• SurVaxM did not extend OS vs. placebo in the overall cohort of patients with newly diagnosed glioblastoma.
• Among patients 65 or younger, those who received the vaccine achieved significantly longer OS and PFS.

A randomized phase 2B trial of a novel peptide-based vaccine missed its primary endpoint, as the immunotherapy failed to significantly extend survival compared with placebo in newly diagnosed glioblastoma, according to a press release.

However, topline data showed SurVaxM (MimiVax Inc.) may have the potential to delay progression and prolong survival in a prespecified subgroup of patients aged 65 years or younger.

“For patients 65 and under, this is one of the strongest signals we have seen in newly diagnosed glioblastoma in a long time,” co-principal investigator Robert Fenstermaker, MD, chair emeritus of neurosurgery at Roswell Park Comprehensive Cancer Center and co-founder of MimiVax, a biotechnology company that spun off from Roswell Park in 2012, said in the release. “In a disease where progress has often been measured in weeks, results like these can be enormously meaningful.”

SurVaxM targets survivin, a protein that regulates cell division and blocks programmed cell death. It is present in nearly all glioblastomas, as well as in several other malignancies, according to the release.

The subcutaneously administered vaccine — which received both orphan drug and fast track designations from FDA — is designed to stimulate the immune system to recognize and attack survivin-expressing cells.

The double blind, multicenter SURVIVE trial assessed the vaccine as treatment of newly diagnosed glioblastoma.

OS served as the primary endpoint, with patients 65 and younger prespecified as a key subgroup for the survival analysis. Secondary endpoints included PFS and safety.

The topline data represent the first results reported from the trial, which launched in 2022.

In the overall cohort — which included 233 evaluable patients — results showed no statistically significant improvement in OS with SurVaxM vs. placebo (median, 22.8 months vs. 20.3 months; HR = 0.75; 95% CI, 0.54-1.03). The placebo group outperformed assumptions when the trial had been designed, according to investigators, who noted the median survival exceeded the 16-month historical benchmark in this population.

Among patients aged 65 or younger, those assigned SurVaxM achieved longer OS (median, 24.2 months vs. 20.2 months; HR = 0.64; 95% CI, 0.44-0.93) and PFS (HR = 0.64; P = .018). They also were more likely to remain progression free for at least 12 months (44% vs. 24%).

In the younger age group, 42% of SurVaxM-treated patients remained alive at 30 months, with no additional deaths occurring between 30 months and 54 months.

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

Nearly half (48%) of patients assigned SurVaxM experienced grade 1/grade 2 injection site reactions, with the most common being pain (41%), erythema (39%), pruritus (38%) and swelling (29%). Thirteen percent developed influenza-like illness.

Grade 3 or higher adverse events occurred at similar rates in the SurVaxM and placebo groups (48% vs. 46%). Four percent of those assigned SurVaxM discontinued treatment due to adverse events, with one discontinuation attributed to study treatment. No treatment-related deaths occurred.

The findings “make a compelling case” for the vaccine and will support discussions company officials intend to have with the FDA about potential regulatory next steps, Ciesielski said.