Personalized Cancer Vaccine Shows Promise In Major Trial

Pharmaceutical companies Merck and Moderna reported that an experimental personalized mRNA vaccine, given alongside the immunotherapy drug Keytruda, reduced the risk of melanoma recurrence or death by 42% compared with Keytruda alone.  

The Phase 3 trial included 1,137 patients with Stage IIB-IV melanoma whose tumors had been surgically removed. The findings could bring the drugmakers closer to regulatory approval for the treatment.

The companies released detailed results Thursday, showing that at two years, 82.2% of patients receiving the vaccine alongside Keytruda were alive without melanoma recurrence, compared with 70% receiving Keytruda alone. The combination also reduced the risk of cancer spreading to distant parts of the body or death by 38%. 

“You’ve effectively immunized the body to recognize the cancer and kill it,” Dr. Marjorie Green, Merck’s head of oncology clinical development, told The New York Times. Green said Merck plans to seek regulatory approval as soon as possible.

The vaccine is personalized. Scientists sequence the patient’s tumor to identify mutated proteins found only on cancer cells, then use mRNA to train the immune system to recognize and attack cells bearing those proteins.

Researchers are also testing therapeutic vaccines for other types of cancer, including kidney, bladder, non-small-cell lung and pancreatic cancer, as well as glioblastoma, one of the deadliest brain cancers. 

“This is the first step,” Dr. Robert Vonderheide, director of the University of Pennsylvania’s Abramson Cancer Center, told The New York Times. “Will it work in other tumors? I’m hopeful. Do we have a lot to learn? For sure.”

Dr. Shirin Bajaj, incoming director of head and neck melanoma at Mount Sinai in New York, told NBC News that patients will need to be followed for several more years to determine whether the vaccine continues to work and improves overall survival. 

She added that providing the personalized treatment on a large scale remains a challenge.

“It’s amazing, but I think some of the logistics are going to need to be worked out,” she said. “But nothing that I saw from this study made me think that the logistics are infeasible. It’s just that it will be a hurdle to actually do this at a wide scale.”