Evaxion’s October 23 update on its personalized melanoma vaccine EVX-01 adds a new immune-response measure to a small Phase 2 study: the Danish biotechnology company says 89% of vaccine neoantigen targets generated tumor-specific T-cell responses. The figure is not a response rate among patients, nor evidence of an 89% treatment success rate. And while the company also reported that all patients in a year-three extension maintained their earlier clinical responses, it had disclosed that clinical result four days earlier. The fresh news is principally the added immune data and its presentation ahead of the European Society for Medical Oncology (ESMO) Congress.Evaxion’s October 23 announcement

What was new on October 23

Evaxion’s release, dated October 23, 2026, describes three-year immune and clinical follow-up for EVX-01 in advanced melanoma. It says the vaccine induced an immune response in all patients and that 89% of the personalized vaccine’s antigen targets induced a tumor-specific immune response. The company also describes sustained T-cell response magnitude and breadth during the third year, when EVX-01 was given alone. Evaxion planned to present the results in poster 2006P at ESMO in Madrid on October 24, from 12:00 to 12:45 Central European Time.Primary release

The calendar distinction matters. On October 19, Evaxion had already announced that patients at three-year follow-up maintained their two-year clinical responses, with no tumor progression observed in the extension. That earlier notice said the accompanying immune data would be presented at ESMO, but did not state the 89% figure. The October 23 disclosure therefore adds an immune-data result, but the continued clinical responses themselves were not first announced that day. The October 19 release and MedPath’s October 19 coverage both establish that chronology.

The independent trade outlet The Pharma Letter reported the October 23 announcement and repeated the company’s 89% target-response claim. That provides contemporaneous independent coverage of the disclosure and date, but not an independent analysis of the underlying trial dataset. The primary evidence available in these sources remains company-reported, so the poster and any fuller scientific account are important context rather than a substitute for independent validation.

What the 89% measures—and does not

Evaxion calls the figure “vaccine target precision.” In the release, the underlying description is that 89% of vaccine neoantigens generated potent, specific T-cell responses. A neoantigen is a protein fragment associated with a tumor that may be recognized as foreign by immune cells. EVX-01 is individualized: each patient receives a vaccine designed around that person’s tumor and immune characteristics. The percentage therefore concerns the share of selected targets for which the company reports an immune response, not the fraction of patients whose tumors shrank or who were cured.

The distinction is important in oncology. A T-cell response is a biological finding; it does not by itself establish durable tumor control, longer survival, or superiority to another treatment. The company’s account describes immune response in all trial patients and the proportion of targets that stimulated a response. The summary available in its release does not give the denominator of targets used to calculate the 89%, a confidence interval, or detailed patient-by-patient results. Those are questions readers should look for in the poster or a later peer-reviewed report.

The 89% also has a historical comparator, but it needs careful handling. Evaxion says 86% of vaccine neoantigens generated specific T-cell responses at the two-year follow-up. It says analysis of additional samples collected during the one-year extension increased the hit rate to 89%. This is not a randomized comparison showing that immune activity improved over time or that the vaccine became more effective. It is a company-reported recalculation using additional samples, with the underlying analysis and denominator not detailed in the press-release summary.Evaxion’s data description

A small extension after combination therapy

The trial enrolled 16 people with advanced melanoma, according to Evaxion. During the first two years, they received EVX-01 together with pembrolizumab, marketed as Keytruda, an anti-PD-1 immunotherapy. The vaccine was administered as monotherapy in the subsequent year for six of the 12 responders who continued into the extension. Evaxion says those six maintained the clinical responses observed at two years and experienced no tumor progression through year three while receiving EVX-01 alone.

That observation is encouraging as a follow-up signal, but the population behind it is narrow. It describes six people selected from responders who entered an extension, not all 16 original participants followed under the same third-year treatment conditions. The result cannot establish what would have happened to the people who did not enter the extension, or how much of the earlier response reflected the initial pembrolizumab combination. Nor can a six-person, non-comparative observation estimate reliably how frequently the outcome would occur across a broader melanoma population.

Earlier two-year results, also summarized in the October 23 release, included a 75% objective response rate and complete responses in 25% of the enrolled patients. Evaxion said 92% of patients were still responding at two years and no relapses had been observed at that time. Those findings are useful context, but they are not a control group for the three-year subset. The study summary available here does not report randomized allocation or a comparator arm. The company’s figures should be read as results from an exploratory Phase 2 program, not as proof of efficacy compared with standard care.

Where AI fits into the vaccine

EVX-01 is a personalized peptide vaccine designed to present tumor-specific neoantigens to the immune system. Evaxion says its AI-Immunology platform helps identify and select targets based on each patient’s tumor and immune profile, after which a unique vaccine is manufactured. The proposed chain is computational selection, vaccine production, and activation of T cells that recognize selected tumor-associated targets.

The trial’s reported target-response percentage offers a clinical setting in which to examine whether the selected targets are immunogenic. It does not isolate the contribution of the AI platform from other steps, including sample quality, the biological rationale for target selection, vaccine formulation, immune status, or accompanying pembrolizumab during the first two years. As a result, the company’s claim that the figure validates its platform is an interpretation, not a finding established by a platform-versus-platform comparison in this study.

The distinction between a vaccine designed with AI and evidence that AI improves patient outcomes is central. The reported 89% suggests that many selected targets elicited measured T-cell responses under the company’s analysis. Demonstrating that this target-selection method consistently outperforms alternatives would require comparative evidence, and demonstrating clinical benefit would require outcomes evaluated across appropriately sized patient groups. Neither conclusion follows from target immunogenicity alone.

What remains unproven

The announcement supplies a promising but preliminary picture, with limited public detail about the three-year analyses. The conference poster may provide methods, target counts, response definitions, patient flow and safety information that are not in the press-release summary. Until those details are available and assessed, the main numbers should remain attributed to Evaxion. The Pharma Letter’s item confirms that the announcement was covered on October 23, but its brief report is not an independent scientific appraisal.

Long-term follow-up is valuable in cancer research because early tumor responses do not always persist. Here, the company reports no progression among the six extension participants through the third year, alongside sustained T-cell measures. That combination supports further study. It does not establish a cure, a survival advantage, or readiness for routine use. EVX-01 remains an investigational candidate being evaluated in advanced melanoma; the release describes no marketing authorization or commercial launch.

The next evidence steps are straightforward: a complete presentation of the dataset, transparent reporting of the immune assay and denominators, longer follow-up, and larger studies capable of assessing clinical outcomes. A controlled design would help separate the vaccine’s contribution from pembrolizumab and other factors. Until then, the appropriate reading is measured: the October 23 update adds a target-level immune result to a small, company-reported program, while its most striking year-three clinical observation had already been announced earlier in the week.

Frequently asked questions

What did Evaxion announce on October 23?

The company reported three-year immune follow-up for its personalized melanoma vaccine EVX-01, including its claim that 89% of vaccine neoantigen targets generated tumor-specific T-cell responses. It scheduled poster presentation of the data at ESMO for October 24.

Does 89% mean the vaccine worked in 89% of patients?

No. The reported 89% refers to the percentage of vaccine targets said to have generated T-cell responses. It is not a patient response rate, cure rate, or measure of tumor shrinkage.

How many patients had no progression at year three?

Evaxion said six of 12 responders continued into the one-year extension and maintained their clinical responses with no tumor progression observed through year three. The finding is limited to that small extension group.

Was the three-year clinical finding first announced October 23?

No. Evaxion announced the year-three clinical outcome on October 19. The October 23 update added the 89% immune-target result and other details about sustained T-cell responses.

Is EVX-01 approved or commercially available?

The cited announcement describes EVX-01 as an investigational vaccine in Phase 2 evaluation. It reports no regulatory approval or commercial launch.

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