Researchers say an experimental vaccine targeting one of the most common genetic drivers of pancreatic cancer successfully prevented disease progression in high-risk patients in an early trial.

The researchers reported in the journal Cancer Discovery that this is believed to be the first human trial to show that a vaccine targeting the KRAS gene mutation can safely generate long-lasting immune responses.

KRAS mutations are found in most pancreatic cancers and early precancerous lesions. The vaccine, known as 'M. KRAS-vax,' developed by researchers at Johns Hopkins University, works by stimulating the immune system to recognize and destroy cells carrying any of six types of these mutations before they become cancerous.

Twenty participants with a high genetic risk for pancreatic cancer and a pancreatic abnormality detected by imaging scans received four doses of the vaccine over 13 weeks.

The vaccine successfully stimulated immune cells capable of recognizing and remembering KRAS mutations in 18 participants, or 90 percent. These immune cells remained detectable for up to two years after vaccination.

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After a median follow-up of 16.5 months, none of the participants developed pancreatic cancer or a high-risk pancreatic lesion requiring surgical removal.

The vaccine was found to be safe, with side effects ranging from mild to moderate, most commonly injection site reactions, fatigue, chills, and flu-like symptoms.

The researchers note that the study was designed primarily to assess safety and immune responses, and does not prove the vaccine prevents pancreatic cancer.

Study leader Dr. Elizabeth Jaffee of the Kimmel Cancer Center at Johns Hopkins University in Baltimore said in a statement, "This is just the beginning, but the results suggest that the immune system is being stimulated."

She added, "We still have a lot of work to do, but this is a good start aimed at prevention, which no one has thought to do before."

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Scientific achievement on the path to treating pancreatic cancer

The KRAS vaccine was first tested in 2020 in patients who had undergone surgery and were at high risk for cancer recurrence.

That study showed that when the vaccine provokes a strong immune response, patients remain disease-free for at least five years. The success of the 2020 trial prompted this new preventive study of the vaccine.

The researchers have launched another study to test the vaccine in patients with high-risk pancreatic cysts who undergo surgery to remove them.

This new study will allow researchers to see how immune cells generated by the vaccine directly affect pancreatic tissue that could potentially become cancerous.