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Enpatoran low dose

Phase 2

Systemic Lupus Erythematosus | Small molecule | Immunology |Merck KGaA|Last Updated: Dec 1, 2025

Target and mechanism

Molecular targetTLR7, TLR8
Target classAntagonist
ModalitySmall molecule

Also known as Enpatoran

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindPLACEBO_CONTROLLEDDMCBiomarker
Total Trials1
Total Enrollment456

FDA Designations

No designations recorded

Clinical trial landscape

Enpatoran low dose · 3 trials · 2 indications

Phase 2 1Phase 1 2
NCT05162586The WILLOW Study With M5049 in SLE and CLE (SCLE and/or DLE) (WILLOW)Systemic Lupus Erythematosus
COMPLETED456 Analytics
PHASE2COMPLETED
The WILLOW Study With M5049 in SLE and CLE (SCLE and/or DLE) (WILLOW)
Systemic Lupus ErythematosusUnlock trial analytics

Study Endpoints

Primary Endpoints

Cohort A: Change From Baseline in Cutaneous Lupus Erythematosus Disease Area and Severity Index-A (CLASI-A) Total Score at Week 16
Baseline, week 16

The CLASI (Cutaneous Lupus Erythematosus Disease Area and Severity Index) was a validated instrument used to assess disease activity (CLASI-A) and damage in lupus erythematosus. The activity scale included erythema, scale/hypertrophy, active alopecia, recent hair loss, and mucous membrane disease, while the damage scale measured dyspigmentation, atrophy, and scarring. CLASI-A scores ranged from 0 to 70, with mild, moderate, and severe disease corresponding to scores of 0-9, 10-20, and 21-70, respectively. Erythema and scale/hypertrophy sub-scores were computed across 13 body areas, with maximum scores of 39 and 26, respectively. The remaining 5 points reflected contributions from active alopecia (0-3), recent hair loss (0-1), and mucous membrane involvement (0-1), completing the total CLASI-A activity score. Directionality reflected worsening with higher scores and improvement with lower scores.

Cohort B: Number of Participants With British Isles Lupus Assessment Group (BILAG)-Based Composite Lupus Assessment (BICLA) Response at Week 24
At Week 24

BILAG-based BICLA response is defined as participants meeting all of the following criteria: 1. Improvement in baseline BILAG scores in all organ systems with moderate or severe disease activity-i.e., all grade A scores (severe disease requiring high-dose therapy) must improve to B (moderate), C (mild), or D (no activity); all grade B scores (moderate disease requiring moderate therapy) must improve to C or D; 2. No new BILAG A scores and no more than one new BILAG B score; 3. No worsening in total SLEDAI-2K score from baseline; 4. No significant deterioration (≤10%) in physician's global assessment; and 5. No treatment failure, defined as initiation of non-protocol therapy. Directionality is toward clinical improvement and disease stabilization.

Placebo-Corrected Change from Baseline in Heart Rate-Corrected QT Interval by Fridericia's Formula (QTcF) for Enpatoran
Pre-dose on Day 1 (baseline) up to 24 hours post-dose
Period 1: Percent Urinary Recovery (feurine) of Total Radioactivity per Sampling Interval
-24-0 hours (pre-dose), 0-4, 4-12, 12-24, 24-48, 48-72, 72-96, 96-120, 120-144, and 144-168 hours after the initiation of the intravenous (IV) dose
Period 1: Percent Fecal Recovery (fefeces) of Total Radioactivity per Sampling Interval
-24-0 hours (pre-dose), 0-24, 24-48, 48-72, 72-96, 96-120, 120-144, and 144-168 hours after the initiation of the intravenous (IV) dose
Period 1: Percent Total Recovery in Urine and Feces (fetotal) of Total Radioactivity per Sampling Interval
Urine: -24-0 hours (pre-dose), 0-4, 4-12, 12-24, 24-48, 48-72, 72-96, 96-120, 120-144, and 144-168 hours post-dose; Feces: -24-0 hours (pre-dose), 0-24, 24-48, 48-72, 72-96, 96-120, 120-144, and 144-168 hours post-dose of IV injection
Period 1: Pharmacokinetic Plasma and Blood Concentration of Total Radioactivity
Pre-dose (Day 1), 15, 30 minutes, 1, 1.5, 2.0, 4.0, 6.0, 8.0, 12, 24, 48, 72, 96, 120, 144, 168 hours post-dose
Period 1: Pharmacokinetic Plasma Concentration of Enpatoran
Pre-dose (Day 1), 15, 30 minutes, 1, 1.5, 2.0, 4.0, 6.0, 8.0, 12, 24, 48, 72, 96, 120, 144, 168 hours post-dose
Period 2: Pharmacokinetic Plasma and Blood Concentration of [14C]Enpatoran and Enpatoran
[14C]Enpatoran: Pre-dose, 5, 15, 30 minutes, 1, 1.5, 2, 4, 6, 8, 12, 24, 48, 72 hours post-dose; Enpatoran: Pre-dose, 30 minutes, 2, 4, 6, 8, 12, 24, 48, 72 hours post-dose

Secondary Endpoints

Cohort A and B: Number of Participants With Treatment-Emergent Adverse Events (TEAEs), Serious TEAEs and Adverse Events (AEs) of Special Interest
From screening upto safety follow up period (up to approximately 33 weeks)
Cohort A and B: Number of Participants With Abnormal Laboratory Parameters
From screening upto safety follow up period (up to approximately 33 weeks)
Cohort A and B: Number of Participants With Clinically Important Increases in QT Interval Corrected Using Fridericia's Formula (QTcF)
From screening upto safety follow up period (up to approximately 33 weeks)
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Study Design & Arms

AllocationRANDOMIZED
MaskingQUADRUPLE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Cohort A: PlaceboPLACEBO_COMPARATORParticipants with CLE (active SCLE and/or DLE) or SLE with predominantly active lupus rash (Cutaneous Lupus Erythematosus Disease Area and Severity Index \[CLASI-A\] greater than or equal to \[\>=\] 8) will be enrolled in Cohort A to receive placebo matched to Enpatoran.
Cohort A: Enpatoran low doseEXPERIMENTALParticipants with CLE (active SCLE and/or DLE) or SLE with predominantly active lupus rash (CLASI-A \>= 8) will be enrolled in Cohort A to receive low dose of Enpatoran.
Cohort A: Enpatoran medium doseEXPERIMENTALParticipants with CLE (active SCLE and/or DLE) or SLE with predominantly active lupus rash (CLASI-A \>= 8) will be enrolled in Cohort A to receive medium dose of Enpatoran.
Cohort A: Enpatoran high doseEXPERIMENTALParticipants with CLE (active SCLE and/or DLE) or SLE with predominantly active lupus rash (CLASI-A \>= 8) will be enrolled in Cohort A to receive high dose of Enpatoran.
Cohort B (Part 1 + Part 2): PlaceboPLACEBO_COMPARATORParticipants with active SLE who have moderate to high systemic disease activity (British Isles Lupus Assessment Group \[BILAG A/2B\]) with 1 or 2 of the following: CLASI-A \>= 8 and/or Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) \>= 6 will be enrolled in Cohort B to receive placebo matched to Enpatoran .
Cohort B (Part 1 + Part 2): Enpatoran high doseEXPERIMENTALParticipants with active SLE who have moderate to high systemic disease activity (BILAG A/2B) with 1 or 2 of the following: CLASI-A \>= 8 and/or SLEDAI \>= 6 will be enrolled in Cohort B to receive high dose of Enpatoran.
Cohort B (Part 2): Enpatoran low doseEXPERIMENTALParticipants with active SLE who have moderate to high systemic disease activity (BILAG A/2B) with 1 or 2 of the following: CLASI-A \>= 8 and/or SLEDAI \>= 6 will be enrolled in Cohort B to receive low dose of M5049.
Cohort B (Part 2): Enpatoran medium doseEXPERIMENTALParticipants with active SLE who have moderate to high systemic disease activity (BILAG A/2B) with 1 or 2 of the following: CLASI-A \>= 8 and/or SLEDAI \>= 6 will be enrolled in Cohort B to receive medium dose of Enpatoran.
Treatment Sequence 1: A-B-C-DEXPERIMENTALParticipants will receive a single oral dose of placebo matched to enpatoran (Treatment A) in treatment period 1, followed by a single oral dose of moxifloxacin tablet (Treatment B) in treatment period 2, followed by a single oral low dose of enpatoran tablet (Treatment C) in treatment period 3, followed by a single oral high dose of enpatoran tablet (Treatment D) in treatment period 4. There will be a washout period of at least 10 days between each treatment period.
Treatment Sequence 2: B-D-A-CEXPERIMENTALParticipants will receive a single oral dose of moxifloxacin tablet (Treatment B) in treatment period 1, followed by a single oral high dose of enpatoran tablet (Treatment D) in treatment period 2, followed by a single oral dose of placebo matched to enpatoran (Treatment A) in treatment period 3, followed by a single oral low dose of enpatoran tablet (Treatment C) in treatment period 4. There will be a washout period of at least 10 days between each treatment period.
Treatment Sequence 3: C-A-D-BEXPERIMENTALParticipants will receive a single oral low dose of enpatoran tablet (Treatment C) in treatment period 1, followed by a single oral dose of placebo matched to enpatoran (Treatment A) in treatment period 2, followed by a single oral high dose of enpatoran tablet (Treatment D) in treatment period 3, followed a by single oral of moxifloxacin tablet (Treatment B) in treatment period 4. There will be a washout period of at least 10 days between each treatment period.
Treatment Sequence 4: D-C-B-AEXPERIMENTALParticipants will receive a single oral high dose of enpatoran tablet (Treatment D) in treatment period 1, followed by a single oral low dose of enpatoran (Treatment C) in treatment period 2, followed by a single oral dose of moxifloxacin tablet (Treatment B) in treatment period 3, followed by a single oral dose of placebo matched to enpatoran (Treatment A) in treatment period 4. There will be a washout period of at least 10 days between each treatment period.
Period 1: Enpatoran + [14C]enpatoran microtracerEXPERIMENTAL -
Period 2: Enpatoran + [14C]enpatoran microdoseEXPERIMENTAL -

Interventions

NameTypeDescription
Enpatoran low doseDRUGParticipants will receive film-coated tablets of Enpatoran at a low dose orally, twice daily (BID) up to 24 weeks.
Enpatoran medium doseDRUGParticipants will receive film-coated tablets of Enpatoran at a medium dose, orally, BID up to 24 weeks.
Enpatoran high doseDRUGParticipants will receive film-coated tablets of Enpatoran at a high dose, orally, BID up to 24 weeks.
PlaceboDRUGParticipants will receive placebo matched to Enpatoran up to 24 weeks.
MoxifloxacinDRUGParticipants will receive a single oral dose of moxifloxacin tablet (Treatment B) in either of treatment period 1, 2, 3 and 4.
EnpatoranDRUGParticipants will receive single oral dose of enpatoran tablet on Day 1
[14C]enpatoran microtracerDRUGParticipants will receive single oral dose of non-labeled enpatoran solution spiked with microtracer of \[14C\]enpatoran on Day 1 of Period 1.
[14C]enpatoran microdoseDRUGParticipants will receive intravenous \[14C\]enpatoran microdose administered at 1.5 hours after the oral dose of enpatoran on Day 1 of Period 2.
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Eligibility Criteria

Age Range18 Years to 75 Years
SexALL
Healthy VolunteersNo
Study Sites153

Inclusion Criteria: * Active CLE (SCLE and/or DLE) with a CLE disease area and activity index (CLASI-A) \>= 8 * Active SLE with presence of: CLASI-A \>= 8 and BILAG 2004 1B, C, D (that is \[i.e.\], No BILAG 2004 A and No BILAG 2004 \>= 2B) or BILAG 2004 \>= 1A or 2B and 1 or 2 of the following: Hyb...

Countries:United StatesArgentinaAustraliaBrazilBulgariaChileChinaColombiaGreeceIsraelJapanMauritiusMexicoMoldovaPhilippinesPolandRomaniaSerbiaSouth AfricaSouth KoreaSpainTaiwanGermanyNetherlands
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Frequently asked questions about Enpatoran low dose

What is Enpatoran used for?

Enpatoran is an investigational small molecule being studied for systemic lupus erythematosus (SLE) and cutaneous lupus erythematosus (CLE), including cutaneous manifestations of lupus with or without systemic disease. It is also used in early-phase studies involving healthy participants to evaluate drug properties.

What does Enpatoran target?

Enpatoran is a small molecule immunology therapy in development for lupus. Its specific molecular target has not been disclosed in available clinical trial information. The drug is being evaluated for its effects on immune pathways involved in systemic and cutaneous lupus.

Who is developing Enpatoran?

Enpatoran is being developed by Merck KGaA, a German pharmaceutical company. The company is conducting clinical trials of Enpatoran across multiple countries, including the United States, Canada, China, Germany, and Switzerland.

What phase is Enpatoran in?

Enpatoran is currently in Phase 3 clinical development. A Phase 3 trial, ELOWEN-2, is recruiting participants with cutaneous manifestations of lupus with or without systemic disease. Earlier Phase 1 and Phase 2 studies have been completed.

What clinical trials is Enpatoran in?

Enpatoran has been studied in several clinical trials. The WILLOW study (NCT05162586) was a completed Phase 2 trial in systemic lupus erythematosus. The ELOWEN-2 study (NCT07355218) is a recruiting Phase 3 trial in cutaneous lupus. Phase 1 trials include NCT05110027 and NCT06589726 in healthy participants.

Is Enpatoran the same as M5049?

Yes, Enpatoran is also known as M5049. The WILLOW study, a completed Phase 2 trial in systemic lupus erythematosus, used the name M5049 in its title. Both names refer to the same investigational drug being developed by Merck KGaA.