A new vaccine that acts as an off-the-shelf treatment for certain patients with pancreatic or colorectal cancer has shown promising initial results, according to a study co-led by researchers at Memorial Sloan Kettering Cancer Center (MSK) published in Nature Medicine on Jan. 9.
The vaccine targets “tumors with mutations (or changes) in the KRAS gene, a driving force in many cancers.” This differs from another type of pancreatic cancer vaccine, which “is custom-made for each patient using messenger RNA (mRNA).” Both of these vaccines are “given to patients after surgery to prevent or delay the cancer from coming back in high-risk patients.” One of the leaders of the trial, Eileen O’Reilly, MD, says that “having a vaccine that’s ‘off-the-shelf’ would make it easier, faster, and less expensive to treat a larger number of patients.”
In the phase 1 trial, “84% of patients had the desired immune response…also in 84% of patients, a marker for lingering cancer cells – the amount of tumor DNA circulating in the blood – was reduced. In 24% of patients, the tumor DNA was completely absent.” The trial also found that “patients who had a higher T cell response [what the vaccine is meant to provoke] also experienced a longer time without the disease returning.”
This vaccine stands in contrast to the aforementioned personalized mRNA vaccine that is currently also being studied. Those vaccines “take time to make and are costly,” whereas this off-the-shelf vaccine could be “manufactured in batches” and would be cheaper to produce.
Dr. O’Reilly also touts this initial trial as a “major breakthrough after decades of trying to find a good KRAS therapy.” This new vaccine is able to target different KRAS mutations which drive about “90% of pancreatic cancers and 40% of colon cancers.” The vaccine is administered with a shot in four places, allowing the peptides to “travel to nearby lymph nodes, which are loaded with the cells critical to generating an effective immune response.” Patients received six doses of the vaccine in a primary phase, followed by a booster phase with four doses a few months later. It caused “mild side effects such as soreness and fatigue, but Dr. O’Reilly reported it was tolerated better than standard treatments such as chemotherapy, radiation, or targeted drugs.”
A phase 2 trial opened in December 2023 to confirm the phase 1 trial’s results. The vaccine in phase 2 will target more KRAS mutations compared to the initial vaccine.
MSK’s website has the story.