October 23, 2025, 10:55 am | Read time: 4 minutes
The relatively new mRNA vaccines, which gained significant recognition during the coronavirus pandemic, are now being explored as potential cancer therapies. However, there is still no clinical application outside of studies. This makes the results of a new research study all the more interesting. It suggests that the COVID vaccine, originally used against the coronavirus, apparently stimulates the immune system to better fight cancer cells. FITBOOK explains the study’s findings.
SARS-CoV-2 mRNA Vaccines Effective Against Cancer, Study Finds
Once hailed as a cure, then initially scarce due to high demand, later critically viewed by larger segments of the population, and now assessed more nuancedly: the COVID vaccine. While potential vaccine injuries are now a field of research, it is also established that the global vaccination campaign between 2020 and 2024 is estimated to have prevented around 2.5 million deaths.1,2 Now, the once-controversial remedy has come into focus in a different scientific context. Several clinical studies are currently examining whether and how mRNA technology can help activate the immune system specifically against tumors. But what about what we already have? Researchers from various U.S. institutions have closely examined whether the available SARS-CoV-2 mRNA vaccines can trigger a corresponding response.3 And this indeed seems to be the case.
To better understand how mRNA vaccines influence the immune system in the fight against cancer, the researchers used animal experiments. They created an mRNA molecule that functions on the same principle as the COVID-19 vaccines: The mRNA contains the blueprint for the spike protein of SARS-CoV-2 and is used on mice with “cold” lung and skin tumors. This means that these tumors typically respond weakly to immune checkpoint inhibitors (ICIs).
They divided the animals into four groups:
- Mice that received only ICIs,
- Mice that received the mRNA construct, and
- Those with a combination treatment of both.
The researchers monitored tumor growth. Certain defense substances, immune cells, and signaling pathways put pressure on tumor cells, allowing the immune system to better recognize and attack tumors. They identified the mechanisms responsible for this effect by selectively blocking individual signaling pathways.
COVID Vaccination Shows Positive Effects on Cancer Treatment
The team found that the COVID vaccine had positive effects on cancer treatment, particularly for patients with non-small cell lung cancer (NSCLC). Those who received the vaccine within 100 days of starting immunotherapy had a significantly better survival rate. Their risk of death was roughly halved compared to those who did not receive the vaccine. Similar improvements were observed in patients with other types of tumors, where vaccination shortly before or at the start of immunotherapy was associated with better survival.
Researchers described the vaccine’s effect on the immune system as a “wake-up call.” The vaccine sends a signal that activates the immune system to recognize and target tumor cells. At the same time, it helps the immune system overcome the challenge of identifying tumors that are typically less visible to the immune response.
Researchers found the effect on “cold” tumors particularly interesting. When patients with these tumors received both a vaccine and immunotherapy, their survival chances improved significantly, almost reaching the level of tumors that were responsive to the immune system from the start.
The cohort of healthy individuals confirmed the activating effect of the COVID vaccine on the immune system. After vaccination, the body releases numerous defense substances.
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Potential Significance of the Results
The study suggests that mRNA vaccines—those against COVID that do not contain specific information about tumor cells—may influence the immune system in a way that allows it to target “cold” tumors. If these observations are confirmed in further research, the researchers hope “this widespread, cost-effective intervention could be quickly adopted into clinical practice,” potentially extending the benefits of immunotherapy to patients who would not otherwise benefit from this treatment.
Limitations
However, there are limitations to note. The clinical data come from a retrospective observational study, and various factors (such as general health status, timing of treatment, and access to medical care) could have influenced the results. Many mechanistic insights come from animal experiments. While there are indications of the safety of combining vaccination and immunotherapy, large-scale studies and long-term data are still lacking. Additionally, much data was collected from a single center during the COVID-19 pandemic. Changes in treatment protocols, infections, vaccination behavior, or incomplete documentation of vaccine types, dosages, and timing could have further influenced the results.