An experimental vaccine increases survival rates by up to 50% in four people with highly-aggressive brain cancer
Spanish biochemist Héctor Méndez and his colleagues from the University of Florida have achieved ‘promising’ results in their initial human trial
Four people suffering from an extremely aggressive type of brain cancer lived up to 50% longer than expected, thanks to a personalized experimental vaccine. This is according to the results published on Wednesday, May 1, by Spanish biochemist Héctor Méndez and his colleagues at the University of Florida in Gainesville.
The patients — now deceased — suffered from glioblastoma, the most common malignant tumor in the brain. They voluntarily participated in the clinical trial while they were in the terminal phase of the disease. “It’s quite promising,” says Méndez, 42, who was born in Salamanca, Spain, and now resides in the United States.
The human body’s defenses often don’t recognize cancer cells as a threat. Hence, the Florida team employs a sophisticated strategy. Researchers inject lipid particles — measuring millionths of a millimeter — into a vein. These contain genetic information obtained directly from each patient’s tumor. This messenger RNA technology, like that of the Pfizer and Moderna vaccines against Covid, trains the immune system to think that tumor cells are dangerous viruses and subsequently destroy them.
Méndez explains that patients given a standard treatment — used as a control — had a survival period of approximately six months. One of the vaccinated people, however, reached nine months: 50% longer. Another participant lived eight months, or 33% longer. In the other two patients, the results were positive, but not so positive, the biochemist admits.
The team, led by American oncologist Elias Sayour, now wants to begin a larger trial, with 24 patients, to confirm the safety of the vaccine and refine the dosage. The next step after that would be another trial, with about 25 children who have been diagnosed with glioblastoma.
“It seems to improve people’s survival rates and we haven’t found any type of chronic toxicity so far,” Méndez says. He received his training at the University of Salamanca and the Cajal Institute in Madrid.
Previous experiments that utilized animals as test subjects were also promising. A dozen dogs with terminal brain cancer lived an average of almost five months after receiving the vaccine, multiplying the usual survival time of one or two months. The results from the first human trial were published this past Wednesday in Cell, a peer-reviewed scientific journal.
Dr. Laura Angelats, an oncologist, applauds the latest work. However, she’s cautiously optimistic. “It’s a very innovative strategy and the preclinical data is quite interesting, but we still have very little data from patients to be able to confirm that it’s a safe and effective treatment,” the expert from the Hospital Clínic of Barcelona emphasizes.
There are two other experimental RNA vaccines currently in advanced human trials. Oncologist Vinod Balachandran is overseeing trials of a pancreatic cancer shot at Memorial Sloan Kettering Cancer Center in New York City, while pharmaceutical companies Moderna and Merck have also obtained promising results with an RNA vaccine against melanoma. All of these vaccines are therapeutic, to treat an already-established cancer. On the other hand, British oncologist Sarah Blagden, from the University of Oxford, is leading a project to develop a preventive vaccine against lung cancer, based on harmless cold viruses in chimpanzees. This is a technology similar to that employed by the AstraZeneca vaccine against Covid.
Angelats notes that glioblastoma consists of “cold tumors” — tumors that are surrounded by cells that suppress the immune response and keep T cells (a type of immune cell) from attacking the tumor cells. Immunotherapy, which involves stimulating one’s own defenses against cancer, is much less effective in cold tumors. The oncologist highlights that, if the experimental vaccine against glioblastoma actually works, the same strategy could be applied against other cold tumors, such as in the case of colon cancer. “There’s a lot left to do, but it’s promising data,” she affirms.
Immunologist Luis Álvarez Vallina also praises the new research. “I find it very promising… it’s one more step towards the coming of age of RNA vaccines, which are going to be very important against cancer. This is a relevant contribution, despite its limitations,” the scientist, head of the Clinical Research Unit in Cancer Immunotherapy at the Madrid-based Spanish National Cancer Research Center, says.
Álvarez Vallina highlights that the lipid nanoparticles used by the American team are larger than usual and have a multi-layered structure, like an onion, which increases their ability to alert the immune system. The immunologist predicts a future with combined strategies, such as vaccination accompanied by other types of immunotherapies, such as immune checkpoint inhibitors. “The scenario is going to be very malleable, depending on the characteristics of each patient and their clinical situation. But I think that vaccines are going to become an important element within the arsenal,” he concludes.
Translated by Avik Jain Chatlani
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