At the turn of the 20th century, New York surgeon William B. Coley observed that injecting cancer patients with weakened bacteria helped clear their tumors. The results were intriguing, but the medical establishment resisted the unconventional approach over concerns about safety and validity. 

Over time, as scientists learned more about the immune system, it became clear that Coley was onto something: Bacteria can effectively fight cancer and overcome the shortcomings of other therapies. And thanks to the genetic revolution of the late 20th century, researchers can now engineer bacteria to be safe for injection and program them to perform sophisticated tasks, creating therapies that target cancer and other diseases.

“What’s really cool about bacteria is they can do many things at once. I think of them like these little biological robots that can be programmed to move around the body and perform different actions to attack cancer,” says Neil Forbes, professor of chemical and biomolecular engineering in UMass Amherst’s Riccio College of Engineering. 

In fall 2026, Forbes and colleagues at UMass and Weill Cornell Medicine were granted a major $13.1 million, five-year award from the U.S. National Institutes of Health (NIH) to lead five new, synergistic research efforts to engineer bacterial therapies to target critical gaps in treatment for drug-resistant, triple-negative breast cancer. This UMass-led consortium will design custom strains of Salmonella to counteract cancer’s immune invisibility and overcome drug resistance and radiation toxicity.
 

Forbes has spent more than 25 years conducting pioneering research to develop microbial therapies to treat cancer, using strains of Salmonella engineered to be nontoxic. He helped found a startup company, Ernest Pharmaceuticals, with former members of his UMass lab to bring their Salmonella-based technology, known as BacID, to market. In August 2026, Forbes chaired the first Gordon Research Conference on microbial therapies, held at Bates College in Maine, bringing together more than 150 scientists researching different microbial therapies. With support from the NIH grant, Forbes hopes to build on this momentum to dramatically advance the field of microbial cancer therapies.

“This grant is the first of its kind for bacterial cancer therapies awarded by the NIH, and speaks to UMass’s strength in this field,” says Forbes. “In the future, I’d love to see UMass become a global center for research and training in microbial therapies.” 
 

Why Bacteria Are a Formidable Adversary Against Cancer

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In the early 2000s, as a postdoc at Massachusetts General Hospital studying tumor hypoxia—a condition in which solid tumors are deprived of adequate oxygen—Forbes found himself frustrated that his research would never lead to the development of effective cancer therapies. If a tiny oxygen molecule couldn’t diffuse into a solid tumor, there was no hope for a much larger drug molecule to do so. As a chemical engineer, Forbes understood that the movement of drug molecules is limited by the tendency of molecules to move from an area of higher concentration to one of lower concentration.

Around that time, a research group at Yale discovered that Salmonella accumulates in tumors. Forbes became intrigued by all the things that Salmonella, a “big, complicated organism,” could do, including swimming independently around the body. Since the Salmonella genome had been sequenced in the late 1990s, Forbes had “a full map” of everything they did. “As engineers, we could genetically engineer them to go where we want, make what we want, and control all their behavior,” he says. “We found that a large number of bacteria penetrate into cancer cells.”

In 2012, Nele Van Dessel joined the Forbes Lab as a postdoc. She and Forbes developed BacID, short for bacterial intracellular delivery, which delivers drugs into cancer cells—overcoming a major challenge for other types of cancer therapies that work only on the outside of cells.

As Van Dessel, today the CEO of Ernest Pharmaceuticals, explains, “We engineer the Salmonella so they are safe to inject into the blood. They get cleared from healthy tissue in the body, but in tumor cells, the same mechanisms that stop the body from recognizing tumors also keep the bacteria hidden. So the bacteria go inside the cancer cell, break open, and deliver the drug, which causes the cell to die.”

Van Dessel says that BacID works for different types of tumors and with different drugs. “Our product is very broadly applicable, and that allows us to make it more affordable for patients,” she adds. 

From Lab to Startup

Ernest Pharmaceuticals, established in 2016 and named after Forbes’s grandfather who died of pancreatic cancer, is focused on developing therapies for liver, pancreatic, and ovarian cancers, which are commonly diagnosed at a metastatic stage. 

“Ernest came to be with a lot of support and encouragement from UMass. I was new to this and had a lot to learn about business, finance, and intellectual property, but the university helped all along the way,” says Forbes. “We received support from the Institute for Applied Life Sciences and the Isenberg School of Management, as well as business grants from the National Science Foundation and NIH.” 

The company is currently running a pilot trial of its products in dogs with cancer, a “stepping stone” that Forbes hopes will demonstrate that the technology is safe and effective while also developing an affordable option for owners to prolong their pets’ lives. Forbes aims to start clinical trials in humans in the next few years.
 

A New Strategy to Prevent Cancer Recurrence

In 2026, the Forbes Lab made another breakthrough when it designed Salmonella bacteria that could deliver oncolytic viruses—which are safe for humans but deadly to cancer cells—directly into tumors. The engineered bacteria can not only safely navigate through the bloodstream and hunt down undetectable microtumors that lead to metastasis, but they can also induce an immune response that helps counter tumors’ ability to hide from the immune system. The approach showed promise in shrinking liver and pancreatic tumors, both cancers with an extremely poor prognosis.

“These immune responses not only contributed to smaller tumors, but they also trained the immune system to fight future tumors, suggesting that this therapy may help prevent recurrence or metastasis,” Forbes says, noting that the new $13.1 million NIH grant will help to advance this line of research.

Forbes remarks on how far this field has come since he began working in it more than 25 years ago. Today, microbial therapy research is being conducted using many different microbes and targeting different diseases—including bowel disease, inflammation, Parkinson’s, and even wound healing—as represented at the recent Gordon Research Conference he chaired.

Furthermore, he says, “When I first started, it took us six months to make a new strain of Salmonella. Using new, modern techniques, my students can have an idea and actually make a bacteria strain that acts a certain way within a week. Some of the newer strains of Salmonella we’ve developed can deliver 50 million times more bacteria to cancer cells than other cells in the body.”

As an engineer, Forbes is gratified to be building something that can improve lives. “It’s like Legos with a purpose. What’s exciting to me is that we’re making things that can really make a difference, that can really help people.”

This story was originally published in October 2026.