Cullinan Therapeutics Shares Additional Preclinical B Cell Depletion Data for CLN-978, Supporting Clinical Development Across Multiple Autoimmune Diseases, at ACR Convergence 2025

CLN-978 led to rapid and deep B cell depletion in vitro and in vivo in multiple autoimmune diseases

CAMBRIDGE, Mass., Oct. 25, 2025 (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, will present new preclinical data for CLN-978, its novel investigational CD19xCD3 bispecific T cell engager. These data will be presented at the American College of Rheumatology (ACR) Convergence 2025, being held in Chicago, Illinois, October 24-29, in a poster presentation session on October 28, 10:30 a.m.-12:30 p.m. CT (Poster Session C, Poster Number 2293). Cullinan will also have a Booth (#1074) in the Exhibit Hall.

New in vitro preclinical data show CLN-978 robustly and specifically depleted target B cells while activating T cells in human peripheral blood mononuclear cells (PBMC) derived from patients with rheumatoid arthritis (RA), Sjögren's disease (SjD), or systemic lupus erythematosus (SLE). These effects were similar to those observed with PBMCs from healthy donors.

Dose-dependent B cell depletion was observed following subcutaneous administration of CLN-978 in nonhuman primates (NHPs). Doses of CLN-978 considered well tolerated in the NHPs achieved deep and sustained B cell depletion in blood and multiple tissues including bone marrow and lymph nodes, suggesting the potential to achieve meaningful B cell depletion in patients.

In a murine model of SLE, CLN-978 treatment led to a reduction in circulating B cells, levels of anti-dsDNA IgG, and IgG deposition in the kidney, indicating a disease-modifying effect in both peripheral blood and affected disease tissues.

“We continue to generate preclinical data that reinforce the potential of CLN-978 as a highly potent T cell engager designed to deplete B cells deeply across multiple autoimmune diseases,” said Jeffrey Jones, MD, MBA, Chief Medical Officer, Cullinan Therapeutics. “In parallel, we are advancing our global clinical programs in rheumatoid arthritis, Sjögren’s disease, and systemic lupus erythematosus, recognizing the significant unmet needs for people living with these diseases. Current therapies are typically limited to addressing disease symptoms whereas CLN-978 has the potential to modify the underlying pathophysiology of the disease itself.”

Cullinan is advancing the global clinical development of CLN-978 through its OUTRACE studies across RA ( NCT06994143 ), SjD ( NCT07041099 ), and SLE ( NCT06613360 ), with active trials now underway across all three indications and in multiple countries.

About CLN-978 CLN-978 is a novel, differentiated and highly potent CD19xCD3 bispecific T cell engager. CLN-978 triggers 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 serum 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 living with autoimmune diseases and is being studied in Cullinan’s OUTRACE studies for patients with rheumatoid arthritis, Sjögren’s disease, and systemic lupus erythematosus. CLN-978 is investigational and has not been approved by any health authority.

About Cullinan Therapeutics Cullinan Therapeutics, Inc. (Nasdaq: CGEM) is a biopharmaceutical company developing potential first- or best-in-class, high-impact therapies for autoimmune diseases and cancer. Cullinan pursues promising therapeutic targets while leveraging core expertise in T cell engagers, which are established in oncology and are now advancing into autoimmune diseases. With a clinical-stage pipeline built on a rigorous scientific approach and purposeful innovation, Cullinan is advancing its mission to deliver new standards of care for patients. Learn more about Cullinan at https://cullinantherapeutics.com/ , and follow Cullinan on LinkedIn and X .

Forward Looking Statements This press release contains forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995. These forward-looking statements include, but are not limited to, express or implied statements regarding the company’s beliefs and expectations regarding: future data presentations, our preclinical and clinical developments plans and timelines for CLN-978, the clinical and therapeutic potential of CLN-978, and other statements that are not historical facts. The words “believe,” “continue,” “could,” “estimate,” “expect,” “intends,” “may,” “plan,” “potential,” “project,” “pursue,” “will,” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words.

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