Nouscom to Present New Positive Phase 1b/2 Clinical and Translational Data on NOUS-209 Immunogenicity and Cancer Interception Potential in Lynch Syndrome Carriers at SITC 2025

Lynch Syndrome (LS) is a common hereditary condition that greatly increases lifetime risk of colorectal, endometrial, urothelial and other cancers
NOUS-209 is an off-the-shelf immunotherapy designed to harness the power of the immune system to recognize and eliminate cancerous cells before tumors develop
Additional results from Phase 1b/2 trial of NOUS-209 in LS carriers demonstrating effective boosting of immune response through annual retreatment to be presented in an oral late-breaker presentation at SITC 2025
Further validation of NOUS-209 mechanism of action enabling broad targeting of primary and metachronous tumors in LS carriers to also be presented
Findings support advancement of NOUS-209 to FDA and EMA aligned registration-enabling clinical study for cancer interception in LS carriers

BASEL, Switzerland – 30 October 2025 - Nouscom, a clinical-stage biotech company developing next-generation neoantigen-targeted off-the-shelf and personalized cancer immunotherapies, today announced it will give an oral late-breaker as well as a poster presentation of additional results from a Phase 1b/2 trial evaluating NOUS-209 in Lynch Syndrome (LS) carriers at the Society for Immunotherapy of Cancer (SITC) 40^th Anniversary Annual Meeting being held in National Harbor, MD, USA on November 5-9, 2025. The company will also present further data validating NOUS-209 mechanism of action (MoA) in LS carriers at the SITC meeting.

Oral Presentation Details:

Title: Final Ph1b/2 Results for NOUS-209 Monotherapy in Lynch Syndrome Carriers: Annual Revaccination Boosts T Cell Immunity Informing Future Cancer Interception Strategies

Session: Clinical Oral Abstract Session 2
Date & Time: Saturday, November 8, 2025, 1:45 PM – 3:00 PM ET
Location: Gaylord National Resort & Convention Center, Potomac Ballroom

Poster Presentations Details:

Poster #118 – NOUS-209 Mechanism of Action Validation
Title: NOUS-209 Enables Broad Targeting of Primary and Metachronous Tumors in Lynch Syndrome

Session: Poster Hall
Time: Saturday, November 8, 2025, 9:00 AM – 6:35 PM ET
Location: Prince George’s ABC

Poster #1336 – NOUS-209 Clinical Data
Title: Final Ph1b/2 Results for NOUS-209 Monotherapy in Lynch Syndrome Carriers

Session: Poster Hall
Time: Saturday, November 8, 2025, 9:00 AM – 6:35 PM ET
Location: Prince George’s ABC

All abstracts are available on the SITC website https://www.sitcancer.org/2025/abstracts/titles-and-publications

LS is a common inherited condition caused by DNA repair gene mutations. It affects approximately 1 in 300 people, leading to a significantly increased lifetime cancer risk of up to 80%. While current LS disease management relies on frequent screenings or preventive surgery, cancer interception with NOUS-209 aims to train the immune system to recognize and eliminate cancerous cells before they fully develop, grow and spread.

NOUS-209 is an off-the-shelf immunotherapy designed to target tumors with specific genetic deficiencies known as mismatch repair deficiency (dMMR) and/or microsatellite instability (MSI). These tumors produce unique markers known as frameshift peptide (FSP) neoantigens, which serve as tumor-specific neoantigens. Because these FSPs are exclusively found in cancerous cells, they are readily recognizable by the immune system and therefore are ideal targets for immunotherapy. NOUS-209 encodes 209 unique FSP neoantigens shared across multiple MSI tumor types, enabling its potential to treat a broad range of MSI-associated cancers.

Following positive Type B and C meetings with the US Food and Drug Administration (FDA), Nouscom has a clear path forward for the advancement of NOUS-209 into a registration-enabling Phase 2/3 clinical study for cancer interception in LS carriers.

The clinical trial NCT05078866 was led by researchers at The University of Texas MD Anderson Cancer Center, in collaboration with the Cancer Prevention Clinical Trials Network (CP-CTNet) and sponsored by the National Cancer Institute (grant # UG1CA242609). The activities are coordinated by the iCAN-PREVENT consortium of MD Anderson Cancer Center.

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About NOUS-209
NOUS-209 is an investigational off-the-shelf cancer immunotherapy that targets tumors with mismatch repair deficiency (dMMR) and high microsatellite instability (MSI-H). These tumors produce unique markers known as frameshift peptide (FSP) neoantigens, which are unique to cancerous cells and absent in healthy cells. NOUS-209 is comprised of two proprietary viral vectors able to deliver 209 shared FSP neoantigens and train the immune system to recognize and attack cancerous and precancerous cells before tumors can develop.

Phase 1b/2 data (NCT05078866) demonstrated the safety of NOUS-209 and its ability to stimulate potent immune responses in LS carriers¹, supporting its advancement into a registration-enabling Phase 2/3 trial in cancer interception. It also demonstrated clinical activity including objective responses and strong disease control in combination with pembrolizumab in a difficult-to-treat patient population of advanced dMMR and/or MSI-H metastatic CRC (mCRC) patients refractory to anti-PD-1 therapy². NOUS-209 is also being studied in a randomized Phase 2 study in combination with pembrolizumab for the first line treatment of advanced dMMR and/or MSI-H mCRC. Data published from the successfully completed Phase 1b trial were published in Science Translational Medicine³.

About Lynch Syndrome
Lynch Syndrome (LS) is a common inherited condition that significantly increases a person’s risk of developing cancer over their lifetime, especially colorectal cancer (CRC) (up to 50% risk, compared to 2% for general population), endometrial cancer (up to 50% risk, compared to 1-2% for general population) and urothelial cancer (up to 25% risk, compared to 1-2% for general population)^4,5^,6,7. LS also elevates the risk of developing other cancers including gastric, ovarian, prostate and pancreatic. LS is caused by inherited mutations in specific genes responsible for repairing DNA, leading to the buildup of harmful genetic errors that can accumulate, triggering development of tumors. Currently, managing LS is limited to frequent screenings - such as colonoscopy to try to catch cancer early, but which will not prevent cancer incidence⁸ - or elective surgery, which is invasive, expensive, and negatively impacts quality of life. As a pioneering approach to cancer interception, Nouscom’s investigational immunotherapy, NOUS-209, is designed to train the immune system to recognize and stop cancer before it develops.

About Cancer Interception
Cancer interception is an innovative approach that aims to stop cancer in its earliest stages before tumors fully develop and spread. Unlike traditional therapies that target established cancers, interception strategies harness advancements in immuno-oncology that can train the immune system to recognize and eliminate precancerous and cancerous cells. This approach is particularly crucial for those with high-risk genetic conditions such as LS who are predisposed to developing MSI-associated cancers.

About Nouscom
Nouscom is a clinical-stage biotech company pioneering next-generation neoantigen-targeted immunotherapies to treat cancer at all stages, from early cancer interception to late-stage metastatic disease. Its proprietary viral vector platform enables broad and durable immune activation by delivering optimized neoantigens that train the immune system to recognize and fight cancer. Nouscom’s lead program, NOUS-209, is an off-the-shelf immunotherapy in advanced clinical development for cancer interception in LS and the treatment of MSI-mCRC. The company’s clinical stage portfolio also includes NOUS-PEV, a personalized neoantigen immunotherapy, with published data from a successfully completed Phase 1b trial⁹.
For more information on Nouscom, please visit the company’s website at www.nouscom.com or follow us on LinkedIn.

References

Willis et al, Cancer Res (2025) 85 (8_Supplement_1): 6427.
Abstract is available on the ESMO website, here.
D’Alise et al., Science Translational Medicine, 2022.
Dominguez-Valentin et al., Genetics in Medicine, 2020.
Dominguez-Valentin et al., The Lancet, 2023.
Strafford, Reviews in Obstetrics & Gynecology, 2012.
Richters et al., World Journal of Urology, 2020.
Ahadova et al., International Journal of Cancer 2020.
D’Alise et al., Clin Cancer Research, 2024.

Contacts
Nouscom
Rick Davis, COO
info@nouscom.com
+41 61 201 1835

MEDiSTRAVA
Sylvie Berrebi, Sandi Greenwood, Mark Swallow
nouscom@medistrava.com
+44 (0)203 928 6900

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