Evaxion A/S (NASDAQ:EVAX) presented three-year follow-up data from its Phase II EVX-01 study in advanced melanoma, reporting a 75% objective response rate among 16 treated patients receiving the personalized cancer vaccine alongside pembrolizumab.
The data were presented at the European Society for Medical Oncology annual congress, according to Birgitte Rønø, Evaxion’s chief scientific officer and chief operating officer. EVX-01 is a peptide-based personalized cancer vaccine designed for each patient using up to 10 tumor-specific neoantigens selected by the company’s AI-Immunology platform.
Phase II study results
Professor Adnan Khattak, a medical oncologist at Hollywood Private Hospital in Perth and lead investigator at the Australian study site, said the trial enrolled patients with treatment-naïve unresectable stage III or metastatic stage IV melanoma. Participants began with a 12-week pembrolizumab run-in before receiving EVX-01 priming doses and subsequent booster doses.
Of 21 screened patients, 17 enrolled, though one progressed before starting the vaccine. Sixteen patients received treatment in the study, and six entered an extension phase that included additional vaccine doses.
Khattak reported that four patients, or 25%, achieved a complete response and eight patients, or 50%, achieved a partial response, producing an objective response rate of 75%. One patient experienced progressive disease, while the remaining patients had stable disease or tumor reductions.
The study also assessed whether responses improved after EVX-01 was added to pembrolizumab. Among patients with stable disease after the pembrolizumab run-in, four of six, or about 67%, converted to a partial response. Among patients with partial responses, three of seven converted to complete responses, according to the presentation.
Khattak said 11 of 12 responding patients maintained their responses at the two-year follow-up point. Median progression-free survival and overall survival had not been reached. He added that none of the six patients participating in the extension phase had experienced disease progression at the time of the presentation.
Safety and immune-response findings
Evaxion and Khattak said the combination did not show new safety signals attributed to EVX-01. Vaccine-related adverse events were limited to Grade 1 and Grade 2 events. One Grade 4 immune-related diabetes event was reported and attributed to pembrolizumab.
The company also reported vaccine-induced neoantigen-specific T-cell responses in patients who received at least six vaccinations. Evaxion said its platform identified immunogenic neoantigens with an 89% success rate in the Phase II study, and that 86% of observed neoantigen responses were de novo responses not driven by pembrolizumab.
Khattak said the immune-response data showed both CD4 and CD8 T-cell activity, although analysis of certain samples remained ongoing. He noted that the limited study size means the findings are preliminary, but said the timing of certain response conversions after vaccine dosing was consistent with a potential contribution from EVX-01.
Personalized vaccine approach
EVX-01 is produced from each patient’s tumor biopsy and blood sample. Evaxion sequences DNA and RNA, identifies tumor mutations, ranks potential neoantigens using its AI platform, and manufactures a vaccine containing up to 10 selected targets. The company said the process from biopsy to vaccine administration takes about seven weeks.
Rønø said the company prioritizes the predicted quality of selected neoantigens over the total number of targets included in a vaccine. She said multi-targeting may help address tumor escape while avoiding the inclusion of targets that do not generate strong immune responses.
Evaxion previously reported Phase I results in 12 patients with unresectable stage III or metastatic stage IV melanoma. In that study, the company reported a 67% objective response rate, treatment-related adverse events limited to Grades 1 and 2, and neoantigen reactivity against 53 of 91 analyzed targets. The Phase II program used a higher 200 microgram-per-peptide dose, booster vaccinations, and an updated AI-Immunology platform.
Potential next steps
During the webinar, Khattak said future clinical work could examine EVX-01 in additional melanoma settings, including patients treated with checkpoint-inhibitor combinations, earlier-stage disease, and neoadjuvant or adjuvant settings. He also said the approach could potentially be explored in other cancers with high mutational burden where checkpoint inhibitors are used.
Rønø said Evaxion’s strategy is to out-license product candidates, including EVX-01, and that further clinical development would be needed. She said the company sees potential for the therapy beyond advanced melanoma, though no additional indication-specific trial plans were announced during the presentation.
About Evaxion A/S (NASDAQ:EVAX)
Evaxion A/S is a Denmark-based biotechnology company that uses artificial intelligence to develop novel immunotherapies and vaccines. Its proprietary AI-Immunology platform is designed to analyze biological data, identify disease-specific targets and support the development of treatments tailored to individual patients or pathogens.
The company’s research and development activities focus primarily on personalized cancer vaccines and vaccines for infectious diseases. Evaxion’s pipeline has included programs intended to stimulate the immune system to recognize and attack cancer cells, as well as vaccine candidates targeting bacterial and viral infections.
Evaxion is headquartered in Copenhagen, Denmark, and conducts its work through an international biotechnology and research network.
