Sitryx Advances Novel Oral Drug for Atopic Dermatitis into Patients

OXFORD, UK and BOSTON, MA – January 26, 2026 – Sitryx Therapeutics has initiated a new clinical trial phase for its lead drug candidate, SYX-5219, dosing the first patients with moderate to severe atopic dermatitis. This move signals a significant step forward for a potentially first-in-class oral therapy aimed at rebalancing the immune system, offering new hope to the more than 200 million people worldwide affected by the chronic inflammatory skin disease.

The advancement into a Phase 1b study follows promising results from a trial in healthy volunteers, which not only showed the drug was safe but also provided the first clinical evidence of its immunomodulatory activity.

The Burdensome Landscape of Atopic Dermatitis

Atopic dermatitis, commonly known as eczema, is far more than a simple skin rash. For millions, it is a relentless cycle of intense itching (pruritus), painful and inflamed skin, and significant sleep disruption that profoundly impacts quality of life. The global market for atopic dermatitis treatments reflects the scale of this need, with estimates placing its value at over $17 billion in 2024 and projecting it to approach $30 billion by the early 2030s.

Current treatment follows a tiered approach. Mild cases are often managed with moisturizers and topical steroids. However, for patients with moderate to severe disease, the options become more complex and invasive. The last decade has seen the rise of highly effective injectable biologics, such as Dupixent (dupilumab), which target specific inflammatory pathways. More recently, oral Janus kinase (JAK) inhibitors, including Rinvoq (upadacitinib) and Cibinqo (abrocitinib), have offered a convenient pill-based alternative.

Despite these breakthroughs, significant unmet needs persist. Not all patients respond to existing therapies, and some struggle with side effects. The JAK inhibitor class, for example, carries regulatory warnings regarding serious infections and other potential risks. Above all, there is a profound need for treatments that can deliver not just temporary relief, but durable, long-term disease remission—a therapy that modifies the underlying disease rather than just suppressing its symptoms.

A New Frontier: Targeting Cellular Metabolism

Sitryx's SYX-5219 represents a fundamentally different approach. It is a first-in-class oral modulator of pyruvate kinase M2 (PKM2), a key enzyme in the central metabolic pathway of glycolysis. While PKM2's role in cellular energy is well-known, recent research has revealed its critical function in regulating immune cell activation and inflammation. In conditions like atopic dermatitis, PKM2 is overexpressed in inflamed tissues and immune cells, helping to fuel the pro-inflammatory response.

By modulating PKM2, SYX-5219 aims to reprogram the metabolic state of key immune cells, such as T lymphocytes and mast cells. This novel mechanism is designed to broadly rebalance immune function, thereby reducing inflammation, alleviating the maddening itch, and promoting the repair of the skin's protective barrier. This strategy moves away from the direct cytokine or pathway blockade of current biologics and JAK inhibitors, targeting the metabolic engine of the inflammatory process itself.

The novelty of this science is a key point of excitement for experts in the field. Alan Irvine, MD, DSc, Professor of Dermatology at Trinity College Dublin and the trial’s Principal Investigator, commented on the drug's potential. “The science behind PKM2 modulation as a target for atopic dermatitis therapy is compelling," he stated in the company's announcement. He noted that the new data aligns with preclinical findings "showing reduction of inflammatory markers and drivers of itch, and enhancement of repair of the skin barrier, all supporting its potential as a novel, disease-modifying approach in atopic dermatitis.”

Promising Early Signals from Clinical Data

The decision to advance SYX-5219 into patients was underpinned by a successful Phase 1a clinical trial in healthy volunteers. The study demonstrated that the oral drug was safe and well-tolerated, with predictable pharmacology and evidence of robust target engagement.

Crucially, the trial also yielded compelling biomarker data. Participants showed a dose-dependent reduction in CCL17, a chemokine also known as TARC (thymus and activation-regulated chemokine). TARC is widely recognized as a reliable and sensitive biomarker for type 2 inflammation, the immunological process at the heart of atopic dermatitis. Its levels in the blood have been shown to correlate directly with disease severity and treatment response across numerous clinical programs for other atopic dermatitis drugs. A reduction in TARC is therefore a strong early indicator that a drug is having its intended biological effect.

Ravi Rao, Chief Medical Officer of Sitryx, emphasized the importance of this finding. “Our latest clinical data for SYX-5219, particularly the strong reduction in the highly disease-relevant Type 2 inflammation biomarker TARC, give us further confidence in the candidate’s differentiated profile,” he said. “A daily oral treatment to rebalance immune function and deliver durable disease remission would be transformative for the treatment of atopic dermatitis.”

The Path Forward: High Stakes and Investor Confidence

With the first patients now dosed, the Phase 1b trial will evaluate the safety, tolerability, and initial efficacy of SYX-5219 in up to 45 adults with moderate to severe atopic dermatitis across sites in the United States and Europe. The company anticipates receiving initial data from this pivotal patient study by the end of the year. In parallel, a KLH antigen-challenge study is underway in healthy volunteers to further assess the drug's impact on early immune response signals.

The progress has been watched closely by the investment community. Sitryx, headquartered in Oxford, UK, with a presence in Boston, is backed by a syndicate of high-profile specialist investors, including SV Health Investors, Sofinnova Partners, and the corporate venture arms of pharmaceutical giants Eli Lilly and Company and GSK. This strong financial backing from both venture capital and strategic corporate partners signals significant confidence in the company's scientific platform and the market potential of its pipeline.

The road ahead is long and challenging. The bar for new atopic dermatitis therapies is high, and SYX-5219 will ultimately need to demonstrate a compelling profile of efficacy and long-term safety to compete with established blockbuster drugs. However, by pursuing a novel mechanism with disease-modifying potential in a convenient oral form, Sitryx is aiming not just to compete, but to redefine the standard of care for millions of patients waiting for a more fundamental solution.