Lynch Syndrome Cancer Vaccines: Which Trials Exist and What They Show

No vaccine for Lynch syndrome is approved, and none is available outside a clinical trial. Six registered programmes test cancer-prevention vaccines in Lynch syndrome carriers: NOUS-209, Tri-Ad5 with N-803, mRNA-4194 and three dendritic-cell trials. None has shown that it prevents cancer. ^{[2,3,4,5,6,7]}

“Investigational” means regulators have not established that a product is safe and effective for routine use. A trial has selection criteria, monitoring in a research setting and, when randomised, may not guarantee that a participant receives the vaccine. NOUS-209’s FDA Fast Track designation is a development designation, not an approval. Larger randomised studies are still needed. ^[1,10]

A Lynch syndrome cancer vaccine does not prevent an infection. It trains T cells to recognise abnormal proteins that appear after DNA mismatch repair fails, aiming to clear precancerous cells before cancer develops. Shared frameshift peptides make an “off-the-shelf” approach possible, but that mechanism has not yet been shown to prevent cancer. ^[1,16]

Lynch syndrome is caused by inherited variants in mismatch-repair genes. When repair fails, frameshift mutations can produce abnormal peptides. Researchers call an attempt to act at this precancer stage “interception.” A vaccine does not change the inherited variant, treat an existing cancer or replace surveillance. Existing cancers may instead be considered for tumour-guided immunotherapy for Lynch-associated cancers.

Antigen categories follow Kuipers et al. Table 1; prevention rationale follows D’Alise et al. ^[1,14]

Six registered trials test preventive vaccines in Lynch syndrome carriers. NOUS-209 has finished enrolment, Tri-Ad5 is active but closed to enrolment, and mRNA-4194 is recruiting in the UK. One dendritic-cell trial is recruiting in Spain and two Dutch trials had not started. Statuses were checked October 5, 2026. ^{[2,3,4,5,6,7]}

The earlier Radboud Phase I/II study NCT01885702 is complete and has longer follow-up. ClinicalTrials.gov’s data timestamp was October 5, 2026; registry statuses can change. For the UK programme, read about Moderna's mRNA-4194 trial. ^[4,8,14]

In the Phase Ib/II NOUS-209 trial, 45 Lynch syndrome carriers received two injections eight weeks apart. No treatment-related serious adverse events occurred, and all 37 people tested had a T-cell response; 85% of 33 tested still did at one year. The study was not designed or powered to show that the vaccine prevents cancer. ^[1]

The authors called the result a “potentially encouraging early signal of efficacy” and said “a larger randomized study will be essential.” MD Anderson and later press coverage highlighted no new advanced polyps, but the paper reports no statistically significant reduction. An AACR interim report said 21 of 43 had no adenomas at 13–17 months; the final paper reports 31 of 43 at end-of-study colonoscopy. ^[1,9,16,17]

Participants had a median age of 50; 47% carried MSH2, 24% MSH6, 18% MLH1 and 11% PMS2 variants. Forty-two percent had survived a previous cancer, 56% were male and 91% self-reported white, limiting generalisability. A revaccination cohort is unpublished. Nouscom announced Fast Track on June 1, 2026 and an ESMO 2026 presentation, but no registration-enabling trial record was found on October 5. ^[1,10]

Tri-Ad5 combines adenovirus-based vaccines against CEA, MUC1 and brachyury with the immune stimulant N-803 in a Phase IIb randomised, placebo-controlled NCI trial. It is active but no longer recruiting, and results are awaited. The ClinicalTrials.gov record was updated June 17, 2026. ^[3]

The primary outcome is cumulative incidence of adenomas, advanced adenomas and colorectal cancer over about two years. Eligibility included defined pathogenic variants and previous colorectal neoplasia for several gene groups, with at least six months since cancer treatment. The registry plans 186 participants; Kuipers et al. tabulated 158 recruited. NCI called it the largest US Lynch syndrome prevention study in 2023. Older pages that still say it is enrolling are stale; UCSF listed it as not accepting patients in June 2026. ^[3,14,15,20]

mRNA-4194 is Moderna’s investigational Lynch syndrome vaccine in a UK Phase 1/2 trial sponsored by the University of Oxford, with no results yet. Three dendritic-cell trials use a participant’s own immune cells loaded with frameshift peptides: one is recruiting in Spain and two in the Netherlands had not started. ^[4,5,6,7]

The mRNA programme targets 194 shared frameshift peptides and plans 110 participants. Dosing and full eligibility belong in the detailed guide to Moderna's mRNA-4194 trial. It has no efficacy data. ^[4,11,12,13]

For dendritic-cell vaccines, cells are collected from the participant, loaded with neopeptides and injected into a lymph node. The Dutch trials require HLA-A*02:01 and generally enrol ages 35–75, or 40–75 for MSH6. Follow-up from an earlier Radboud study is encouraging but cannot be generalised: Kuipers and D’Alise describe no Lynch-related cancers over ten years among participants who had a TGFBR2 response. ^[1,5,6,8,14]

How durable mRNA responses will be remains open. NCI noted in 2023 that RNA vaccines may need repeated boosts for long-term immunity, and Kuipers et al. said transient antigen expression may require frequent boosters. The current trial is designed to help answer that question. ^[14,15]

People cannot get a Lynch syndrome vaccine outside a clinical trial. Trials enrol adults with a confirmed germline mismatch-repair variant and no active cancer, then add rules about polyps, earlier cancer treatment, tissue type or medicines. Only mRNA-4194 and the Dutch and Spanish programmes were recruiting or opening; none listed a recruiting US site. ^{[2,3,4,5,6,7]}

Do not stop or change aspirin, an NSAID or any medicine to qualify without a clinician’s advice. Check ClinicalTrials.gov and ISRCTN by registry ID and ask a genetics or gastroenterology team; this page lists records, not enrolment links. These trials require a confirmed diagnosis. Read how Lynch syndrome testing works.

No Lynch syndrome vaccine has shown that it lowers the number of cancers. The NOUS-209 study was small, had no comparison group and was not powered for adenoma or cancer outcomes. The placebo-controlled Tri-Ad5 and Radboud trials have not reported results. Platform, durability and how vaccination interacts with surveillance or aspirin remain open questions. ^[1,3,6]

• EfficacyCancer incidence has not been shown to fall in any programme.
• DurabilityNOUS-209 responses persisted in 85% of 33 evaluable people at one year; booster-cohort results are unpublished.
• SafetyLong-term safety in larger and more diverse populations is unknown.
• GeneralisabilityNinety-one percent of NOUS-209 participants self-reported white.
• Non-colorectal cancersThree of 45 participants later had non-colorectal cancers; without a control group this is not interpretable.
• RegulationFast Track is not approval, and no registration trial was listed on October 5, 2026.

No source reviewed supports forecasting an approval date. ^[1,2,10]

Care for Lynch syndrome today is regular surveillance with colonoscopy, risk-reducing surgery in selected cases and, for some people, daily aspirin discussed with a clinician. Vaccine trials do not replace this care. Participants in the NOUS-209 study continued standard-of-care colonoscopy. ^[1,12,18]

A vaccine is not a substitute for colonoscopy. Trials also require continued surveillance: the mRNA-4194 materials include colonoscopies at 28 weeks and 24 months, while DELAY requires colonoscopy every one to two years. See the colonoscopy schedule and aspirin for Lynch syndrome; do not change care because of an investigational programme. ^[4,7]

Lynch syndrome vaccine headlines can blur immune response, early precancer signals and proven prevention. The short answers keep those outcomes separate. Trial status is dated because recruitment and study milestones change.

Questions about diet belong in the treatment guide. For prognosis, read about Lynch syndrome life expectancy. The reviewed sources did not support an answer about life insurance.

Vaccine trials enrol people with a confirmed Lynch syndrome diagnosis, usually made by clinical genetic testing after family history or a tumour result raises suspicion. A result from a consumer genome service is a starting point, not proof of eligibility. Confirmatory clinical testing and genetic counselling are needed, and the trial team decides whether its laboratory standard is met.

Routes include family-history assessment, tumour testing (MSI and IHC) followed by germline testing, and cascade testing for relatives. These trials enrol people with a confirmed Lynch syndrome diagnosis. Knowing status through clinical genetic testing is what makes eligibility assessment possible; testing does not guarantee eligibility or access. Read how Lynch syndrome testing works.

Human Longevity describes its $599 whole-genome service as including a cancer risk assessment, but its exact Lynch-gene scope is unconfirmed. It does not test tumours, detect existing cancer, provide a clinical Lynch diagnosis, refer to a vaccine trial or enrol anyone. See what the $599 genome service includes.