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Phase 3 Study of Enpatoran in Patients with Active Cutaneous Lupus Erythematosus (with or without Systemic 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

The condition being studied is Cutaneous Manifestations of Lupus Erythematosus, an autoimmune disease that can cause red, scaly patches on the skin and may occur with or without involvement of internal organs. The investigational medication is Enpatoran, an oral tablet taken daily, and it is being compared with a matching placebo. The purpose of the study is to determine whether Enpatoran can significantly reduce skin disease activity, defined as at least a 70% improvement in a skin severity score.

Participants are randomly assigned to receive either Enpatoran or placebo for a period of 24 weeks while continuing any usual care. The skin severity is measured using the CLASI score, which rates the extent and intensity of rash, and overall lupus activity is also evaluated with the BICLA assessment. Throughout the study, safety is monitored by recording any adverse events and laboratory changes. Visits occur at regular intervals to collect the necessary information and to ensure participant well‑being.

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

    Randomization and baseline assessment

    After joining the study, you will be assigned to receive either enpatoran or a matching placebo without knowing which one you receive.

    A baseline visit will be performed to record your skin condition using the cutaneous lupus erythematosus disease area and severity index (clasi-a) and to collect routine laboratory tests.

  2. Step 2

    Start of study medication

    You will begin taking an oral, film‑coated tablet each day.

    The tablet contains either enpatoran hemihydrate or an inactive substance (placebo); the exact dose is defined by the study protocol.

    The medication will be taken for a total period of 24 weeks.

  3. Step 3

    Regular safety monitoring

    Throughout the 24‑week period you will be asked to report any new symptoms, side effects, or changes in health.

    Routine laboratory tests may be performed at scheduled visits to check for significant changes.

  4. Step 4

    Interim efficacy assessment at week 4

    A follow‑up visit will occur at week 4 to repeat the clasi-a skin assessment and to evaluate any early response to the medication.

  5. Step 5

    Mid‑study assessment at week 12

    Another visit will be scheduled at week 12 to assess skin improvement, review laboratory results, and determine whether the dose of any concomitant corticosteroid medication can be reduced.

  6. Step 6

    Final assessment at week 24

    The last study visit will take place at week 24.

    The primary goal is to determine whether a reduction of at least 70% in the clasi-a score has been achieved.

    Secondary goals include evaluating overall lupus activity, safety outcomes, and any reduction in corticosteroid use.

  7. Step 7

    Study completion

    After the week 24 visit, the study medication will be stopped and you will receive any necessary follow‑up care as directed by your physician.

Who can join the trial?

9 criteria

  • Age: You must be between 18 and 75 years old.
  • Vaccinations: Your routine vaccinations must be up to date according to local guidelines; a shingles vaccine (recombinant zoster) is encouraged but not required.
  • Diagnosis of skin lupus: You need a documented diagnosis of Discoid Lupus Erythematosus (a type of chronic skin rash) and/or Subacute Cutaneous Lupus Erythematosus (a milder, widespread skin rash), with or without Systemic Lupus Erythematosus (a disease that can affect many organs).
  • Acute skin flare: If the only skin problem is Acute Cutaneous Lupus Erythematosus (a sudden, severe skin flare), you must also have Systemic Lupus Erythematosus and the flare must have been present for at least 6 weeks before the screening visit.
  • Lupus classification criteria: If you have Systemic Lupus Erythematosus, you must meet the 2019 classification criteria set by the European Alliance of Associations for Rheumatology (EULAR) and the American College of Rheumatology (ACR), and you must have active skin disease (Discoid, Subacute, or Acute Cutaneous Lupus).
  • Disease duration: Your skin disease (and, if applicable, your overall lupus) must have been diagnosed at least 6 months before the screening visit.
  • Skin severity score: At the screening and first study visit, you must have a CLASI‑A score (a numeric measure of skin disease activity) of 8 or higher.
  • Both men and women are eligible to participate.
  • Participants who are considered vulnerable (for example, due to age, disability, or other factors) may be included.

Who cannot join the trial?

7 criteria

  • People who have a primary diagnosis of another autoimmune rheumatic disease such as systemic sclerosis or rheumatoid arthritis (conditions where the immune system attacks the body's own tissues) are not allowed.
  • Anyone who has skin diseases other than lupus‑related skin problems, such as psoriasis, or who has uncontrolled illnesses like asthma, chronic obstructive pulmonary disease (COPD), interstitial lung disease, bronchiectasis, or pulmonary arterial hypertension, or life‑threatening lupus problems such as active systemic vasculitis (inflammation of blood vessels) is excluded.
  • People whose lupus was caused by a medication, known as drug‑induced lupus, cannot participate.
  • Patients who have active lupus nephritis (kidney inflammation caused by lupus) and are currently receiving initial high‑dose treatment (called induction therapy), or who finished that induction therapy within the last 3 months, are excluded. Ongoing stable maintenance medicines such as mycophenolate, azathioprine, or an oral calcineurin inhibitor are allowed.
  • Anyone with a urine test showing a Urine Protein-to-Creatinine Ratio (UPCR) higher than 339 mg/mmol, or a kidney function test showing an estimated Glomerular Filtration Rate (eGFR) below 40 mL/min/1.73 m² (a measure of how well the kidneys filter blood), is not eligible.
  • People who have had any active signs, symptoms, or diagnoses related to central nervous system (CNS) lupus in the past 3 months, or who have a history of uncontrolled seizures, cannot join the study.
  • Any other reasons defined in the study protocol that make participation unsafe or inappropriate will also exclude a person.
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Investigated drugs

Enpatoran is an oral, film‑coated tablet being studied as a new treatment for people who have active skin involvement from lupus erythematosus, whether or not they also have disease affecting other parts of the body. In this trial the medication is taken in addition to the standard care that participants already receive. The purpose of the study is to find out if Enpatoran can lower the severity of skin disease by at least 70% after 24 weeks, compared with a placebo. Enpatoran is designed to act on the immune system to reduce the inflammation that causes the skin lesions in lupus.

What is already known about the treatment

  • Placebo to match Enpatoran

    It is an oral tablet without any active ingredient, given to participants to mimic the appearance of the test drug. The product is not used as a treatment in regular medicine and has no therapeutic effect. It serves only as a control in clinical studies and is classified as a placebo.

  • Enpatoran

    Enpatoran is taken as an oral film‑coated tablet and is currently being studied in Phase 3 trials, so it is not yet approved for general use. It is being investigated for treating the skin symptoms of lupus erythematosus, with or without systemic disease. The drug works by blocking Toll‑like receptors 7 and 8, which lowers the signals that cause inflammation. It is classified as a small‑molecule TLR7/8 antagonist and an immunomodulatory agent.

Investigated diseases

Cutaneous lupus erythematosus - Cutaneous lupus erythematosus is an autoimmune condition that causes skin inflammation and rash. The rash may appear as red patches, scaly plaques, or disc‑shaped lesions, often worsening with sun exposure. Over time, lesions can become thicker, cause pigment changes, or lead to scarring if not controlled. The disease can appear alone or together with systemic lupus, and skin symptoms may fluctuate, with periods of flare and remission. New lesions may develop in previously unaffected areas as the condition evolves.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-523871-44-00Protocol codeMS504908_0001Estimated enrolment202 patientsSponsorMerck Healthcare KGaA

sourced from the EU Clinical Trials Register and site verification

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