Re-vaccination with the Nous-209 vaccine boosted T-cell immune responses in Lynch syndrome carriers in a Phase 1 trial expansion presented at the ESMO Congress in Madrid, with no advanced colorectal cancers found in follow-up colonoscopies.
Re-vaccination with Nous-209, an investigational neoantigen-based vaccine, strengthened immune responses in people with Lynch syndrome, researchers at the University of Texas MD Anderson Cancer Center reported at the European Society for Medical Oncology Congress in Madrid. The findings come from a cohort expansion of a Phase 1 trial testing whether vaccination can intercept cancer before it develops in people with the hereditary condition, which sharply raises the risk of colorectal, endometrial and other cancers.
Participants who had received an initial vaccine series were re-vaccinated one year later under two strategies: the same vaccine again, or only part of the full vaccine. Both approaches were well tolerated, with no severe side effects, and both boosted T-cell immune responses. The strongest immune boost came in patients who received a single neoantigen booster dose, and no advanced colorectal cancers were detected in follow-up colonoscopies for study participants.
The trial is designed around a different idea from most cancer vaccines. Nous-209 is an off-the-shelf immunotherapy that targets neoantigens shared across patients, rather than a vaccine built from one person's tumour, and its aim is interception: training the immune system to recognise and remove abnormal cells before cancer forms. The programme's developer, Nouscom, reported that 43 participants evaluated at one year and 17 at two years had no advanced adenomas or colorectal cancer, against roughly three events that natural-history data would predict in a comparable surveilled group.
The design and the immune-response findings are the cancer centre's own account of its ESMO presentation, while the participant counts and the expected-events comparison come from the developer's briefing, not from the centre. This is early-phase evidence: it shows the vaccine is safe and immunogenic on re-vaccination, but it does not prove it prevents cancer, and the small numbers and the historical comparison mean the clinical result is a signal, not a verdict.
The next step is a larger trial. MD Anderson said the results will inform dosing for a Phase 2/3 study, and Nouscom said a single global registration-enabling trial, with event-free survival as its primary endpoint, has been discussed and agreed with the United States Food and Drug Administration and the European Medicines Agency. Nous-209 already holds FDA Fast Track designation, and details of the pivotal trial are expected when it is registered in the coming months.