Vaccines are a sensitive subject for some, but research is looking into using them to stop cancer before it even starts, by vaccinating healthy people.

We already have vaccines that prevent some cancers – the ones caused by viruses, like HPV (papillomavirus) which leads to cervical cancer, or hepatitis B which can cause liver cancer. But most cancers aren’t caused by viruses. Now, researchers are working on a new generation of vaccines that could stop non-viral cancers in their tracks.

The theory is surprisingly straightforward: teach the body’s immune system to recognise and destroy cancer cells as soon as they appear. Ten years ago, this idea seemed far-fetched. But now several research teams are testing these vaccines in clinical trials. Their efforts have been propelled by new insights into the genetic changes in early cancers, along with the recognition that because even nascent tumours can suppress the immune system, the vaccines should work best in healthy people who have never had cancer.

One of the most promising efforts focuses on people who have Lynch syndrome, a mutation in a DNA repair gene that lets genetic errors pile up in dividing cells. It comes with up to a 70% lifetime risk of cancer. Dr. Eduardo Vilar-Sanchez at MD Anderson Cancer Center is leading a trial of a vaccine that targets 209 different cancer markers specific to Lynch syndrome cancers.

Other teams are working on vaccines for different types of cancer. Some target breast cancer in women with BRCA gene mutations, who face a high risk of developing the disease. Others aim to prevent pancreatic cancer in high-risk individuals. Each vaccine is custom-designed for specific types of cancer, using different approaches to trigger the immune system.

Early results are encouraging. In one study, a vaccine helped prevent the recurrence of precancerous growths in the colon. In another trial, a different vaccine kept pancreatic cancer at bay longer than expected in patients who had been treated for the disease.

The ‘holy grail’ would be to teach the immune system to recognise 50 common cancer-causing mutations, potentially preventing multiple types of cancer with a single vaccine.

Some scientists think this goal might be too optimistic. Dr. Olivera Finn, a pioneer in cancer vaccine research, points out that creating a universal cancer vaccine would be “heroic” because it would need to account for the vast differences in how individuals’ immune systems respond to vaccines.

But others are more optimistic. Dr. Bert Vogelstein of Johns Hopkins notes that most cancers involve a relatively small number of gene changes, suggesting that a vaccine targeting these common mutations might work. While it sounds like science fiction, he believes a coordinated effort by many laboratories could make it possible.

Meanwhile, researchers are already testing a multi-cancer prevention vaccine in dogs. The five-year trial involves 800 middle-aged dogs, half receiving a vaccine that targets eight common canine cancers. If successful, this could provide valuable insights for developing human vaccines.

While these vaccines won’t eliminate cancer risk entirely, they could dramatically reduce it. However, researchers face challenges in proving these vaccines work without waiting decades to see if healthy people develop cancer. They’re looking for other ways to measure success, such as monitoring immune responses or tracking precancerous changes.

For millions of people at high risk of cancer, these vaccines could offer something precious: peace of mind and a chance at a healthier future.

This article is a simplified summary of one published by Science.org
Main photo by Swarnavo Chakrabarti on Unsplash