Cullinan Aims for Autoimmune 'Reset' with T Cell Engager Data

CAMBRIDGE, Mass. – June 10, 2026 – Cullinan Therapeutics (Nasdaq: CGEM) today unveiled compelling clinical data that could signal a paradigm shift in the treatment of severe autoimmune diseases. The company reported promising results for two T cell engager (TCE) therapies, CLN-978 and velinotamig, in patients with hard-to-treat systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). The findings, presented during the company's Immunology Day event, suggest these therapies may offer more than just symptom management, aiming instead for a deep “immune reset” that could lead to durable, treatment-free remissions.

For millions living with chronic autoimmune conditions, the standard of care often involves a lifetime of immunosuppressive drugs that manage symptoms but rarely alter the disease's fundamental course. Cullinan is challenging this reality by repurposing a powerful cancer-fighting technology to target the root cause of these conditions, offering hope to patients who have exhausted other options.

A New Paradigm: The Promise of 'Immune Reset'

The central promise of Cullinan's approach lies in the concept of an “immune reset.” Unlike traditional therapies that broadly dampen the immune system, T cell engagers are designed to selectively eliminate the specific B cells and plasma cells that produce pathogenic autoantibodies. The goal is a profound but transient depletion, creating an opportunity for the immune system to repopulate with healthy, non-autoreactive cells, potentially re-establishing self-tolerance and leading to long-lasting remission without the need for continuous medication.

This strategy represents a significant departure from the chronic management model. “We continue to build strong momentum across our T cell engager portfolio and are highly encouraged by the compelling data,” said Nadim Ahmed, President and Chief Executive Officer of Cullinan Therapeutics. “These data support the potential for CLN-978 to deliver durable, treatment-free remissions in the community out-patient setting, representing a meaningful shift in how these diseases may be managed.”

Data for CLN-978, which targets the CD19 protein on B cells, showed deep, dose-dependent B cell depletion not only in the blood but also in tissues like lymph nodes and the synovium—the lining of the joints inflamed in rheumatoid arthritis. This thorough cleansing of pathogenic cells is the mechanistic underpinning of the immune reset hypothesis.

The Science Behind the Shift

T cell engagers are bispecific antibodies that act as a bridge, connecting a patient's own T cells (the immune system's killers) directly to a target cell, instructing the T cell to destroy it. This technology has proven highly effective in oncology, and its application in autoimmunity is a major area of innovation.

Cullinan is pursuing a two-pronged strategy with complementary assets:

• CLN-978 (CD19xCD3): This therapy targets CD19, a protein found on the surface of most B cells. By eliminating these cells, it aims to halt the production of a wide range of autoantibodies involved in diseases like RA and SLE. Notably, CLN-978 is a small (65 kDa) molecule engineered for subcutaneous injection. This “off-the-shelf” convenience and potential for outpatient administration stands in contrast to more complex cell therapies like CAR-T, which require individualized manufacturing.
• Velinotamig (BCMAxCD3): This agent targets BCMA, a protein expressed on long-lived plasma cells. These cells are mature, antibody-producing factories that are often culprits in autoantibody-driven diseases and may not be effectively eliminated by therapies that only target earlier-stage B cells. Velinotamig is therefore being developed for conditions like lupus nephritis and autoimmune cytopenias.

A critical factor in adapting this technology from oncology is safety. The severe side effects sometimes seen in cancer treatment, such as cytokine release syndrome (CRS) and neurotoxicity (ICANS), have been a major question. Cullinan's data provides early reassurance. Most CRS events with CLN-978 were low-grade, and initial data for velinotamig showed no CRS or ICANS at all, suggesting a more favorable safety profile in the autoimmune setting.

Decoding the Data: Clinical Signals and Cautious Optimism

While the patient numbers are small, as expected in early-phase trials, the clinical activity reported is significant. The studies enrolled heavily pretreated patients, many of whom had failed multiple prior therapies and were taken off all background immunosuppressants before receiving treatment—a high bar for efficacy.

For CLN-978, the results in the OUTRACE RA and SLE trials were striking. In a patient with poly-refractory rheumatoid arthritis—a notoriously difficult-to-treat condition—a multi-dose regimen led to clinical remission. The patient’s disease activity score (DAS28-ESR) dropped from 4.0 at baseline to 2.2 by week four, a level maintained through the eight-week follow-up. This clinical improvement was accompanied by a rapid reduction in RA-associated autoantibodies.

In patients with lupus, clinical observations included rapid improvements in proteinuria, a marker of kidney damage, supporting the company's plan to specifically evaluate CLN-978 in lupus nephritis.

The initial data for velinotamig in two refractory lupus patients with severe kidney involvement was equally compelling. Both patients achieved a complete renal response, with their disease activity scores (SLEDAI-2K) plummeting from 16 and 14 at baseline to 0 and 2, respectively, by week eight. These clinical improvements correlated directly with the drug's expected pharmacodynamic effects.

Despite the exciting results, experts caution that the data is interim and based on a limited number of patients. Longer-term follow-up in larger, randomized trials will be essential to confirm the durability of these remissions and the broader applicability of the safety and efficacy findings.

Charting the Course Forward

Cullinan has laid out an aggressive development timeline to build on this momentum. The company plans to report additional multi-dose data for CLN-978 in RA in the third quarter of 2026, followed by SLE data in the fourth quarter. For velinotamig, more data from a trial in China is expected before the end of the year.

Looking ahead to 2027, the company plans to initiate a Phase 2a expansion study of CLN-978 specifically for patients with lupus nephritis. It will also launch a Phase 1/2a basket trial for velinotamig in patients with autoimmune cytopenias—rare blood disorders like ITP and AIHA with high unmet need.

With a market for autoimmune diseases characterized by large patient populations and a significant need for more effective therapies, Cullinan’s strategy to address the full spectrum of B cell- and plasma cell-driven diseases positions it as a key player in this emerging therapeutic space. If the promise of durable, treatment-free remission holds true in larger studies, these T cell engagers could truly redefine the standard of care for patients battling severe autoimmune disease.