Dr. Stacy Norton’s early encounter with colon cancer had a profound impact on her life. At just 7 years old, she lost her mother to the disease. Now, decades later, she participates in pioneering efforts to determine if a new vaccine could shield her and her children from cancer. As a doctor in Houston, Norton is among approximately 1 million Americans diagnosed with Lynch syndrome. This genetic disorder dramatically increases the risk of colorectal cancer and other types of cancer.
Individuals with Lynch syndrome are advised to undergo frequent colonoscopies, significantly more than the general population, to detect and remove precancerous polyps early. However, scientists are now developing vaccines aimed at enhancing this preventive measure by training the immune system to halt the progression of potential cancerous growths before they turn into tumors.
The Promise of New Vaccines
There are currently three promising vaccines, specifically targeting Lynch syndrome. Two are in the early stages of clinical trials in the United States, while a third is making headway in Britain.
One such vaccine, which Norton helped test, is led by Dr. Eduardo Vilar-Sanchez at the MD Anderson Cancer Center. His research indicates the potential for a more extensive study soon. “It gives me hope,” Norton shares, referring to this possibility. A successful vaccine could reduce, or even eliminate, the need for her children to undergo annual colonoscopies.
Understanding Lynch Syndrome
Lynch syndrome results from a genetic mutation that impedes the functioning of mismatch-repair genes, whose role is to correct DNA errors. When these genes malfunction, the body struggles to control the accumulation of mutations, leading to an increased risk of tumors—often before individuals reach 50.
The risks associated with Lynch syndrome are significant. For instance, while the general population experiences a 5% lifetime risk of colorectal cancer, Lynch carriers face a risk as high as 80%, depending on which gene is affected. Other cancer risks include endometrial, pancreatic, stomach, ovarian, certain skin cancers, and even specific brain tumors.
Norton’s experience reflects these risks. A gene test in her 40s confirmed her Lynch syndrome diagnosis, prompting a shift to yearly colonoscopies. She also underwent a preventive hysterectomy, which unveiled early-stage uterine cancer.
Progress in Vaccine Research
Historically, the HPV and hepatitis B vaccines have demonstrated success in preventing virus-related cancers. However, creating vaccines to tackle cancers arising from genetic causes poses unique challenges compared to confronting viral threats.
Vilar-Sanchez explains that Lynch-related growths accumulate numerous mutations, creating abnormal proteins. Vaccines can train the immune system to recognize and respond to these proteins. In an initial study, Norton and 44 other Lynch carriers tested a vaccine from Swiss biotech company Nouscom, targeting 209 such mutations. The results were promising, with an increase in tumor-eliminating T cells and fewer precancerous growths noted at colonoscopies.
Dr. John Marshall, a Georgetown University oncologist, remarks on the potential of stimulating the immune system to further manage tumor formation. Norton’s subsequent colonoscopies revealed no polyps for the first time in several years, supported further by a booster shot study.
In parallel efforts, Oxford University researchers are testing a comparable vaccine developed by Moderna, leveraging mRNA technology from its COVID-19 vaccine. Meanwhile, researchers are evaluating the efficacy of ImmunityBio’s Tri-Ad5 vaccine in a larger study.
Addressing Young Adult Colon Cancer
Although most of the 158,000 annual colorectal cancer diagnoses in the U.S. affect individuals over 50, younger adults face rising incidence rates. While the precise reasons remain unclear, Lynch syndrome affects about 1 in 279 people. Though many are unaware, increasing genetic testing—especially for families with a history of Lynch-related cancers—may help identify those at risk.
For most people, U.S. guidelines recommend starting routine colorectal cancer screenings at age 45. However, individuals of any age should seek medical evaluation if they experience symptoms like blood in the stool, rectal bleeding, changes in bowel habits, unintended weight loss, or abdominal pain.
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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education and the Robert Wood Johnson Foundation. The AP is solely responsible for all content.
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