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Study of AEF0217 compared to placebo for improving behavior and thinking skills in adults and older adolescents with Down syndrome

Verified siteInvestigationalNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

This study is looking at Down syndrome, a genetic condition that can affect learning, behavior, and thinking abilities. The treatment being tested is called AEF0217, which is an oral solution that is taken by mouth. Some people in the study will receive AEF0217 at different dose levels, while others will receive placebo. The medication works as a CB1 signaling specific inhibitor, which means it affects certain signals in the brain that may influence behavior and thinking.

The purpose of the study is to find out which doses of AEF0217 given over 24 weeks can help improve daily living skills and behaviors compared to placebo, and to see how these effects develop over time and whether they differ based on age, level of disability, certain genes, and blood levels of specific substances at the start of the study. The study will also look at whether the treatment can improve thinking skills, language abilities, quality of life, and sleep, and will check if the treatment is safe and well tolerated.

The study will last for 32 weeks in total. During the first 24 weeks, participants will take either AEF0217 or placebo every day. Throughout the study, participants will have regular visits where different tests and questionnaires will be done to measure changes in adaptive behaviors, which are the everyday skills needed for living independently, as well as thinking abilities, language skills, quality of life, mood, anxiety, and sleep quality. Safety will be monitored throughout the study by checking vital signs like blood pressure and heart rate, doing blood and urine tests, and performing heart monitoring tests. After the 24 weeks of treatment, there will be an additional 8-week period to continue monitoring participants.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial assessment and baseline measurements

    Your baseline measurements will be recorded at the beginning of the study. These measurements will serve as reference points for comparison throughout the trial.

    A neuropsychologist will conduct assessments to evaluate your adaptive functioning. Your parent or caregiver will provide detailed information about your daily living skills and abilities.

    Several tests will be performed, including the VABS-3 (a test measuring adaptive behavior in nine different areas), the NIH-ToolBox for ID (a set of tests measuring thinking abilities), and the WISC-V (a test measuring verbal comprehension).

    Quality of life questionnaires called Peds-QL will be completed to assess your physical and mental well-being, as well as the impact on your family.

    The ADAMS scale will be used to assess behavioral and emotional patterns.

    The PSQI questionnaire will evaluate your sleep quality.

    Your vital signs (such as heart rate and body temperature), blood tests, urine tests, and ECG (a test recording heart electrical activity) will be checked to ensure all parameters are within safe ranges.

    Blood samples will be taken to measure baseline levels of certain substances in your blood.

  2. Step 2

    Treatment period with study medication

    You will receive either AEF0217 or placebo (an inactive substance that looks like the actual medication but contains no active ingredient). The assignment will be random, and neither you nor the study staff will know which treatment you are receiving.

    The study medication will be given as an oral solution, which means a liquid that you will take by mouth.

    The treatment period will last for 24 weeks.

    Your parent or caregiver will ensure that you take the medication according to the prescribed schedule.

    During this period, regular clinic visits will be scheduled to monitor your progress and safety.

  3. Step 3

    Regular monitoring and assessments during treatment

    Throughout the 24-week treatment period, you will attend clinic visits accompanied by your parent or caregiver.

    At these visits, your vital signs will be measured, including cardiovascular parameters and body temperature.

    Blood samples will be collected at scheduled intervals to check safety laboratory parameters, including chemistry, blood cell counts, and urine analysis.

    ECG recordings will be performed at designated time points to monitor your heart's electrical activity.

    The neuropsychologist will conduct assessments to evaluate changes in your adaptive behaviors and thinking abilities.

    Your parent or caregiver will provide updated information about your daily functioning and any changes observed.

    Any side effects or health changes will be documented and assessed by the medical team.

  4. Step 4

    End of treatment assessment at week 24

    At the end of the 24-week treatment period, comprehensive assessments will be conducted.

    The same tests performed at baseline will be repeated, including the VABS-3, NIH-ToolBox for ID, and WISC-V.

    Quality of life questionnaires (Peds-QL) will be completed again to assess any changes.

    The ADAMS scale will be administered to evaluate behavioral and emotional patterns.

    The PSQI questionnaire will assess your sleep quality.

    Complete safety evaluations will be performed, including vital signs, blood tests, urine tests, and ECG.

    These measurements will be compared to your baseline values to determine any changes that occurred during the treatment period.

  5. Step 5

    Follow-up period after treatment ends

    After completing the 24-week treatment period, you will enter an 8-week follow-up period.

    During this time, you will no longer receive the study medication.

    You will continue to attend clinic visits for monitoring and assessments.

    Safety evaluations will continue, including vital signs, blood tests, and ECG recordings.

    The ADAMS scale will be administered again to assess behavioral and emotional patterns after treatment has stopped.

  6. Step 6

    Final assessment at week 32

    At the end of week 32, which marks the completion of the trial, final assessments will be conducted.

    The ADAMS scale will be completed to evaluate your behavioral and emotional status.

    Final safety evaluations will be performed, including vital signs, blood tests, urine tests, and ECG.

    All collected data will be compared to baseline and week 24 measurements to assess the overall effects of the treatment and any changes during the follow-up period.

    This visit concludes your participation in the clinical trial.

Who can join the trial?

11 criteria

  • The participant can be male or female.
  • The participant must be between 16 and 32 years old.
  • The participant's BMI (body mass index, a measure that relates weight to height) must be between 18.0 and 35.
  • The participant must have a confirmed diagnosis of Down syndrome (full trisomy 21 or translocations) proven by chromosomal analysis (a test that examines the chromosomes in cells).
  • The participant must be able to walk independently and have enough vision and hearing to take part in the study tests.
  • The participant must have an IQ (intelligence quotient, a measure of thinking ability) between greater than 35 and 70. If the IQ is between greater than 35 and less than 40, the participant must have adequate thinking and behavioral abilities as judged by the main doctor.
  • The participant must score greater than 4 on a specific language test called VCI of WISC-V, based on their mental age.
  • The participant must be able to understand most of the time and be able to express when they do not understand, so they can accept the study procedures. The participant must not use other forms of communication such as signs, symbol boards, or devices as their main way of communicating.
  • The participant must have a parent or other reliable caregiver (a person who provides care and support) who agrees to come to all clinic visits, provide information about the participant as needed, and make sure the participant takes the medication and follows the study requirements.
  • The parent or caregiver must have regular and close contact with the participant and know enough about the participant's daily functioning to answer questions accurately during assessments.
  • The participant's vital signs (such as blood pressure and heart rate), ECG (a test that checks the heart's electrical activity), and safety laboratory tests must not show any clinically significant problems as judged by the doctor, except for: stable type 1 or 2 diabetes (a condition affecting blood sugar levels) if the participant is regularly monitored before and during the study to ensure good blood sugar control; or hypothyroidism (underactive thyroid gland) controlled by treatment so that thyroid hormone levels are normal and stable for at least 6 weeks before starting the study.

Who cannot join the trial?

1 criterion

  • No specific exclusion criteria have been provided in the available study information.
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Investigated drugs

  • AEF0217

    is an investigational medication being studied in this trial. It is being tested to see if it can help improve adaptive behaviors in adults and older adolescents with Down syndrome. Adaptive behaviors are everyday skills that people use to function in their daily lives, such as communication, social skills, and practical life skills. The medication will be given for 24 weeks to participants in the study.

  • Placebo

    is an inactive substance that looks like the real medication but contains no active treatment. It is used in this study to compare against AEF0217 to help determine if the actual medication is effective. Some participants will receive the placebo instead of the active medication so researchers can measure the true effects of AEF0217.

What is already known about the treatment

AEF0217 – AEF0217 is an experimental medication currently being studied in Phase 2B clinical trials for the treatment of behavioral and cognitive problems in people with Down syndrome. This medication is administered orally for a period of 24 weeks and is being tested in adults and older adolescents to see if it can improve their adaptive behaviors, which are everyday skills needed for independent living. The study is examining how well the medication works, whether it is safe, and how well patients tolerate it compared to a placebo. AEF0217 appears to work by affecting the body's endocannabinoid system, which involves natural substances in the brain that help regulate mood, memory, and behavior.

Investigated diseases

Down Syndrome – Down syndrome is a genetic condition that occurs when a person is born with an extra copy of chromosome 21. This additional genetic material affects how a child's body and brain develop. People with Down syndrome often experience delays in cognitive development, which affects learning, thinking, and problem-solving abilities. They may also show difficulties with adaptive behaviors, which are the everyday skills needed for independent living, such as communication, social interaction, and self-care. Behavioral challenges can include issues with attention, emotional regulation, and social functioning. The degree of cognitive and behavioral impairment varies among individuals, ranging from mild to moderate levels of intellectual disability.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IITrial ID2025-521013-10-00Protocol codeAEF0217-201Estimated enrolment188 patientsSponsorAelis Farma

sourced from the EU Clinical Trials Register and site verification

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On this site, “treatment” means an investigational medicine being studied in a clinical trial. Its safety and efficacy for the use being studied have not yet been confirmed, some participants may receive a placebo or a comparator medicine, and taking part does not guarantee any health benefit. The decision to take part is made by the doctor at the research site. This site is for information only and does not replace medical advice.

This service is not affiliated with the European Commission, the EMA, or the official CTIS system. Most information comes from publicly available international clinical-trial registries, supplemented by data from academic sites, national regulators and commercial sponsors. On this site, “treatment” and “therapy” mean a medicine being tested in a clinical trial. Its safety and effectiveness in the use being studied are not yet confirmed, some participants may receive a placebo or a comparator, and taking part does not guarantee a health benefit. The doctor at the research site decides who can take part. This site provides information, not medical advice. Certain content and visual elements on this website have been generated or enhanced using artificial intelligence (AI).