Merck Announces First Dose in Phase 3 Study with Enpatoran for Lupus Patients with Active Skin Manifestations

Significant unmet need remains for 85% of lupus patients whose disease includes skin manifestations, often associated with substantial physical and psychosocial burdenEnpatoran, an oral TLR7/8 inhibitor, is designed for lupus patients with active cutaneous manifestations, with the goal of broadening the treatment paradigm beyond the current standardsELOWEN is a global Phase 3 program evaluating enpatoran’s impact on both skin and systemic symptoms in patients with lupus and potential links between skin and systemic disease activity

Merck, a leading global science and technology company, today announced the first patient was dosed in the Phase 3 program, ELOWEN-1 (NCT07332481) and ELOWEN-2 (NCT07355218), evaluating enpatoran in people living with lupus who experience active skin manifestations.

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David Weinreich, Global Head of R&D and Chief Medical Officer

“People living with lupus continue to face significant challenges in achieving disease control and are very often affected by itchy, painful and stigmatized skin manifestations,” said David Weinreich, Global Head of R&D, Merck. “With enpatoran, we aim to target the underlying drivers of lupus and redefine how to approach the disease by understanding both visible skin manifestations and systemic activity.”

Enpatoran is an oral selective toll-like receptor (TLR) 7/8 inhibitor designed to modulate pathways central to lupus-related inflammation.¹ By targeting these upstream drivers, enpatoran has the potential to impact disease activity and address a key aspect of the lupus mechanism that remains difficult to manage with current treatment approaches, while preserving the body’s broader immune function.¹

“The ELOWEN program builds on Phase 2 findings, where enpatoran demonstrated clinically meaningful improvements in patients with active cutaneous manifestations, regardless of their underlying lupus diagnosis,” said Professor Eric Morand, principal investigator. “These studies are designed to further explore how targeting shared inflammatory pathways may benefit patients across the lupus spectrum.”

Lupus is a chronic autoimmune disease that can affect multiple organ systems, including the skin, joints, kidneys and central nervous system.² Up to 85% of patients experience skin manifestations, which are among the most visible signs of disease and may reflect underlying immune-driven inflammation.¹

Skin manifestations can be life-altering and sometimes are irreversible on their own.^3,4 They can present as inflamed, photosensitive lesions on the face, scalp and other areas, and may lead to scarring or pigment changes.⁵ Despite their prevalence and the fact that skin manifestations are the first sign of disease in nearly one third (29%) of cases,¹ many patients still do not achieve adequate disease control.⁶

“Skin symptoms impose a profound and multilayered burden that lingers long after flares subside. The lesions are visible, disfiguring and often painful, and the psychological weight can be equally debilitating, breeding a loss of identity that standard clinical assessments often fail to capture,” said Dr. Joy Buie, PhD, VP of Research at the Lupus Foundation of America. “These consequences erode participation in work, social life, and intimate relationships as self-consciousness and deliberate avoidance quietly reshape how patients navigate the world around them. It is vital we recognize skin manifestations as a visible and clinically actionable signal of underlying systemic disease "

ELOWEN-1 and ELOWEN-2 are two global randomized, double-blind, placebo-controlled Phase 3 studies evaluating enpatoran taken twice daily versus placebo, on top of standard of care, in patients with lupus who have active cutaneous manifestations. The ELOWEN studies will be conducted in 266 sites in 26 countries. Each study will recruit approximately 200 lupus participants, and the primary endpoint will be a change in CLASI-A from baseline.

About Enpatoran

Enpatoran is an investigational, oral, selective inhibitor of toll-like receptors 7 and 8 (TLR7/8), which play a key role in immune pathways involved in lupus. Enpatoran has the potential to be the first targeted therapy for lupus patients with active cutaneous manifestations, with the goal of broadening the treatment paradigm beyond the current standards of care for patients with CLE and SLE.

Enpatoran is currently under clinical investigation and has not been approved for any use anywhere in the world.

About the Phase 3 ELOWEN Program

ELOWEN-1 (NCT07332481) and ELOWEN-2 (NCT07355218) are two global randomized, double-blind, placebo-controlled Phase 3 studies evaluating enpatoran taken twice daily versus placebo, on top of standard of care, in patients with lupus who have active cutaneous manifestations. The ELOWEN studies will be conducted in 266 sites in 26 countries. Each study will recruit approximately 200 lupus participants, and the primary endpoint will be a change in CLASI-A from baseline.

About Lupus Erythematosus

Lupus erythematosus is a chronic autoimmune disease characterized by inflammation that can affect multiple organs and systems in the body. The disease is heterogeneous, with symptoms ranging from mild to life-threatening, and often follows a relapsing-remitting course.

Cutaneous manifestations are common (72-85%) of patients and can occur alongside or independently of systemic involvement. Beyond their physical presentation, they are associated with increased disease burden, including scarring, psychological impact and reduced quality of life.

Lupus disproportionately affects women and people of color, and many patients continue to experience unmet medical needs due to insufficient disease control or treatment-related side effects.

Merck in Neurology and Immunology

Merck has a long-standing legacy in neurology and immunology. The company’s current neurology portfolio includes two products for the treatment of relapsing MS – Rebif^® (interferon beta-1a) and MAVENCLAD^® (cladribine) tablets. Merck aims to improve the lives of patients by addressing areas of unmet medical needs. In addition to Merck’s commitment to MS, the company also has a pipeline focusing on discovering new therapies that have potential in other neuroinflammatory and immune-mediated diseases, including lupus and generalized myasthenia gravis (gMG).

About Merck

Merck, a leading science and technology company, operates across life science, healthcare and electronics. More than 62,000 employees work to make a positive difference to millions of people’s lives every day by creating more joyful and sustainable ways to live. From providing products and services that accelerate drug development and manufacturing as well as discovering unique ways to treat the most challenging diseases to enabling the intelligence of devices – the company is everywhere. In 2025, Merck generated sales of € 21.1 billion in 65 countries.

Scientific exploration and responsible entrepreneurship have been key to Merck’s technological and scientific advances. This is how Merck has thrived since its founding in 1668. The founding family remains the majority owner of the publicly listed company. Merck holds the global rights to the Merck name and brand. The only exceptions are the United States and Canada, where the business sectors of Merck operate as MilliporeSigma in life science, EMD Serono in healthcare, and EMD Electronics in electronics.

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