CCCC Announces Phase 1 Presentation and Furnished Exhibits for Cemsidomide

Rhea-AI Filing Summary

C4 Therapeutics, Inc. (CCCC) reported that it issued a press release and presented clinical data from its Phase 1 trial of cemsidomide plus dexamethasone for relapsed/refractory multiple myeloma at the International Myeloma Society (IMS) Meeting in an oral presentation on September 20, 2025. The company furnished the press release as Exhibit 99.1 and posted the presentation slides on its investor relations site, filing those slides as Exhibit 99.2 to this Current Report on Form 8-K. The filing states these materials are "furnished" (not "filed") and does not include financial results or detailed trial outcomes within the Form text. The company also notes the furnishing does not constitute an admission as to materiality.

Positive

• Oral presentation of Phase 1 cemsidomide+dexamethasone data at the IMS Meeting on September 20, 2025
• Slides publishedExhibit 99.2
• Press release furnishedExhibit 99.1, making the data publicly available

Negative

• No clinical results
• Financial impact

Insights

Clinical Development Expert

Phase 1 clinical data were presented publicly at a major conference.

The company presented Phase 1 combination data for cemsidomide plus dexamethasone at the IMS Meeting on September 20, 2025, and published slides on its website.

What it means: public presentation at a leading disease-specific conference increases scientific visibility and allows peer scrutiny of early clinical data; however, the 8-K itself does not disclose the efficacy or safety results or numerical endpoints.

Investor Relations / Capital Markets Expert

Company furnished materials but did not file substantive results in the 8-K.

The press release (Exhibit 99.1) and presentation slides (Exhibit 99.2) were furnished and posted online, meaning they are available to investors but are described as "furnished" rather than "filed."

Why it matters: furnished exhibits are accessible to the market but limit Exchange Act Section 18 liabilities; investors must review the exhibits themselves for numeric details because the Form's narrative contains no trial metrics or financial impact statements.

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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): September 22, 2025 (September 20, 2025)

_________________________________________________________________

C4 THERAPEUTICS, INC.

(Exact name of Registrant as Specified in Its Charter)

_________________________________________________________________

Delaware			001-39567			47-5617627
(State or Other Jurisdiction of Incorporation)			(Commission File Number)			(IRS Employer Identification No.)
490 Arsenal Way,   Suite 120 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:

o			Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
o			Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
o			Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
o			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:

Title of each class

Trading Symbol(s)

Name of each exchange on which registered

Common Stock, $0.0001 par value per share

CCCC

The Nasdaq Global Select Market

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 o

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. o

Item 7.01 Regulation FD Disclosure.

On September 20, 2025, C4 Therapeutics, Inc. (the “Company”) issued a press release announcing data from its Phase 1 clinical trial of cemsidomide, an orally bioavailable IKZF1/3 degrader, in combination with dexamethasone for the treatment of relapsed/refractory multiple myeloma (“RRMM”), as presented in an oral presentation at the International Myeloma Society Annual Meeting (the "IMS Meeting"). A copy of the 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 attached hereto 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 September 20, 2025, the Company presented data from its Phase 1 clinical trial of cemsidomide in combination with dexamethasone for the treatment of RRMM in an oral presentation at the IMS Meeting. A copy of the slides from this presentation, which has been published to the “Events & Presentations” page of the investor relations section of the Company’s website, is filed as Exhibit 99.2 to this Current Report on Form 8-K and incorporated herein by reference.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits. 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.

Exhibit Number						Description
99.1						Press release issued September 20, 2025
99.2						Data presentation from International Myeloma Society Annual Meeting, dated September 20, 2025
104						Cover Page Interactive Data File (embedded within the Inline XBRL document)

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.

			C4 Therapeutics, Inc.
Date: September 22, 2025			By:			/s/ Jolie M. Siegel
						Jolie M. Siegel
						Chief Legal Officer and Secretary

FAQ

What did C4 Therapeutics (CCCC) announce in this 8-K?

The company announced it issued a press release and presented Phase 1 data for cemsidomide plus dexamethasone at the IMS Meeting on September 20, 2025, and furnished the press release as Exhibit 99.1 and slides as Exhibit 99.2.

Where can I find the presentation slides mentioned by CCCC?

The slides were published on the company's "Events & Presentations" page in the investor relations section and are filed as Exhibit 99.2 to the Form 8-K.

Does the 8-K include numerical trial results or safety data for cemsidomide?

No. The Form 8-K notes the presentation and exhibits but does not include efficacy or safety metrics in the filing text; investors should review Exhibit 99.1 and Exhibit 99.2 for details.

Is the press release filed or furnished in the 8-K for CCCC?

The press release is described as furnished as Exhibit 99.1, which the company says is not "filed" for purposes of Exchange Act Section 18.

Did C4 Therapeutics disclose any financial guidance or material business changes?

No. The 8-K does not disclose financial results, guidance, or material transactions; it only references the clinical presentation and posted slides.