Study results: Study: Does the mRNA vaccination help against black skin cancer?

Madrid/Berlin. In the case of black skin cancer, after the tumor has been removed, an individual mRNA vaccination in addition to standard therapy can reduce the risk of its return by almost half (42 percent) over about two years. The risk of the formation of distant metastases fell by 38 percent during this period. However, these eagerly awaited interim results of a phase 3 study are not based on publication in a peer-reviewed scientific journal, but were announced by the pharmaceutical companies Moderna and MSD in a statement - parallel to a cancer congress in Madrid.

Based on these figures, MSD announced that it will be in contact with the regulatory authorities. What that exactly means, however, remains vague. If approved, it would be the first approval in the USA or EU for a cancer vaccine based on individualized mRNA. However, decisive results are still pending: The vaccination has not brought a clear advantage for overall survival over the observation period of almost 25 months.

Five years is a typical time frame for findings on overall survival, said Niels Halama from the German Cancer Research Center (DKFZ) to the German Press Agency. The expert who attended the congress in Madrid emphasized that it is by no means self-evident that the current results are sufficient to convince licensing authorities.

“Ultimately, the survival data will show whether the vaccination permanently prevents relapses or only delays them,” said Thomas Eigentler from the Berlin Charité, commenting on the result. And expert Lennard Lee from the University of Oxford also emphasized: “The main limitation is that we don’t yet know whether the vaccine helps patients live longer.”

In general, the current study, which is still ongoing, confirms the already published results of a smaller study. In the current double-blind study, 1,137 people whose melanoma had been successfully removed received standard therapy with the so-called checkpoint inhibitor pembrolizumab, trade name Keytruda. Around two thirds of them - 757 patients selected by lottery - also received nine intramuscular injections of the mRNA vaccine Intismeran, and the remaining 380 received a placebo.

After a good two years, with the additional mRNA therapy, a good 82.2 percent lived without the tumor returning; in the placebo group it was 70 percent. This corresponds to a reduction in the risk of return by 42 percent. 88.5 percent of the Intismeran group were still alive without distant metastases, and 80.2 percent of the control group. The risk of distant metastases occurring was reduced by 38 percent. Severe side effects occurred at similar rates in the groups with and without mRNA vaccines.

The checkpoint inhibitor pembrolizumab is intended to ensure that the immune system attacks the tumor cells. The mRNA vaccination is intended to additionally sensitize the body's defenses to specific structures of the individual tumor. For this purpose, the tumor tissue removed from the participants was analyzed. The personalized vaccination contained up to 34 typical characteristics of these carcinomas, so-called tumor antigens.

In Germany, black skin cancer is one of the most common tumors, with well over 20,000 new cases per year and the number is rising. If approved, the therapy would only be an option for a few thousand of them, Eigentler, who heads the Skin Tumor Center at the Berlin Charité and who was also involved in the current study, said in the summer.