MimiVax’s cancer vaccine fails phase 2 glioblastoma study, but CEO still sees data as ‘inspiring’

Biotech MimiVax’s cancer vaccine fails phase 2 glioblastoma study, but CEO still sees data as ‘inspiring’ By Marissa Russo Oct 7, 2026 8:00am cancer vaccine glioblastoma multiforme (GBM) Clinical Data MimiVax's cancer vaccine missed the primary endpoint of a phase 2 study in patients with newly diagnosed glioblastoma, although the biotech claimed it can still see a path forward for the candidate. The New York-based company evaluated the peptide-mimic immunotherapeutic vaccine, called SurVaxM, against placebo in 233 evaluable patients with newly diagnosed brain cancer. SurVaxM was tied to a median overall survival (OS) of 24.2 months compared to 20.2 months for the placebo cohort.

While MimiVax claimed this improvement was “clinically meaningful,” the company admitted in an Oct. 7 release that the result missed the study's primary endpoint. Looking for positive news, the biotech drilled into a subset of patients aged 65 years and younger.

Among this subgroup, the OS difference was 24.2 months and 20.2 months, which MimiVax described as a “significant benefit.” This subset of patients also saw an improvement in progression-free survival at 12 months, with 44% of those who received SurVaxM reaching this mark compared to 24% on placebo. A long-term survival analysis showed that approximately 42% of SurVaxM-treated patients 65 and under were alive through 30 months or longer, with no further deaths reported up to 54 months. Despite the topline fail, MimiVax said these subgroup findings still give the company the confidence to pursue a path toward potential FDA approval for SurVaxM.

“Even very small increases in survival are very significant to the patients, taking into perspective that there hasn't been a new GBM drug in over 20 years,” MimiVax CEO Michael Ciesielski, Ph.D., told Fierce. “There are really no options for these patients,” he added. “There's nothing else to offer them, so any improvement is significant.” Glioblastoma is the most common and aggressive brain tumor in adults.

After diagnosis, patients typically succumb to the tumor within about 18 months, despite standard-of-care therapy. These tumors have multiple mechanisms for skirting treatment, making them notably hard to treat, with no advances since the addition of the chemotherapy agent temozolomide in 2005. “There just hasn't been anything in such a long time for these patients, and there's been so many failed trials in between,” Ciesielski said.

“It's inspiring to finally see something start to move the needle against this disease.” SurVaxM is engineered against survivin, a protein that stymies programmed cell death and can make tumor cells resistant to standard treatments. The cancer vaccine aims to train the immune system to recognize survivin-expressing cells and respond to them, as the protein is highly expressed in nearly 95% of GBM tumors and many other cancers, Ciesielski noted. “We wanted to target something that was highly expressed and accessible to the immune system—this fit the bill,” the CEO explained.

The phase 2b study built on an open-label phase 2a trial that concluded in 2022, where patients treated with SurVaxM alongside adjuvant temozolomide showed a median OS of 25.9 months. Patients received four primary injections of SurVaxM—one dose every two weeks for four doses, followed by a booster injection every two months—after undergoing standard-of-care therapy that included maximum tumor resection, chemo and radiotherapy. When it came to safety, adverse events being mainly Grade 1 and 2 injection site reactions.

Grade 3 or higher adverse events were seen in 48% of patients treated with SurVaxM versus 46% with placebo. MimiVax spun out of the Roswell Park Comprehensive Cancer Center in Buffalo, New York in 2012. Besides SurVaxM, the biotech is currently running multiple mid-stage trials testing its cancer vaccines in metastatic neuroendocrine tumors and multiple myeloma, and it plans to open a study soon for preventative lung cancer.

Other companies have joined MimiVax in trying to find a fresh approach to treating glioblastoma—with mixed results. Imvax's phase 2b study of its autologous cell immunotherapy and device combination product flunked a phase 2b study at the end of last year. Meanwhile, Evaxion is prioritizing glioblastoma for its off-the-shelf therapeutic vaccine in collaboration with Duke University, while BrainChild Bio is attacking pediatric brain cancer with its triple-targeting CAR T-cell therapy that is expected to enter the clinic next year.

Rethinking clinical trial recruitment is one of the hot topics being discussed at Fierce Biotech's high-impact event in London next month. Find out more information and register by clicking on the banner below: Rethinking Clinical Trial Recruitment banner cancer vaccine glioblastoma multiforme (GBM) Clinical Data Biotech