# EDGAR Filing Document

**Accession Number:** 0001662579
**File Stem:** 0001628280-25-043290
**Filing Date:** 2025-10
**Character Count:** 13514
**Document Hash:** c26d6eb2defc7ef43a4961eeece9e211
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001628280-25-043290.hdr.sgml**: 20251001

**ACCESSION NUMBER**: 0001628280-25-043290

**CONFORMED SUBMISSION TYPE**: 8-K

**PUBLIC DOCUMENT COUNT**: 14

**CONFORMED PERIOD OF REPORT**: 20251001

**ITEM INFORMATION**: Regulation FD Disclosure

**ITEM INFORMATION**: Other Events

**ITEM INFORMATION**: Financial Statements and Exhibits

**FILED AS OF DATE**: 20251001

**DATE AS OF CHANGE**: 20251001

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** C4 Therapeutics, Inc.
- **CENTRAL INDEX KEY:** 0001662579
- **STANDARD INDUSTRIAL CLASSIFICATION:** BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 475617627
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 8-K
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-39567
- **FILM NUMBER:** 251362549

**BUSINESS ADDRESS:**
- **STREET 1:** 490 ARSENAL WAY
- **STREET 2:** SUITE 120
- **CITY:** WATERTOWN
- **STATE:** MA
- **ZIP:** 02472
- **BUSINESS PHONE:** (617) 231-0700

**MAIL ADDRESS:**
- **STREET 1:** 490 ARSENAL WAY
- **STREET 2:** SUITE 120
- **CITY:** WATERTOWN
- **STATE:** MA
- **ZIP:** 02472

?xml version='1.0' encoding='ASCII'? cccc-20251001

**UNITED STATES**

**SECURITIES AND EXCHANGE COMMISSION**

**WASHINGTON, D.C. 20549**

_________________________________________________________________

**FORM 8-K**

_________________________________________________________________

**CURRENT REPORT**

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

**Date of Report (Date of earliest event reported): October 1, 2025**

_________________________________________________________________

**C4 THERAPEUTICS, INC.**

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

_________________________________________________________________

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| | | |
|:---|:---|:---|
| **Delaware** | **001-39567** | **47-5617627** |
| **(State or Other Jurisdiction**<br>**of Incorporation)** | **(Commission File Number)** | **(IRS Employer**<br>**Identification No.)** |
| **490 Arsenal Way, Suite 120**<br>**Watertown, MA** | | **02472** |
| **(Address of Principal Executive Offices)** | | **(Zip Code)** |

---

**Registrant's Telephone Number, Including Area Code: (617) 231-0700**

**Not Applicable**

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

_________________________________________________________________

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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| | | |
|:---|:---|:---|
| **Title of each class** | **Trading**<br>**Symbol(s)** | **Name of each exchange on which registered** |
| Common Stock, $0.0001 par value per share | CCCC | 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 October 1, 2025, C4 Therapeutics, Inc. (the "**Company**") issued a press release announcing that the Company had entered into a clinical trial collaboration and supply agreement (the "**Agreement**") with Pfizer Inc. ("**Pfizer**"). A copy of this press release is being furnished as Exhibit 99.1 to this Current Report on Form 8-K.

The information contained in Item 7.01 of this Current Report on Form 8-K and Exhibit 99.1 is intended to be furnished and 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 (the "**Securities Act**"), or the Exchange Act, except as expressly set forth by specific reference in such a filing. The furnishing of this information hereby shall not be deemed an admission as to the materiality of any such information.

**Item 8.01 Other Events.** 

On October 1, 2025, the Company announced that it had entered into the Agreement with Pfizer. Under the terms of the Agreement, Pfizer will supply elranatamab (ELREXFIO<sup>®</sup>), a B-cell maturation antigen CD3 targeted bispecific antibody (BCMAxCD3 bispecific), to the Company for its upcoming Phase 1b trial evaluating the safety and tolerability of cemsidomide, an IKZF1/3 degrader, and dexamethasone in combination with elranatamab as a second line or later therapy for patients with multiple myeloma. Pursuant to the Agreement, Pfizer will supply elranatamab to the Company at no cost in exchange for access to data from the trial, while the Company will sponsor and conduct the trial.

**Item 9.01 Financial Statements and Exhibits.**

(d) <u>Exhibits</u>. The exhibits shall be deemed to be filed or furnished, depending on the relevant item requiring such exhibit, in accordance with the provisions of Item 601 of Regulation S-K (17 CFR 229.601) and Instruction B.2 to this form.

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| | |
|:---|:---|
| **Exhibit**<br>**Number** | **Description** |
| 99.1 | <u>[Press release issued October 1, 2025](cccc-20251001xexx991.htm)</u> |
| 104 | Cover Page Interactive Data File (embedded within the Inline XBRL document) |

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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 thereunto duly authorized.

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| | | |
|:---|:---|:---|
| | C4 Therapeutics, Inc. | C4 Therapeutics, Inc. |
| Date: October 1, 2025 | By: | /s/ Jolie M. Siegel |
|  |  | **Jolie M. Siegel** |
|  |  | **Chief Legal Officer and Secretary** |

---

## Exhibit 99.1

**Exhibit 99.1**

![c4tlogo1.jpg](c4tlogo1.jpg)

**C4 Therapeutics Announces Clinical Trial Collaboration and Supply Agreement with Pfizer for the Combination of Cemsidomide and Elranatamab for the Treatment of Relapsed/Refractory Multiple Myeloma**

WATERTOWN, Mass., October 1, 2025 (GLOBE NEWSWIRE) -- C4 Therapeutics, Inc. (C4T) (Nasdaq: CCCC), a clinical-stage biopharmaceutical company dedicated to advancing targeted protein degradation science, today announced that it has entered into a clinical trial collaboration and supply agreement with Pfizer Inc. Under the terms of the agreement, Pfizer will supply elranatamab (ELREXFIO<sup>®</sup>), a B-cell maturation antigen CD3 targeted bispecific antibody (BCMAxCD3 bispecific), to C4T for its upcoming Phase 1b trial.

The Phase 1b trial will evaluate the safety and tolerability of cemsidomide, an IKZF1/3 degrader, and dexamethasone in combination with elranatamab as a second line or later therapy for patients with multiple myeloma. This Phase 1b trial, which is expected to initiate in Q2 2026, will seek to establish an optimal dose for cemsidomide in combination with elranatamab. Under the terms of the agreement, Pfizer will supply elranatamab at no cost while C4T will sponsor and conduct the trial.

"We look forward to initiating this trial to evaluate cemsidomide in combination with elranatamab in the hopes we can develop a new treatment regimen and potentially improve outcomes for multiple myeloma patients in earlier lines of therapy," said Andrew Hirsch, president and chief executive officer of C4 Therapeutics. "Our supply agreement with Pfizer creates an opportunity for cemsidomide to be combined with elranatamab, which is on the path to potentially becoming a standard of care BCMAxCD3 bispecific in a growing market."

Data generated from the cemsidomide Phase 1 trial in relapsed/refractory multiple myeloma demonstrate robust T-cell activation and cytokine expression across multiple doses. By activating immune T-cells, cemsidomide, when combined with a BCMAxCD3 bispecific such as elranatamab, may amplify the anti-myeloma immune response and lead to higher quality of responses.

**About C4 Therapeutics**

C4 Therapeutics (C4T) (Nasdaq: CCCC) is a clinical-stage biopharmaceutical company dedicated to delivering on the promise of targeted protein degradation science to create a new generation of medicines that transforms patients' lives. C4T is progressing targeted oncology programs through clinical studies and leveraging its TORPEDO<sup>®</sup> platform to efficiently design and optimize small-molecule medicines to address difficult-to-treat diseases. C4T's degrader medicines are designed to harness the body's natural protein recycling system to rapidly degrade disease-causing proteins, offering the potential to overcome drug resistance, drug undruggable targets and improve patient outcomes. For more information, please visit www.c4therapeutics.com.

**About Cemsidomide** 

Cemsidomide is an investigational, orally bioavailable small-molecule degrader in clinical development for the treatment of relapsed/refractory multiple myeloma. Data from the Phase 1 trial, which has completed enrollment, demonstrate cemsidomide's differentiated safety and tolerability profile and class-leading anti-myeloma activity that together support the potential for durable outcomes. Two clinical trials are planned to further evaluate cemsidomide in relapsed/refractory multiple myeloma: a Phase 2 single-arm registrational trial to evaluate cemsidomide in combination with dexamethasone, which is expected to

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initiate in Q1 2026; and a Phase 1b trial to evaluate the safety and tolerability of cemsidomide and dexamethasone in combination with elranatamab, which is expected to initiate in Q2 2026.

**Forward Looking Statements** 

This press release contains "forward-looking statements" of C4 Therapeutics, Inc., within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements may include, but may not be limited to, express or implied statements regarding our ability to develop potential therapies for patients; the design and potential efficacy of our therapeutic approaches; the predictive capability of our TORPEDO® platform in the development of novel, selective, orally bioavailable BiDAC™ and MonoDAC™ degraders; the potential timing, design and advancement of our preclinical studies and clinical trials, including the potential timing for and receipt of regulatory authorization related to clinical trials and other clinical development activities including clinical trial commencement or cohort initiation; our ability and the potential to successfully manufacture and supply our product candidates for clinical trials; our ability to replicate results achieved in our preclinical studies or clinical trials in any future studies or trials; our ability to replicate interim or early-stage results from our clinical trials in the results obtained when those clinical trials are completed or when those therapies complete later-stage clinical trials; the potential timing for updates on our clinical and research programs; and our ability to fund our future operations. Any forward-looking statements in this press release are based on management's current expectations and beliefs of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to: uncertainties related to the initiation, timing, advancement and conduct of preclinical and clinical studies and other development requirements for our product candidates; the risk that any one or more of our product candidates will cost more to develop or may not be successfully developed and commercialized; and the risk that the results of preclinical studies and/or clinical trials will or will not be predictive of results in connection with future studies or trials. For a discussion of these and other risks and uncertainties, and other important factors, any of which could cause our actual results to differ from those contained in the forward-looking statements, see the section entitled "Risk Factors" in C4 Therapeutics' most recent Annual Report on Form 10-K and/or Quarterly Report on Form 10-Q, as filed with the Securities and Exchange Commission. All information in this press release is as of the date of the release and C4 Therapeutics undertakes no duty to update this information unless required by law.

**Contacts:**<br>Investors:<br>Courtney Solberg<br>Associate Director, Investor Relations<br>CSolberg@c4therapeutics.com

Media:<br>Loraine Spreen<br>Senior Director, Corporate Communications & Patient Advocacy<br>LSpreen@c4therapeutics.com

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