A new mRNA-based cancer vaccine from Moderna and Merck has shown promising results in people with melanoma, adding to growing excitement about the potential for personalized vaccines to help treat cancer.
UBC professor Dr. Pieter Cullis is one of the world’s leading experts in lipid nanoparticle (LNP) technology, the delivery system that makes mRNA medicines possible. He and UBC professor Dr. Anna Blakney are leading a major research effort through Canada’s Immuno-Engineering and Biomanufacturing Hub to develop next-generation LNP mRNA cancer vaccines right here in Canada.
We spoke with Dr. Cullis about what the latest results mean, how cancer vaccines work and their potential to transform cancer treatment.
What was your reaction to these latest results from Moderna and Merck?
These are the most compelling results we’ve seen yet for personalized LNP mRNA cancer vaccines. While we still need to see the full data, the fact that a large Phase III trial has shown significant improvements in both recurrence-free survival and metastasis-free survival is extremely encouraging and shows the approach can be highly effective.
I think we’re looking at the beginning of a major change in how we treat cancer, where mRNA cancer vaccines have the potential to become part of the standard of care.
What exactly is an mRNA cancer vaccine, and how does it work?
At a fundamental level, all vaccines work by training the immune system to recognize and fight a particular threat. When most people think about vaccines, they think about preventing an infection before it happens. Cancer vaccines are different: they train the immune system to recognize and attack cancer cells that are already in the body and help prevent them from coming back.
To do this, we take advantage of the fact that every cancer is different. We sequence a patient’s tumour to identify unique targets (antigens) that distinguish cancer cells from healthy cells, and then create personalized mRNA containing instructions to make these targets.
The mRNA is packaged in lipid nanoparticles, which deliver it into cells. The cells then produce the antigens that essentially teach the immune system to identify cancer cells and attack them. The mRNA is quickly broken down and cleared from the body, but the immune system retains what it has learned, allowing it to continue recognizing and attacking cancer cells for much longer.
How could mRNA cancer vaccines change the way we treat cancer?
The real promise is precision. Many traditional cancer treatments affect healthy cells as well as cancer cells. With a personalized cancer vaccine, we’re directing the immune system to eliminate cancer cells specifically. Because each person’s cancer is different, the vaccine has to be designed specifically for the individual patient.
Initially, these vaccines will likely be used in combination with existing treatments. But as the technology improves, I think they could become an increasingly important part of how we treat cancer and prevent it from coming back.
