An experimental vaccine targeting one of the most common genetic drivers of pancreatic cancer has kept the cancer from developing in high-risk patients in a pilot trial, researchers say.
The study is believed to be the first-in-human demonstration that a vaccine targeting the KRAS mutation can safely generate lasting immune responses, they reported in Cancer Discovery.
KRAS mutations are present in most pancreatic cancers and precancerous lesions. The vaccine, mKRAS-VAX, being developed by researchers at John Hopkins University, causes the immune system to recognize and destroy cells carrying any of six such mutations before they can develop into cancer.
Twenty participants at high genetic risk for pancreatic cancer and a pancreatic abnormality identified through imaging received four doses of the vaccine administered over 13 weeks.
In 18 participants, or 90%, the vaccine successfully activated immune cells capable of recognizing and remembering KRAS mutations. These immune cells remained detectable for as long as two years after vaccination.
At a median follow-up of 16.5 months, none of the participants had developed pancreatic cancer or a high-risk pancreatic lesion requiring surgical removal.
The vaccine was found to be safe, with only mild to moderate adverse effects – most often injection-site reactions, fatigue, chills and flu-like symptoms.
The investigators note that the study was designed primarily to evaluate safety and immune responses and does not prove the vaccine prevents pancreatic cancer.
“This is just the beginning, but the findings suggest that the immune system is getting activated,” study leader Dr. Elizabeth Jaffee of the John Hopkins Kimmel Cancer Center in Baltimore said in a statement.
“We have more work to do, but this is a good start aimed at prevention, which no one had thought about doing before.”
The KRAS vaccine was first tested in 2020 in patients who had undergone surgery and were at high risk of cancer recurrence. That study found that when the vaccine generated a strong immune response, patients remained disease-free for at least five years. The success of the 2020 testing prompted this prevention vaccine study.
The researchers have launched an additional study to test the vaccine in patients with high-risk pancreatic cysts undergoing surgical resection. This new study will enable them to see how vaccine-induced immune cells directly affect precancerous pancreatic tissue.
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