Brain tumors: New vaccine offers patients hope for more time

Brain tumors are difficult to treat. Because even tumors that can be operated on can rarely be removed completely through surgery. Patients typically receive chemotherapy and radiation therapy but even so, people with aggressive tumors often live no more than five years after diagnosis.

In a study by researchers at the German Cancer Research Center, University Medical Center Mannheim, Heidelberg University Hospital and other research institutions, 33 patients also received a vaccine.

Eight years later, the research team published the long-term follow-up results in the journal Nature. And there is reason for cautious optimism: 66% of the people who took part in the study were still alive after eight years. In 42% of participants, the tumor had not grown back during that time.

One of the study's lead authors, Michael Platten, director of the department of neurology at University Medical Center Mannheim and head of a research division at the German Cancer Research Center, said he was particularly surprised that the tumors had not returned in such a large share of patients over such a long period.

A vaccine against brain tumors does not prevent cancer

Whether for measles, mumps or COVID-19 — vaccines are best known as a preventive measure that helps to keep us from getting a particular disease or trains the immune system to make the illness less severe. These are known as preventive vaccines.

Therapeutic vaccines, by contrast, are designed to destroy tumors by activating the immune system. In the case of the therapy developed by Platten and his team, the vaccine targets a genetic mutation found only in certain brain tumors. All 33 participants had high-grade astrocytomas, meaning they had aggressive tumors in the brain that carry a high risk of returning after treatment.

Vaccine trains immune system to fight tumor cells

Astrocytomas are among the most common tumors of the central nervous system, which includes the brain and spinal cord. They are divided into four grades, ranging from less aggressive to highly aggressive. Grade three and four astrocytomas share a specific genetic mutation that the researchers targeted with their vaccine.

"An identical genetic error causes a specific amino acid to be substituted in the IDH1 enzyme," the German Cancer Research Center explained in a press release. "This results in a novel protein structure — a so-called neoepitope. What makes this special is that, on the one hand, the neoepitope drives tumor growth — and, at the same time, it is recognized as foreign by the patient’s immune system, making it an ideal target for immunotherapies."

The vaccine tested in the study activated the immune system in two ways: It produced T cells that directly attacked abnormal cells and B cells that produced antibodies against the tumor. The goal is "to prevent the tumor from returning after completed treatment, in this case radiochemotherapy," Platten said.

Ulrich Herrlinger is director of neuro-oncology at University Hospital Bonn and was not involved in the study. He sees the work of his colleagues as a real opportunity for patients.

High-grade astrocytomas have "an almost 100% likelihood of returning, continuing to grow and eventually becoming untreatable," Herrlinger said. Researchers do not know what causes these tumors. "Nobody knows why it affects this particular person," the cancer researcher said.

That is also why the research by Platten gives him hope: "If we could keep the immune system permanently active, that would come with the hope of suppressing the tumor over the long term."

Follow-up study to begin in 2027

However Herrlinger joined the study author Platten in urging caution about overinterpreting the data: "You cannot draw strong conclusions from 33 patients," he says. The next step must be a controlled, randomized study, Herrlinger added.

Such a study is already being planned: The project, with more than 200 patients, will begin in March 2027, Platten said. "As of today, we are talking about a period of nine years before we will actually have reliable results from the study."

Only then will it become clear how effective the vaccine really is and whether booster shots can further strengthen the immune response. Nevertheless, Platten says, the current study is reason for cautious optimism. Hope, he said, is something people can never have too much of.

This article was originally published in German