Cancer vaccine may extend survival for glioblastoma patients

The experimental cancer vaccine SurVaxM may improve survival in people with newly diagnosed glioblastoma, an aggressive form of glioma.

The therapy’s developer, Mimivax, in collaboration with Roswell Park Comprehensive Cancer Center, announced results from the Phase 2 SURVIVE clinical trial (NCT05163080), which has been running since 2022. The trial enrolled people with newly diagnosed glioblastoma; all participants received standard treatment plus either SurVaxM or a placebo.

The study’s main goal was to determine whether SurVaxM would improve overall survival. Results from 233 evaluable patients showed the median survival time was two and a half months higher with SurVaxM than placebo (22.8 months vs. 20.3 months). However, this difference was not statistically significant — meaning that, mathematically, there is a non-negligible chance the difference is due simply to random chance.

According to a press release from Mimivax and Roswell Park, part of the reason for the lack of statistical significance may be that patients given placebo had better-than-expected outcomes. When the trial was designed, researchers predicted that patients given placebo would have a median survival time of about 16 months — but actually, their median survival time was more than 20 months. Nonetheless, the therapy’s developers argue that even a two-month improvement in survival is clinically meaningful.

“Every patient with glioblastoma is facing one of the hardest diagnoses in medicine,” said Ajay Abad, MD, study principal investigator and a neurologist at Roswell Park. “To see many of our study patients living longer, and several of them living years longer, is deeply meaningful to every one of us who has participated in the work to develop and study this new treatment approach. In a disease where we’ve had limited progress over the last 20 years, an improvement in survival of this magnitude is noteworthy.”

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In a prespecified analysis of patients younger than 65, median survival time was about four months longer with SurVaxM than placebo (24.2 months vs. 20.2 months). This difference was statistically significant, meaning it’s extremely unlikely the difference is due to random chance. SurVaxM also showed statistically significant benefits in delaying disease progression among patients younger than 65.

After 2.5 years, nearly half (42%) of SurVaxM-treated patients younger than 65 were still alive, and all patients alive at 2.5 years were still alive at the latest follow-up, 4.5 years after starting treatment. According to Mimivax and Roswell Park, such long-term survival outcomes are uncommon in people with newly diagnosed glioblastoma.

“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, MD, 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.”

Safety data from the Phase 2 study showed the most common safety issues reported among patients given SurVaxM were injection-site reactions and flu-like illness. Rates of serious safety complications were similar among patients given SurVaxM or placebo, and no treatment-related deaths were reported during the study. Among patients on SurVaxM, 4% discontinued treatment due to safety issues.

Mimivax plans to discuss further development of SurVaxM for glioblastoma with the U.S. Food and Drug Administration (FDA). Michael Ciesielski, PhD, the company’s co-founder and CEO, said the company may pursue accelerated approval, a type of conditional approval that would allow the therapy to be brought to market while trials to confirm its clinical benefit are still ongoing. Mimivax is also interested in obtaining FDA designations that may help speed the therapy’s development, such as a breakthrough therapy designation.

“These initial results from the SURVIVE trial give us a clear and coherent picture,” Ciesielski said. “SurVaxM showed a consistent survival signal, with a substantial group of patients living well past what we typically see in this disease. We believe these data make a compelling case for SurVaxM, and we look forward to discussing these robust findings with the FDA.”

SurVaxM is designed to trigger an immune response targeting survivin, a cell-survival protein that’s commonly expressed at high levels by cancer cells. Mimivax is developing the vaccine for glioblastoma and other forms of glioma, as well as myeloma.