Covid vaccines may come with an exciting benefit that has nothing to do with the virus they are designed to protect against: boosting the immune system to better fight tumors during cancer treatment.
That’s according to new findings presented Sunday in Berlin at the European Society of Medical Oncology Congress. The research is still in its early stages, and has not yet been tested in a phase 3 clinical trial, but experts say it shows promise.
“I’m cautiously optimistic,” said Stephanie Dugan, an assistant professor of cancer immunology and virology at Dana-Farber Cancer Institute, who was not involved in the work. “There is a scientific logic to why this could work.”
The researchers found that among cancer patients receiving immunotherapy, those who received the mRNA Covid vaccine within 100 days before starting their treatment lived longer.
Just about 20% of cancer patients Those who receive immunotherapy — which harnesses a person’s immune system to fight cancer cells — respond to treatment. Finding a way to enhance the effectiveness of immunotherapy drugs is a feat that researchers have been exploring for years, with little success.
Typically, immune-stimulation methods used in the past did too little or too much to activate the immune system, resulting in an over-response that can harm the body. There is a possibility that mRNA Covid vaccines could be found in the temperate zone.
“We probably only needed something of moderate strength, and that’s likely to be the case,” said Duggan, who stressed the need for more research.
That research will begin soon: Dr. Adam Gribbin, a senior resident in radiation oncology at The University of Texas MD Anderson Cancer Center who co-led the study, said his team is launching a phase 3 clinical trial to confirm the preliminary findings.
In the research presented Sunday, Gribbin and his colleagues looked at survival rates among more than 1,000 people who developed advanced non-small cell lung cancer and got immunotherapy as part of their treatment from 2019 through 2023. Of those, 180 people received the mRNA Covid vaccine within 100 days of starting treatment.
The group’s median survival – when half of those who underwent treatment were still alive – was almost twice as high for those who were vaccinated as for those who were not: about three years compared to just over 1.5 years.
The researchers also compared survival rates in a smaller group of patients receiving immunotherapy for metastatic melanoma. Forty-three of them received the mRNA Covid vaccine; 167 did not do so. For those who did not get vaccinated, the average survival was just over two years. Those who were vaccinated before treatment have not yet reached the median survival point after more than three years of follow-up.
In further experiments on mice, researchers obtained an answer that they believe matches the way vaccines work in humans.
“It stimulates the immune system against tumors,” Gribbin said.
Create a lighthouse
Vaccines using mRNA are already a promising area of cancer research. Scientists have developed personalized mRNA cancer vaccines designed to fight a person’s unique tumor, as well as vaccines that target genes commonly found in certain types of cancer, including pancreatic cancer. (These developments come as the Trump administration has eliminated half a billion dollars in funding for mRNA vaccine research for infectious diseases.)
If the subsequent Gripen trial confirms the findings of early research, it may represent the next frontier for research into mRNA vaccines and cancer.
Immunotherapy drugs work by: Enhancing the immune system’s ability to fight cancer, often by boosting the strength of immune cells called T cells that attack invaders, or by making it easier for T cells to find tumors.
The mouse portion of the new research found that the Covid mRNA vaccine appears to make the immune system more attuned to recognizing tumors as a threat by stimulating dendritic cells, a type of white blood cell. When stem cells detect a threat, they turn on a kind of beacon that leads T cells to the perceived invader so they can attack. However, not everyone naturally has T cells capable of fighting tumors, which is why scientists believe immunotherapies only work in some cancer patients who take them. In these people, the immune system recognizes cancer cells as a threat, but their specific T cells are unable to stop the growth of tumors.
“It’s just random chance whether you have those cells or not,” said Jeff Kohler, a professor of RNA biology and therapeutics at Johns Hopkins Medicine, who was not involved in the research.
Getting the mRNA Covid vaccine doesn’t change whether a person has the specific T cells needed to fight their tumors, but it does seem to increase the likelihood that tumor stem cells will detect a problem and direct a person’s existing T cells toward the tumor. If these cells are programmed to be able to kill cancer cells, getting an mRNA vaccine that lights up the target before a person starts immunotherapy could give their immune system a boost that helps cancer treatment work better.
One reason why mRNA technology is the best tool to elicit this response is that every cell in the body already contains mRNA, Kohler said.
“We’re really taking advantage of that natural process that your body already knows how to respond to,” he said. “You’re using your body’s natural system to fight tumors.”
Duggan said it is possible that there are other factors that may be responsible for better survival among people who were vaccinated before immunotherapy. For example, a coronavirus infection may have weakened an unvaccinated person’s body and hampered their ability to fight cancer cells. In the past, early studies like this showed promising results that didn’t pan out in later trials.
“We’ve been misled by retrospective studies before,” she said.
Gribbin agreed that the findings require a closer look.
“These data are exciting, but all of these results need to be validated in phase III clinical trials to determine whether these vaccines should be used in our patients,” he said.