Cancer Vaccines: What the Science Shows—and What “Universal” Really Means

Many types of ongoing cancer research focus on different types of cancer vaccines. Some of these seek to develop cancer vaccines that are specific to particular mutations that are unique to individual patients. Others work to create cancer vaccines based on the shared features of different patients. Additionally, there is research being done to determine if there are ways to utilize RNA to modify tumors to be more responsive to immunotherapy.

Although these advances in research should be acknowledged and encouraged, it is important to recognize that a cancer vaccine entering a clinical trial is just the beginning of an evaluation of the vaccine; it does not mean the vaccine has been proven effective. Evaluating the evidence requires looking beyond the study title and considering the cancer treatment being tested, the type of study being conducted, the patient population, and many other factors.

What is a cancer vaccine?

Cancer prevention and cancer treatment vaccines have different purposes and functions.

Cancer prevention vaccines can protect against viral infections that are known to cause some types of cancer. An example of this is the hepatitis B vaccine and the HPV vaccine. On the other hand, a cancer treatment vaccine, or therapeutic vaccine, is designed for a patient who has already been diagnosed with cancer in order to help the patient's immune system to recognize and attack cancer cells.

Therapeutic vaccination is not entirely new. Sipuleucel-T, for example, has FDA approval for patients with metastatic prostate cancer in a specific clinical setting. This FDA approval, however, doesn't imply that cancer vaccines in general work beyond this one cancer.

Personalized vaccines

Some personalized cancer vaccines are developed to target neoantigens. These are abnormal protein fragments that are unique to tumors and are formed by tumor mutations.

In a pancreatic cancer study, researchers used a number of methods to choose neoantigens for each patient. These included sequencing of both the tumor and some of the normal tissues, as well as tumor RNA sequencing. The researchers computationally prioritized these neoantigens. The study then generated an individualized mRNA vaccine for each patient, to direct the production of T cells targeting the prioritized neoantigens.

Sequencing techniques and computational biology are important for prioritizing neoantigens for further study. The final test is to determine if they elicit an immune response in the patient.

What do the studies show?

A small (phase 1) study of patients with pancreatic cancer found that 8 of the 16 patients who were vaccinated developed an immune response to the vaccine. Patients with the immune response to the vaccine had improved recurrence-free survival compared to patients who did not develop the immune response.

Limitations are important: patients in the study received other treatments, and there was no control group who did not receive the vaccine. The findings support the need for further study, but they do not show the vaccine caused the difference in recurrence.

Evidence from the MELOanie trial, a randomized controlled study, shows an individualized neoantigen therapy when combined with pembrolizumab showed an improvement in recurrence free survival at 3 years compared to pembrolizumab alone. This improvement was seen in the patients with completely removed high-risk melanoma.

Phase 3, the INTerpath-001 trial, is evaluating the individualized neoantigen therapy in combination with pembrolizumab compared to placebo and pembrolizumab in patients with completely removed high-risk melanoma. This trial provides evidence that registration for the individualized neoantigen therapy, in combination with pembrolizumab, is warranted.

What does “universal” mean?

"Universal" can describe a desire to create a more generally applicable approach. It shouldn't be interpreted to mean that one vaccine will target every cancer.

A 2025 study in Nature Biomedical Engineering encodes RNA particles to present antigens unrelated to the tumor. In mouse models, the approach led to early-phase type I interferon responses and overcame checkpoint inhibitor resistance. While this preclinical study suggests a possible broader strategy, it does not indicate that this approach will be effective in human cancers.

Another study in 2025, also published in Nature, conducted laboratory studies and a retrospective analysis on patient data to evaluate the effects of the COVID-19 mRNA vaccine on cancer patients. COVID-19 vaccination at the start of checkpoint inhibitor treatment was associated with improved survival in the patient cohort. Again, an observational study cannot describe a medical intervention to be the cause of an improvement in patient outcomes.

What should readers look for next?

In studies, what should be noted are vaccines clearly identified, who got them, a comparison group, side effects, and if the vaccine lessened cancer recurrence and/or survival.

An immune response is a biologic finding. An improvement in patient outcomes is further evidence.

As noted earlier, research on cancer vaccines has given the field many reasons to be optimistic. The objective of the science is to identify which strategies work in which patients and under what conditions and with what risks. Careful reporting allows that science to be understood and progress to be recognized without turning an experimental hope into a certainty.

This article is for informational and educational purposes only. It is not medical advice and does not replace consultation with a qualified clinician. Diagnosis and treatment decisions belong with the treating medical team.