[8-K] Shuttle Pharmaceuticals Holdings, Inc. Reports Material Event

Rhea-AI Filing Summary

Shuttle Pharmaceuticals Holdings, Inc. entered a release and settlement agreement with Theradex Systems under which it will pay $300,000 as full and final settlement of Theradex-related obligations totaling approximately $557,000. In exchange, both parties release all claims tied to these liabilities and Theradex will wind down the company’s Ropidoxuridine clinical trials in compliance with Food and Drug Administration requirements.

Separately, Shuttle estimates it still owes about $750,000 under five research site agreements with various hospitals. The company has committed to discontinue the Ropidoxuridine trials, immediately halt enrollment, and begin trial closeout. It expects to incur additional winddown expenses, with the vast majority of these charges recorded in the fourth quarter of 2025, though final costs may differ from current estimates.

Positive

• None.

Negative

• Discontinuation of Ropidoxuridine clinical trials and added costs: Shuttle is halting its Ropidoxuridine trials, will incur additional winddown expenses mainly in Q4 2025, and still estimates about $750,000 owed to hospital sites.

Insights

Biotech and capital structure analyst

Core Ropidoxuridine trials are being discontinued while Shuttle settles Theradex debt at a discount and faces new winddown and site obligations.

Shuttle Pharmaceuticals has agreed to pay Theradex Systems $300,000 to settle obligations of approximately $557,000, eliminating this legacy liability while Theradex manages a compliant winddown of the Ropidoxuridine clinical trials. This addresses a specific contract dispute and clarifies that Theradex-related claims tied to these outstanding liabilities are being released by both parties.

However, the strategic impact is unfavorable because the company is discontinuing its Ropidoxuridine clinical trials and stopping enrollment, effectively halting this development program as structured under the terminated master agreement. Shuttle also still estimates about $750,000 owed under five hospital research site agreements and expects additional trial closeout costs, with most charges recognized in Q4 2025. Overall, this combines balance-sheet cleanup of one obligation with a setback to the clinical pipeline and added near-term expenses.

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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 20, 2025

SHUTTLE PHARMACEUTICALS HOLDINGS, INC.

(Exact name of registrant as specified in its charter)

Delaware		001-41488		82-5089826
(State or other jurisdiction of incorporation)		(Commission File Number)		(IRS Employer Identification No.)

401 Professional Drive, Suite 260

Gaithersburg, MD 20879

(Address of principal executive offices) (Zip Code)

(240) 430-4212

(Registrant’s telephone number, including area code)

N/A

(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 $0.00001 per share		SHPH		The Nasdaq Stock Market LLC

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 1.01. Entry into a Material Definitive Agreement.

As previously disclosed by the Company in its Current Report on Form 8-K, filed with the U.S. Securities and Exchange Commission (the “SEC”) on October 21, 2025, on October 15, 2025, Shuttle Pharmaceuticals Holdings, Inc. (the “Company”) received a letter from Theradex Systems, Inc. (“Theradex”), providing written notice of termination of the master agreement, dated November 1, 2018 (the “Master Agreement”), between Shuttle Pharmaceuticals, Inc. (the Company’s wholly-owned subsidiary) and Theradex, and all work orders thereunder.

Pursuant to the notice of termination, on November 20, 2025, the Company and Theradex entered into a release and settlement agreement (the “Settlement Agreement”), pursuant to which the Company will pay a partial payment of $300,000 to Theradex as full and final payment of any and all claims relating to the debt or obligation previously owed by the Company to Theradex, totalling approximately $557,000 (the “Outstanding Liabilities”) and in consideration of such payment, each party will release, acquit and discharge each other from all claims arising from the Outstanding Liabilities and Theradex will properly wind down the Clinical Trials (as defined below) in a manner compliant with the Food and Drug Administration. After the payments pursuant to the Settlement Agreement, the Company will still owe amounts, under five separate research site agreements between the Company and various hospitals, as disclosed in the Settlement Agreement. The Company currently estimates these amounts to be approximately $750,000.

Item 1.02. Termination of a Material Definitive Agreement.

The information set forth above under Item 1.01 of this Current Report on Form 8-K is incorporated herein by reference.

Item 2.05. Costs Associated with Exit or Disposal Activities.

The information set forth above under Item 1.01 of this Current Report on Form 8-K is incorporated herein by reference.

On November 20, 2025, in light of the foregoing, the Company committed to a plan to discontinue its clinical trials of Ropidoxuridine (the “Clinical Trials”), as provided for under the Master Agreement. The Company expects to immediately end enrollment and initiate winddown activities for the Clinical Trials, with full completion of winddown activities expected to occur as soon as practicable in a manner compliant with the requirements of the Food and Drug Administration.

As a result of the termination of the Clinical Trials, the Company expects to incur additional expenses related to trial closeout activities. The Company is currently assessing and estimating these costs and expects that the vast majority of these charges will be recorded in the fourth quarter of 2025.

The costs that the Company expects to incur in connection with the foregoing are subject to a number of assumptions, and actual results may materially differ. The Company may also incur other costs or charges not currently contemplated as a result of, or associated with, the foregoing events.

Item 2.05 contains “forward-looking” statements and estimates, including anticipated winddown costs. These statements are subject to a number of risks and uncertainties that could cause actual results to differ materially, including whether the Company will successfully winddown the Clinical Trials and other risks detailed in the “Risk Factors” section of the Company’s most recent periodic report filed with the SEC. These statements represent the Company’s estimates and assumptions only as of the date of this Current Report on Form 8-K. The Company does not undertake any obligation to update publicly any such forward-looking statements, even if new information becomes available.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits

Exhibit No.		Description
10.1		Release and Settlement Agreement, by and between Shuttle Pharmaceuticals Holding, Inc. and Theradex Systems, Inc., dated November 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 hereunto duly authorized.

	SHUTTLE PHARMACEUTICALS HOLDINGS, INC.
Date: November 21, 2025	By:	/s/ Christopher Cooper
		Christopher Cooper
		Interim Chief Executive Officer

FAQ

What agreement did SHPH enter into with Theradex Systems?

Shuttle Pharmaceuticals entered into a release and settlement agreement with Theradex Systems under which it will pay $300,000 as full and final settlement of obligations totaling approximately $557,000. Both parties agreed to release all claims related to these outstanding liabilities, and Theradex will wind down the clinical trials in compliance with Food and Drug Administration requirements.

How much is SHPH paying and what liabilities are being settled?

The company will pay $300,000 to Theradex as a partial payment that serves as full and final settlement of claims tied to outstanding liabilities of about $557,000 previously owed to Theradex under the terminated master agreement and related work orders.

What is happening to Shuttle Pharmaceuticals Ropidoxuridine clinical trials?

Shuttle has committed to discontinue its Ropidoxuridine clinical trials. It plans to immediately end enrollment and begin winddown activities, with Theradex handling the winddown in a way that complies with Food and Drug Administration requirements. Full completion of these winddown activities is expected to occur as soon as practicable.

What additional obligations does SHPH have related to research sites?

Beyond the Theradex settlement, Shuttle estimates it still owes approximately $750,000 under five separate research site agreements with various hospitals. These obligations are separate from the liabilities settled with Theradex and are referenced in the settlement agreement.

What costs does SHPH expect from winding down the clinical trials?

The company expects to incur additional expenses related to trial closeout activities as a result of terminating the Ropidoxuridine trials. It currently expects that the vast majority of these charges will be recorded in the fourth quarter of 2025, although actual costs may differ from its estimates.

Does this filing include forward-looking statements for SHPH?

Yes. The company notes that its discussion of anticipated winddown costs and related matters includes forward-looking statements, which are subject to risks and uncertainties. It highlights the risk of whether it will successfully wind down the clinical trials and refers to risk factors described in its most recent periodic report filed with the SEC.