[8-K] Cullinan Therapeutics, Inc. Reports Material Event

Rhea-AI Filing Summary

Cullinan Therapeutics, through its subsidiary Cullinan Amber Corp., is ending development of its CLN-617 cancer immunotherapy program. On November 18, 2025, the company notified the Massachusetts Institute of Technology that it is terminating their Exclusive Patent License Agreement covering the technology behind CLN-617, with the termination effective February 18, 2026. Under that agreement, MIT had granted Cullinan exclusive worldwide rights to develop the CLN-617 technology, which will now be returned to MIT. This move confirms CLN-617 will no longer be advanced within Cullinan’s pipeline.

Insights

Biotech equity analyst

Cullinan is discontinuing its CLN-617 program and returning IP to MIT.

Cullinan Therapeutics has chosen not to pursue further development of CLN-617, a cancer immunotherapy candidate licensed from the Massachusetts Institute of Technology. Cullinan Amber Corp. has given notice to terminate the Exclusive Patent License Agreement dated December 20, 2019, which had granted exclusive worldwide rights to the underlying technology.

The termination becomes effective on February 18, 2026, after which the licensed patent rights revert to MIT. This removes CLN-617 from Cullinan’s development pipeline and simplifies its obligations under the license, but also eliminates any future upside from this specific asset.

Investors evaluating Cullinan’s story will now focus more on the remaining programs in its oncology portfolio, since CLN-617 is no longer part of potential future products. Subsequent company disclosures may clarify how strategic priorities and resources are reallocated following this decision.

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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): November 18, 2025

CULLINAN THERAPEUTICS, INC.

(Exact name of Registrant as Specified in Its Charter)

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

Registrant’s Telephone Number, Including Area Code: 617 410-4650

(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:

Title of each class		Trading Symbol(s)		Name of each exchange on which registered
Common Stock, $0.0001 par value per share		CGEM		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 ☐

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. ☐

Item 1.02 Termination of a Material Definitive Agreement.

On November 18, 2025, in connection with its decision not to pursue further development of CLN-617, Cullinan Amber Corp. (the "Company"), a subsidiary of Cullinan Therapeutics, Inc. notified Massachusetts Institute of Technology ("MIT") of its decision to terminate the Exclusive Patent License Agreement, dated December 20, 2019 between the Company and MIT, as amended from time to time (the "License Agreement"), effective as of February 18, 2026. Pursuant to the License Agreement, MIT had granted the Company exclusive worldwide rights to the technology underlying CLN-617 to develop a cancer immunotherapy product worldwide. In connection with the termination of the License Agreement, the Company will return the licensed patent rights for the technology underlying CLN-617 to MIT.

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.

			CULLINAN THERAPEUTICS, INC.
Date:	November 21, 2025	By:	/s/ Mary Kay Fenton
			Mary Kay Fenton Chief Financial Officer

FAQ

What did Cullinan Therapeutics (CGEM) announce about CLN-617?

Cullinan Therapeutics announced that its subsidiary Cullinan Amber Corp. has decided not to pursue further development of CLN-617, a cancer immunotherapy candidate, and is terminating the related license with MIT.

Which agreement is Cullinan Amber terminating with MIT?

Cullinan Amber is terminating the Exclusive Patent License Agreement dated December 20, 2019 with the Massachusetts Institute of Technology, which covered the technology underlying CLN-617.

When does the CLN-617 license termination become effective for CGEM?

The termination of the CLN-617 Exclusive Patent License Agreement becomes effective on February 18, 2026, following Cullinan Amber’s notice to MIT on November 18, 2025.

What happens to the CLN-617 patent rights after termination?

In connection with the termination, Cullinan Amber will return the licensed patent rights for the technology underlying CLN-617 to MIT, ending Cullinan’s exclusive worldwide rights.

How does this 8-K affect Cullinan Therapeutics’ pipeline?

The 8-K confirms that CLN-617 will no longer be advanced within Cullinan Therapeutics’ pipeline, as the company is discontinuing development and giving up the associated patent license.