Patients given an experimental personalised mRNA vaccine alongside the approved immunotherapy Keytruda had a 42% lower risk of their melanoma returning after surgery, or of dying, than patients given Keytruda alone, full trial data released this week shows.
The developers, Merck and Moderna, announced in August that the late-stage trial had succeeded but did not then say by how much. The detailed results were released early on Thursday after reports that they had been published online and withdrawn, and are due to be presented on Saturday at the European Society for Medical Oncology meeting in Madrid, CNN reported.
The vaccine is known as intismeran autogene until it is given a brand name. It uses the same mRNA technology behind Moderna’s Covid-19 vaccine, but is tailored to an individual patient’s tumour rather than to a virus.
What the trial measured
The trial enrolled 1,137 participants, all of whom received Keytruda; the comparison was between those who also received the vaccine and those who received a placebo alongside it. The 42% figure reflects a median of about two years after treatment. Hiru News reported a 38% reduction in the risk of the cancer spreading to other parts of the body over two years.
“This new vaccine is something that we’ve never really seen before in terms of the efficacy that it has demonstrated and the way that it works,” said Dr. Michael Postow, chief of the melanoma service at Memorial Sloan Kettering Cancer Center.
Caveats
The trial is continuing so that the durability of the effect can be assessed, along with overall survival — whether patients actually live longer, which researchers describe as the most important measure and which the data does not yet establish.
The companies say they are engaging with regulators, and are testing the technology in other cancers, including lung and pancreatic disease.
