but is cleared from healthy oxygen-rich tissues after systemic injection.
- Combining the bacterial therapy with chemotherapy, radiation, or anti-PD-L1 immunotherapy produced better tumor control and longer survival in animal models than any single treatment alone, lead author Ralph Weichselbaum, MD, said.
- Engineering the organism required specialists in microbiology, synthetic biology, oncology, and immunology; Mark Mimee, PhD called Bifidobacterium 'not the easiest organism to work with' due to its anaerobic nature, slow growth, and limited genetic tools.
- The treatment has not yet been tested in humans; future research will examine long-term safety, durability of the immune response, whether the bacteria can be delivered orally, and combinations with KRAS inhibitors.
Why it matters: Pancreatic cancer has resisted immunotherapy because tumors create 'cold' microenvironments that block immune attack. BifidoSumIL-2 exploits the tumor's low-oxygen core to concentrate an immune-stimulating molecule on-site, and the combination data with chemo, radiation, and anti-PD-L1 showed stronger results than any single treatment alone in animal models. The therapy remains untested in humans.
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