Nouscom Presents New Positive Phase 1/2b data of NOUS-209 at SITC 2025, Supporting Plans to Initiate Registration-Enabling Study for Cancer Interception in Lynch Syndrome Carriers

Nouscom Presents New Positive Phase 1/2b data of NOUS-209 at SITC 2025, Supporting Plans to Initiate Registration-Enabling Study for Cancer Interception in Lynch Syndrome Carriers

New data from Phase 1b/2 trial show annual NOUS-209 retreatment boosts durable T cell immunity in Lynch Syndrome (LS) carriers.
First clinical evidence of NOUS-209 cancer interception approach with no advanced adenomas detected one year post-treatment.
Neoantigen analysis supports broad preventive potential of NOUS-209 across LS-associated microsatellite instable (MSI) tumors.

BASEL, Switzerland – November 7, 2025 – Nouscom, a clinical-stage biotech company developing next-generation off-the-shelf and personalized neoantigen cancer immunotherapies, today announced the presentation of new clinical and translational data on its lead candidate NOUS-209 at the 40th Annual Society for Immunotherapy of Cancer (SITC) Meeting.

Following positive safety and immunogenicity data reported at AACR 2025¹, these additional results from the Phase 1b/2 trial of NOUS-209 in Lynch Syndrome (LS) carriers demonstrate effective boosting of durable immune responses after retreatment as well as first evidence of clinical efficacy through the absence of advanced adenomas at end of study.

NOUS-209 is an off-the-shelf cancer immunotherapy designed to intercept cancer before it develops. It leverages Nouscom’s proprietary viral vector platform to deliver 209 shared frameshift peptide (FSP) neoantigens found in MSI tumors, training the immune system to recognize and eliminate pre-cancerous and cancerous cells. LS is the most common hereditary cancer syndrome, significantly increasing the lifetime risk of colorectal, endometrial, urothelial, and other cancers. Current preventive management is limited to intensive screening or elective organ removal surgery.

Key Highlights from SITC 2025 Oral and Poster Presentations:

Durable and Potent Immune Responses: Annual retreatment with NOUS-209 was shown to be safe and to effectively boost long-lived, broad polytopic T cell immunity in LS carriers, with T cells capable of killing tumor cells ex vivo.
First Clinical Evidence of Cancer Interception: While 4.7% of LS participants had advanced adenomas at baseline (which were removed as part of standard of care), no new advanced adenomas were detected after treatment despite an expected annual incidence of around 4%, providing initial evidence of NOUS-209’s cancer preventive efficacy in LS carriers.
Broad Neoantigen Targeting Across Tumor Evolution: Analysis of primary and metachronous colorectal and urothelial MSI tumors confirmed that a high number of FSP neoantigens targeted by NOUS-209 are consistently present, supporting its utility in preventing both first and recurrent cancers in LS patients.

“These results are a step forward in intercepting cancer in LS carriers,” said the study’s principal investigator, Eduardo Vilar-Sanchez, M.D., Ph.D., Professor of Clinical Cancer Prevention at The University of Texas MD Anderson Cancer Center. “NOUS-209-induced T cells persist, and annual retreatment was found to be safe, boosting long-term immune protection. The absence of advanced adenomas post-treatment is encouraging.”

“These data highlight NOUS-209’s broad applicability beyond colorectal cancer. Its ability to target evolving neoantigens is critical for sustained protection against recurrent LS-associated malignancies," said Toni Seppälä, M.D., Ph.D., Professor of Cancer Research, and chief physician at Tampere University.

“Nouscom’s proprietary viral vector platform is uniquely positioned to deliver rapid, potent, broad and durable immune activation against a large number of shared neoantigens,” said Elisa Scarselli, M.D., Chief Scientific Officer of Nouscom. “NOUS-209’s Phase 1b/2 data reinforce our confidence in its ability to safely and effectively prime the immune system for cancer interception in LS carriers.”

Marina Udier, Ph.D., CEO of Nouscom concluded, “We are proud to present these compelling data at SITC 2025 and remain deeply committed to pioneering cancer interception strategies for LS carriers, who deserve a better way to manage their cancer risk. These data, together with the recently presented results of NOUS-209 in MSI-H mCRC patients² and FDA and EMA alignment, support our commitment to advancing NOUS-209 into a registration-enabling study for cancer interception in Lynch Syndrome carriers.”

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 Georges’ ABC

All abstracts are available on the SITC website: here

The clinical trial NCT05078866 was supported by the National Cancer Institute of the National Institutes of Health under Award Number UG1CA242609 (project director Dr. Eduardo Vilar-Sanchez). The trial was conducted through the iCAN-PREVENT consortium at The University of Texas MD Anderson Cancer Center, with support from the Data Management, Auditing, and Coordination Center (grant U24CA242637).

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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 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-H 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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