Experimental Vaccine Shows Promise Against Brain Cancer

An experimental cancer vaccine extended survival for some patients with glioblastoma, the most aggressive and deadly form of brain cancer, researchers announced Wednesday, offering a rare glimmer of progress against a disease that has resisted meaningful treatment advances for more than two decades.

The vaccine, called SurVaxM, improved median overall survival across the full trial population to 22.8 months compared with 20.3 months for placebo, a clinically meaningful but statistically inconclusive result, according to results from the Phase 2b SURVIVE trial, announced by developer MimiVax Inc. and Roswell Park Comprehensive Cancer Center. The finding did not quite reach the conventional threshold for statistical significance (hazard ratio 0.75; p=0.076).

Among a prespecified subgroup of patients aged 65 and under, however, the results were considerably stronger. In that group, median overall survival reached 24.2 months for those who received SurVaxM versus 20.2 months for placebo. The difference was statistically significant (HR 0.64; p=0.019), and progression-free survival — the time before the cancer worsened — improved as well. Twelve months after treatment, 44% of vaccinated patients in the younger group had not progressed, compared with 24% of those on placebo.

“For patients 65 and under, this is one of the strongest signals we have seen in newly diagnosed glioblastoma in a long time,” said Robert Fenstermaker, co-principal investigator of the SURVIVE trial, Chair Emeritus of Neurosurgery at Roswell Park, and chief medical officer and co-founder of MimiVax. “In a disease where progress has often been measured in weeks, results like these can be enormously meaningful.”

The trial’s most striking data appeared in its long-term survival numbers. Approximately 42% of vaccinated patients aged 65 and under were alive at 30 months or longer, with no further deaths reported between 30 and 54 months — roughly double the 18% rate seen in the placebo group.

“These initial results from the SURVIVE trial give us a clear and coherent picture,” said Michael Ciesielski, chief executive and co-founder of MimiVax. “SurVaxM showed a consistent survival signal, with a substantial group of patients living well past what we typically see in this disease.”

A Miss With an Asterisk

The results arrived with an important caveat. The trial’s primary endpoint — overall survival across all 233 evaluable patients — did not meet the standard threshold for statistical significance. Some industry observers framed the outcome accordingly; the biotech publication FierceBiotech described the result as a missed primary endpoint, while MimiVax and Roswell Park emphasized the strength of the younger-patient subgroup and the durability of the long-term survival signal.

Company officials attributed the inconclusive overall result in part to a control arm that performed better than the trial had anticipated. The placebo group’s median overall survival of 20.3 months exceeded the trial’s 16-month historical benchmark — a reflection, the company said, of a contemporary standard of care that has quietly improved since older reference data were gathered. A stronger control arm raises the bar that any experimental therapy must clear, making a clean statistical separation harder to achieve even when a real benefit exists.

“Every patient with glioblastoma is facing one of the hardest diagnoses in medicine,” said Ajay Abad, the study’s principal investigator and an assistant professor of oncology and neurology in the Department of Neuro-Oncology at Roswell Park. “In a disease where we’ve had limited progress over the last 20 years, an improvement in survival of this magnitude is noteworthy.”

The Science Behind the Shot

SurVaxM is a first-in-class vaccine that targets survivin, a cell-survival protein present in about 95% of glioblastomas and many other cancers. It is delivered by subcutaneous injection into the arm, much like a flu shot, and is designed to train a patient’s own immune system to recognize and attack survivin-expressing cancer cells.

Glioblastoma is notoriously difficult to treat. The tumors grow rapidly and send tendrils into surrounding brain tissue, making complete surgical removal nearly impossible. “It’s like octopus tentacles reaching into other parts of the brain,” Honggang Cui, an associate professor of chemical and biomolecular engineering at Johns Hopkins, told NBC News in earlier coverage of the vaccine.

The disease strikes roughly 15,000 Americans each year. Median survival under standard therapy is about 16 to 18 months, and the five-year survival rate stands at just 6.8%. The standard of care — surgery followed by radiation and the chemotherapy drug temozolomide — has not fundamentally changed in more than 20 years.

Unlike checkpoint inhibitors, which have transformed the treatment of many cancers but struggle to cross the blood-brain barrier, SurVaxM is intended to generate antibodies and immune cells capable of reaching the brain. The SURVIVE trial, a randomized, double-blind, placebo-controlled study, enrolled 249 patients at 11 U.S. cancer centers before completing enrollment in 2024.

A Patient’s Perspective

The trial has given some patients years they did not expect to have. Tracey Kassman, 68, a retired lawyer from Buffalo, was diagnosed with glioblastoma in January 2022 at age 64. She enrolled in the trial that April — three months after her diagnosis — and has received an injection every two months since, without knowing whether she is receiving the vaccine or a placebo, because the study is double-blinded.

“I had sort of made peace with the idea that this is a terminal illness,” she told NBC News. “But I also realized that there was a whole lot of other stuff that I wanted to do.”

Kassman said the regimen fits into her life with little disruption. “This treatment doesn’t interfere with any part of my life really, other than getting here two days every two months.”

Safety and Next Steps

SurVaxM was generally well tolerated. Side effects were predominantly mild to moderate injection-site reactions — redness, pain, swelling and itching — along with flu-like symptoms in about 13% of patients. Rates of serious adverse events were similar between the two groups (25% for SurVaxM versus 21% for placebo), and there were no treatment-related deaths in either arm.

Attention now turns to regulators. SurVaxM already holds FDA Orphan and Fast Track designations for newly diagnosed glioblastoma — designations intended to speed review of therapies for serious conditions with unmet need. MimiVax said it plans to request a meeting with the FDA in the coming months to discuss a Breakthrough Therapy Designation and other expedited pathways, including accelerated approval.

“The path to making SurVaxM available to patients will be determined in consultation with the agency,” Ciesielski said.

The vaccine is not approved for any indication, and there are currently no SurVaxM studies enrolling patients with glioblastoma. The company announced the trial’s data cutoff in July 2026, handing the dataset to an independent statistical team before Wednesday’s release.

What to Watch

Whether the FDA views the younger-patient subgroup as sufficient grounds for an expedited pathway will be the pivotal question in the months ahead. Prespecified subgroup analyses are more credible than after-the-fact ones, but a benefit seen in a subgroup does not always hold up in a larger, confirmatory Phase 3 trial — a step that would likely be required if regulators decline to move forward on the current data.

For now, the SURVIVE results represent the most advanced test yet of a vaccine-based approach to glioblastoma in a randomized setting. In a disease where progress has long been measured in weeks, even an imperfect result has given researchers and patients a reason to keep pushing forward.