Personalized mRNA Vaccine Shows Promise in Early-Stage Pancreatic Cancer Trial

A Phase 1 clinical trial has reported promising long-term results for a personalized messenger RNA (mRNA) vaccine designed to prevent the recurrence of pancreatic cancer. The trial, led by Dr. Vinod Balachandran of Memorial Sloan Kettering Cancer Center, involved 16 patients with early-stage, operable disease.

Six years after treatment, seven of the eight patients who mounted an immune response to the vaccine, and two of the eight who did not, are still alive.

Pancreatic cancer has a five-year survival rate of less than 13%. There is no routine screening, and symptoms often appear only in advanced stages. Only about 20% of cases are operable at diagnosis, a requirement for joining this type of vaccine trial.

How the Trial Worked

Patients underwent surgery to remove their tumors. Researchers then used genetic material from the tumor cells to create a personalized vaccine for each patient. After surgery, patients received this vaccine followed by standard chemotherapy.

The vaccine is not designed to remove existing tumors. Instead, it aims to prompt the immune system to eliminate lingering cancer cells and prevent recurrence.

Key Findings from the Six-Year Follow-Up

• Eight of the 16 patients generated an immune response, producing T cells that target their tumor cells.
• Among the eight responders, seven are alive six years later. Two experienced a cancer recurrence, and one responder has died.
• Among the eight non-responders, two are alive six years later.
• New data from this follow-up period will be presented at the upcoming American Association for Cancer Research's annual meeting.

Follow-up research suggests that in responders, both "killer T cells" and "helper T cells" may work together to create a durable immune response.

Expert Perspectives

Dr. William Freed-Pastor of Dana-Farber Cancer Institute noted the correlation between immune response and survival. "The most important finding is that patients who mounted an immune response lived longer than those who did not," he said, while cautioning that the results come from a small group. "There could be another factor underlying why some patients mount a response that could be the reason they are also surviving."

Dr. Robert Vonderheide of the American Association for Cancer Research provided important context, noting that a subgroup of pancreatic cancer patients typically survives longer than five years. He also observed that while earlier mRNA vaccine research for advanced cancer was disappointing, newer research suggests it may work in less advanced cases.

"The moment we have something that we think is effective, cancer cells find a way to work around it, and the solution to that is to have multiple tools to fight it," said Dr. Vonderheide.

Dr. Vinod Balachandran described pancreatic cancer as "the poster child for these difficult-to-treat cancers" and noted that generating an immune response in this cancer is particularly challenging.

The Road Ahead

Based on these early results, the drugmakers Genentech and BioNTech have launched a larger Phase 2 clinical trial.

In parallel, other research avenues are being explored. Another team is developing an "off-the-shelf" vaccine targeting the KRAS protein, which is present in up to 90% of pancreatic cancers. An early trial of that vaccine showed about 85% of participants mounted an immune response.

Traditional immunotherapies, which have revolutionized treatment for some cancers, are effective in only about 20% of all cancers, underscoring the need for new approaches like these personalized vaccines.