Cancer vaccines are entering unfamiliar territory. Instead of treating an existing tumour, several experimental injections are being developed to help the immune system identify and destroy abnormal cells before those cells become cancerous.
The research is focused on people with Lynch syndrome, an inherited disorder caused by faults in genes responsible for repairing mistakes in DNA. Without an effective repair system, mutations can accumulate whenever cells divide, creating conditions in which cancer may emerge at an unusually young age.
Colorectal cancer is the condition most frequently associated with Lynch syndrome. Depending on the gene involved, a carrier’s lifetime risk can reach approximately 80%. The disorder also increases vulnerability to uterine, ovarian, stomach, pancreatic, urinary-tract and certain skin cancers.
People diagnosed with the syndrome commonly undergo frequent medical surveillance, including colonoscopies every one or two years. These examinations can locate and remove precancerous polyps, but they cannot prevent abnormal growths from forming in the first place.
Researchers now hope vaccination could provide an additional defensive layer.
In an early study, 45 Lynch syndrome carriers received an experimental vaccine developed to teach the immune system to recognise more than 200 abnormal proteins associated with Lynch-related precancers. Investigators detected stronger activity among cancer-fighting T cells following vaccination.
Colonoscopies conducted one year later found fewer precancerous growths among participants, while no advanced polyps were identified. Although encouraging, the findings do not yet prove that the vaccine can prevent cancer. A larger trial will be needed to determine whether the apparent protection lasts and whether it meaningfully reduces cancer diagnoses.
Other vaccine candidates are also moving through development. Researchers at the University of Oxford are preparing early testing of an mRNA-based vaccine developed with Moderna. Another clinical study is evaluating a vaccine from ImmunityBio against a placebo.
The approach differs from established cancer-prevention vaccines. Existing injections against human papillomavirus and hepatitis B reduce cancer risk by blocking infections capable of causing tumours. The new candidates attempt to prevent cancers created by inherited genetic defects rather than infectious diseases.
Scientists believe Lynch-related cells provide recognisable targets because their faulty DNA-repair machinery produces unusual proteins that healthy cells normally do not make. A vaccine could train the immune system to detect these warning signals and eliminate dangerous cells during their earliest stages.
The research arrives as colorectal cancer diagnoses among younger adults continue to rise. Lynch syndrome does not explain every early case, but wider genetic testing could identify families carrying the condition and allow relatives to begin surveillance sooner.
Even if the vaccines succeed, researchers say they are unlikely to replace colonoscopies immediately. Instead, vaccination and screening could work together—one suppressing the development of abnormal cells and the other detecting any growths that escape the immune response.
