MimiVax’s SurVaxM cancer vaccine improved overall survival in a Phase 2b glioblastoma trial, with a statistically significant benefit seen in patients aged 65 and under.

Overall survival

The randomised, double-blind, placebo-controlled SURVIVE trial evaluated SurVaxM alongside standard of care in 233 evaluable patients with newly diagnosed glioblastoma across 11 US cancer centres.

Median overall survival was 22.8 months for patients receiving SurVaxM compared with 20.3 months for those receiving placebo. The hazard ratio was 0.75, although the difference did not reach statistical significance across the full trial population (95% CI 0.54 to 1.03; p=0.076).

A prespecified analysis of patients aged 65 and under produced a statistically significant result. Median overall survival was 24.2 months with SurVaxM compared with 20.2 months with placebo, with a hazard ratio of 0.64 (95% CI 0.44 to 0.93; p=0.019).

Progression-free survival also improved in this subgroup, with a hazard ratio of 0.64 (p=0.018). Progression-free survival at 12 months was 44% with SurVaxM compared with 24% for placebo.

The trial’s primary endpoint was overall survival, while secondary endpoints included progression-free survival, landmark survival, safety and survivin-specific immune responses.

Robert Fenstermaker, co-principal investigator of the SURVIVE trial and chief medical officer and co-founder of MimiVax, said: “For patients 65 and under, this is one of the strongest signals we have seen in newly diagnosed glioblastoma in a long time.”

Long-term survival

MimiVax said approximately 42% of SurVaxM-treated patients aged 65 and under remained alive at 30 months or longer, compared with 18% of patients in the placebo group.

The company said no further deaths were reported among the SurVaxM group between 30 and 54 months, although longer follow-up will be needed to assess the durability of the finding.

The placebo arm also performed better than the historical benchmark used when the trial was designed, with median overall survival of 20.3 months compared with an expected 16 months.

The company said the stronger-than-expected control-arm survival increased the difference required for SurVaxM to demonstrate a statistically significant benefit across the full population.

SurVaxM was generally well tolerated. The most common adverse events included injection-site reactions, pain, erythema, pruritus and swelling, with most reported events being Grade 1 or 2.

Grade 3 or higher adverse events occurred in 48% of patients receiving SurVaxM and 46% receiving placebo. Serious adverse events occurred in 25% and 21% of patients, respectively.

Treatment discontinuation because of adverse events occurred in 4% of SurVaxM patients, with one discontinuation attributed to study treatment. No treatment-related deaths were reported in either group.

FDA discussions planned

MimiVax plans to request a meeting with the US Food and Drug Administration (FDA) to discuss the Phase 2b data and potential expedited regulatory pathways for SurVaxM in newly diagnosed glioblastoma.

The company said it intends to discuss Breakthrough Therapy designation and accelerated approval with the agency.

Michael Ciesielski, chief executive officer and co-founder of MimiVax, said: “We believe these data make a compelling case for SurVaxM, and we look forward to discussing these robust findings with the FDA.”

SurVaxM is an investigational peptide-mimic immunotherapeutic vaccine targeting survivin, a protein involved in cell survival that the company says is present in approximately 95% of glioblastomas.

The treatment is designed to stimulate an immune response against survivin-expressing cancer cells. It has received FDA Orphan and Fast Track designations for newly diagnosed glioblastoma but has not been approved by the FDA or any other regulatory authority.

The SURVIVE trial has completed enrolment and is no longer recruiting patients with glioblastoma.