Quell Therapeutics Launches Phase 1/2 Trial of Novel CAR-Treg Therapy for Autoimmune Diseases
Key Insights
Quell Therapeutics (search) has initiated the CHILL phase 1/2 trial of QEL-005 (search), an autologous CAR-Treg therapy targeting rheumatoid arthritis (search) and systemic sclerosis (search) across the UK, Germany, and Spain.
The therapy uses a CD19 (search)-directed CAR to restore immune balance by regulating rather than depleting immune cells, distinguishing it from traditional CAR-T therapies that "kill" pathogenic cells.
Early results are expected in early 2027, with the company positioning QEL-005 (search) as a potential "pipeline-in-a-product" for complex autoimmune diseases (search).
UK biotech Quell Therapeutics (search) has launched the CHILL phase 1/2 clinical trial of QEL-005 (search), an autologous CAR-Treg therapy designed for patients with rheumatoid arthritis (search) and systemic sclerosis (search). The multinational study will recruit up to 16 adults across the UK, Germany, and Spain, with enrollment already underway at leading UK centers following approval from the UK Medicines and Healthcare products Regulatory Agency.
The advancement of QEL-005 (search) into clinical testing represents a strategic pivot for the London-headquartered company, which recently paused development of its former lead program QEL-001 for liver transplant rejection (search) after reviewing interim results from a phase 1/2 trial. Quell is now seeking a partner for the transplant project while focusing internal efforts on QEL-005 in diseases characterized by "complex autoimmunity."
Novel Regulatory Approach to Autoimmune Disease
QEL-005 (search) is built on Quell's proprietary phenotype locked CAR-Treg platform and is engineered to activate selectively within inflamed tissues and nearby lymphoid structures. The therapy uses a Treg-optimized CD19 (search)-directed CAR to trigger immune regulation in the presence of B cells, aiming to suppress a range of pro-inflammatory cell types.
Chief executive Iain McGill emphasized the therapy's differentiated approach, stating that the goal with QEL-005 (search) is "to 'CHILL, not KILL' – taking a differentiated therapeutic approach that restores immune balance, rather than relying solely on B-cell depletion." The therapy is based on a CD19 (search) CAR and exerts effects on B-cells, T-cells and inflammatory macrophages.
Professor Christopher Buckley of the University of Oxford-based Kennedy Institute of Rheumatology, the CHILL trial's lead investigator, highlighted the distinction from existing therapies. "CAR-T cells that kill pathogenic cells have emerged as therapies for autoimmune diseases (search), but kill, don't regulate," he said. "We believe that using CAR-Tregs, that are natural tissue regulators, we will be able to achieve deep and durable disease control and achieve a cure."
Preclinical Evidence and Safety Profile
Pre-clinical data presented at the American College of Rheumatology's 2025 meeting showed immunomodulatory activity across multiple immune cell lineages. According to Quell, the breadth of this mechanism distinguishes QEL-005 (search) from CAR-T and other B-cell-depleting therapies.
Additional findings from the company's LIBERATE phase 1/2 trial in liver transplantation demonstrated safety, persistence and functional stability of phenotype locked CAR-Tregs for more than a year. Chief medical officer Dr. Luke Devey noted that "the interim LIBERATE data demonstrate that QEL-001 has been well tolerated to date, with supportive translational evidence of durable in vivo persistence, trafficking to the transplanted liver, and suppressive Treg phenotype."
Clinical Trial Design and Timeline
The CHILL trial is expected to deliver results early next year, with early findings anticipated in early 2027. Professor Georg Schett, principal investigator at the University Hospital Erlangen site, described the therapeutic concept as "mesmerizing," explaining that "providing a stable regulatory immune cell environment at sites of inflammation is a mesmerizing therapeutic concept for chronic inflammatory diseases."
The therapy's site-directed activation approach aims to provide peripheral immune tolerance and intercept autoimmune disease by activating T regulatory cells in B-cell rich lymphatic tissues and sites of inflammation.
McGill noted that the company has positioned QEL-005 (search) as having the potential to become a "pipeline-in-a-product" for complex autoimmune diseases (search), reflecting the therapy's broad mechanism of action across multiple immune cell types including T and B cells, macrophages and proinflammatory fibroblasts.