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A double‑blind, placebo‑controlled trial of oral BI 1015550 in patients with systemic sclerosis

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What is this trial about?

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

Systemic sclerosis is a rare condition that causes hardening of the skin and can affect internal organs such as the lungs, heart, and kidneys. The study evaluates an oral medication called nerandomilast, which is designed to reduce disease activity, and compares it with a matching placebo pill that contains no active drug.

The purpose of the study is to determine whether nerandomilast can more effectively delay death or disease worsening compared with the placebo.

Participants will be randomly assigned to receive either the active medication or the placebo for about one year. During this time, they will attend regular clinic visits where doctors will check skin thickness, lung function (including a test called FVC that measures how much air can be forced out of the lungs), physical ability, and overall health. The study will track any serious health events, changes in symptoms, and overall survival throughout the treatment period.

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

    Randomisation and receipt of study medication

    After joining the study you will be assigned to one of the treatment groups by chance. this is called randomised assignment. the study is double‑blind, meaning you and the study staff will not know whether you receive the active drug or a matching placebo. you will receive a film‑coated tablet that looks the same in each group.

  2. Step 2

    Taking the study medication

    The active medication is called nerandomilast (identified as BI 1015550). it is taken by mouth as a film‑coated tablet. depending on the randomised group you will take either 36 mg or 18 mg once daily. if you are assigned to the placebo group you will take a tablet that contains no active substance but has the same size, weight, colour and shape. you will continue to take the assigned tablet every day for up to 52 weeks unless you stop the study early.

  3. Step 3

    Clinic visits and assessments

    You will attend scheduled clinic visits where the study team will check your health status and collect data. the first visit occurs shortly after you start the medication (baseline). a major assessment is performed at week 52 to evaluate changes in disease measures. additional visits may be required if the study team needs information about safety or disease progression.

  4. Step 4

    Study completion or early termination

    The study continues for up to 52 weeks. it will end for you either after completing the 52‑week period, or earlier if a confirmed disease progression, a serious health event, or death occurs. at the end of the study you will stop taking the study medication and the study team will perform a final assessment.

Who can join the trial?

10 criteria

  • Signed consent: You must sign and date a written form that shows you understand the study and agree to take part.
  • You must be at least 18 years old and meet the official 2013 criteria for systemic sclerosis (a condition that affects skin and internal organs).
  • You must have been diagnosed with either limited cutaneous systemic sclerosis (lcSSc) or diffuse cutaneous systemic sclerosis (dcSSc), which are two types of the disease defined by how much skin is involved.
  • The first symptom of the disease that is not Raynaud’s phenomenon (a finger‑color change) must have started within the last 7 years.
  • If you have the diffuse type (dcSSc), you need to show that the disease is currently active during the screening visits.
  • If you have the limited type (lcSSc), you also need to show active disease, and you must test negative for anti‑centromere antibodies (a blood test that can be present in some people with this disease).
  • Your lung function test called forced vital capacity (FVC) must be at least 45 % of the value predicted for someone your age, sex and size.
  • Your lung test called diffusing capacity for carbon monoxide (DLCO) must be at least 25 % of the predicted value after adjusting for hemoglobin (the protein in blood that carries oxygen).
  • If you are a woman who could become pregnant, you must be ready and able to use a highly effective form of birth control throughout the study.
  • You may be untreated or you may be on stable doses of allowed medicines such as immunosuppressive or immunomodulatory drugs, or the medication nintedanib. These treatments must stay the same before the second visit and during the screening period.

Who cannot join the trial?

4 criteria

  • People who have active, unstable, or uncontrolled vasculitis (a condition where the blood vessels become inflamed) within the 8 weeks before the first study visit or during the screening period.
  • Anyone who has shown suicidal behaviour (actions taken to harm oneself) at any time in the past two years.
  • Anyone who has had strong thoughts of suicide, called suicidal ideation, that were rated as type 4 or 5 on the C-SSRS (a questionnaire that measures how serious suicidal thoughts are) in the past three months.
  • Other reasons not listed here may also prevent participation.
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Investigated drugs

BI 1015550 is an experimental oral tablet that is being studied to see if it can slow down the worsening of systemic sclerosis, a disease that can affect the skin and internal organs. Participants take the tablet by mouth, and researchers are looking to find out whether the medicine can reduce the risk of death or disease progression compared with no active treatment. The drug is designed to target processes that cause inflammation and tissue scarring, with the goal of improving patients’ overall health and quality of life.

What is already known about the treatment

BI 1015550 - BI 1015550 is taken as an oral film‑coated tablet, given once daily at doses such as 18 mg or 36 mg in the trial. The drug is still investigational and is being studied in clinical trials for systemic sclerosis, so it is not yet approved for general medical use. It is intended to treat systemic sclerosis, a disease that causes skin thickening and organ fibrosis. BI 1015550 works by blocking an enzyme called phosphodiesterase‑4, which lowers inflammation and may help slow the disease, and it belongs to the class of PDE4 inhibitors, a type of anti‑inflammatory oral medication.

Investigated diseases

Systemic sclerosis - Systemic sclerosis is a rare autoimmune condition that causes hardening and tightening of the skin. Over time, the skin changes can spread from the fingers to larger areas of the body. The disease also leads to buildup of scar tissue in internal organs such as the lungs, heart, and kidneys. As fibrosis progresses, organ function may become increasingly limited. Patients may notice worsening of joint mobility and the appearance of small ulcers on the fingertips. The overall pattern is a gradual increase in tissue stiffness and organ involvement.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-523884-39-00Protocol code1305-0052Estimated enrolment448 patientsSponsorBoehringer Ingelheim Espana S.A.

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