Breakthrough discovery may lead to universal cancer vaccine

A New Approach to Cancer Treatment

An experimental mRNA vaccine has shown promising results in enhancing the effectiveness of immunotherapy in a mouse-model study. This breakthrough brings researchers closer to developing a universal vaccine that can "wake up" the immune system against cancer. The study, published in Nature Biomedical Engineering, highlights how pairing the test vaccine with common anticancer drugs called immune checkpoint inhibitors triggered a strong antitumor response.

One of the most surprising aspects of the research was that the results were achieved not by targeting a specific protein found in tumors but by boosting the immune system itself. The researchers stimulated the expression of a protein called PD-L1 inside tumors, making them more receptive to treatment. This approach mimics the body's natural response to a virus, prompting the immune system to act as if it were fighting an infection.

Senior author Elias Sayour, M.D., Ph.D., a UF Health pediatric oncologist, emphasized the potential of this new treatment path. He noted that this method could serve as an alternative to traditional treatments like surgery, radiation, and chemotherapy, with broad implications for treating various types of treatment-resistant tumors.

"This paper describes a very unexpected and exciting observation: that even a vaccine not specific to any particular tumor or virus—so long as it is an mRNA vaccine—could lead to tumor-specific effects," said Sayour, principal investigator at the RNA Engineering Laboratory within UF's Preston A. Wells Jr. Center for Brain Tumor Therapy.

Sayour also highlighted the potential for commercializing these vaccines as universal cancer vaccines. These vaccines could sensitize the immune system against a patient's individual tumor, offering a new direction in cancer treatment.

Until now, cancer-vaccine development has primarily focused on two approaches: finding a specific target expressed in many people with cancer or tailoring a vaccine to targets unique to a patient's own cancer. However, this study suggests a third emerging paradigm. By using a vaccine designed not to target cancer specifically but rather to stimulate a strong immunologic response, researchers could elicit a very strong anticancer reaction.

Duane Mitchell, M.D., Ph.D., a co-author of the paper, explained that this approach has significant potential for use across a wide range of cancer patients. It could even lead to an off-the-shelf cancer vaccine, which would be a major advancement in the field.

For over eight years, Sayour has been pioneering high-tech anticancer vaccines by combining lipid nanoparticles and mRNA. mRNA, found in every cell, serves as a blueprint for protein production. This new study builds upon a breakthrough from last year when Sayour's lab conducted the first-ever human clinical trial of an mRNA vaccine that reprogrammed the immune system to attack glioblastoma, an aggressive brain tumor.

In the latest study, Sayour's team adapted their technology to test a "generalized" mRNA vaccine. Unlike previous versions, this vaccine was not aimed at a specific virus or mutated cells of cancer but was engineered to prompt a strong immune system response. The mRNA formulation was similar to the technology used in COVID-19 vaccines but did not target the spike protein of the virus.

In mouse models of melanoma, the team observed promising results in treatment-resistant tumors when combining the mRNA formulation with a common immunotherapy drug called a PD-1 inhibitor. This type of monoclonal antibody helps the immune system recognize a tumor as foreign.

Taking the research further, the investigators tested a different mRNA formulation as a solo treatment in mouse models of skin, bone, and brain cancers. In some cases, the tumors were completely eliminated. Sayour noted that using an mRNA vaccine to activate immune responses unrelated to cancer could prompt T cells to multiply and kill the cancer if the immune response is strong enough.

Mitchell, who directs the UF Clinical and Translational Science Institute, emphasized the striking implications of the study. He stated that this approach could potentially be a universal way of waking up a patient's immune response to cancer, which would be profound if applicable to human studies.

The results show the potential for a universal cancer vaccine that could activate the immune system and work in tandem with checkpoint-inhibitor drugs to target cancer. In some cases, the vaccine might even work on its own to eliminate cancer.

Now, the research team is working to improve current formulations and move toward human clinical trials as quickly as possible. This ongoing effort aims to translate these promising findings into real-world applications for cancer treatment.