Quell Therapeutics to Unveil Promising Data for QEL-005, a Novel CAR-Treg Cell Therapy for Complex Autoimmune Diseases, at ACR Convergence 2025

• Results from pre-clinical studies demonstrate immunomodulatory activity of QEL-005 across multiple immune cell lineages involved in complex autoimmune inflammation, including B cells, T cells and inflammatory macrophages
• Broad mechanism of action of QEL-005 provides clear product differentiation compared to CAR-T and other B-cell depletion approaches, offering a potentially safer and better tolerated therapeutic option
• Data being presented supports CTA filings in Q4 ahead of initiating the CHILL clinical study in H1 2026 in patients with Rheumatoid Arthritis and Systemic Sclerosis

London, UK – 25 October, 2025 – Quell Therapeutics Ltd (“Quell”), a pioneer in engineered T-regulatory (Treg) cell therapies for people with immune-mediated diseases, will present promising data from pre-clinical studies of QEL-005 that highlight its potential to treat complex autoimmune inflammatory diseases, such as Rheumatoid Arthritis (RA) and Systemic Sclerosis (SSc), at the American College of Rheumatology annual meeting (ACR Convergence 2025) to be held in Chicago, IL from 24–29 October.

QEL-005 is a novel CAR-Treg product candidate, designed using Quell’s multi-modular engineered Treg platform, incorporating the proprietary Foxp3 Phenotype Lock™ and targeted to be activated in both the inflamed tissue and lymph nodes. Utilizing a CD19 CAR, the QEL-005 CAR-Tregs are activated via B cells present and are designed to modulate multiple pathogenic immune cells via a bystander mechanism of action in both tissue compartments.

The data being presented demonstrate the broad mechanism of action of QEL-005 CAR-Tregs, including suppression of T cell activity, modulation of B cell activity and antibody production, as well as modulation of other immune cells in the inflamed niche, such as disease-associated inflammatory macrophages. QEL-005’s non-cytolytic MoA to control a breadth of immune cell types (‘chill not kill’) is highly differentiated from CAR-T and other B-cell depletors and offers potentially a much safer and better tolerated therapeutic option.

Nathalie Belmonte PhD, SVP Research and Product Development, commented: “These exciting new data demonstrate the unique ability of QEL-005 to control the pro-inflammatory effects of multiple immune cell types, with a single CAR-Treg cell therapy. This includes modulation of pro-inflammatory macrophages into a pro-resolution phenotype. These mechanisms of QEL-005 are highly differentiated from conventional CD19-focused CAR-T approaches that target only the B-cell compartment and will be crucial in developing the next generation of therapies for complex autoimmune diseases such as RA and SSc, which are driven by multiple immune pathways. Our focus now is on completing our CTA regulatory applications necessary to advance QEL-005 into clinical development in H1 2026.”

Details of the presentation are:

• Abstract title: QEL-005: CD19 CAR-Regulatory T cell therapy, a novel approach for the treatment of complex immune mediated inflammatory diseases including Rheumatoid Arthritis and Systemic Sclerosis
• Abstract Number: 0006
• Date & Time: Sunday, October 26, 2025, 10:30 am – 12:30 pm Central Time
• Poster Session: (0001–0018) B Cell Biology & Targets in Autoimmune & Inflammatory Disease Poster I
• Room: Hall F1
• Presenter: Jenny McGovern, Director / Non-Clinical Group Leader at Quell Therapeutics

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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 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 pipeline includes QEL-001 currently being investigated in the Phase 1/2 LIBERATE clinical trial designed to investigate its ability to induce operational tolerance following liver transplantation; and QEL-005, a pipeline-in-a-product for complex rheumatic autoimmune diseases that 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. www.quell-tx.com.

Contacts

Luke Henry, Chief Business Officer
Quell Therapeutics
IR@quell-tx.com

Media: Mark Swallow, Sandi Greenwood, Erica Hollingsworth
MEDiSTRAVA
Quell-Tx@Medistrava.com

Investors: Corey Davis
LifeSci Advisors
cdavis@lifesciadvisors.com