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A Study Testing the Safety of IRL757 in Adults with Parkinson's Disease Who Have Apathy

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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 Parkinson's Disease in people who also experience apathy, which means a lack of interest or motivation to do things. Apathy can include having less energy to start activities, feeling less interested in daily life, or showing fewer emotions than usual. The study will test a medication called IRL757, which is given as a capsule taken by mouth. Some people in the study will receive IRL757 at different dose levels, while others will receive placebo capsules that do not contain active medication.

The purpose of this study is to find out if IRL757 is safe and well tolerated when taken daily for 12 weeks by people with Parkinson's Disease who have moderate to severe apathy. The study will look at whether the medication causes any unwanted effects and how the body responds to it over time. Participants will need to have a caregiver who spends time with them regularly and can come to study visits.

During the study, participants will take the assigned capsules every day for 12 weeks. The doctors will check for any side effects by doing physical examinations, blood tests, heart tests, and asking questions about mood, behavior, and sleepiness. They will also measure changes in apathy symptoms using questionnaires that ask about motivation, interest in activities, and emotional responses. Participants must continue taking their regular medications for Parkinson's Disease at the same doses throughout the study.

The research process

The trial runs in 4 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial assessment and baseline measurements

    At the beginning of the trial, your current health status will be assessed. This includes a physical examination, laboratory tests, and measurements of vital signs such as blood pressure and heart rate.

    An electrocardiogram (a test that records the electrical activity of your heart) will be performed.

    Your cognitive function will be evaluated using the MoCA test, which assesses memory and thinking abilities.

    The level of apathy (lack of interest or motivation) will be measured using specific questionnaires: the LARS (a scale that evaluates apathy) and the NPI-C apathy domain (which assesses behavioral symptoms).

    Additional assessments will include the C-SSRS (a questionnaire about suicidal thoughts), the QUIP-RS (which evaluates impulse control), and the ESS (a scale measuring daytime sleepiness).

    Your primary caregiver, who spends more than 10 hours per week with you, will need to accompany you to this visit and participate in the assessments.

  2. Step 2

    Beginning of treatment period

    After the baseline assessments, you will be assigned to receive either IRL757 or placebo capsules. The assignment will be random, and neither you nor the medical team will know which treatment you are receiving.

    You will begin taking the assigned medication orally (by mouth) in capsule form.

    The treatment will be taken daily for a period of 12 weeks.

    The dosage will be determined according to the trial protocol, and you should take the medication as instructed.

    If you are currently taking medications for Parkinson's disease, antidepressants, or other approved medications, you should continue taking them at the same dose throughout the trial period.

  3. Step 3

    Regular monitoring visits during treatment

    Throughout the 12-week treatment period, you will attend scheduled visits for safety monitoring and assessments.

    At each visit, the medical team will check for any adverse events (unwanted or harmful effects that may occur during the trial).

    Physical examinations, laboratory tests, vital signs measurements, and electrocardiograms will be repeated at specific time points to monitor your health.

    The questionnaires assessing apathy, suicidal thoughts, impulse control, and daytime sleepiness will be administered again to track any changes.

    Your caregiver will continue to accompany you to these visits and provide information about your condition and behavior.

  4. Step 4

    End of treatment assessment

    After completing the 12-week treatment period, a final assessment will be conducted.

    All the same measurements and tests performed at baseline will be repeated, including physical examination, laboratory tests, vital signs, electrocardiogram, and all questionnaires.

    The changes in apathy symptoms will be evaluated by comparing the results from the beginning and end of the treatment period using the LARS and NPI-C apathy domain.

    The safety and tolerability of the medication will be assessed by reviewing all adverse events, laboratory results, and other health measurements collected during the trial.

Who can join the trial?

11 criteria

  • You must be between 50 and 90 years old
  • You must have a diagnosis of Parkinson's disease, which is a condition that affects movement and is caused by changes in the brain
  • Your Parkinson's disease must be at a certain stage, measured by a scale called Hoehn and Yahr stage, and must be at stage 4 or lower
  • You must score 20 or higher on a test called MoCA, which checks memory and thinking abilities
  • You must have apathy, which means a lack of interest, motivation, or emotional response. This must include at least one symptom in at least two of these areas: reduced ability to start activities on your own, reduced interest in things around you, or reduced emotional reactions. These symptoms must occur at least 3 days per week for at least 4 weeks
  • Your apathy symptoms must be a clear change from how you normally behave and must affect your daily life, work, or relationships
  • Your apathy symptoms must not be caused by other mental health conditions, intellectual disabilities, physical limitations, or effects of medications or substances
  • You must score at least minus 16 on the LARS, which is a specific test that measures the severity of apathy, showing you have moderate to severe apathy
  • You must have a primary caregiver, someone who spends more than 10 hours per week with you and helps supervise your care, who can come with you to study visits
  • If you are taking medications for Parkinson's disease, antidepressants, or certain memory medications called ChEIs, your doses must be stable for at least 1 month before joining the study and must stay the same during the study
  • Both men and women can participate in this study

Who cannot join the trial?

13 criteria

  • Pregnancy or breastfeeding: Women who are pregnant, planning to become pregnant during the study, or currently breastfeeding cannot participate.
  • Severe heart problems: Patients with serious heart conditions or recent heart attacks cannot join the study.
  • Uncontrolled high blood pressure: Blood pressure that is not well managed with medication is a reason for exclusion.
  • Severe kidney or liver disease: Serious problems with kidney or liver function prevent participation. The kidneys filter waste from blood, and the liver helps process medications.
  • History of stroke: Patients who have had a stroke, which is when blood flow to the brain is blocked, cannot participate.
  • Seizure disorder: A condition causing repeated seizures, which are sudden electrical disturbances in the brain, is an exclusion reason.
  • Other major brain disorders: Conditions affecting the brain besides Parkinson's disease may prevent participation.
  • Active cancer: Patients currently being treated for cancer or with recent cancer diagnosis cannot join.
  • Severe depression or suicidal thoughts: Serious mental health conditions or thoughts of self-harm are reasons for exclusion.
  • Substance abuse: Current problems with alcohol or drug abuse prevent participation in the study.
  • Allergies to study medication: Known allergic reactions to the study drug or its ingredients are an exclusion criterion.
  • Participation in other studies: Being in another clinical trial or having recently participated in one may prevent enrollment.
  • Unable to follow study requirements: Patients who cannot attend visits, take medication as directed, or complete study tasks cannot participate.
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Investigated drugs

IRL757 is an experimental medication being tested in this clinical trial. It is given by mouth (orally) and is being studied to see if it is safe and well-tolerated when taken daily for 12 weeks by people with Parkinson's Disease who experience apathy. Apathy means having a lack of interest, motivation, or emotion. This medication is being compared to a placebo to understand its effects better.

What is already known about the treatment

IRL757 – IRL757 is an experimental medication currently being tested in clinical trials and is administered orally on a daily basis. This drug is being studied for the treatment of apathy in people with Parkinson's Disease, specifically targeting moderate to severe apathy symptoms. The exact way IRL757 works at the molecular level has not been fully disclosed in public medical literature, as it is still in early Phase 1b testing to evaluate its safety and tolerability when taken repeatedly over a 12-week period. At this stage, researchers are primarily focused on determining whether the medication is safe for patients before moving forward with larger studies to assess its effectiveness.

Investigated diseases

  • Parkinson's Disease

    Parkinson's disease is a brain disorder that affects movement and develops gradually over time. It occurs when nerve cells in the brain that produce dopamine, a chemical messenger important for controlling movement, become damaged or die. The main symptoms include trembling of the hands, arms, legs, or face, stiffness of the limbs and trunk, slowness of movement, and problems with balance and coordination. As the disease progresses, people may also experience non-movement symptoms such as apathy, which is a lack of interest, motivation, or emotional response to activities. The symptoms typically start mild and worsen slowly over months and years. This condition primarily affects older adults, though it can occur in younger people as well.

  • Apathy

    Apathy is a condition characterized by a lack of motivation, interest, and emotional response to activities that would normally be engaging or important. It involves reduced goal-directed behavior, decreased initiative to start or complete tasks, and diminished emotional reactions to events. People with apathy may appear indifferent, show little concern about their personal affairs, and have difficulty engaging in social interactions. This condition can occur on its own or as a symptom of other brain disorders such as Parkinson's disease, dementia, or stroke. The severity can range from mild disinterest to complete lack of motivation that significantly impacts daily functioning. Apathy differs from depression, though the two conditions can sometimes occur together.

Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase ITrial ID2025-523612-37-00Protocol codeIRL757C003Estimated enrolment125 patientsSponsorIntegrative Research Laboratories Sweden AB

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