October 2023 | George M. Pikler, M.D., Ph.D., FACP

The Vaccine Trial Everyone Is Talking About

Researchers have long suspected that therapeutic vaccines customized to a patient’s cancer might help raise the immune system to fight off the disease. A phase II randomized clinical trial of a personalized cancer vaccine, mRNA-4157, has caused a surge of excitement about the technology. The findings were presented at the annual meeting of the American Association of Cancer research in Orlando, FL last April.

In the study, (1) 107 eligible patients with completely resected, high-risk cutaneous melanoma were randomly assigned 2:1 (stratified by stage) to receive mRNA-4157 in combination with pembrolizumab or pembrolizumab alone. mRNA-4157 (1mg) was administered intramuscularly every 3 weeks for a total of 9 doses and pembrolizumab (200mg) intravenously was given every 3 weeks for up to 18 cycles. Safety was evaluated as a secondary endpoint. Recurrence free survival (RFS) in the overall intention-to-treat population was the primary end point. The primary analysis for RFS was specified to occur after all patients completed a minimum of 12 months on study and at least 40 RFS events were observed.

After 18 months, the patients who received the adjuvant therapy with the mRNA vaccine in combination with pembrolizumab had a 44% lower risk of death or relapse compared with those in the pembrolizumab-only group, without an increase in clinically meaningful adverse events. A phase III study will be initiated in patients with melanoma.

“It’s the best proof-of-principle that the field could have,” stated oncologist Ryan Sullivan, who was involved in the trial, run by the US pharmaceutical company Moderna. “If this was a negative trial, it would have been a disaster.”

(1) Cancer Res (2023) 83 (8_Supplement): CT001

Erica Cross, PA


Erica is a board certified Physician Assistant. She obtained her Master’s degree in Physician Assistant studies from Our Lady of the Lake College in Baton Rouge, LA. She began practicing in 2011 and has worked clinically in Orthopedics and Dermatology. The majority of her career has been spent in a Dermatology practice where she assisted in Mohs surgery, treating various types of skin cancer. She also teaches in the medical simulation department at the University of South Alabama and enjoys every aspect of medical education.