Scientists are developing and testing a new generation of vaccines designed to intercept the earliest signs of colon cancer in individuals with Lynch syndrome, an inherited genetic disorder that significantly increases cancer risk. These experimental vaccines aim to train the immune system to recognize and eliminate precancerous growths before they develop into tumors.
Lynch syndrome affects an estimated 1 million Americans and is caused by a mutation in mismatch-repair genes, which normally correct DNA errors as cells divide. When these genes are faulty, the body struggles to fix abnormalities, leading to a higher risk of certain cancers, primarily colorectal and endometrial cancer, often at younger ages.
Several potential vaccines for Lynch syndrome are currently in development. Two are undergoing early clinical trials in the U.S., and a third is set to begin in Britain. One such vaccine, developed by Swiss biotech Nouscom, was tested in a preliminary study involving 45 individuals with Lynch syndrome. This vaccine teaches the immune system to identify specific abnormal proteins found in precancerous growths. Researchers reported in Nature Medicine that after a year, colonoscopies showed fewer precancerous growths and no advanced polyps in participants, indicating a potential immune system response that could target tumor development.
Dr. Eduardo Vilar-Sanchez, a lead researcher at the MD Anderson Cancer Center, expressed optimism about the initial findings and anticipates a larger study to commence early next year. He noted that Lynch-fueled growths accumulate mutations that create novel proteins, which the immune system can be trained to recognize.
Another vaccine approach is being explored by Oxford University researchers, utilizing mRNA technology similar to that used in COVID-19 vaccines. Massachusetts-based Moderna is involved in this research. Additionally, scientists are awaiting results from a slightly larger study comparing ImmunityBio's Tri-Ad5 vaccine, which targets different cancer markers, against a placebo.
For individuals with Lynch syndrome, the lifetime risk of developing colorectal cancer can be as high as 80%, compared to about 5% for the general population. They also face increased risks for endometrial, pancreatic, stomach, ovarian, and certain skin and brain cancers. Regular colonoscopies, typically starting much earlier than for the general population, are standard practice for monitoring and removing precancerous polyps.
While the HPV and hepatitis B vaccines protect against tumor-causing viruses, developing vaccines for gene-caused cancers presents unique challenges due to the nature of the mutations involved. However, the early success in stimulating tumor-eliminating T cells offers hope for a new preventative strategy.
Colorectal cancer is diagnosed in about 158,000 people in the U.S. annually, with a rising number of cases in younger adults, though the reasons for this increase are not yet clear. Lynch syndrome is estimated to affect approximately 1 in 279 people. Increased awareness and accessibility of genetic testing are leading more individuals to learn about their inherited risk, which also helps identify at-risk family members.
Routine colorectal cancer screening for the general population in the U.S. is recommended to begin at age 45. However, individuals experiencing symptoms such as changes in bowel habits, unexplained weight loss, or abdominal pain should seek medical attention regardless of age or known risk factors.