AuthorisedHuman Pharmacology (Phase I)- First administration to humansInterventional

A phase 1 first-in-human study of a phenylalanine-binding polymer (phelimin) in healthy volunteers and adult, classical PKU patients

Phenylketonuria (PKU) is a rare genetic condition where the body cannot break down phenylalanine, a natural substance found in protein. Without a very strict diet, phenylalanine builds up in the blood and can cause serious health issues. This clinical trial is testing an experimental medicine called phelimin. Phelimin is designed to act like a sponge in the gut, soaking up phenylalanine from food so the body does not absorb it. Because this is a 'first-in-human' Phase 1 trial, the main goal is to find out if phelimin is safe, what side effects it might cause, and how the body handles it. The trial is looking for adult men aged 18 and older, including both healthy volunteers and men with classical PKU. Doctors will monitor all participants closely to protect their health and well-being.

At a glance

Status

Authorised

Phase

Human Pharmacology (Phase I)- First administration to humans

Sponsor

Mipsalus ApS

Enrolment target

Start

17 Jun 2026

Phenylketonuria

What is this study about?

Phenylketonuria, usually called PKU, is an inherited condition that affects how your body handles food. People with PKU cannot break down an amino acid called phenylalanine, which is found in all dietary protein. If phenylalanine builds up in the body, it can harm the brain and nervous system. Because of this, people with PKU usually have to follow a very strict, low-protein diet for life, which can be difficult to manage.

Researchers have developed an experimental medicine called phelimin. Phelimin is a special polymer designed to bind to phenylalanine inside the digestive tract before it can be absorbed into the bloodstream. It then carries the phenylalanine safely out of the body in the stool. If it works as hoped, it could eventually offer a new way to help manage PKU alongside or in place of strict dietary limits.

This study is a Phase 1 'first-in-human' trial. This means the medicine has been tested in laboratories, but this is the very first time it is being given to people. The primary focus of Phase 1 is safety rather than proving how well it cures a condition. Doctors want to learn what doses are safe, whether there are any unwanted side effects, and how the gut and body respond to the drug.

Taking part helps scientists understand the basic biology of this new treatment. While this trial is an early step on a long journey, the results could help guide larger studies in the future and could one day lead to better treatment options for people living with PKU.

Key takeaways

This is a Phase 1 trial testing a new PKU treatment called phelimin in humans for the first time.
Phelimin is designed to trap phenylalanine in the gut to prevent it entering the blood.
The study is enrolling adult men aged 18 and over, including healthy volunteers and men with PKU.
The main goal is to test the drug's safety, tolerability, and how it moves through the digestive tract.
Participants will be closely looked after by doctors and can leave the trial at any time.

Who may be eligible?

This trial is open to adult men aged 18 and older. The study is looking for two groups of participants: healthy male volunteers with no major medical conditions, and men who have been diagnosed with classical PKU.

Because this is an early safety trial, it is only enrolling men at this stage. Participants must be willing to attend regular clinic appointments and follow study rules, such as taking the study medicine as instructed and reporting any symptoms.

You may not be able to join if you have other serious medical issues, severe gut problems that affect how you digest food, or if you take certain medicines that could interfere with the study. The study doctors will carry out full health checks before anyone is accepted into the trial.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

I am a man aged 18 or older.
I am either in good general health, or I have a confirmed diagnosis of classical PKU.
I am able and willing to attend all required clinic visits and health checks.
I am happy to provide blood, urine, and stool samples as part of the study.
I do not have major gut or bowel conditions that affect how I digest food.

Answer every question to see your result.

What does participation involve?

If you take part, you will first attend a screening visit where doctors check your medical history, carry out a physical examination, and take blood and urine samples. If you are eligible, you will receive doses of phelimin under close medical supervision. You may be asked to stay overnight at the clinic for a short period or attend several day visits so the medical team can monitor your vital signs, check for side effects, and collect regular blood and stool samples to see how much phenylalanine is bound. You will also need to track what you eat during certain parts of the study. The trial team will confirm the exact number of visits and total duration, but Phase 1 studies typically last from a few weeks to a couple of months, followed by a final health check.

Potential risks and benefits

Because this is the first time phelimin is being given to people, there is a risk of unexpected side effects, which might include stomach ache, nausea, changes in bowel habits, or allergic reactions. You may also feel slight discomfort or bruising from blood tests. Since this is an early safety study, you might not receive any direct medical benefit from taking the medicine. However, your participation will provide vital information that could help develop new treatments for PKU in the future. Your safety is the highest priority, you will be monitored closely, and you can choose to leave the study at any time without giving a reason.

Locations (1)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

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Unverified
Denmark

Common questions

What does 'first-in-human' mean?

It means this is the very first time the experimental medicine is being tested in people. Before this stage, it was only tested in laboratory settings.

Will taking phelimin cure my PKU?

No. Phelimin is not a cure for PKU, and Phase 1 trials are not designed to cure diseases. The main purpose is to test whether the drug is safe to use in humans.

Do I have to change my diet during the study?

The study team will give you clear instructions about your diet. You may need to record what you eat or follow specific meal plans so researchers can measure how well the drug binds phenylalanine.

Will I be paid for taking part?

Phase 1 trials often provide payment or compensation to volunteers for their time, travel, and inconvenience. The study team can give you full details about this.

Can I leave the trial if I change my mind?

Yes. Taking part is completely voluntary. You are free to withdraw from the study at any point, and doing so will not affect your normal NHS medical care.