Nouscom will present long-term Phase 1b/2 data for NOUS-209 at ESMO 2026, highlighting durable immune responses and favorable safety in Lynch syndrome.
Written By: Nalam Karthik, PharmD
Reviewed By: Pharmacally Editorial Team
Nouscom will present new clinical findings from its investigational off-the-shelf cancer vaccine NOUS-209 at the ESMO Congress 2026, where the study has been selected for an oral presentation. The data come from an ongoing Phase 1b/2 clinical trial evaluating the vaccine in individuals with Lynch syndrome, an inherited cancer predisposition disorder associated with a substantially increased lifetime risk of colorectal, endometrial, and several other malignancies.
The presentation will focus on long-term follow-up and re-treatment results, providing further evidence that NOUS-209 can generate durable anti-tumor immune responses while maintaining a favorable safety profile. The selection also marks another important milestone for Nouscom’s clinical program as the company prepares for late-stage development.
NOUS-209 Targets Shared Neoantigens in Lynch Syndrome
Lynch syndrome is caused by inherited mutations in DNA mismatch repair (MMR) genes, leading to microsatellite instability and the generation of characteristic frameshift mutations that produce tumor-specific neoantigens. Current management relies largely on intensive cancer surveillance and preventive surgery rather than disease prevention.
NOUS-209 is an investigational, off-the-shelf viral vector vaccine that encodes 209 shared frameshift peptide neoantigens commonly found in microsatellite instability-high (MSI-H) tumors. The vaccine is intended to stimulate broad T-cell responses capable of eliminating precancerous or early malignant cells before invasive cancers develop, offering a novel immunopreventive approach for individuals at high genetic risk.
Phase 1b/2 Trial Demonstrates Durable Immunogenicity
The ongoing open-label, multicenter Phase 1b/2 trial (NCT05078866) is enrolling individuals with genetically confirmed Lynch syndrome to evaluate the safety, immunogenicity, and long-term clinical activity of NOUS-209.
Co-primary endpoints include safety, tolerability, and vaccine-induced immune responses, while secondary endpoints assess immune persistence, polyp burden, incidence of neoplastic lesions, and long-term clinical outcomes.
The data selected for presentation showed that NOUS-209 generated strong, broad neoantigen-specific T-cell responses that remained durable for at least one year following vaccination. Re-treatment further enhanced existing immune responses while inducing additional responses against vaccine neoantigens, supporting sustained immune memory. Long-term follow-up continued to demonstrate persistent immunogenicity consistent with the vaccine’s proposed cancer interception strategy.
Favorable Safety Profile Supports Continued Development
NOUS-209 remained well tolerated throughout the study, including after re-treatment. Investigators reported no serious treatment-related adverse events or dose-limiting toxicities. Most adverse events were transient and limited to Grade 1 or Grade 2 severity, supporting continued clinical evaluation of repeated vaccination.
ESMO Presentation Reinforces Program Momentum
Selection for an oral presentation at ESMO 2026 underscores the growing clinical interest in immunopreventive strategies for hereditary cancers. The presentation will highlight the durability of vaccine-induced immune responses, successful immune boosting following re-treatment, and the consistent safety profile observed during long-term follow-up.
The presentation also represents the latest scientific update from Nouscom’s Lynch syndrome program, which has previously generated encouraging immunogenicity data supporting the potential of therapeutic vaccination to intercept cancer development in genetically high-risk individuals.
Company Advances Toward Registrational Development
Commenting on the announcement, Nouscom’s leadership said the ESMO oral presentation recognizes the continued progress of the NOUS-209 program and reinforces the potential of cancer vaccination as a preventive strategy for Lynch syndrome. The company noted that the long-term follow-up findings provide additional support for advancing the program into registrational development.
Nouscom is preparing a global registrational clinical trial of NOUS-209 in individuals with Lynch syndrome. The long-term follow-up and re-treatment data presented at ESMO are expected to support ongoing regulatory discussions as the company advances what could become a first-in-class immunopreventive therapy for hereditary cancer prevention.
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About the Writer
Nalam Karthik (LinkedIn) is a healthcare writer and PharmD graduate with interests in pharmacovigilance, drug safety, clinical data analysis, and quality assurance. He is passionate about translating clinical and pharmaceutical knowledge into accessible healthcare content while staying engaged with advancements in drug development and patient safety initiatives.