The mRNA vaccines that protected billions from COVID-19 may also hold an unexpected benefit against cancer. A new study published on 22 October 2025 in Nature reveals that these vaccines can make difficult-to-treat cancers more responsive to modern immunotherapy treatments called immune checkpoint inhibitors.
COVID-19 mRNA Vaccines Found to Enhance Immunotherapy Response in Cancer Patients
When Vaccines Do More Than Prevent Disease
Scientists turned to mice with aggressive lung and skin tumours to uncover how mRNA vaccines can improve cancer outcomes.
Immunotherapy has revolutionized cancer care by teaching the immune system to recognize and destroy tumors. But many cancers resist these treatments because they do not have enough immune activity to respond. Scientists have long sought ways to make these tumors immunologically active without needing complex custom-designed cancer vaccines.
A team led by the University of Texas MD Anderson Cancer Center discovered that mRNA vaccines for COVID-19, such as those developed by Pfizer-BioNTech and Moderna, might already perform this immune awakening. They examined thousands of patients with advanced lung cancer and melanoma who were treated with immune checkpoint inhibitors.
Patients who received their vaccines near the start of their immunotherapy had a median survival of 37 months. The survival benefit was seen across cancer types and vaccine brands. In contrast, patients who received other vaccines, like influenza or pneumonia shots, showed no similar improvement, suggesting a unique effect from the mRNA platform.
Nevertheless, to understand why this happened, the researchers turned to animal models. In mice with aggressive lung and skin tumors, giving a COVID-19 mRNA vaccine together with an immune checkpoint drug slowed tumor growth. The combination with immunotherapy activated a powerful and coordinated immune assault on cancer cells.
Discovering How COVID-19 mRNA Vaccines Work Against Tumors
The vaccine does not attack tumors directly. Instead, it sends a strong immune alert through molecules, which act like cellular distress signals.
The mRNA vaccine worked not by targeting the tumor directly but by sending a broad immune response. This was driven by molecules known as type I interferons, which alert the body to viral threats. The resulting chain reaction activated immune cells, boosted tumor antigen presentation, and increased the infiltration of cancer-fighting T cells into tumors.
Note that the same immune storm from the vaccine also caused tumors to raise levels of a protein called PD-L1. This helps cancer cells hide from immune attacks. Immune checkpoint inhibitors block this protein. Hence, when both treatments were given together, the T cells overcame the defense of cancer cells to produce a potent anti-cancer synergy.
Blood samples from healthy volunteers who received a COVID-19 mRNA vaccine also revealed telltale signs of similar immune awakening within 24 hours. Within 24 hours, levels of interferon-alpha surged dramatically, and immune cells became highly activated. Markers of immune readiness, such as PD-L1 on circulating cells, also rose temporarily.
The team then analyzed tumor samples from more than 2000 cancer patients. Those who received a COVID-19 mRNA vaccine within 100 days of a tumor biopsy showed significantly higher levels of PD-L1 than unvaccinated individuals. This shift in tumor biology made them more likely to respond to anti-cancer immunotherapy needing checkpoint inhibitors.
Note that the study proposes a simple sequence. mRNA vaccines trigger a burst of interferons that awaken the immune system. This draws attention to existing tumor antigens. T cells expand and infiltrate tumors. Tumors then increase the levels of PDL-1 protein as a defense, which immune checkpoint drugs subsequently block, allowing a full immune attack.
Flexible Applications of mRNA Vaccine Platform
The mRNA platform can be universal immune boosters. Formulations are readily available, clinically validated, and safe across populations.
The discovery underscores the flexibility of the mRNA vaccine platform. It suggests that existing vaccines, originally built for infectious diseases, can act as universal immune stimulants to aid cancer treatment. Unlike personalized cancer vaccines, which require tailoring, off-the-shelf mRNA formulations are already available and globally proven safe.
However, based on the results, timing appears crucial. The survival benefits were strongest when vaccination occurred close to the start of immunotherapy. This is roughly within 3 months. The observation hints that the mRNA vaccines may temporarily prime the immune system, and timing them with scheduled cancer treatments could yield the best outcomes.
The researchers emphasize that this study does not mean mRNA vaccines alone cure cancer. They work by amplifying the response to existing immunotherapies by providing a systemic immune spark. Future trials will determine optimal timing, dosing, and whether modified mRNA structures can further boost this effect without causing excess inflammation.
Nevertheless, once validated, the findings could reshape how oncologists use mRNA technology. Routine vaccination might become part of cancer care planning, not just for infection prevention but to improve therapeutic response. This could democratize access to immune sensitization without the high cost or delay of personalized cancer vaccines.
FURTHER READING AND REFERENCE
- Grippin, A. J., Marconi, C., Copling, S., Li, N., Braun, C., Woody, C., Young, E., Gupta, P., Wang, M., Wu, A., Jeong, S. D., Soni, D., Weidert, F., Xie, C., Goldenberg, E., Kim, A., Zhao, C., DeVries, A., Castillo, P., … Lin, S. H. 2025. “SARS-CoV-2 mRNA Vaccines Sensitize Tumors to Immune Checkpoint Blockade.” Nature. DOI: 1038/s41586-025-09655-y