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A Phase 3 Study of Enpatoran to Treat Active Cutaneous Lupus in Patients With or Without Systemic Disease

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What is this trial about?

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

The study focuses on people who have Cutaneous Manifestations of Lupus Erythematosus, a form of lupus that causes red patches, rashes, and sometimes scarring on the skin, with or without involvement of other organs. Lupus is an autoimmune condition in which the body’s immune system mistakenly attacks its own tissues. The medication being tested is an oral tablet called Enpatoran. Participants will receive either this tablet or a matching placebo while continuing any standard treatments they already use.

The main purpose of the study is to determine whether Enpatoran can lower skin disease activity. Participants will take the study medication daily for about 24 weeks and will attend regular clinic visits to check their skin and overall health. Skin severity will be measured with a tool called the CLASI, which gives a number based on how much of the skin is affected and how severe the rash is. Overall lupus activity may also be evaluated using the BICLA score. Safety will be monitored by recording any side effects, referred to as TEAEs. The study will finish after the 24‑week period, and the results will show whether the drug provided a meaningful improvement.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Baseline visit and randomization

    After enrollment, a baseline visit is performed to record the initial skin disease score (clasi-a) and other health measures.

    Participants are randomly assigned to receive either enpatoran or a matching placebo without knowing which one they receive.

  2. Step 2

    Start of study medication

    The assigned medication is taken by mouth as a film‑coated tablet.

    The dose and frequency are specified in the study protocol and are taken each day for the duration of the trial.

  3. Step 3

    Daily dosing period

    Participants continue the daily oral intake of the study tablet for a total of 24 weeks.

    The medication may be taken with or without food, as instructed by the study staff.

  4. Step 4

    Scheduled clinic visits and assessments

    Clinic visits are scheduled at week 4, week 12, and week 24.

    At each visit, the skin disease score (clasi-a) is measured again, and other evaluations such as the bicla response and laboratory tests are performed.

    The visits also include monitoring for any adverse events, including serious adverse events and events of special interest.

  5. Step 5

    Final evaluation and study completion

    At week 24, the primary goal is to determine whether the participant achieved a clasi-70 response, meaning a reduction of at least 70% from the baseline skin score.

    Secondary goals, such as the bicla response, corticosteroid reduction, and safety outcomes, are also reviewed.

    After the final assessments, the study medication is discontinued and the participant completes the trial.

Who can join the trial?

8 criteria

  • Age must be between 18 and 75 years.
  • All routine vaccinations should be up to date according to local guidelines; a recombinant zoster vaccine (a newer shingles shot) is recommended but not required.
  • You must have a recorded diagnosis of Discoid Lupus Erythematosus (DLE) and/or Subacute Cutaneous Lupus Erythematosus (SCLE), with or without Systemic Lupus Erythematosus (SLE). DLE and SCLE are types of lupus that affect the skin; SLE is lupus that can affect many organs.
  • If you have active Acute Cutaneous Lupus Erythematosus (ACLE) as the only skin problem, you must also have SLE, and the skin rash must have been present for at least 6 weeks before the screening visit. ACLE is a sudden, severe skin flare of lupus.
  • If you have SLE, you must meet the 2019 EULAR/ACR classification criteria (a set of guidelines used by doctors to confirm lupus) and have active DLE, SCLE, or ACLE.
  • For participants with SLE, the disease (both skin involvement and, if present, SLE) must have been diagnosed for at least 6 months before the screening visit.
  • For participants with SLE, the CLASI‑A score (a numeric measure of skin disease activity) must be 8 or higher at both the screening visit and the first day of the study. A higher score means more active skin disease.
  • Any additional protocol‑defined inclusion requirements may also apply.

Who cannot join the trial?

7 criteria

  • Having another autoimmune rheumatic disease (a condition where the immune system attacks the body’s own joints or tissues) such as systemic sclerosis or rheumatoid arthritis, instead of cutaneous lupus or systemic lupus.
  • Having any skin disease other than lupus skin problems (for example, psoriasis), or having uncontrolled illnesses like asthma, chronic obstructive pulmonary disease, interstitial lung disease, bronchiectasis, or pulmonary arterial hypertension, or having life‑threatening lupus problems such as active systemic vasculitis, as judged by the doctor.
  • Having lupus that was caused by medication, known as drug‑induced lupus.
  • Having active lupus nephritis (lupus affecting the kidneys) that is being treated with induction therapy, or having finished induction therapy within the past 3 months. Ongoing maintenance medicines such as mycophenolate, azathioprine, or an oral calcineurin inhibitor are allowed.
  • Having a urine test result called Urine Protein-to-Creatinine Ratio (UPCR) higher than 339 mg/mmol, or an estimated Glomerular Filtration Rate (eGFR) less than 40 mL/min/1.73 m² (a measure of kidney function calculated by the Modification of Diet in Renal Disease (MDRD) equation).
  • Having any current signs, symptoms, or diagnoses related to Central Nervous System (CNS) lupus within the past 3 months, or a history of uncontrolled seizures (episodes of abnormal brain activity that are not well‑managed).
  • Any other exclusion rules that are defined in the study protocol.
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Investigated drugs

Enpatoran is an oral tablet being tested as a new treatment for people with lupus that affects the skin. In this study, participants take Enpatoran along with their regular care to see if it can lower the severity of skin symptoms. Researchers are looking to find out whether Enpatoran can reduce the skin disease activity by at least 70% after 24 weeks compared with usual treatment alone.

What is already known about the treatment

  • Enpatoran

    Enpatoran is taken as an oral, film‑coated tablet and is administered by swallowing the pill with water. It is an experimental drug currently in phase 3 clinical trials and is being studied in medical literature for skin involvement in lupus. The drug is intended to treat active cutaneous lupus erythematosus, with or without systemic disease, by blocking specific immune receptors that trigger inflammation. Enpatoran belongs to the class of Toll‑like receptor 7/8 antagonists, which are immune‑modulating agents that reduce inflammatory signals at the molecular level.

  • Placebo to match Enpatoran

    The placebo is also an oral, film‑coated tablet designed to look like Enpatoran and is taken by swallowing with water. It contains no active drug and is used only as a control in the clinical trial, so it has no therapeutic use in medicine. Because it is inert, it does not have a mechanism of action or a pharmacological class. The placebo helps researchers compare the effects of Enpatoran against a neutral baseline.

Investigated diseases

Cutaneous lupus erythematosus - This is an autoimmune condition that causes skin rashes and lesions, often appearing on the face, scalp, or exposed areas. The skin changes may start as red patches or raised bumps and can become thickened or scarred over time. Sun exposure often makes the rash worse, leading to new spots or flare‑ups. Lesions may heal and then reappear, sometimes spreading to larger areas of the body. In some people, the skin involvement can occur alone, while in others it may be accompanied by symptoms affecting other organs. The disease typically follows a pattern of periods of activity followed by quieter phases.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-524855-30-00Protocol codeMS504908_0008Estimated enrolment202 patientsSponsorMerck Healthcare KGaA

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