Cullinan Therapeutics to Present Initial Clinical Data for CLN-978 in Treatment-Refractory Rheumatoid Arthritis and Systemic Lupus Erythematosus at EULAR 2026 Congress (Form 8-K)

Cullinan Therapeutics to Present Initial Clinical Data for CLN-978 in Treatment-Refractory Rheumatoid Arthritis and Systemic Lupus Erythematosus at EULAR 2026 Congress

CAMBRIDGE, Mass., May 18, 2026 (GLOBE NEWSWIRE) -- Cullinan Therapeutics, Inc. (Nasdaq: CGEM), a clinical-stage biopharmaceutical company accelerating potential first- or best-in-class, high-impact therapies in autoimmune diseases and cancer, today announced that initial clinical data from two ongoing Phase 1 studies evaluating CLN-978, a subcutaneously administered CD19xCD3 T cell engager, will be presented at the European Alliance of Associations for Rheumatology (EULAR) European Congress of Rheumatology being held June 3-6, 2026 in London, United Kingdom.

The presentation will feature data from the Phase 1 OUTRACE RA and OUTRACE SLE studies which are evaluating CLN-978 in patients with active, treatment-refractory rheumatoid arthritis (RA) and moderate to severe systemic lupus erythematosus (SLE), respectively. The abstract reports that single target doses of CLN-978 demonstrate a favorable safety profile at the initial dose levels. Robust B cell depletion in both peripheral blood and tissue was observed, along with early signals of promising clinical activity in patients with RA and SLE. Updated data beyond the available published abstract, including additional patients, will be presented at the EULAR Congress.

Poster Presentation Details

Title: CLN-978, a bispecific CD19 x CD3 T cell engager, induces robust B cell depletion in patients with rheumatoid arthritis and systemic lupus erythematosus
Session Name: Poster View VIII
Session Date: Saturday, June 6, 2026
Session Time: 10:15 a.m. - 11:15 a.m. BST
Room: Poster View
Poster Number: POS1179

About CLN-978

CLN-978 is a novel, differentiated and highly potent CD19xCD3 bispecific T cell engager. CLN-978 triggers T cell-redirected lysis of CD19-expressing target cells in vitro and in vivo. CLN-978 is engineered to achieve very high affinity binding to CD19 to efficiently target B cells, including those with very low CD19 levels. Small in molecular size (65 kDa), CLN-978 contains two single-chain variable fragments, one binding with very high affinity to the CD19 target and the other binding to CD3 on T cells, and a single-domain antibody binding to human serum albumin to extend half-life. CLN-978 was developed by an internal Cullinan team and is a wholly owned asset. CLN-978 has the potential to offer a convenient, off-the-shelf, subcutaneously delivered therapeutic option for patients with autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, and Sjögren's disease.

About OUTRACE RA and OUTRACE SLE

OUTRACE RA and OUTRACE SLE are global Phase 1 studies of CLN-978 evaluating safety, as well as effects on disease activity and the immune system. Both studies are currently recruiting.

OUTRACE RA enrolls patients with active rheumatoid arthritis (DAS28-ESR ≥3.2) who have been treated with ≥2 prior targeted treatments and have evidence of B cell driven disease. Assessments include DAS28, synovial ultrasound, and optional synovial and lymph node biopsies.

OUTRACE SLE enrolls patients with active systemic lupus erythematosus (hSLEDAI ≥6) who have been treated with at least one biologic or immunosuppressive agent and are seropositive. Assessments include hSLEDAI, CLASI, and physician global assessment.

About Rheumatoid Arthritis (RA)

Rheumatoid arthritis is a chronic autoimmune disease primarily characterized by inflammation of the joints, which can lead to pain, swelling, stiffness, and permanent joint damage.1,2 The disease often affects multiple joints simultaneously, commonly the hands, wrists, and feet, but it can also involve other organ systems.2 Roughly 5.3 million adults live with rheumatoid arthritis across the U.S., France, Germany, Italy, Spain, the UK, Japan, and Australia, and the disease is more common in women than men.3-10 While disease-modifying antirheumatic drugs (DMARDs) have improved treatment outcomes, many patients continue to rely on chronic immunosuppression, have inadequate responses, experience disease flares, and face significant impairments in quality of life.11

About Systemic Lupus Erythematosus (SLE)

Systemic lupus erythematosus (SLE) is a chronic, heterogeneous autoimmune disease in which the immune system attacks a patient's own tissues. The most common manifestations of SLE include skin rashes, arthritis, extreme fatigue, and low fevers. Lupus nephritis (LN) is a kidney disease and the most common severe manifestation of SLE. Approximately 40% of patients with SLE develop LN, which has a 10-year 30% mortality rate.12,13 The prevalence of SLE in the US is estimated at 160,000 to 320,000 cases and SLE affects approximately 3.4 million individuals globally.14,15 SLE is more prevalent in women and people of color. It occurs most often in people between the ages of 15 and 45 years but can occur in childhood or later in life as well. Currently available treatments can reduce the signs and symptoms of SLE; however, they do not routinely induce treatment-free remission, and most patients require lifelong immune suppression that treats symptoms without modifying the course of disease.