Phio Pharmaceuticals (NASDAQ: PHIO) details FDA-cleared PH-762 tox study plan

Rhea-AI Filing Summary

Phio Pharmaceuticals Corp. reported a development milestone for its investigational therapy PH-762. On December 23, 2025, the company announced that the U.S. Food and Drug Administration accepted its nonclinical protocol study design for PH-762, a key step that allows planned toxicology testing to move ahead. The company stated that this toxicology study is expected to begin in the first quarter of 2026, marking progress in advancing PH-762 through the preclinical development process.

8-K Event Classification

2 items: 8.01, 9.01

2 items

Item 8.01 Other Events Other

Voluntary disclosure of events the company deems important to shareholders but not covered by other items.

Item 9.01 Financial Statements and Exhibits Exhibits

Financial statements, pro forma financial information, and exhibit attachments filed with this report.

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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):  December 23, 2025

PHIO PHARMACEUTICALS CORP.

(Exact name of registrant as specified in its charter)

Delaware	001-36304	45-3215903
(State or other jurisdiction of incorporation)	(Commission File Number)	(I.R.S. Employer Identification No.)

411 Swedeland Road, Suite 23-1080
King of Prussia, PA	19406
(Address of principal executive offices)	(Zip Code)

Registrant’s telephone number, including area code: (610) 947-0251

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 (see General Instruction A.2. below):

☐	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, par value $0.0001 per share		PHIO		The Nasdaq Capital 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 8.01. Other Events.

On December 23, 2025, the Company issued a press release announcing a significant step forward in its drug development program for PH-762 with the acceptance of its nonclinical protocol study design by the Federal Drug Administration (FDA). The toxicology study will commence in first quarter of 2026.

The full text of the press release is attached hereto as Exhibit 99.1 and incorporated herein by reference.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits

Exhibit No.		Description
99.1		Press release issued by the Company on December 23, 2025.
104		Cover Page Interactive Data File (embedded within the Inline XBRL document).

2

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.

	PHIO PHARMACEUTICALS CORP.
Date: December 23, 2025	By:	/s/ Robert J. Bitterman
		Robert J. Bitterman President & Chief Executive Officer

3

FAQ

What did Phio Pharmaceuticals (PHIO) announce regarding PH-762?

Phio Pharmaceuticals announced that the U.S. Food and Drug Administration accepted its nonclinical protocol study design for its investigational therapy PH-762.

What stage of development is PH-762 entering according to the 8-K?

The company reported that PH-762 is moving into a toxicology study phase based on the accepted nonclinical protocol study design.

When will the PH-762 toxicology study begin for Phio Pharmaceuticals?

Phio Pharmaceuticals stated that the PH-762 toxicology study will commence in the first quarter of 2026.

How did Phio Pharmaceuticals communicate this PH-762 milestone?

The company issued a press release on December 23, 2025, and furnished it as Exhibit 99.1 to the current report.

Does the 8-K filing include the full PH-762 press release?

The filing states that the full text of the press release is attached as Exhibit 99.1 and is incorporated by reference.

What form did Phio Pharmaceuticals use to report the PH-762 update?

Phio Pharmaceuticals reported this development under Item 8.01 (Other Events) of a current report on Form 8-K.