A breakthrough Alzheimer’s disease treatment that removes toxic proteins from the brain has reignited interest in a vaccine to treat the memory-depriving disease, according to interviews with 10 scientists and business executives. It has the potential to provide a cheap and easy-to-administer option for as many as a million people.
At least seven Alzheimer’s disease vaccine clinical trials designed to use the immune system to remove beta-amyloid, or tau, a protein associated with the disease, from the brain are underway, a review of the U.S. government’s ClinicalTrials.gov database finds. or was found to be completed. More are in development.
Renewed interest in an Alzheimer’s disease vaccine comes after a promising first attempt was made more than 20 years ago but was halted after 6% of study volunteers developed a life-threatening brain inflammation known as meningoencephalitis. This is based on the following.
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So researchers pivoted to a safer route, injecting patients with highly targeted engineered antibodies that evade the body’s immune system.
Eisai and Biogen’s newly launched Rekenbi and Eli Lilly’s donanemab, currently under review by U.S. regulators, show that removing amyloid is key to fighting Alzheimer’s in early-stage Alzheimer’s patients. There are two treatment methods that solidify this view. That success followed years of failures that left many experts doubting the amyloid theory.
Scientists including Vaxxinity, AC Immune and Prothena believe they have figured out what went wrong with the first vaccines and are testing the shots in hopes of triggering an immune response without causing excessive inflammation. are doing. The U.S. Food and Drug Administration has granted fast-track status to the first two, which should speed up the review of these vaccines.
Dr. Leisa Sperling, an Alzheimer’s disease researcher at Massachusetts General Brigham in Boston, said she believes vaccines will play an important role as researchers focus on preventing Alzheimer’s disease. She said: “I feel very strongly that we need to get there.”
Professor Sperling is leading a trial in cognitively normal people who have Alzheimer’s disease proteins in their brains. She is considering the vaccine for an upcoming study in asymptomatic people who have Alzheimer’s disease proteins in their blood, but not enough to show up on brain scans.
Alzheimer’s vaccines are still in their early stages and will require years of large-scale trials to prove their effectiveness.
Still, quarterly or twice-yearly vaccinations could give Rekenbi a respite from expensive twice-monthly IV infusions and expand access for the estimated 39 million Alzheimer’s patients worldwide. There is.
“They have the potential to be widely available around the world, and they’re not very expensive,” said Dr. Walter Korosietz, director of the Division of Neurological Disorders at the National Institutes of Health.
A doctor points out possible evidence of Alzheimer’s disease found on a PET scan at Brigham and Women’s Hospital in Boston on March 30, 2023. (Reuters/Brian Snyder/File Photo)
“The gate is open”
Vaxxinity may be the most advanced, having already completed a small Phase 2 trial of its vaccine UB-311. Chief Executive Officer May May Fu said Lekembi’s success validated a long-questioned hypothesis.
“What we know is that if you knock out certain bad forms of amyloid, you see an effect on clinical outcomes, which is surprising,” she says of Requembi’s ability to slow cognitive decline. said.
Data from a Phase 2a trial of Vaxxinity in 43 volunteers in Taiwan published in August showed the vaccine was safe and well-tolerated after 78 weeks, with nearly all participants developing an antibody response. It was shown that There were no cases of brain swelling, but 14% (6 people) developed cerebral hemorrhage. This is a common side effect of injection therapy.
Vaxxinity is looking for partners to fund larger-scale demonstration trials, but the weather has proven to be “very frigid” in recent years, Hu said. “(Rekembi’s) approval opens the door and there is more enthusiasm and more investment.”
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what went wrong
The first Alzheimer’s disease vaccines showed signs of effectiveness, but they also triggered an uncontrolled response in the immune system’s T cells, which should only destroy infected cells.
Most new vaccines target B cells, which are immune cells that produce antibodies. According to Dr. Michael Laffey of the University of Southern California, AC Immune’s vaccine only activates B cells. In the phase 1 trial led by Rafii, the AC vaccine did not cause meningoencephalitis, but only a proportion of participants developed an immune response. The company is currently testing a reworked version.
Andrea Pfeiffer, CEO of AC Immune, said the sustained immune response to the company’s vaccine in some patients means the brain swelling and bleeding seen with monoclonal antibodies such as Rekenbi may be less severe. It suggests that this explains what does not happen, and this peaks with each injection. More data is expected to be available in the first half of 2024. AC is also collaborating with Johnson & Johnson on a vaccine that targets tau, a toxic Alzheimer’s disease protein associated with brain cell death. Prothena, which was spun out a decade ago from the company that co-developed the first vaccine, hopes to start trials next year for a vaccine targeting both amyloid beta and tau to prevent Alzheimer’s disease. .
Prothena also has an anti-amyloid antibody in Phase 1 trials and an anti-tau antibody licensed to Bristol-Myers Squibb.
Prothena CEO Gene Kinney said the company’s vaccine produces high levels of mature antibodies. It is important for such vaccines to generate a strong immune response, he said, and they are usually given to older people with weaker immune systems.
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He believes the vaccine is ideal for patients with pre-symptomatic Alzheimer’s disease. “What you want to do is prevent the disease from occurring in the first place.”
