— "We may be witnessing the beginning of an entirely new way of treating cancer," expert says
October 23, 2026 • 3 min read
Adjuvant treatment with the mRNA-based cancer vaccine intismeran autogene plus pembrolizumab (Keytruda) significantly improved recurrence-free survival (RFS) in patients with resected stage IIB-IV melanoma, the phase III INTerpath-001 study showed.
In the primary prespecified analysis, the combination significantly reduced the risk of recurrence or death by 42% (HR 0.58, 95% CI 0.45-0.75, two-sided P<0.001) compared with pembrolizumab alone, with 24-month RFS rates of 82.2% versus 70%, respectively.
The combination also significantly reduced the risk of distant metastasis or death (HR 0.62, 95% CI 0.45-0.85, two-sided P=0.002), with a 24-month distant metastasis-free survival rate of 88.5% compared with 80.2% with pembrolizumab alone.
The study is scheduled to be presented by Georgina Long, MBBS, PhD, of the University of Sydney, at the European Society for Medical Oncology congressopens in a new tab or window in Madrid on Saturday, but results were released early after an online data leak.
These findings "have the potential to make a foundational shift in how we treat patients with earlier-stage melanoma in the adjuvant setting," Long said in a press releaseopens in a new tab or window. "For decades, cancer treatment has largely been defined by where a tumor originates in the body. The INTerpath-001 findings support a fundamentally new and individualized approach to treating resected melanoma in the adjuvant setting, one that tailors treatment to the unique mutational signature of a patient's tumor to enhance an antitumor immune response."
"While these results are in patients with completely resected stage IIB-IV melanoma, they provide valuable insights and will help inform our understanding of intismeran as clinical research continues into other tumor types and across settings," she added.
In comments posted on the Science Media Centre websiteopens in a new tab or window, Lennard Lee, DPhil, BmBCh, of the University of Oxford in England, noted that "this is the Rolls-Royce of clinical trials," adding that its findings provide strong evidence that intismeran can reduce cancer recurrence.
"Off-the-shelf cancer vaccines remain an important area of research, yet this trial provides compelling evidence for the personalized approach," he wrote. "We may be witnessing the beginning of an entirely new way of treating cancer."
The fact that this is a phase III trial "provides stronger evidence that a personalized cancer vaccine can make a meaningful difference to patients," pointed out Alan Melcher, PhD, of the Institute of Cancer Research in London, on the same website. However, he cautioned that while "it is an important proof of principle for the field ... we can't assume from one melanoma trial that the same approach will work across all cancers, and longer follow-up will be important to understand the effect on overall survival."
Intismeran autogeneopens in a new tab or window is an investigational mRNA-based individualized neoantigen therapy consisting of synthetic mRNA coding for up to 34 neoantigens designed and produced based on the unique mutational signature of the DNA sequence of the patient's tumor.
Combining it with pembrolizumab may increase pre-existing and de novo antitumor T-cell responses against patient-specific tumor neoantigens and stimulate immune-mediated antitumor activity.
INTerpath-001opens in a new tab or window enrolled 1,137 patients who, after complete surgical resection, were randomized 2:1 to receive intismeran 1 mg every 3 weeks for up to 9 doses and pembrolizumab 400 mg every 6 weeks for up to 9 cycles, or placebo plus pembrolizumab for approximately 1 year until disease recurrence or unacceptable toxicity, or for a total treatment duration of up to approximately 56 weeks, whichever was sooner. Median follow-up was 24.6 months.
These results were generally consistent across prespecified patient subgroups, and while overall survival (OS) data are not yet mature, there was a trend in favor of intismeran plus pembrolizumab.
Treatment-related adverse events (TRAEs) occurred in 95.8% of patients receiving intismeran plus pembrolizumab and 90% of those receiving pembrolizumab alone. Grade 3-5 TRAEs occurred in 14.2% versus 13.4%, respectively.
The most common adverse events in the combination arm were pyrexia (52.2%), injection-site pain (51%), and fatigue (38.5%).