Two pharmaceutical companies based in the U.S. have reported encouraging results from a “Phase 3 clinical trial” indicating that a personalized mRNA cancer vaccine can enhance patient outcomes when combined with standard immunotherapy for those with high-risk melanoma.
This experimental treatment, known as intismeran autogene (mRNA-4157/V940), was jointly developed by Moderna and Merck. It achieved its main goal of recurrence-free survival (RFS) and a significant secondary goal of distant metastasis-free survival (DMFS) during the comprehensive INTerpath-001 trial, as announced by the companies.
The trial results mark a significant milestone, being the first positive Phase 3 outcome for both an individualized neoantigen therapy and an mRNA-based cancer treatment. It’s also noteworthy as the first Phase 3 study indicating a meaningful improvement over pembrolizumab (Keytruda) used alone in the adjuvant setting for patients with resected melanoma.
This international Phase 3 study included 1,137 patients with completely removed stage IIB through stage IV cutaneous melanoma who had not previously undergone systemic therapy.
Participants were split into two groups: one received the personalized mRNA vaccine along with pembrolizumab, while the other received pembrolizumab alone. An interim analysis showed that the combination treatment resulted in statistically significant and clinically relevant improvements in both RFS and DMFS when compared to pembrolizumab only.
Unlike traditional vaccines, intismeran autogene is tailored specifically for each individual patient. A sample of the patient’s removed tumor is sequenced to identify up to 34 unique tumor-specific neoantigens — mutations that exist only in the cancer cells. Synthetic mRNA is then created to help the immune system recognize and target any remaining cancer cells.
These Phase 3 results build upon the long-term follow-up from an earlier Phase 2b KEYNOTE-942 trial, which indicated that the combination treatment decreased the risk of recurrence or death by 49% and lowered the risk of distant metastasis or death by 59% compared to pembrolizumab alone over a five-year period.
Investigators noted that there were no new safety concerns during the INTerpath-001 trial, and the safety profile was consistent with previous studies, according to their announcement.
Moreover, Merck and Moderna have plans to present detailed results at an upcoming international medical conference and will be engaging with global health regulators regarding possible submissions for market authorization. They also mentioned that overall survival data continues to evolve.
Despite the positive findings, there has been growing skepticism around mRNA technology following the COVID-19 pandemic. This skepticism is largely fueled by concerns about the rapid development of these technologies, potential unintended effects, and general distrust in public health initiatives, as well as questions regarding lipid-nanoparticle delivery systems and the long-term effects of synthetic genetic material on cellular functions.
Critics emphasize that the long-term safety of mRNA platforms isn’t fully understood, which raises questions about its reliability.
Nevertheless, researchers like Dr. Elias Sayour argue that applying the same level of skepticism that emerged during the pandemic to the Phase 3 melanoma results overlooks significant differences between vaccines aimed at prevention for infectious diseases and personalized therapeutic cancer treatments.
He points out that the fundamental differences lie in their purpose and design. While COVID-19 vaccines provide a fixed mRNA sequence for broad population use to promote protective immunity, intismeran autogene is crafted specifically for one patient, being manufactured by analyzing the patient’s own tumor, identifying those unique neoantigens, and creating a tailored mRNA construct to train the immune system to target residual cancer cells.
Addressing high-risk resected melanoma (stage IIB–IV) is critical due to its high rates of recurrence and mortality even after surgery and standard treatments. In this context, a targeted approach is being regarded as a serious strategy against a significant existing threat, rather than a comparison with the baseline risk healthy individuals would face from receiving a preventative vaccine.
