Turning routine vaccines into weapons against cancer

Using Salmonella to fight pancreatic cancer: How CD8 T cells can help.


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Researchers from the University of Massachusetts Amherst have found a way to use a part of a childhood vaccine to help the body fight cancer. They use particular bacteria to deliver this vaccine part directly into tumor cells, which stops the cancer from growing and coming back.

In a recent study, Professor Neil Forbes and his team at the University of Massachusetts Amherst found a way to use a particular bacterial system as a ready-made treatment for various types of cancer. This research can help patients with tough-to-treat liver, metastatic breast, and pancreatic tumors. 

The university has applied for a patent, and a startup called Ernest Pharmaceuticals, co-founded by Forbes and his colleagues plans to seek approval from the FDA for clinical trials in the coming years.

Forbes explains, “The idea is that everybody is vaccinated with a whole bunch of things, and if you could take that immunization and target it towards cancer, you could use it to eliminate it. But cancers aren’t going to display viral molecules on their surface. So the question was, could we take a molecule inside the cancer cell using Salmonella and then have the immune system attack that cancer cell as if it was an invading virus?”

To check if their idea could help the immune system fight cancer, Forbes and his team modified Salmonella bacteria to carry a chicken egg protein called ovalbumin. They put this into the tumors of mice that had received the ovalbumin “vaccine.” 

They found that the ovalbumin spread within the cells of the tumors and caused a type of immune response that attacked the cancer cells. This treatment cleared 43% of the pancreatic tumors in the mice, made them live longer, and stopped the tumors from returning.

Forbes said, “We had the complete cure in three of seven pancreatic mice models. We’re excited about that; it dramatically extended survival.”

The researchers tried to return pancreatic tumors to the mice given the ovalbumin vaccine. Surprisingly, none of the tumors grew, meaning the mice had become immune to the ovalbumin and the cancer itself. This suggests that the immune system recognized the tumor as something it needed to fight. 

The team had previously shown that using the modified Salmonella to treat liver tumors in mice worked well, and they built on that success with this study on pancreatic tumors.

Before they can start testing this treatment on people, the researchers will do more tests on animals and ensure the modified Salmonella bacteria is safe for humans. They plan to start with liver cancer and then move on to pancreatic cancer. 

Professor Forbes is determined to turn this discovery into a natural cancer treatment, and it’s not just an academic project for him; it’s personal because his grandfather, for whom Ernest Pharmaceuticals is named, died from prostate cancer.

This study explores a novel approach that leverages the immune response triggered by routine vaccinations to target and destroy cancer cells. The research shows promising results in mouse models, and further studies and refinements are needed before transitioning to human trials. The ultimate objective is to develop a viable and potent cancer treatment strategy based on this innovative concept.

Journal reference:

  1. Vishnu Raman, Lars M. Howell et al., Intracellular Salmonella delivery of an exogenous immunization antigen refocuses CD8 T cells against cancer cells, eliminates pancreatic tumors, and forms antitumor immunity. Frontiers in Immunology. DOI: 10.3389/fimmu.2023.1228532.