A Study of BCX17725 Safety and Effects in Healthy People and Patients with Netherton Syndrome

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What is this study about?

This study involves people with Netherton Syndrome, a rare genetic skin condition that causes red, scaly, and inflamed skin along with severe itching. The condition is caused by changes in a specific gene called SPINK5, which leads to problems with the skin’s protective barrier. People with this condition often experience ongoing skin inflammation and discomfort that can significantly affect their daily lives.

The treatment being tested is called BCX17725, which is an experimental medication given as an injection either into a vein, under the skin, or into a muscle. This medication is designed to work by blocking a specific protein that is overactive in people with Netherton Syndrome and contributes to the skin problems. The purpose of the study is to evaluate how safe and well-tolerated BCX17725 is when given to people with Netherton Syndrome, to measure how the body processes the medication, and to see if it has the potential to improve the skin condition.

During the study, participants will receive BCX17725 for 12 weeks. The study will include both adults and adolescents between the ages of 12 and 65 years who have been diagnosed with Netherton Syndrome. Throughout the study, doctors will monitor participants for any side effects and will assess changes in their skin condition using various scoring systems that measure the severity of scaling, redness, and itching. Blood samples will be taken to measure the amount of medication in the body over time, and skin samples may be collected using strips. Participants will need to attend regular study visits and complete questionnaires about their symptoms.

1 Initial assessment and confirmation

At the beginning of the study, your diagnosis of Netherton Syndrome will be confirmed. This is a genetic skin condition that will be verified through existing medical records.

If previous documentation of the SPINK5 gene variant (the genetic change that causes Netherton Syndrome) is not available, a blood sample will be collected for genetic testing.

Your skin condition will be assessed using two scoring systems: the Investigator Global Assessment score (a measure of overall skin severity) and the Ichthyosis Area and Severity Index score (a measure of the extent and severity of scaling and redness). These scores must meet specific levels to participate.

If you are female and able to become pregnant, or if you are male with a female partner who can become pregnant, you will need to agree to use contraception methods from this point until 90 days after receiving the last dose of the study medication.

2 Baseline evaluation on Day 1

On Day 1, which is considered the baseline, your skin condition will be evaluated again to confirm the severity scores.

Assessments will include the Investigator Global Assessment score and the Ichthyosis Area and Severity Index score.

You will also complete a questionnaire about the Worst Itch Numerical Rating Scale, which measures the intensity of itching you experience.

Skin strip samples will be collected. This involves applying and removing adhesive strips from your skin to collect cells for analysis.

3 Treatment period with BCX17725

You will receive the study medication called BCX17725 for a period of 12 weeks.

The medication is a solution for injection that will be administered through one of the following routes: into a vein (intravenous), under the skin (subcutaneous), or into a muscle (intramuscular).

The specific dose, frequency, and exact method of administration will be determined as part of the study design.

Throughout this period, blood samples will be collected to measure the concentration of BCX17725 in your blood. This helps determine how the medication moves through and is processed by your body.

4 Regular monitoring and assessments

During the 12-week treatment period, regular assessments will be conducted to monitor your skin condition.

The Ichthyosis Area and Severity Index score will be measured repeatedly to track changes in the extent and severity of your skin scaling and redness compared to the baseline.

The Investigator Global Assessment score will be evaluated to monitor overall changes in your skin condition.

You will continue to complete the Worst Itch Numerical Rating Scale questionnaire to report changes in itching intensity.

Additional skin strip samples may be collected at specified times during the treatment period.

Safety monitoring will occur throughout the study to identify any treatment-emergent adverse events, which are any unwanted medical occurrences or side effects that happen during or after receiving the study medication.

5 Week 12 evaluation

At Week 12, a comprehensive evaluation will be performed to assess the effects of the treatment.

The change in your Ichthyosis Area and Severity Index score from baseline will be measured as the primary indicator of treatment effectiveness.

The change in your Investigator Global Assessment score from baseline will be evaluated.

The change in your Worst Itch Numerical Rating Scale score from baseline will be assessed to determine if itching has improved.

Blood samples will be collected to measure BCX17725 concentrations in your blood.

Any side effects or adverse events will be documented.

6 End of study

After completing the 12-week treatment period and final assessments, you will reach the end of study phase.

Final safety evaluations will be conducted to document any adverse events that occurred throughout the entire study period.

Final blood samples may be collected to measure remaining BCX17725 concentrations.

You will need to continue using contraception, if applicable, for 90 days after receiving the last dose of BCX17725.

Who Can Join the Study?

You must be able to provide written informed consent. If you are an adolescent, you should provide your agreement along with consent from your parent or legal guardian.
You must be male or female, aged between 12 and 65 years.
You must be female who is not pregnant and not breastfeeding.
You must have a confirmed diagnosis of Netherton Syndrome, which is a rare genetic skin condition. If you do not have existing documentation of a change in the SPINK5 gene (the gene responsible for this condition), you will need to provide a blood sample for genetic testing during the screening visit.
You must have an IGA score of 3 or higher. The IGA score is a measure used by doctors to assess the overall severity of your skin condition.
You must have an IASI score of 16 or higher. The IASI score is a tool that measures the extent and severity of skin symptoms in Netherton Syndrome.
If you are a female who can become pregnant, or a male with a female partner who can become pregnant, you must agree to use proper birth control methods from the screening visit until 90 days after your last dose of the study medicine.
You must be willing and able to understand and follow all study requirements, including being available to complete the entire study, understanding the study procedures, completing any questionnaires or assessments on your own, and being willing to have skin strip samples collected (small samples taken from the surface of your skin).
If you are under 18 years old, your parent or legal guardian must also be willing and able to help you comply with all study requirements.

Who Cannot Join the Study?

The patient is younger than 12 years old
The patient has a known allergy, which means a bad reaction, to BCX17725 or any of its ingredients
The patient is pregnant or breastfeeding, which means nursing a baby
Women who can become pregnant and are not using reliable birth control methods to prevent pregnancy
The patient has a serious infection that needs treatment at the time of starting the study
The patient has used certain medications that affect the immune system, which is the body’s defense against illness, within a specific time before joining the study
The patient has a history of cancer or abnormal cell growth within the past 5 years
The patient has severe liver problems, where the liver is an organ that cleans the blood and helps digest food
The patient has severe kidney problems, where the kidneys are organs that filter waste from the blood
The patient has a serious heart condition or uncontrolled high blood pressure
The patient has any other serious medical condition that the doctor believes would make it unsafe to participate
The patient has participated in another research study with an investigational drug within 30 days before this study
The patient is unable to follow the study requirements or attend scheduled visits

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

Site Name	City	Country	Status
Universitaetsklinikum Heidelberg AöR	Heidelberg	Germany
University Hospital Maastricht	Maastricht	The Netherlands

Other Sites

Site Name	City	Country	Status
Hopital Beaujon	Clichy	France
Ebvxura Uolsbyrbmcqb Msfeamf Cybqiyv Rhtugaqka (qdxddnp Mei	Rotterdam	The Netherlands

Trial status

Country	Status	Recruitment Start
France	Not yet recruiting	02.01.2026
Germany	Not yet recruiting	02.01.2026
The Netherlands	Recruiting	02.01.2026

Trial locations

BCX17725 is an investigational medication being tested in this clinical trial. It is being studied to see if it can help treat people with Netherton Syndrome, which is a rare genetic skin condition. The medication will be given to participants over a period of 12 weeks to test how safe it is, how well the body tolerates it, and whether it may be helpful in treating the condition. Researchers will also measure how much of the medication stays in the blood over time and check if the body’s immune system reacts to it.

Investigated diseases:

Netherton's syndrome

Netherton Syndrome – Netherton Syndrome is a rare genetic skin disorder that affects the skin, hair, and immune system from birth. The condition is caused by mutations in a specific gene that leads to problems with the skin’s protective barrier. People with this syndrome experience red, scaly skin similar to ichthyosis, which means the skin appears dry and flaky across large areas of the body. The hair is typically brittle, breaks easily, and has a characteristic bamboo-like appearance under microscopic examination. The weakened skin barrier often leads to increased water loss through the skin, making individuals prone to dehydration and temperature regulation problems. Many people with Netherton Syndrome also experience severe itching and are more susceptible to skin infections and allergic reactions throughout their lives.

Trial ID:

2025-521973-16-00

Protocol code:

BCX17725-101

NCT ID:

NCT06539507

Trial Phase:

Human Pharmacology (Phase I) – Other

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A Study of BCX17725 Safety and Effects in Healthy People and Patients with Netherton Syndrome

What is this study about?

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Who Cannot Join the Study?