A major study led by The University of Texas MD Anderson Cancer Center, shared at the 2025 European Society for Medical Oncology Congress, tracked over 1,000 cancer patients treated between August 2019 and August 2023. It found that timely mRNA COVID vaccination—within 100 days of starting immune checkpoint inhibitor therapy—led to dramatically improved long-term survival.
“These results show that commercially available mRNA COVID vaccines can help retrain the immune system to find and attack cancer,” explained Dr. Adam Grippin, one of the study leaders. “Patients who combined vaccines and immunotherapy saw powerful anti-tumor effects and much better odds of living longer.”
“The really exciting part of our work is that it points to the possibility that widely available, low-cost vaccines have the potential to dramatically improve the effectiveness of certain immune therapies,” Grippin said. “We are hopeful that mRNA vaccines could not only improve outcomes for patients being treated with immunotherapies but also bring the benefits of these therapies to patients with treatment-resistant disease.”
How does it work? The mRNA vaccine acts as an alert, arming the body’s immune system to target cancer cells more effectively. In response, tumors often produce more of the immune checkpoint protein PD-L1 to try and shield themselves. That’s where checkpoint inhibitors come in—by blocking the PD-L1 escape route, these drugs allow the immune system to do its job and attack the cancer head-on.
What’s next: These promising results have led to a new randomized Phase III trial to see if COVID mRNA vaccines should become part of standard care for patients starting immunotherapy. While researchers are still exploring all the ways these vaccines interact with cancer treatments, the study suggests they could be a key tool in boosting survival for more patients in the future.