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

Rhea-AI Summary

Cullinan Therapeutics (Nasdaq: CGEM) will present initial Phase 1 clinical data for CLN-978, a subcutaneous CD19xCD3 T cell engager, at the EULAR 2026 Congress in London on June 3-6, 2026.

Data from the OUTRACE RA and OUTRACE SLE studies in treatment-refractory rheumatoid arthritis (RA) and moderate to severe systemic lupus erythematosus (SLE) show single target doses with a favorable safety profile at initial dose levels, robust B cell depletion in blood and tissue, and early signals of clinical activity. Updated data, including additional patients, will be shared in Poster POS1179 on June 6, 2026.

AI-generated analysis. Not financial advice.

Key Figures

Conference dates: June 3–6, 2026 Session date: June 6, 2026 Session time: 10:15–11:15 a.m. BST +3 more

6 metrics

Conference dates June 3–6, 2026 EULAR European Congress of Rheumatology in London

Session date June 6, 2026 Poster View VIII session for CLN-978 data

Session time 10:15–11:15 a.m. BST EULAR 2026 Poster View VIII slot for CLN-978

Poster number POS1179 CLN-978 RA and SLE poster at EULAR 2026

Trial phase Phase 1 OUTRACE RA and OUTRACE SLE studies of CLN-978

Congress year 2026 EULAR European Congress of Rheumatology

Market Reality Check

Price: $14.87 Vol: Volume 1,940,864 is 2.29x...

high vol

$14.87 Last Close

Volume Volume 1,940,864 is 2.29x the 20-day average (848,907), indicating elevated interest pre-EULAR data. high

Technical Shares at $14.87 trade above the 200-day MA $10.65, sitting 11.17% below the $16.74 52-week high and 161.8% above the $5.68 low.

Peers on Argus

CGEM fell 2.6% while peers were mixed: AUTL +11.11%, LXRX -3.6%, PRTC -4.62%, IN...

3 Up 1 Down

CGEM fell 2.6% while peers were mixed: AUTL +11.11%, LXRX -3.6%, PRTC -4.62%, INBX -2.61%. Momentum scanner flagged PRTC, LXRX, AUTL, FULC with no same-day news theme, suggesting stock-specific trading rather than a coordinated biotech move.

Previous Clinical trial Reports

5 past events · Latest: Apr 28 (Positive)

Same Type Pattern 5 events

Date	Event	Sentiment	Move	Catalyst
Apr 28	NDA acceptance	Positive	-3.3%	FDA accepted zipalertinib NDA for EGFR ex20ins NSCLC with set PDUFA date.
Dec 08	AML trial update	Positive	+17.5%	Phase 1 CLN-049 AML data at ASH showed meaningful CR rates and manageable safety.
Dec 01	Fast Track status	Positive	-5.5%	CLN-049 received FDA Fast Track for R/R AML based on promising early efficacy.
Nov 20	Rolling NDA start	Positive	+3.2%	Initiated rolling NDA for zipalertinib in EGFR ex20ins NSCLC leveraging REZILIENT1 data.
Oct 25	Preclinical CLN-978 data	Positive	+3.9%	Preclinical CLN-978 data showed robust B cell depletion across autoimmune models.

Pattern Detected

Clinical and regulatory catalysts often trigger sharp but inconsistent moves: several positive trial or NDA milestones have seen both strong rallies and notable selloffs.

Recent Company History

Over the past months, CGEM has steadily advanced a multi-asset pipeline. Clinical-trial news has included zipalertinib NDA milestones and CLN‑049 AML data, with moves ranging from -5.45% to +17.47%. For CLN‑978 specifically, preclinical B‑cell depletion data on Oct 25, 2025 was followed by a 3.87% gain. Today’s initial Phase 1 CLN‑978 readout for refractory RA and SLE at EULAR 2026 extends that narrative from preclinical promise toward early human proof-of-concept.

Historical Comparison

+3.1% avg move · Historically, CGEM’s clinical-trial headlines have produced an average move of 3.15%, with reactions...

clinical trial

+3.1%

Average Historical Move clinical trial

Historically, CGEM’s clinical-trial headlines have produced an average move of 3.15%, with reactions ranging from negative on regulatory wins to strong rallies on CLN‑049 data. The CLN‑978 EULAR update fits this pattern of data-driven autoimmune and oncology catalysts.

Clinical-trial news shows a pipeline progressing from preclinical CLN‑978 B‑cell depletion data in 2025 to today’s initial Phase 1 RA and SLE results, alongside CLN‑049 AML updates and zipalertinib NDA milestones, indicating parallel advancement across autoimmune and oncology programs.

Regulatory & Risk Context

Active S-3 Shelf · $200,000,000

Shelf Active

Active S-3 Shelf Registration 2026-04-28

$200,000,000 registered capacity

An effective Form S-3ASR allows CGEM to sell up to $200,000,000 of common stock via an at-the-market program with TD Securities (USA) LLC, providing flexible access to capital for R&D, clinical trials, in-licensing and acquisitions.

Market Pulse Summary

This announcement advances CLN‑978 from preclinical promise toward initial Phase 1 data in refractor...

Analysis

This announcement advances CLN‑978 from preclinical promise toward initial Phase 1 data in refractory rheumatoid arthritis and systemic lupus erythematosus, with early signs of safety and B‑cell depletion. It builds on prior CLN‑978 and CLN‑049 updates and follows zipalertinib’s NDA milestones. Investors may watch for full EULAR 2026 data, further autoimmune readouts through 2026, and how the company uses its $200,000,000 ATM capacity to support ongoing trials.

Key Terms

cd19xcd3 t cell engager, systemic lupus erythematosus, rheumatoid arthritis, b cell depletion, +2 more

6 terms

cd19xcd3 t cell engager medical

"CLN-978, a subcutaneously administered CD19xCD3 T cell engager, will be presented"

A CD19xCD3 T cell engager is a type of engineered antibody that physically links CD19, a marker on B cells, to CD3, a protein on T cells, guiding a patient’s immune cells to attack and kill targeted B cells such as those in certain blood cancers. For investors, these drugs matter because their clinical effectiveness, safety profile and regulatory approval determine potential market size and revenue, while manufacturing complexity and side effects drive development risk—think of it as bringing the shooter and target together to increase aim but raising safety and production challenges.

systemic lupus erythematosus medical

"moderate to severe systemic lupus erythematosus (SLE), respectively."

Systemic lupus erythematosus is a chronic autoimmune disease in which the body's immune system mistakenly attacks healthy tissue, causing inflammation that can affect skin, joints, kidneys, heart, lungs and other organs. It matters to investors because disease severity, prevalence, and gaps in effective treatments drive demand for new drugs and diagnostics—think of it as a large, persistent market need where a successful therapy can change patient outcomes and create significant commercial value.

rheumatoid arthritis medical

"patients with active, treatment-refractory rheumatoid arthritis (RA) and moderate"

A long-term autoimmune disease that causes the immune system to mistakenly attack the lining of joints, leading to pain, swelling, stiffness and progressive joint damage; it can also affect other organs. For investors, it matters because the condition drives sustained demand for treatments, influences clinical trial and regulatory outcomes, and affects healthcare spending and workplace disability—so drug approvals, new therapies or cost shifts can materially change the market value of companies involved.

b cell depletion medical

"Robust B cell depletion in both peripheral blood and tissue was observed"

B cell depletion is a medical treatment or effect that reduces the number of B lymphocytes, a type of white blood cell responsible for making antibodies. Think of it as temporarily thinning out a specific unit in the immune system’s army to reduce harmful activity; this can control autoimmune diseases or blood cancers but raises infection risk. Investors track it because drugs or therapies that cause B cell depletion can drive sales, shape clinical trial outcomes, and influence safety, regulatory approval, and long‑term market uptake.

phase 1 medical

"initial clinical data from two ongoing Phase 1 studies evaluating CLN-978"

Phase 1 is the first stage of testing a new drug or medical treatment in people, focused primarily on safety, how the body handles the product, and finding a tolerated dose. Think of it as a short, tightly controlled experiment with a small group to check for dangerous side effects before wider testing; for investors it is an early milestone that reduces some uncertainty but still carries high risk and potential for both big value changes and setbacks.

t cell engager medical

"CLN-978, a subcutaneously administered CD19xCD3 T cell engager, will be presented"

A T cell engager is an engineered protein drug that physically links a patient’s T cell — the immune system’s attack cell — to a diseased cell so the T cell will recognize and kill it. For investors it matters because clinical trial results, manufacturing success and safety profiles determine whether the therapy becomes a widely adopted, high-value treatment or a costly failure; think of it like a matchmaker that must reliably bring soldiers to the right target without triggering friendly fire.

AI-generated analysis. Not financial advice.

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.

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: the efficacy and safety data from the Company’s ongoing Phase 1 OUTRACE RA and OUTRACE SLE clinical trials; our clinical development plan and timeline for CLN-978, the clinical and therapeutic potential of CLN-978, our plans regarding future data presentations, and other statements that are not historical facts. The clinical trials referenced in this release are ongoing, and the data described are interim, subject to change, and based on data available as of a specified date. As patient enrollment continues and additional follow-up data is obtained, the reported safety profile and other clinical outcomes may change materially. There can be no assurance that the interim results will be predictive of final study results or that additional data will confirm or support these observations. 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.

Any forward-looking statements in this press release are based on management's current expectations and beliefs of future events and are subject to known and unknown risks and uncertainties that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. These risks include, but are not limited to, the following: uncertainty regarding the timing and results of regulatory submissions; the risk that any INDs, NDAs or other global regulatory submissions we may file with the United States Food and Drug Administration or other global regulatory agencies are not cleared on our expected timelines, or at all; the success of our clinical trials and preclinical studies; the risks related to our ability to protect and maintain our intellectual property position; the risks related to manufacturing, supply, and distribution of our product candidates; the risk that any one or more of our product candidates, including those that are co-developed, will not be successfully developed and commercialized; the risk that the results of preclinical studies or clinical studies will not be predictive of future results in connection with future studies; and the success of any collaboration, partnership, license or similar agreements. These and other important risks and uncertainties discussed in our filings with the Securities and Exchange Commission, including under the caption “Risk Factors” in our most recent Annual Report on Form 10-K and subsequent filings with the SEC, could cause actual results to differ materially from those indicated by the forward-looking statements made in this press release. While we may elect to update such forward-looking statements at some point in the future, we disclaim any obligation to do so, even if subsequent events cause our views to change, except to the extent required by law. These forward-looking statements should not be relied upon as representing our views as of any date subsequent to the date of this press release. Moreover, except as required by law, neither the company nor any other person assumes responsibility for the accuracy and completeness of the forward-looking statements included in this press release. Any forward-looking statement included in this press release speaks only as of the date on which it was made.

Contacts:

Investors
Nick Smith
+1 401.241.3516
Nsmith@cullinantx.com

Media
Rose Weldon
+1 215.801.7644
Rweldon@cullinantx.com

1. World Health Organization. (2023). Rheumatoid arthritis. https://www.who.int/news-room/fact-sheets/detail/rheumatoid-arthritis
2. Johns Hopkins Arthritis Center. Rheumatoid Arthritis Signs and Symptoms. Rheumatoid Arthritis Symptoms: Johns Hopkins Arthritis Center 
3. Hunter, T. M., et al. (2017). Prevalence of rheumatoid arthritis in the United States adult population in healthcare claims databases, 2004–2014. Rheumatology International, 37(9), 1551–1557. https://doi.org/10.1007/s00296-017-3726-1
4. Guillemin, F., et al. (2005). Prevalence of rheumatoid arthritis in France: 2001. Annals of the Rheumatic Diseases, 64(10), 1427–1430. https://doi.org/10.1136/ard.2004.029199 
5. Steffen, A., et al. (2017). Epidemiologie der rheumatoiden Arthritis in Deutschland – eine Analyse anhand bundesweiter vertragsärztlicher Abrechnungsdaten. Zentralinstitut für kassenärztliche Versorgung in Deutschland, (17), 1–20. https://doi.org/10.20364/VA-17.08 
6. Rossini, M., et al. (2014). Prevalence and incidence of rheumatoid arthritis in Italy. Rheumatology International, 34(5), 659–664. https://doi.org/10.1007/s00296-014-2974-6 
7. Fina-Aviles, F., et al. (2016). The descriptive epidemiology of rheumatoid arthritis in Catalonia: A retrospective study using routinely collected data. Clinical Rheumatology, 35(3), 751–757. https://doi.org/10.1007/s10067-014-2801-1 
8. Abhishek, A., et al. (2017). Rheumatoid arthritis is getting less frequent: Results of a nationwide population-based cohort study. Rheumatology (United Kingdom), 56(5), 736–744. https://doi.org/10.1093/rheumatology/kew468 
9. Kojima, M., et al. (2019). Epidemiological characteristics of rheumatoid arthritis in Japan: Prevalence estimates using a nationwide population-based questionnaire survey. Modern Rheumatology. Advance online publication. https://doi.org/10.1080/14397595.2019.1682776 
10. Ackerman, I. N., et al. (2018). Projected burden of osteoarthritis and rheumatoid arthritis in Australia: A population-level analysis. Arthritis Care & Research, 70(6), 877–883. https://doi.org/10.1002/acr.23414 
11. Radu, A. F., & Bungau, S. G. (2021). Management of rheumatoid arthritis: An overview. Cells, 10(11), 2857. https://doi.org/10.3390/cells10112857
12. Mahajan, A. et al. (2020). Systemic lupus erythematosus, lupus nephritis and end-stage renal disease: A pragmatic review mapping disease severity and progression. Lupus, 29(9), 1011–1020. https://doi.org/10.1177/0961203320932219
13. Hocaoglu, M. et al. (2023). Incidence, prevalence, and mortality of lupus nephritis: A population-based study over four decades using the Lupus Midwest Network. Arthritis & Rheumatology, 75(4), 567–573. https://doi.org/10.1002/art.42375
14. Tian, J. et al. (2022). Global epidemiology of systemic lupus erythematosus: A comprehensive systematic analysis and modelling study. Annals of the Rheumatic Diseases, 82(3), 351–356. https://doi.org/10.1136/ard-2022-223035
15. Dall’Era, M. (2013). Chapter 21. Systemic lupus erythematosus. In J. B. Imboden, D. B. Hellmann, & J. H. Stone (Eds.), CURRENT Diagnosis & Treatment: Rheumatology (3rd ed.). McGraw-Hill. https://accessmedicine.mhmedical.com/content.aspx?aid=57272268
    

FAQ

What did Cullinan Therapeutics (CGEM) announce about CLN-978 at EULAR 2026?

Cullinan Therapeutics will present initial Phase 1 data for CLN-978 in rheumatoid arthritis and systemic lupus erythematosus at EULAR 2026. According to Cullinan Therapeutics, the abstract describes favorable safety at initial dose levels, robust B cell depletion, and early signals of clinical activity.

When and where will Cullinan Therapeutics present CLN-978 data at the EULAR 2026 Congress?

Cullinan Therapeutics will present CLN-978 data at the EULAR 2026 Congress in London on June 6, 2026. According to Cullinan Therapeutics, the poster session runs from 10:15 a.m. to 11:15 a.m. BST under Poster View VIII, Poster Number POS1179.

What diseases are targeted in Cullinan Therapeutics' CLN-978 Phase 1 OUTRACE studies?

The CLN-978 Phase 1 OUTRACE studies target treatment-refractory rheumatoid arthritis and moderate to severe systemic lupus erythematosus. According to Cullinan Therapeutics, OUTRACE RA evaluates patients with active RA, while OUTRACE SLE focuses on patients with moderate to severe SLE receiving the subcutaneous T cell engager.

What early clinical signals were observed with CLN-978 in RA and SLE patients?

Early signals of promising clinical activity were observed with CLN-978 in patients with RA and SLE. According to Cullinan Therapeutics, the abstract notes robust B cell depletion in both peripheral blood and tissue, alongside these initial signs of clinical benefit at early dose levels.

How does CLN-978 affect B cells in Cullinan Therapeutics' Phase 1 trials?

CLN-978 induces robust B cell depletion in patients with rheumatoid arthritis and systemic lupus erythematosus. According to Cullinan Therapeutics, this effect is seen in both peripheral blood and tissue in the Phase 1 OUTRACE RA and OUTRACE SLE studies using subcutaneous administration.

Will Cullinan Therapeutics provide updated CLN-978 data for CGEM investors beyond the published abstract?

Yes, updated CLN-978 data beyond the currently available abstract will be presented at EULAR 2026. According to Cullinan Therapeutics, the update will include additional patients and more detailed safety, B cell depletion, and early clinical activity information during the poster session.