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A Study of S-606001 Added to Enzyme Replacement Therapy for Patients with Late-Onset Pompe Disease

Fast replyInvestigationalNo placebo
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What is this trial about?

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

This study involves people with late-onset Pompe disease, which is a rare inherited condition where the body cannot properly break down a complex sugar called glycogen. This leads to a buildup of glycogen in muscles, causing muscle weakness that gets worse over time, including weakness in the muscles used for breathing and walking. The study will test a medication called S-606001, which will be given as tablets taken by mouth. Some participants will receive S-606001 while others will receive placebo. All participants will continue to receive their regular treatment called enzyme replacement therapy, which is a standard treatment for Pompe disease where missing enzymes are given through an infusion into a vein.

The purpose of this study is to see if S-606001 when added to enzyme replacement therapy can improve lung function in people with late-onset Pompe disease. The study will also look at how safe the medication is and how it affects the body. During the study, participants will be randomly assigned to receive either S-606001 or placebo in addition to their regular enzyme replacement therapy. The treatment period will last for about one year.

Throughout the study, participants will have regular check-ups to measure their lung function, muscle strength, and ability to walk and perform daily activities. These measurements will include breathing tests while sitting and lying down, a walking test where participants walk for six minutes, and tests of muscle strength. Participants will also be asked questions about their energy levels, pain, breathing difficulties, and quality of life. Blood samples will be taken to check how the medication works in the body and to monitor safety. The study team will also monitor for any side effects and perform regular physical examinations, heart tests, and laboratory tests throughout the study period.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial treatment period begins

    Upon joining the study, you will begin receiving either S-606001 or a placebo. The placebo is an inactive substance that looks identical to the actual medication but contains no active ingredient.

    You will not know whether you are receiving the active medication or the placebo. This is called a double-blind study, meaning neither you nor your doctor will know which treatment you are receiving.

    The medication will be provided as a film-coated tablet that you will take by mouth.

    This treatment will be given in addition to your current enzyme replacement therapy, which is a treatment that provides the missing enzyme your body needs.

  2. Step 2

    Regular monitoring and assessments

    Throughout the study, your lung function will be monitored using a test called forced vital capacity, which measures how much air you can forcefully exhale after taking a deep breath.

    You will undergo physical examinations and have your vital signs measured, including blood pressure, heart rate, and temperature.

    Blood and urine samples will be collected for laboratory evaluations to check your blood cells, organ function, and other health markers.

    Your heart function will be monitored using electrocardiograms, which are tests that record the electrical activity of your heart.

    Blood samples will be taken to measure the concentration of S-606001 in your bloodstream.

  3. Step 3

    Functional assessments

    You will perform a 6-minute walk test, where you will be asked to walk as far as you can in six minutes to assess your physical endurance.

    Your breathing strength will be tested by measuring maximal inspiratory pressure (the strongest breath you can take in) and maximal expiratory pressure (the strongest breath you can push out).

    Your motor function will be evaluated using the GSGC score, which assesses your ability to walk, climb stairs, stand up from the floor, and rise from a chair.

    Your ability to perform daily activities will be assessed.

  4. Step 4

    Quality of life questionnaires

    You will complete several questionnaires to assess how you are feeling and functioning in daily life.

    These questionnaires will evaluate your levels of fatigue (tiredness), physical function, shortness of breath, and pain.

    You will also complete a general health questionnaire called SF-36 and a questionnaire about your overall impression of the severity of your condition.

  5. Step 5

    Treatment continues for 52 weeks

    You will continue taking the study medication (either S-606001 or placebo) daily by mouth for a total of 52 weeks.

    During this period, all the assessments and monitoring described in the previous steps will be performed at scheduled intervals.

    Your enzyme replacement therapy will continue throughout the study as your background treatment.

  6. Step 6

    Safety monitoring throughout the study

    Any side effects or health problems you experience will be recorded and monitored throughout the study.

    Your doctor will assess whether these events are related to the study medication.

    All safety information will be reviewed regularly to ensure your wellbeing during the study.

  7. Step 7

    End of treatment period

    After completing 52 weeks of treatment, you will stop taking the study medication.

    Final assessments will be performed to evaluate the effects of the treatment on your lung function, physical abilities, and overall health.

    If you are a male participant, you should continue to follow contraception guidelines for at least 14 weeks after your last dose.

    If you are a female participant of childbearing potential, you should continue to use contraception for at least 184 days (approximately 26 weeks) after your last dose.

Who can join the trial?

8 criteria

  • You must be between 18 and 65 years old and weigh at least 40 kilograms when you sign the consent form.
  • You must have a confirmed diagnosis of late-onset Pompe disease, which can be shown by either a test proving your body does not make enough of a specific enzyme called acid alpha-glucosidase, or by genetic testing that shows changes in the gene responsible for making this enzyme.
  • Your lung function test called Forced Vital Capacity, which measures how much air you can breathe out, must be between 30% and 80% of normal when sitting upright, or your lung function must drop by at least 10% when lying down compared to sitting up, with at least 20% function when lying down.
  • You must be able to complete a 6-minute walk test, where you walk for six minutes, and you must walk at least 75 meters but no more than 90% of the distance expected for healthy adults of your age and size.
  • If you are a man, you must agree not to donate semen during the study and for at least 14 weeks after the last dose of the study medicine, and you must either avoid sexual intercourse with women or use reliable birth control methods.
  • If you are a woman who can become pregnant, you must use highly effective birth control during the study and for at least 184 days after the last dose of the study medicine, and you must not donate eggs during this time. If you cannot become pregnant due to surgery or age, or if you are not pregnant or breastfeeding, you may participate.
  • You must be able to understand and sign the consent form, and agree to follow all study rules and requirements.
  • You must already be receiving enzyme replacement therapy, which is a treatment where the missing enzyme is given to you through an infusion into your vein.

Who cannot join the trial?

1 criterion

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

  • S-606001

    is an investigational medication being studied as an additional treatment to be given alongside enzyme replacement therapy for patients with late-onset Pompe disease. This medicine is designed to work together with the standard enzyme replacement therapy that patients are already receiving. The purpose of adding this medication is to see if it can help improve lung function in people living with this condition. S-606001 is still being tested to understand how safe it is and how well it works when used in combination with the existing treatment.

  • Enzyme replacement therapy

    is the standard treatment for Pompe disease. This therapy works by providing the body with a manufactured version of an enzyme that people with Pompe disease are missing or do not have enough of naturally. In this study, all participants will continue receiving their regular enzyme replacement therapy, and some will also receive the additional investigational medication to see if the combination provides better results than enzyme replacement therapy alone.

  • Placebo

    is an inactive substance that looks like the real medication but contains no active medicine. Some participants in this study will receive placebo instead of the investigational medication S-606001, while still continuing their regular enzyme replacement therapy. This helps researchers compare the effects of adding the real medication versus not adding it, so they can determine if S-606001 actually provides additional benefits.

What is already known about the treatment

S-606001 – S-606001 is an investigational medication currently being studied in clinical trials as an add-on treatment to enzyme replacement therapy for patients with late-onset Pompe disease, a rare genetic disorder that causes progressive muscle weakness. The drug is being tested in its Phase 2 stage to evaluate its safety and potential effectiveness, particularly in improving lung function in affected patients. While the exact mechanism of action has not been fully disclosed in available trial information, it is designed to work alongside existing enzyme replacement therapy to enhance treatment outcomes. S-606001 belongs to the category of experimental therapies for metabolic disorders and is administered as part of a combination treatment approach.

Investigated diseases

Late-onset Pompe disease – Late-onset Pompe disease is a rare inherited disorder caused by the deficiency of an enzyme called acid alpha-glucosidase. This enzyme is responsible for breaking down glycogen, a stored form of sugar, in the body's cells. When the enzyme is lacking, glycogen accumulates in various tissues, particularly in muscles. The disease primarily affects skeletal muscles used for movement and the muscles involved in breathing. Over time, this buildup leads to progressive muscle weakness and respiratory problems. Unlike the infantile form, late-onset Pompe disease typically appears in childhood, adolescence, or adulthood and progresses more slowly.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IITrial ID2025-522146-40-00Protocol code2405N1221Estimated enrolment47 patientsSponsorShionogi B.V.

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