# EDGAR Filing Document

**Accession Number:** 0001789972
**File Stem:** 0001193125-26-264916
**Filing Date:** 2026-6
**Character Count:** 35374
**Document Hash:** 1947592e8e3226885d51df0a41016fcb
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-26-264916.hdr.sgml**: 20260610

**ACCESSION NUMBER**: 0001193125-26-264916

**CONFORMED SUBMISSION TYPE**: 8-K

**PUBLIC DOCUMENT COUNT**: 10

**CONFORMED PERIOD OF REPORT**: 20260610

**ITEM INFORMATION**: Regulation FD Disclosure

**ITEM INFORMATION**: Other Events

**ITEM INFORMATION**: Financial Statements and Exhibits

**FILED AS OF DATE**: 20260610

**DATE AS OF CHANGE**: 20260610

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Cullinan Therapeutics, Inc.
- **CENTRAL INDEX KEY:** 0001789972
- **STANDARD INDUSTRIAL CLASSIFICATION:** BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 813879991
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 8-K
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-39856
- **FILM NUMBER:** 261078051

**BUSINESS ADDRESS:**
- **STREET 1:** ONE MAIN STREET
- **STREET 2:** SUITE 1350
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142
- **BUSINESS PHONE:** 617-410-4650

**MAIL ADDRESS:**
- **STREET 1:** ONE MAIN STREET
- **STREET 2:** SUITE 1350
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Cullinan Oncology, Inc.
- **DATE OF NAME CHANGE:** 20210225

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Cullinan Management, Inc.
- **DATE OF NAME CHANGE:** 20210107

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Cullinan Oncology, LLC
- **DATE OF NAME CHANGE:** 20191001

?xml version='1.0' encoding='ASCII'? 8-K

**UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549**

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## FORM 8-K

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**CURRENT REPORT**

**Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934**

**Date of Report (Date of earliest event reported):** June 10, 2026<br>

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CULLINAN THERAPEUTICS, INC.

**(Exact name of Registrant as Specified in Its Charter)**

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| | | |
|:---|:---|:---|
| Delaware | 001-39856 | 81-3879991 |
| **(State or Other Jurisdiction<br>of Incorporation)** | **(Commission File Number)** | **(IRS Employer<br>Identification No.)** |
| One Main Street<br>Suite 1350 |  |  |
| Cambridge**,** Massachusetts |  | 02142 |
| **(Address of Principal Executive Offices)** |  | **(Zip Code)** |

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**Registrant's Telephone Number, Including Area Code:** 617 410-4650<br>

**(Former Name or Former Address, if Changed Since Last Report)**

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Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

**Securities registered pursuant to Section 12(b) of the Act:**

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| | |
|:---|:---|
| **<br>Title of each class** | **<br>Name of each exchange on which registered** |
| Common Stock, $0.0001 par value per share<br> CGEM | The Nasdaq Global Select Market |

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Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

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## Item 7.01 Regulation FD Disclosure.
On June 10, 2026, Cullinan Therapeutics, Inc. (the "Company") issued a press release announcing that the Company is presenting updated clinical data from its Phase 1 OUTRACE clinical trials for CLN-978 in patients with treatment-refractory rheumatoid arthritis ("RA") and treatment-refractory moderate to severe systemic lupus erythematosus ("SLE") and initial data from the Phase 1b/2a clinical trial in velinotamig in patients with treatment-refractory SLE being conducted by Chongqing Genrix Biopharmaceutical Co., Ltd. ("Genrix") in China. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

The information in this report furnished pursuant to Item 7.01, including Exhibit 99.1 attached hereto, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act") or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such filing.

## Item 8.01 Other Events.
*CLN-978*

On June 10, 2026, the Company shared updated clinical data from its Phase 1 OUTRACE clinical trials for CLN-978 in patients with treatment-refractory RA ("OUTRACE RA") and in patients with treatment-refractory moderate to severe SLE ("OUTRACE SLE").

As of May 20, 2026, new multi-dose data in the Phase 1 OUTRACE RA clinical trial demonstrate the robust efficacy profile of CLN-978 observed in two heavily pre-treated, poly-refractory patients, including a DAS28-ESR remission in one patient. A patient refractory to immediate prior rituximab experienced a DAS28-ESR remission, with a baseline disease score of 4.0 quickly reduced to 2.2 at week four and maintained through the latest follow-up at week eight. The achievement of clinical remission in this patient was associated with rapid reduction in RA-associated autoantibodies.

As of May 20, 2026, safety data for the first three patients with SLE treated with a multi-dose regimen in the Phase 1 OUTRACE SLE clinical trial are consistent with the favorable safety profile observed in the initial RA multi-dose cohort presented by the Company at the European Alliance of Associations for Rheumatology 2026 Congress ("EULAR").

Clinical observations in SLE patients with nephritis, notably rapid improvement in proteinuria, support planned evaluation of CLN-978 in patients with lupus nephritis, with Phase 2a expansion expected to begin in early 2027.

The Company plans to report additional multi-dose regimen data for RA in the third quarter of 2026 and for SLE in the fourth quarter of 2026.

*Velinotamig*

On June 10, 2026, the Company shared initial clinical data from the Phase 1b/2a clinical trial for velinotamig in patients with treatment-refractory SLE being conducted by Genrix in China.

As of May 15, 2026, in the first two patients with refractory SLE who had completed treatment with four intravenous doses of velinotamig (3 µg/kg on day 1 followed by three doses of 10 µg/kg), both patients experienced rapid and marked reductions in SLEDAI-2K scores and proteinuria. Both patients achieved complete renal response. The patients' SLEDAI-2K scores were 16 and 14 at baseline, respectively, and at the latest follow-up at week eight were zero and two, respectively. Clinical improvements correlated with pharmacodynamic changes consistent with the mechanism of action of velinotamig. Velinotamig demonstrated a favorable safety profile in both patients, with no cytokine release syndrome or immune effector cell-associated neurotoxicity syndrome observed.

Additional multi-dose regimen data in patients with SLE from the Genrix clinical trial in China are expected be shared in the fourth quarter of 2026. The Company plans to initiate a Phase 1/2a clinical trial in the first quarter of 2027 in patients with autoimmune cytopenias, including immune thrombocytopenia and autoimmune hemolytic anemia, autoantibody-mediated diseases with high unmet need.

**Forward-Looking Statements**

This Current Report on Form 8-K contains forward-looking statements within the meaning of the U.S. Private Securities Litigation Reform Act of 1995. Any statements in this Current Report on Form 8-K that are not historical facts may be considered "forward-looking statements," including statements regarding the initial safety data and observed efficacy from the Company's ongoing Phase 1 OUTRACE RA and OUTRACE SLE clinical trials for CLN-978, the initial safety data and observed efficacy from the ongoing Phase 1 clinical trial in velinotamig, the clinical and therapeutic potential of both CLN-978 and velinotamig, including their therapeutic potential in additional indications, and the Company's clinical development plans and anticipated development timelines for CLN-978 and velinotamig. The clinical trials referenced in this Current Report on Form 8-K are ongoing, and the data described are interim,

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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 clinical trial results or that additional data will confirm or support these observations. Forward-looking statements are typically, but not always, identified by the use of words such as "estimate," "expect," and other similar terminology. Any forward-looking statements in this Current Report on Form 8-K 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 the Company's actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. Such risks and uncertainties include, but are not limited to, uncertainty regarding the timing and results of clinical trial data and regulatory submissions, the risk that any INDs, NDAs or other global regulatory submissions the Company may file with the United States Food and Drug Administration or other global regulatory agencies are not cleared on the Company's expected timelines, or at all, the success of the Company's clinical trials and preclinical studies, the risks related to the Company's ability to protect and maintain the Company's intellectual property position, the risks related to manufacturing, supply, and distribution of the Company's product candidates, the risk that any one or more of the Company's 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 trials will not be predictive of future results in connection with future studies or clinical trials, and the success of any collaboration, partnership, license or similar agreements, along with the risks detailed in the Company's recent filings on Forms 10-K and 10-Q with the Securities and Exchange Commission. While the Company may elect to update such forward-looking statements at some point in the future, the Company disclaims any obligation to do so, even if subsequent events cause its views to change, except to the extent required by law. These forward-looking statements should not be relied upon as representing the Company's views as of any date subsequent to the date of this Current Report on Form 8-K. Any forward-looking statement included in this Current Report on Form 8-K speaks only as of the date on which it was made.

## Item 9.01 Financial Statements and Exhibits.
(d) Exhibits

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| | |
|:---|:---|
| <u>Exhibit No.</u> | <u>Description</u> |
| 99.1 | [<u>Press release issued by Cullinan Therapeutics, Inc. on June 10, 2026, furnished herewith</u>](cgem-ex99_1.htm) |
| 104 | Cover page from this Current Report on Form 8-K, formatted in Inline XBRL |

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**SIGNATURES**

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

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| | | | |
|:---|:---|:---|:---|
|  |  |  | **CULLINAN THERAPEUTICS, INC.** |
| Date: | June 10, 2026 | By:  | /s/ Mary Kay Fenton |
|  |  |  | Mary Kay Fenton<br>Chief Financial Officer |

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## Exhibit 99.1

Exhibit 99.1

**Cullinan Therapeutics Shares New Clinical Data Across Its Portfolio of T Cell Engager Programs Targeting CD19 and BCMA in Autoimmune Diseases** 

*CLN-978 (CD19 TCE) EULAR data demonstrated potential for immune reset, including remissions, in both systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA)*

*CLN-978 data from the first RA multi-dose regimen cohort demonstrated robust efficacy, including clinical remission in a poly-refractory patient, with a favorable safety profile*

*Initial velinotamig (BCMA TCE) data show promising clinical activity, including complete renal responses in lupus nephritis, supporting potential in plasma cell–driven autoimmune diseases*

*Complementary T cell engager portfolio unlocks broad commercial opportunity across B cell–driven and autoantibody-mediated diseases* 

*Management to host Immunology Day event today at 8:30 a.m. ET* 

CAMBRIDGE, Mass., June 10, 2026 (GLOBE NEWSWIRE) -- Cullinan Therapeutics, Inc. (Nasdaq: CGEM), a clinical-stage biopharmaceutical company accelerating potential first- or best-in-class, disease-modifying T cell engagers in autoimmune diseases and cancer, today reported clinical data and outlined global clinical development plans for CLN-978, a CD19xCD3 T cell engager, and velinotamig, a BCMAxCD3 T cell engager.

"We continue to build strong momentum across our T cell engager portfolio and are highly encouraged by the compelling data we have generated for our immunology programs, which demonstrate the broader potential of T cell engagers in autoimmune diseases. Importantly, these data also support our strategy to develop differentiated CD19 and BCMA T cell engagers, designed to address the full spectrum of B cell– and plasma cell–driven autoimmune diseases. For CLN-978, our OUTRACE SLE and RA clinical trials show that in heavily pretreated patients, all of whom discontinued background immunosuppressive therapies prior to study entry, CLN-978 achieved clinical remissions and deep B cell depletion, including indicators of immune reset. 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. With our global clinical footprint, we are prepared to advance quickly into the next phase of development, including planned indication expansion," said Nadim Ahmed, President and Chief Executive Officer, Cullinan Therapeutics. "In parallel, velinotamig has demonstrated promising early clinical efficacy, including complete renal responses, with

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pharmacodynamic effects aligned with its mechanism. Based on these initial observations, we are focused on expanding the current dataset and advancing into additional autoantibody-mediated conditions with high unmet need. Looking ahead, we have a defined path of multiple near-term catalysts anticipated for both programs, with additional multi-dose data for CLN-978 in RA next quarter and in SLE in Q4, and additional data for velinotamig before the end of the year."

**CLN-978 (CD19xCD3 T cell engager): Treatment-refractory moderate to severe SLE and difficult-to-treat RA** 

*Data cutoff: May 20, 2026*

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;•New multi-dose data in the Phase 1 OUTRACE RA clinical trial demonstrate the robust efficacy profile of CLN-978 observed in two heavily pre-treated, poly-refractory patients, including a DAS28-ESR remission in one patient

oA patient refractory to immediate prior rituximab experienced a DAS28-ESR remission, with a baseline disease score of 4.0 quickly reduced to 2.2 at week 4 and maintained through the latest follow-up at week 8

oAchievement of clinical remission was associated with rapid reduction in RA-associated autoantibodies

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;•Safety data for the first three patients with SLE treated with a multi-dose regimen in the Phase 1 OUTRACE SLE clinical trial are consistent with the favorable safety profile observed in the initial RA multi-dose cohort presented at the European Alliance of Associations for Rheumatology (EULAR) 2026 Congress

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;•Clinical observations in SLE patients with nephritis, notably rapid improvement in proteinuria, support planned evaluation of CLN-978 in patients with lupus nephritis, with Phase 2a expansion expected to begin in early 2027

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;•The Company plans to report additional multi-dose regimen data for RA in Q3 2026 and SLE in Q4 2026

**Velinotamig (BCMAxCD3 T cell engager): Treatment-refractory autoimmune diseases driven by long-lived plasma cells**

*Data cutoff: May 15, 2026*

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;•In the first two patients with refractory SLE who had completed treatment with four intravenous doses of velinotamig (3 µg/kg on day 1 followed by three doses of 10 µg/kg), at the time of the data cut-off, both patients experienced rapid and marked reductions in SLEDAI-2K scores and proteinuria and both achieved complete renal response

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oSLEDAI-2K scores were 16 and 14 at baseline, respectively, and at the latest follow-up at week 8 were 0 and 2, respectively

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;•Clinical improvements correlated with pharmacodynamic changes consistent with the mechanism of action of velinotamig

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;•Velinotamig demonstrated a favorable safety profile in both patients, with no cytokine release syndrome (CRS) or immune effector cell–associated neurotoxicity syndrome (ICANS) observed

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;•Additional multi-dose regimen data in patients with SLE from the Genrix Bio clinical trial in China expected to be shared in Q4 2026

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;•Cullinan plans to initiate a Phase 1/2a clinical trial in Q1 2027 in patients with autoimmune cytopenias, including immune thrombocytopenia (ITP) and autoimmune hemolytic anemia (AIHA), autoantibody-mediated diseases with high unmet need

**Cullinan Therapeutics Immunology Day Event Today** 

Cullinan Therapeutics will host an Immunology Day event today at 8:30 a.m. ET. Key opinion leaders Dr. Ricardo Grieshaber-Bouyer and Dr. John Tesser will join Cullinan Therapeutics management to discuss the data and their clinical perspectives. A webcast will be available via the events page of the Company's investor relations website at https://investors.cullinantherapeutics.com/events.

**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**

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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 (RA) is a chronic autoimmune disease primarily characterized by inflammation of the joints, which can lead to pain, swelling, stiffness, and permanent joint damage.<sup>1,2</sup> The disease often affects multiple joints simultaneously, commonly the hands, wrists, and feet, but it can also involve other organ systems.<sup>2</sup> 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.<sup>3-10</sup> 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.<sup>11</sup>

**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.<sup>12,13</sup> 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.<sup>14,15</sup> SLE is more prevalent in women<sup>14,16</sup>and people of color.<sup>16</sup> 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.<sup>17</sup> Currently available treatments can reduce the signs and symptoms of SLE; however, they do not routinely induce

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treatment-free remission, and most patients require lifelong immune suppression that treats symptoms without modifying the course of disease.<sup>18-20</sup>

**About Velinotamig** 

Velinotamig is a BCMAxCD3 bispecific T cell engager designed to redirect cytotoxic T cells to target BCMA-expressing cells including pathogenic, autoantibody-producing plasma cells. Velinotamig is engineered with high-affinity binding to BCMA and lower affinity binding to CD3, with the goal of enhancing target cell depletion while minimizing non-specific T cell activation and associated toxicity. By targeting BCMA-expressing cells, velinotamig has the potential to address autoimmune diseases driven by pathogenic autoantibodies.

Cullinan holds a global (ex-Greater China), all indication, exclusive license to velinotamig from Genrix Bio. Genrix Bio is currently evaluating velinotamig in a Phase 1b/2a clinical trial in patients with refractory systemic lupus erythematosus (SLE) in China, with additional autoimmune indications under consideration. Cullinan Therapeutics plans to initiate a global basket trial of velinotamig in autoimmune cytopenias, including immune thrombocytopenia (ITP) and autoimmune hemolytic anemia (AIHA).

**About Autoimmune Cytopenias** 

Autoimmune cytopenias are a heterogeneous group of rare, immune-mediated blood disorders that involve the destruction of blood cells by the immune system, and, in some cases, impaired production of blood cells.<sup>21</sup>Autoimmune cytopenias can be serious, chronic, and potentially life-threatening, leading to bleeding, severe anemia, and debilitating fatigue, and often place a significant burden on patients.<sup>21-23</sup> With a significant unmet need for treatment options, many patients remain on chronic immunosuppression, experience persistent or relapsing disease, and have impaired quality of life.<sup>22-23</sup>

Cullinan Therapeutics plans to initiate clinical research in autoimmune cytopenias including immune thrombocytopenia (ITP) and autoimmune hemolytic anemia (AIHA).

**About Cullinan Therapeutics** 

Cullinan Therapeutics, Inc. (Nasdaq: CGEM) is a biopharmaceutical company developing potential first- or best-in-class, disease-modifying T cell engagers 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

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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: the implications of the initial safety data and observed efficacy from the Company's ongoing Phase 1 OUTRACE RA and OUTRACE SLE clinical trials; the implications of the initial safety data and observed efficacy from the ongoing Phase 1 clinical trial in velinotamig; the Company's clinical development plans and anticipated development timelines for CLN-978 and velinotamig; the clinical and therapeutic potential of both CLN-978 and velinotamig, including their therapeutic potential in additional indications; the Company's beliefs regarding the broader potential of T cell engagers in the treatment of autoimmune diseases and its planned strategy to develop differentiated CD19 and BCMA T cell engagers; and other statements that are not historical facts. The clinical trials referenced in this press 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 clinical trial 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 clinical trial data and 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,

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including those that are co-developed, will not be successfully developed and commercialized; the risk that the results of preclinical studies or clinical trials will not be predictive of future results in connection with future studies or clinical trials; 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**<br>Nick Smith<br>+1 401.241.3516<br>**Nsmith@cullinantx.com**

**Media**<br>Rose Weldon<br>+1 215.801.7644<br>**Rweldon@cullinantx.com**

**References**

&nbsp;&nbsp;&nbsp;&nbsp;1.World Health Organization. (2023). Rheumatoid arthritis. https://www.who.int/news-room/fact-sheets/detail/rheumatoid-arthritis

&nbsp;&nbsp;&nbsp;&nbsp;2.Johns Hopkins Arthritis Center. Rheumatoid Arthritis Signs and Symptoms. https://www.hopkinsarthritis.org/arthritis-info/rheumatoid-arthritis/ra-symptoms

&nbsp;&nbsp;&nbsp;&nbsp;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

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&nbsp;&nbsp;&nbsp;&nbsp;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

&nbsp;&nbsp;&nbsp;&nbsp;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

&nbsp;&nbsp;&nbsp;&nbsp;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

&nbsp;&nbsp;&nbsp;&nbsp;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

&nbsp;&nbsp;&nbsp;&nbsp;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

&nbsp;&nbsp;&nbsp;&nbsp;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

&nbsp;&nbsp;&nbsp;&nbsp;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

&nbsp;&nbsp;&nbsp;&nbsp;11.Radu, A. F., & Bungau, S. G. (2021). Management of rheumatoid arthritis: An overview. *Cells, 10*(11), 2857. https://doi.org/10.3390/cells10112857

&nbsp;&nbsp;&nbsp;&nbsp;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

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