Covid vaccines may have an enticing 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.
These are the new results presented on Sunday in Berlin at the European Society of Medical Oncology conference. The research is still in its early stages—it has not yet entered phase 3 clinical trials—but experts say it is promising.
“I'm cautiously optimistic,” said Stephanie Dugan, 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 might work.”
Researchers found that among cancer patients receiving immunotherapyThose who received the mRNA Covid vaccine within 100 days of treatment lived longer.
Only about 20% of cancer patients those who receive immunotherapy, which uses a person's immune system to fight cancer cells, respond to treatment. Finding a way to make immunotherapy drugs more effective has been a feat that researchers have been studying for years, without much success.
Typically, immune stimulation tactics used in the past either did too little to activate the immune system or were too strong, causing an overactive response that could damage the body. There is a possibility that Covid mRNA vaccines may exist in a Goldilocks zone.
“Maybe we just need something in between strengths, and this could potentially be what we need,” Dugan said, emphasizing the need for more research.
That study is about to begin: Dr. Adam Grippin, a senior resident in radiation oncology at the University of Texas MD Anderson Cancer Center who co-led the study, said his team is starting a phase 3 clinical trial to confirm the initial results.
In a study presented Sunday, Grippin and his co-authors analyzed survival rates among more than 1,000 people who had advanced non-small cell lung cancer and who received immunotherapy as part of treatment from 2019 to 2023. Of these, 180 received the Covid mRNA vaccine within 100 days of starting treatment.
Median survival in the group – when exactly half of those treated are still alive – was almost twice as long for those who were vaccinated compared with those who were not: about three years compared with just over 1.5 years.
The researchers also compared survival rates in a small group of patients who received immunotherapy for metastatic melanoma. Forty-three people have received the mRNA Covid vaccine; 167 did not do this. For those who were not vaccinated, the average survival rate was just over two years. Those who were vaccinated before treatment had not yet reached their median survival point after more than three years of follow-up.
Through further experiments in mice, the researchers obtained an answer that they believe matches how the vaccines work in humans.
“It boosts the immune system against tumors,” Grippin said.
Creating a beacon
mRNA vaccines are already a promising area of cancer research. Scientists have developed personalized mRNA vaccines against cancer which are designed to target a person's unique tumor and also target genes that are commonly found in certain types of cancer. including pancreas. (These events come as the Trump administration canceled half a billion dollars in funding for mRNA vaccine research for infectious diseases).
If Grippin's later trial confirms the earlier studies, it could represent the next frontier in research into mRNA vaccines and cancer.
Immunotherapy drugs work increasing the immune system's ability to fight cancer, often by enhancing the power of immune cells called T cells that attack invaders or by making tumors easier to detect by T cells.
Part of a new study in mice found that Covid mRNA vaccination appears to make the immune system better equipped to recognize tumors as a threat by stimulating dendritic cells, a type of white blood cell. When dendritic cells detect a threat, they turn on a kind of beacon that directs the T cells to the suspected invader so they can attack. However, not everyone naturally has T cells that can fight tumors, so scientists believe immunotherapy only works for some cancer patients who take it. In these people, the immune system recognizes cancer cells as a threat, but their specific T cells cannot stop the tumors from growing.
“It's just a matter of chance whether you have these cells or not,” said Jeff Koller, a professor of RNA biology and therapeutics at Johns Hopkins University of Medicine who was not involved in the study.
Getting an mRNA vaccine for Covid doesn't change whether a person has the specific T cells needed to fight tumors, but it does seem to make it more likely that dendritic cells will detect the tumor as a problem and direct the T cells the person has to the tumor. If these cells are programmed to kill tumor cells, having an mRNA vaccine that illuminates the target before a person begins immunotherapy could give their immune system a boost, helping the cancer therapy work better.
Koller said one reason why mRNA technology may be the best tool to achieve this response is because every cell in the body already contains mRNA.
“We're really tapping into this natural process that your body already knows how to respond to,” he said. “You're using your body's natural system to fight tumors.”
Dugan said it was possible that other factors could explain the better survival rates among people who were vaccinated before immunotherapy treatment. For example, a Covid infection could weaken an unvaccinated person's body and prevent it from fighting cancer cells. In the past, early studies like this one showed promising results that didn't pan out in later trials.
“In the past, we were misled by retrospective studies,” she said.
Grippin agreed that the results require closer study.
“These data are exciting, but all of these results need to be tested in phase 3 clinical trials to determine whether these vaccines should be used in our patients,” he said.
