Merck melanoma trial finds a 42% reduction in recurrence or death

FDA approval could come next year as kidney and bladder trials continue

Merck presented results from the first large clinical test of the cancer-vaccine concept at a European cancer conference over the weekend. The data showed that adding a personalized mRNA vaccine to immunotherapy reduced recurrence or death from melanoma by 42% over two years. NPR reporter Yuki Noguchi reported the presentation.

Doctors used tumor samples from each of the 1,100 participants to design a personalized mRNA vaccine, and the trial paired each vaccine with immunotherapy. The results indicated that the vaccine reprogrammed immune cells to recognize mutant proteins on cancerous cells before killing those cells.

The treatment drew on advances enabled by the launch of mRNA vaccine technology during the COVID-19 pandemic and the identification of mutant proteins on cancer cells.

Patients, doctors and Wall Street investors had eagerly awaited release of the data. Some of the information had already leaked over social media Thursday, before the conference presentation. NPR reported that the leak prompted some investors hoping for even more dramatic results to sell shares and shave off some of the recent stock gains for the vaccine sponsors, Merck and Moderna.

The leak did not dampen the medical community’s response. Antoni Ribas, a melanoma tumor specialist, investigator and author of the study, described the reaction at Saturday’s conference. He said, “The room was full. There was overflow rooms. That’s because the interest was way beyond people who treat melanoma and are experts in melanoma.”

Merck Chief Medical Officer Eliav Barr said the melanoma results were only the beginning. He is overseeing clinical trials of similar vaccines for kidney and bladder cancers. Barr said, “If these studies are positive, then we have a very large landscape of cancers that we can start to address.”

Barr said Merck would apply to the Food and Drug Administration for approval of the melanoma vaccine. NPR reported that approval could come next year.

Merck declined to estimate the vaccine’s cost. NPR said it was likely to be pricey because the process of developing a personalized vaccine is complex.