Quell Therapeutics Ltd.

London, UK – 3 March, 2026 – Quell Therapeutics Ltd (“Quell”), today announced that it has initiated a Phase 1/2 basket clinical study evaluating its autologous CAR-Treg therapy, QEL-005, in patients with Rheumatoid Arthritis and Systemic Sclerosis – the “CHILL” study. Advancement of the QEL-005 program into clinical development follows the recent approval by UK MHRA (Medicines and Healthcare products Regulatory Agency) of the company’s Clinical Trial Application (CTA). CHILL is a multinational clinical study that will recruit up to 16 adult participants in the UK, Germany and Spain, with patient enrolment underway at leading clinical centres across the UK. Early clinical findings are expected during Q1 2027. QEL‑005 is a novel product candidate built on Quell’s proprietary Phenotype Locked™ CAR‑Treg platform. It is designed to be selectively activated and exert immune suppression within inflamed tissues and the surrounding lymphoid structures, providing broad control of disease activity. By leveraging a Treg-optimized CD19‑directed CAR, QEL‑005 CAR-Tregs are activated in the presence of B cells and mediate immune regulation through bystander suppression, modulating pro‑inflammatory T cells, B cells, macrophages and stroma – a unique approach. Results from pre-clinical studies, presented at American College of Rheumatology annual meeting (ACR Convergence 2025) in October 2025 , demonstrated the immunomodulatory activity of QEL-005 across multiple immune cell lineages involved in complex autoimmune inflammation, including B cells, T cells and inflammatory macrophages. QEL-005’s broad mechanism of action clearly differentiates it from CAR‑T and other B‑cell–depletion therapies, offering a safer, better‑tolerated option with potential broader efficacy in more complex autoimmune diseases. In addition, findings from Quell’s LIBERATE Phase 1/2 trial in liver transplantation ( see separate announcement today ) demonstrate the clinical safety, persistence, and functional stability of Quell’s Phenotype Locked™ CAR‑Treg cells for over one year, with evidence of trafficking and engraftment within target tissues in proximity to infiltrating immune cells and molecular drivers of inflammation. Iain McGill, Chief Executive Officer of Quell , commented: “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 pro-inflammatory 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 from the Kennedy Institute of Rheumatology and Chief Investigator for the CHILL study, commented: “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. As Chief Investigator in this study I am delighted to be working with Quell and an amazing team of European Clinician Scientists in the CHILL study that aims for durable cures for our patients.” Professor Georg Schett, Principal Investigator for the University Hospital Erlangen CHILL site , commented: “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." -ENDS- About Complex Autoimmune Inflammatory Diseases Rheumatoid Arthritis (RA) and Systemic Sclerosis (SSc) are autoimmune diseases where a complex interplay of tissue and activated immune cells drives a chronic loop of inflammation resulting in significant tissue damage. B cell depletion approaches highlight the contribution of B cells in such diseases but are limited to targeting a single immune cell type and carry safety and tolerability risks in certain patient populations. Regulatory T cells (Tregs) are key mediators of immune and tissue homeostasis across multiple immune cell populations (T-cells, B-cells, APCs, Macrophages and proinflammatory stroma) with an essential role in restraining autoimmunity. Tregs employ a wide array of mechanisms to mediate this effect and therefore can exert control over multiple immune pathways across a broad range of tissues and cell types. About Quell Therapeutics Quell Therapeutics is the world leader in developing engineered T-regulatory (Treg) cell therapies that aims to harness, direct and optimize their immune suppressive properties to address serious medical conditions driven by the immune system. The Company is leveraging its pioneering Foxp3 Phenotype Lock™ technology, unique multi-modular platform and integrated manufacturing capabilities to design and develop a pipeline of highly engineered Treg cell therapies with greater potential for persistence, potency and stability than earlier generations of Treg cell therapy approaches. Quell’s lead asset QEL-005, a pipeline-in-a-product for complex autoimmune diseases will be initiating clinical development in the Phase 1/2 CHILL clinical trial in H1 2026 . In addition, Quell is advancing two programs in partnership with AstraZeneca: QEL-002 for Type 1 Diabetes and QEL-003 for Inflammatory Bowel Disease. . Contacts Quell Therapeutics IR@quell-tx.com Media: Mark Swallow, Sandi Greenwood, Erica Hollingsworth MEDiSTRAVA Quell-Tx@Medistrava.com

Quell CEO Iain McGill\n Quell Therapeutics is pressing pause on an engineered regulatory T (Treg) cell therapy for liver transplant patients in order to focus resources on a preclinical autoimmune candidate.The London- and Boston-based biotech had been evaluating QEL-001, an autologous engineered CAR-Treg therapy, in a phase 1/2 trial to see whether the candidate can stop organ rejection and end the need for lifelong immunosuppression among liver transplant patients.At one point, the company had touted QEL-001 as a “potentially transformational paradigm for these patients” that could “bring targeted and durable immune tolerance and eliminate their need for chronic immunosuppression.”But Quell has decided to pause the study, according to an quarterly update from life sciences investor Syncona, which owns a 33.7% stake in the biotech.Instead, the capital earmarked for QEL-001 has been rerouted to another CAR-Treg called QEL-005. Quell has previously branded QEL-005 as “pipeline-in-a-product for complex rheumatic autoimmune diseases.”QEL-005 has yet to enter the clinic, although Quell has plans to launch a phase 1 study in patients with rheumatoid arthritis and systemic sclerosis in the first half of this year. Quell describes the approach of QEL-005, which uses a CD19 CAR and is intended to reduce modulating multiple immune cell types rather than simply kill B cells, as “chill not kill.”While QEL-001’s future looks in doubt, Quell said data from the phase 1 study had “provided the company with key insights that de-risk the QEL-005 [program], which could access a potentially larger commercial opportunity.”Syncona noted that the switch in strategy would push back Quell’s key inflection point from this year into 2027, but the investor said it is “encouraged by the technical progress in the field and supports management’s decision to allocate capital to the [program] with the best risk adjusted return.”Quell’s founding hypothesis is that Treg cell therapies can stop immune attacks in a targeted way. The idea combines the role Tregs play in the body, where they calm unwanted immune responses, with CARs like the targeting technology that enables cancer cell therapies.The biotech has found a willing Big Pharma partner in the form of AstraZeneca, which paid $85 million upfront in 2023 to enter into an exclusive option and license agreement for assets in Type 1 diabetes and inflammatory bowel disease.  

Plus, news about Quell Therapeutics, Third Arc, BARDA and ALTx Therapeutics: ⛩️ Eisai teams with Henlius: The Tokyo-based pharma will get the Japanese commercialization rights to the Shanghai biotech’s anti-PD-1 called serplulimab. Henlius’ medicine is approved in China as Hansizhuang and Hetronify in the EU. Eisai will pay $75 million upfront, plus regulatory biobucks of as much as $80 million and sales milestones of up to $233 million. — Kyle LaHucik 🗽 LB Pharmaceuticals lands $100M: The NYC-based biotech secured the private placement from Balyasny Asset Management, Caligan Partners, TCGX and others. The money will help fund a Phase 2 test of its drug LB-102 as an adjunctive treatment for major depressive disorder. The medicine is also expected to enter Phase 3 in schizophrenia and recently entered Phase 2 in bipolar depression. LB went through a $285 million IPO last September. — Kyle LaHucik 🫸 Quell Therapeutics pauses liver transplant drug : The company put the Phase 1/2 LIBERATE study of its engineered CAR-Treg cell therapy QEL-001 on hiatus . Quell will spend the saved cash on developing another asset, the CD19 CAR-Treg QEL-005, for rheumatologic autoimmune diseases. It plans to start a Phase 1/2 trial called CHILL in RA conditions and systemic sclerosis this year, with a readout due in 2027. — Elizabeth Cairns ⛽ Third Arc adds more fuel: The oncology and I&I biotech replenished with a $52 million extension to the $165 million Series A it originally outlined in July 2024. Spring House, PA-based Third Arc is led by former Johnson & Johnson oncology R&D leader Peter Lebowitz. The company recently did a T cell engager deal with China and US biotech Adagene . — Kyle LaHucik 🏆 BARDA’s $100M prize for antiviral drugs: The Biomedical Advanced Research and Development Authority has opened its $100 million fund called the Small Molecule Approaches for Rapid and Robust Treatment (SMART) Antiviral Prize for small molecule antiviral drugs targeting viruses in the Togaviridae and Flaviviridae families. SMART is open to drug development, virology, artificial intelligence, medicinal chemistry and public health experts. The first stage is to submit a concept paper to BARDA outlining plans to discover small molecule antivirals . — Anna Brown 💷 UK cancer startup nets £12.55M: ALTx Therapeutics launched with funding from Syncona, the Francis Crick Institute and Cancer Research Horizons. The startup was founded on work from Crick scientist Simon Boulton. It plans to tackle a pathway some cancers rely on called the Alternative Lengthening of Telomeres, or ALT, pathway. — Lei Lei Wu