Quell Therapeutics has begun its chill phase 1/2 clinical trial evaluating QEL‑005, an autologous CAR‑Treg therapy designed for people with rheumatoid arthritis and systemic sclerosis. The move follows approval of the company’s clinical trial application by the UK Medicines and Healthcare products Regulatory Agency.
The multinational study will recruit up to 16 adults across the UK, Germany and Spain, with enrolment already underway at leading UK centres. Early findings are expected in early 2027.
QEL‑005 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‑optimised CD19‑directed CAR to trigger immune regulation in the presence of B cells, aiming to suppress a range of pro‑inflammatory cell types.
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 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.
Iain McGill, chief executive officer of Quell, said: “Initiating the CHILL study with QEL‑005 following CTA approval marks an exciting milestone for Quell and our pre‑clinical package adds to the growing evidence that Tregs can modulate multiple drivers of autoimmune inflammation, including T and B cells, macrophages and proinflammatory fibroblasts.
“With QEL 005, our goal is to ‘CHILL, not KILL’ – taking a differentiated therapeutic approach that restores immune balance rather than relying solely on B cell depletion. This milestone reflects the outstanding dedication of our team and collaborators as we work to deliver durable, transformative therapies for people living with autoimmune diseases.”
Professor Christopher Buckley, chief investigator for the study, explained: “People with Rheumatoid Arthritis and Systemic Sclerosis dream of a cure for their disease. Until now treatments for Immune Mediated Inflammatory Diseases have relied on suppressing inflammation.
“Excitingly, CAR‑T cells which kill pathogenic cells have now emerged as therapies that appear to help reset damaged tissues. However CAR T cells kill, they don’t regulate. 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.”
Professor Georg Schett, principal investigator at the University Hospital Erlangen site, said: “Providing a stable regulatory immune cell environment at sites of inflammation is a mesmerizing therapeutic concept for chronic inflammatory diseases. The idea of activating T regulatory cells in a site‑directed way, in B‑cell rich lymphatic tissues and sites of inflammation, may provide peripheral immune tolerance and intercept autoimmune disease.”
