Danish vaccine developer Evaxion has released long-term data for its lead personalized cancer vaccine, with the shot scoring a 75% objective response rate (ORR) in patients with advanced melanoma after two years. But the trial enrolled far fewer patients than originally planned, making it impossible to measure statistical significance.
Out of 16 evaluable patients in the phase 2 trial, 12 showed a clinical response to Evaxion’s EVX-01, including four who saw their cancer clear completely, the biotech reported in an Oct. 17 release.
The company’s chief scientific officer and interim CEO, Birgitte Rønø, Ph.D., called the 75% ORR “unprecedented” in the release, though the trial’s primary endpoint could not be analyzed due to Evaxion shrinking the trial’s enrollment from a planned 90 patients to just 17, one of whom dropped out before receiving the vaccine.
That decision came as part of a 2023 restructure that included a round of layoffs, Mads Kronborg, Evaxion’s vice president of investor relations and communication, told Fierce Biotech.
“We are a cash-burning company and have been ever since inauguration, as many biotechs are,” Kronborg said. “If you had all the money in the world, you would probably have gone with 90 patients. We don’t, so we had to scale it down.”
In the trial, patients first received treatment with Merck’s Keytruda (pembrolizumab) for 12 weeks before a total of 10 shots of EVX-01 spaced out over 78 weeks. Keytruda treatment continued throughout the immunization process, up to week 102. EVX-01 is customized for each patient to target specific proteins found in their tumors.
Evaxion presented the data today at the 2025 European Society for Medical Oncology (ESMO) congress in Berlin.
There were two grade 2 adverse events and 18 grade 1 adverse events attributed to EVX-01 alone, according to the presentation, with one case of grade 4 pancreatitis and diabetic ketoacidosis pinned on the Keytruda-vaccine combination.
One of the 12 responding patients has since died from an intracranial hemorrhage, which Kronborg said was unrelated to the treatment. The remaining 11 patients continue to respond to treatment, and none have relapsed, Evaxion said in the release.
“We are delighted to present these two-year phase 2 data for EVX-01 demonstrating high response rates and an impressive durability of responses, whilst confirming the favorable safety profile observed in our phase 1 study,” Rønø said. “We are looking forward to discussing the data with stakeholders and potential partners. Further clinical development, which is clearly supported by this data, will only be done in a partnership.”
As Evaxion seeks a partner for EVX-01, the phase 2 trial will continue for another year with patients receiving just the vaccine, the company said in the release.
Evaxion’s stock slipped about 34% after the Oct. 17 data drop, sliding from $9.60 per share at the close of Oct. 16 to $6.28 as of 1:30 p.m. ET on Oct. 17.
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One potential partner is Merck, which, in addition to supplying Keytruda for the trial, has also recently licensed a preclinical vaccine for an undisclosed pathogen from Evaxion as part of a 2024 deal potentially worth more than $1 billion. And Merck’s Evaxion roots go even deeper: the Big Pharma actually helped develop the vaccine it licensed, EVX-B3, and led a private placement for the Danish biotech in December 2023.
Merck has a demonstrated interest in cancer vaccines, partnering with Moderna for an mRNA-based shot that is a key piece of Merck’s three-pronged cancer strategy.
Kronborg declined to comment on which companies Evaxion is in talks with for an EVX-01 partnership, but said the biotech has “a number of parallel discussions in terms of business development now that’s both on our platform and our pipeline.”
The same fiscal reality that made Evaxion shrink the phase 2 EVX-01 trial has also led the Danish company to prioritize partnerships for late-stage clinical development and commercialization.
“We have no ambition of doing registrational trials and launching product ourselves,” Kronborg said. Evaxion instead aims to remain an independent company, he added, that “can do the entire target discovery, the initial preclinical development,” and then partner with others for phase 2 and beyond.
