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Merck-Moderna mRNA vaccine for melanoma shows promise in study, companies say

The Cambridge biotech reported that the experimental shot reduced the risk of recurrence or death by 44 percent.

Moderna's headquarters in Cambridge.Blake Nissen for the Boston Globe/file

An experimental cancer treatment developed by Moderna and its pharma partner Merck significantly reduced death and cancer progression in people with high-risk skin cancer, the companies announced Tuesday.

Moderna used the same technology behind its messenger RNA vaccines for COVID-19 to develop personalized cancer vaccines that train a patient’s immune system to spot unique genetic mutations in their tumors and destroy any cancer cells matching that molecular mugshot.

“We make a new personalized vaccine for every individual in the study,” chief medical officer Dr. Paul Burton said in an interview.

In an intermediate-stage study of 157 people with skin cancer, Moderna and Merck’s cancer vaccine reduced the relative risk of cancer recurrence or death by 44 percent when paired with Merck’s cancer immunotherapy Keytruda, compared with people who got Keytruda alone. The patients were followed for an average of two years.


The study included people with stage 3 or stage 4 melanoma, characterized by cancer that has spread locally or throughout the body. The patients had their melanoma surgically removed before the study, and the cancer vaccine was designed to help the immune system root out any lingering cancer.

“It offers a completely new way of thinking about cancer therapy,” said Dr. Ryan Sullivan, associate director of the melanoma program at Mass General Cancer Center, who was a clinical investigator in the study. “This doesn’t change the way that we treat patients tomorrow, but it’s still pretty exciting.”

The highly anticipated results represent a major step forward in the Cambridge firm’s mission to apply messenger RNA technology to diseases beyond COVID. “We really think that it has the potential to be a paradigm shift in the treatment of cancer patients. And it’s a landmark finding for mRNA therapeutics,” Burton said. “We’re thrilled with it.”

The topline results were announced in a press release and have yet to be published in a medical journal or presented at a scientific conference. Burton said Moderna would publish the study results “as quickly as possible” and that a more detailed analysis of the study’s results would “be coming very soon.”


Moderna and Merck plan to discuss the results with regulators to see if the firms still need to conduct a larger study before seeking approval. “We’re certainly prepared to do that,” Burton said. The companies are planning to begin an advanced study next year.

Burton also said that Moderna would “double down” on applying its personalized vaccines to other kinds of cancer. “We’re going to begin to really increase our efforts and activities in this space, given the strength of the finding.”

“It’s really the first study of a cancer vaccine that shows clinical efficacy in a randomized setting,” said Dr. Patrick Ott, clinical director of the Melanoma Disease Center at Dana-Farber Cancer Institute, who was involved in the trial. “It is good news for melanoma patients, but obviously it has to be confirmed in a larger trial.”

The results come two months after Merck that it was committed to moving forward with the program, which the two companies have been working on since 2016. That decision to split costs and profits on the cancer vaccine earned Moderna a $250 million milestone payment.

The vaccine is an injection like the COVID shot, but with a dose that’s 20 times larger. Patients got nine total shots administered every three weeks. Burton said that the cancer vaccine was well tolerated by patients in the study with no unexpected safety concerns, even though about 14 percent of patients who got the vaccine experienced treatment-related adverse events compared to 10 percent of people who only got Keytruda.


Moderna makes the custom shots at its manufacturing plant in Norwood. The company collects cancer cells and normal cells from a patient and sequences their genes to identify mutations that are important for the growth of the cancer. The firm’s algorithms then select up to 34 tidbits of genetic code from the cancer cells to encode in its mRNA molecules, which train immune cells to seek and destroy cells with those distinctive features.

Several companies have tried, and failed, to develop cancer vaccines over the years, yet some scientists hope that mRNA technology will help turn the tides.

“A ton of effort went into developing cancer vaccines in the eighties, nineties, and into the aughts,” Sullivan said. “A lot of them were tested in melanoma, and almost all of them fell flat on their face.”

Sullivan thinks the combination of using mRNA ― tailoring the vaccine to a patient’s unique mutations ― and algorithms to pick the best mutations all helped make the shots “more successful than any of the cancer vaccines that preceded it.”

Moderna is not without competition in the cancer vaccine field. The German firm BioNTech, which made a COVID vaccine with Pfizer, is developing its own personalized cancer vaccines with its partner Genentech. Smaller biotech firms, including California-based Gritstone Bio, are working on similar approaches.


If mRNA technology ultimately proves successful for multiple kinds of cancers, analysts expect that the vaccines will fetch prices far higher than COVID shots and could become a multibillion-dollar market.

“We’re absolutely committed to seeing the full potential here,” Burton said. “We’ll continue to work in melanoma and also explore other cancers.”

Ryan Cross can be reached at ryan.cross@globe.com. Follow him on Twitter @RLCscienceboss.