Cancer therapies based on mRNA vaccine technology have been among the most promising medical developments of the past decade. That promise is now beginning to show early signs of being realized. An extended follow-up of a phase 1 pancreatic cancer trial published last year reported striking outcomes for some patients:
Six years after treatment, Gustafson and six others who responded to the treatment are still alive, along with two of the eight people who did not respond. Two of the responders, including the one who died, had a cancer recurrence; Gustafson’s cancer has not come back.
In other words, after six years, 7/8 responders are still alive, while only 2/8 non-responders are.
Pancreatic cancer is a particularly aggressive form of cancer, with a 5-year relative survival rate of just 13%. Famously, it was the type of cancer that killed Steve Jobs. It has long been an intense target for research due to its grim prognosis and lack of progress compared to other forms of cancer.
At the same time, this remains very early evidence from a small group of patients. Phase 1 clinical trials are not primarily designed to evaluate efficacy (rather, they are designed to assess safety and establish dosing and side effects). While the difference between responders and non-responders is striking, it does not by itself show the vaccine caused the survival benefit: “responders” are defined after treatment, so they are not a proper control group.
Phase 2 trials are now underway for the treatment, but most drugs that make it to phase 2 fail to reach the market. So although these results are encouraging, and for the handful of patients involved they may seem almost miraculous, any good news about an experimental therapy should be met with appropriate caution.
Still, the larger reason for optimism is that the promise of mRNA for cancer is not limited to this single early experimental success. This is because mRNA is flexible platform for designing many kinds of therapies, quickly and in an individualized way. For cancers that have seen too little progress for too long, that alone is a meaningful step forward.