At the University of Massachusetts Amherst, Neil Forbes and his team have engineered a microscopic duo: Salmonella bacteria designed to slip through the body's defenses and deliver cancer-killing viruses directly into liver and pancreatic tumors. In mice, the results were striking—tumors shrank to a quarter of the size seen in untreated animals, and treated mice lived up to 65 days longer than their counterparts.
This breakthrough matters because liver and pancreatic cancers are among the deadliest. Standard treatments offer limited hope, and most therapies that work on surface cancers like melanoma fail inside the body, where the immune system destroys them before they reach their target. Forbes saw a solution hidden in biology itself: use one organism to deliver another organism that actually kills cancer.
Here's how it works. The engineered Salmonella bacteria carry oncolytic viruses—viruses that are harmless to humans but lethal to cancer cells. When delivered intravenously through a standard IV line, the bacteria navigate the bloodstream with remarkable precision. Inside tumors, the bacteria deposit their viral payload, achieving a concentration 50 million times higher than in healthy liver or spleen tissue. Once released, the virus enters cancer cells and hijacks their machinery, forcing them to produce more virus particles. Those particles burst out, destroying the cell and infecting neighboring cancer cells in a cascade of destruction. This process also recruits immune cells to the tumor, training the body's defenses to recognize and attack cancer on its own.
The specificity is what sets this approach apart. In the mice studies, tumors treated with virus-carrying Salmonella were only 27% the size of tumors in mice given Sorafenib, a standard liver cancer drug. Equally important, the treatment worked just as effectively when administered through a simple IV rather than through direct injection into the tumor—a procedure that is invasive and dangerous for patients with deeply seated internal cancers.
Shradha Khanduja, the first author on the research and a UMass chemical engineering Ph.D. candidate, emphasized what this means in practice. "Injecting treatments directly into internal tumors is incredibly difficult and often dangerously invasive for cancer patients," she said. "This therapy completely bypasses that hurdle by utilizing a simple, standard intravenous line, allowing the engineered bacteria to safely navigate through the bloodstream and hunt down deep-seated tumors on their own."
The treatment also addresses the hidden threat of microtumors—tiny cancerous clusters that can spread and cause metastasis—and by triggering immune responses, it may help overcome tumors' ability to hide from the body's natural defenses.
Forbes is characteristically measured about what comes next. "There's so much more research to be done before this treatment could be available to humans, but the potential of giving years to a liver or pancreatic cancer patient is exciting," he said. Khanduja added: "Our goal is to build therapies that don't just shrink tumors, but give patients real, lasting time. Seeing these results in two of the deadliest cancers tells us we're on the right path and that biology still has tools we haven't fully tapped."