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Experimental mRNA Brain Cancer Vaccine Evaluated in Small Trial

A needle inserted into a vaccine vial.
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A new experimental mRNA vaccine has shown promise in activating the immune system against a highly lethal type of brain tumor, according to results from a first-in-human clinical trial of four adult patients with glioblastoma.

The study, which also included data from pet dogs with the disease, was published in Cell.

Tackling lethal brain tumors

Glioblastoma is a highly lethal type of brain tumor. Current treatments include surgery and radiation, sometimes administered alongside chemotherapy. But with a median survival of 15 months, more effective therapies are sorely needed.

“New treatment outcomes are necessary for glioblastoma and pediatric brain tumors where outcomes have not precipitously changed in several decades,” explained Dr. Elias Sayour, the senior author of the study, speaking to Technology Networks

mRNA technology – known to many for its role in some COVID-19 vaccines – may offer a new solution. Several candidates are under evaluation in clinical trials for various cancer types, including melanoma.

In the new study, Sayour and colleagues report their results using a novel take on this vaccine technology for glioblastoma, testing it in both pet dogs with the disease as well as a small cohort of four human patients.

“Our brain tumor program has developed promising effects with other forms of immunotherapy against brain cancer and wanted to test a novel mRNA vaccine design to enhance responses for these difficult-to-treat diseases,” said Sayour.

Provoking immune responses

The vaccine uses mRNA and lipid nanoparticles in a similar way to some COVID-19 vaccines but with a newly engineered delivery system and personalized to the patient’s tumor cells.

The vaccine is produced by extracting and amplifying mRNA from the patient’s surgically removed tumor and packaging it inside lipid nanoparticles. This causes the vaccine to resemble a virus when injected into the patient’s bloodstream, leading to an immune response.

“Instead of us injecting single particles, we’re injecting clusters of particles that are wrapping around each other like onions, like a bag full of onions,” Sayour said.

The vaccine was first tested in mice and then moved to a trial of 10 pet dogs with terminal glioma, which has no other treatment options. Dogs with the disease typically have a median survival of 30–60 days, though the animals in the trial survived for a median of 139 days.

“These vaccines have elicited strong responses against mouse gliomas with long-term survival and improved outcomes for pet dogs with natural forms of the human disease,” Sayour added.

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The promising results from the dog study paved the way for a small trial of four human patients approved by the US Food and Drug Administration (FDA), aiming to evaluate its safety before moving on to larger trials. The trial was too early to evaluate the clinical efficacy of the vaccine, but the patients either lived disease-free or survived longer than expected.

“The demonstration that making an mRNA cancer vaccine in this fashion generates similar and strong responses across mice, pet dogs that have developed cancer spontaneously and human patients with brain cancer is a really important finding, because oftentimes we don’t know how well the preclinical studies in animals are going to translate into similar responses in patients,” explained study co-author Dr. Duane Mitchell, director of the UF Clinical and Translational Science Institute and the UF Brain Tumor Immunotherapy Program.

Additional clinical trials planned

“We expect the Phase 1 clinical trial to include up to 24 adult and pediatric patients to validate the findings. Once an optimal and safe dose is confirmed, an estimated 25 children will be enrolled [in] the Phase 2,” Sayour explained.

“We expect this work to create a new paradigm that rapidly activates the immune system against cancer,” Sayour continued. “To win the war on cancer, the immune system needs a better head start.  We hope this approach gives the immune system the head start it needs to win the race against rapidly evolving tumors.”


Reference: Mendez-Gomez HR, DeVries A, Castillo P, et al. RNA aggregates harness the danger response for potent cancer immunotherapy. Cell. 2024. doi: 10.1016/j.cell.2024.04.003

Dr. Elias Sayour was speaking to Dr. Sarah Whelan, Science Writer for Technology Networks.

About the interviewee:

Dr. Elias Sayour is an associate professor of neurosurgery and pediatrics at the University of Florida. He is also the principal investigator of the RNA Engineering Laboratory in the Preston A. Wells, Jr. Center for Brain Tumor Therapy and UF Brain Tumor Immunotherapy Program. He holds a medical degree from the University at Buffalo and a doctorate from Duke University.