Study: Early trial of new vaccine shows promise for people with Lynch syndrome

RELEVANCE

Most relevant for: People with Lynch syndrome.

It may also be relevant for:

• previvors
• people with a genetic mutation linked to cancer risk

Relevance: Medium

Strength of Science: Medium-High

Research Timeline: Human Research

More rating details

What is this study about?

This study looked at an experimental vaccine called Nous-209. The goal of the vaccine is to help prevent cancer in people with Lynch syndrome. The Nous-209 vaccine works by training the immune system to recognize and attack abnormal proteins commonly found in cancers that are linked to Lynch syndrome.

Why is this study important?

Lynch syndrome affects about 1 in 300 people in the US; nearly 1 million people are estimated to have it.

People with Lynch syndrome are born with a change (inherited mutation) in one of five DNA repair genes (EPCAM, MLH1, MSH2, MSH6 and PMS2). These mutations cause errors in DNA when cells divide, resulting in abnormal proteins that can lead to cancer.

Since people with Lynch syndrome have a much higher lifetime risk of developing colorectal, endometrial and other cancers, new prevention options are needed. Researchers want to know if the Nous-209 vaccine can provide an extra layer of protection against developing cancer for people with Lynch syndrome. By teaching the immune system to identify and respond to cancer-related proteins, the vaccine may help the body detect and destroy cancer cells before they develop into tumors.

Unlike other vaccines that show promise in treating the Lynch syndrome-related cancers, the Nous-209 vaccine is designed to prevent them.

Study approach and findings

This was an early-phase clinical trial. Early-phase trials are not meant to prove that a treatment prevents cancer. They usually include only a small group of participants and are designed to test the safety of a treatment and see how the body responds to it.

This study enrolled 45 people with Lynch syndrome. All of the participants received the vaccine.

Safety

Safety was evaluated in all study participants. The vaccine was found to be generally safe and well tolerated. No participants left the study due to side effects.

Some people experienced mild side effects from the vaccination. The most common side effects reported were: 

• Injection site reactions, such as muscle soreness (91%) 
• Fatigue (80%)

Since this was a small study, less common or rare side effects may not yet be known.

Immune system response

Immune system response was measured in 37 of the 45 participants. For 7 participants, there were not enough live cells to measure. A sample was not collected for one participant. 

The immune system response data showed that:

• The vaccine successfully activated an immune response in all participants (37) who were evaluated.
• 97% had a detectable immune response at 6 months
• 85% had a detectable immune response at 1 year

While these early results are promising, more research is needed to confirm these findings and understand how well the vaccine may prevent different types of cancer in people with Lynch syndrome.

What does this mean for me?

Researchers hope the Nous-209 vaccine can be used as a cancer prevention option for people with Lynch syndrome. However, the vaccine is still being studied and is currently available only in clinical research studies.

Results of this early-phase trial showed promising safety and immune system response data. The next steps involve conducting larger studies to confirm how well the Nous-209 vaccine prevents cancer in people with Lynch syndrome.

Additional trials will monitor participants over a longer period to see if their immune response leads to a meaningful reduction in cancer rates. If the vaccine continues to show safety and effectiveness, it could move toward approval for wider use. This could reduce the likelihood of getting colorectal, endometrial and other Lynch syndrome-related cancers, potentially lowering the need for frequent, invasive screenings or treatments.

For now, people with Lynch syndrome should continue their regular screenings and follow the advice of their healthcare providers.

Reference

D’Alise, A.M., Willis, J., Duzagac, F. et al. Nous-209 neoantigen vaccine for cancer prevention in Lynch syndrome carriers: a phase 1b/2 trial. Nat Med (2026).

Disclosure: FORCE receives funding from industry sponsors, including companies that manufacture cancer drugs, tests and devices. All XRAYS articles are written independently of any sponsor and are reviewed by members of our Scientific Advisory Board prior to publication to assure scientific integrity.

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posted 3/22/26