In a Phase 2b clinical trial, Moderna's experimental, personalized mRNA cancer vaccine combined with Merck's Keytruda immunotherapy reduced the risk of cancer recurrence or death among melanoma patients by over 40%—promising results that some health experts say may mark a "tipping point" in cancer treatments.

Moderna's mRNA cancer vaccine shows promise in new trial

The trial included 157 patients with Stage 3 or 4 melanoma that spread to a lymph node and whose tumors had already been surgically removed. According to CDC, the five-year survival rates melanoma is 60.3% for Stage 3 of the disease and 16.2% for Stage 4.

During the study, the patients were randomly divided into two groups. In one group, patients received nine doses of the vaccine and Keytruda every three weeks for roughly a year. The other group received the immunotherapy treatment alone.

To create the vaccines, researchers collected samples of patients' tumors and healthy tissues and analyzed them to isolate mutant proteins that were associated only with the cancer. Using this information, personalized vaccines— aimed to trigger an immune response to target and destroy cancer cells—were created for each patient.

Overall, researchers found that the combination vaccine and Keytruda treatment reduced the risk of relapse or death among patients by around 44% compared to Keytruda alone. According to the companies, these results were statistically significant.

The combination treatment was also found to be generally safe. Serious drug-related side-effects occurred in 14.4% of patients who received the combination treatment and 10% of patients who received Keytruda alone.

These "results are highly encouraging for the field of cancer treatment," said Moderna CEO Stéphane Bancel. "mRNA has been transformative for COVID-19, and now, for the first time ever, we have demonstrated the potential for mRNA to have an impact on outcomes in a randomized clinical trial in melanoma."

Eliav Barr, Merck's CMO and its head of global clinical development, also noted that the results are "a tremendous step forward in immunotherapy."

Going forward, Moderna and Merck said they will share the study data with health authorities and are planning to run a larger Phase 3 study to confirm the combination treatment's safety and efficacy next year. The companies also said they are looking into testing the combination against other types of cancer.

"We don't want to waste time," Bancel said. "Given the data is so strong, for me it's a Covid-like moment."

Could other cancer vaccines be coming?

After the success of mRNA vaccines against the coronavirus, several biotech companies began using the technology to develop vaccines against cancers. Currently, there are two types of mRNA vaccines against cancer: personalized vaccines tailored to a specific target or "off the shelf" vaccines that target antigens shared across all patients.

Being able to go from assessing a tumor to design a personalized vaccine to producing it and getting it into a patient within a few weeks is where "genomics meets computational biology meets immunology meets my patient in my clinic," said Jason Luke, director of the Cancer Immunotherapeutics Center at UPMC Hillman Cancer Center.

"It really sounds like science fiction," Luke said. "But I really do think that's the world we're moving into."

"Cancer vaccines have had a lot of promise, but they have been really not quite taking hold because the cycle time was just too long," said Francis Collins, former NIH director. "Now with mRNAs, you can do that so much more quickly."

According to the Washington Post, there are currently dozens of clinical trials testing mRNA vaccines for different cancers, including pancreatic and colorectal cancer. For example, BioNTech in October 2021 launched a phase 2 trial for colon cancer patients who had remaining cancer cells in their blood after their tumors were surgically removed.

"In general, I think cancer vaccines are kind of at a tipping point, and there are going to probably be a lot of vaccines coming down the pipeline in the next five years," said Mary Lenora Disis, director of the UW Medicine Cancer Vaccine Institute. (Loftus, Wall Street Journal, 12/13; Steenhuysen/Erman, Reuters, 12/13; AP/NBC News, 12/13;  Gumbrecht, CNN, 12/13; Bernstein, Washington Post, 12/13)