Phio submits FDA package for PH-762 skin cancer trial

Phio details an FDA briefing package and outlines 2027 readiness for the next PH-762 skin cancer study.

Rhea-AI Filing Summary

Phio Pharmaceuticals Corp. (PHIO) reports a key development milestone for its lead INTASYL siRNA candidate PH-762, submitting a meeting request and comprehensive briefing package to the U.S. Food and Drug Administration to support the next stage of clinical development in cutaneous squamous cell carcinoma, including a planned Phase 2b neoadjuvant study.

The submission summarizes nonclinical development, integrated clinical pharmacology data, and results from a completed Phase 1b trial in several skin cancers. Phio is preparing to manufacture clinical supplies for the next planned study, with availability and final activities supporting the next phase of development expected in the first quarter of 2027.

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, or exhibit attachments filed with this report.

Key Figures

FDA briefing package submission date: September 14, 2026 Expected availability of PH-762 clinical supplies: First quarter of 2027 Completion of final activities for next development phase: First quarter of 2027 +1 more

4 metrics

FDA briefing package submission date September 14, 2026 Date Phio announced submission of the PH-762 briefing package and meeting request

Expected availability of PH-762 clinical supplies First quarter of 2027 Timeline for manufacturing clinical supplies for the next planned study

Completion of final activities for next development phase First quarter of 2027 Expected timing for final activities supporting the next phase of PH-762 clinical development

Phase 1b trial identifier NCT 06014086 Identifier for the Phase 1b PH-762 trial in several skin cancers

Key Terms

INTASYL, siRNA, neoadjuvant, cutaneous squamous cell carcinoma, +2 more

6 terms

INTASYL medical

"developing therapeutics using its proprietary INTASYL® gene silencing technology"

siRNA medical

"Phio is a clinical-stage siRNA biopharmaceutical company developing therapeutics"

Small interfering RNA (siRNA) is a short strand of genetic material that binds to and destroys the messenger RNA that carries instructions for making a specific protein, effectively switching that gene off. Investors care because siRNA is a platform for precise medicines: successful trials or approvals can create high-value drugs, while delivery challenges, manufacturing complexity, patent positions and regulatory risk can sharply affect a biotech company's prospects.

neoadjuvant medical

"next planned Phase 2b neoadjuvant clinical study in cutaneous squamous cell carcinoma"

"Neoadjuvant" describes treatments or interventions that are given before the main or primary procedure, such as surgery or a major decision. It’s like preparing the ground before planting seeds, aiming to improve the final outcome. For investors, understanding neoadjuvant approaches can provide insight into how companies enhance results or effectiveness in their processes or products.

cutaneous squamous cell carcinoma medical

"clinical development in cutaneous squamous cell carcinoma and a planned Phase 2b"

A common form of skin cancer that starts in the thin, outer layer of the skin and can grow or, in some cases, spread to nearby tissue or organs. For investors, it matters because diagnosis rates, available treatments, and regulatory approvals shape demand for therapies, influence clinical trial results, and affect potential revenue for companies developing drugs, devices, or diagnostics — like spotting a stubborn weed that may require different tools to remove.

pharmacokinetic medical

"includes the scientific rationale, study design, and pharmacokinetic strategy intended"

Pharmacokinetic describes how a drug moves through and leaves the body — how it is absorbed, spread to tissues, broken down and excreted — like tracking a package from pickup to delivery and disposal. For investors, these properties determine effective dose, safety risks, how often a medicine must be taken, and how reliably it works, which in turn influence clinical trial success, regulatory approval chances, production complexity and a drug’s commercial value.

nonclinical toxicology study medical

"the dosing phase of the company's nonclinical toxicology study has been completed"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did PHIO announce about PH-762 in this Form 8-K?

Phio announced submission of a meeting request and comprehensive briefing package to the FDA for PH-762, describing nonclinical and clinical data and proposing a planned Phase 2b neoadjuvant study in cutaneous squamous cell carcinoma.

What is the next planned clinical step for PHIO’s PH-762 program?

The company describes a planned Phase 2b neoadjuvant clinical study in cutaneous squamous cell carcinoma, supported by data from a completed Phase 1b trial in cutaneous squamous cell carcinoma, melanoma and Merkel cell carcinoma.

When does PHIO expect PH-762 clinical supplies to be ready?

Phio states it is preparing to manufacture clinical supplies for the next planned PH-762 study, which are expected to be available in the first quarter of 2027.

What development activities for PH-762 has PHIO completed so far?

Phio reports the formal completion of a Phase 1b clinical study of PH-762 and completion of the dosing phase of a nonclinical toxicology study, along with submission of an FDA briefing package.

When are final activities for the next PH-762 development phase expected to finish?

Final activities supporting the next phase of clinical development for PH-762 are expected to be completed during the first quarter of 2027, according to the company.

What indication is PHIO targeting with PH-762?

PH-762 is described as an INTASYL siRNA compound that silences the PD-1 gene and is being developed as a potential non-surgical treatment for skin cancers, including cutaneous squamous cell carcinoma.

AI-generated analysis. How Rhea-AI works. Not financial advice.

Understanding 8-K Material Events →

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Available on EDGAR 09/14/2026 - 09:00 AM Accepted by SEC EDGAR 09/14/2026 - 08:59 AM Learn about SEC filing dates

false 0001533040 0001533040 2026-09-14 2026-09-14

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 14, 2026

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 September 14, 2026, the Company issued a press release announcing a key development milestone for PH-762, including the submission of materials to the FDA to support the next phase of clinical development in cutaneous cell carcinoma and a planned Phase 2b neoadjuvant study.

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 September 14, 2026.
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: September 14, 2026	By:	/s/ Robert J. Bitterman
		Robert J. Bitterman President & Chief Executive Officer

3

Exhibit 99.1

Phio Announces Key Development Milestone for PH-762 with FDA Submission Supporting Next Stage of Clinical Development in Cutaneous Squamous Cell Carcinoma

Company Proposes Planned Phase 2b Neoadjuvant Study Following Successful Completion of Phase 1b Trial

KING OF PRUSSIA, Pennsylvania-(Newsfile Corp.-September 14, 2026) — Phio Pharmaceuticals Corp. (Nasdaq: PHIO) is a clinical-stage siRNA biopharmaceutical company developing therapeutics using its proprietary INTASYL® gene silencing technology to eliminate cancer. Phio announced today that, following the formal completion of the Phase 1b clinical study, it has submitted a meeting request and comprehensive briefing package to the U.S. Food and Drug Administration (FDA). 

The submission describes the nonclinical development program and integrated clinical pharmacology data for PH-762 and provides details of the completed Phase 1b study as well as the next planned Phase 2b neoadjuvant clinical study in cutaneous squamous cell carcinoma. The briefing package includes the scientific rationale, study design, and pharmacokinetic strategy intended to support the next stage of clinical development.

“Delivering this comprehensive briefing package to the FDA is a key achievement for the PH-762 program and an important step toward unlocking its clinical potential in cutaneous squamous cell carcinoma,” said Robert J. Bitterman, President and CEO of Phio Pharmaceuticals. “We are encouraged by the Phase 1b findings and look forward to working with the FDA as we pursue the next phase of development.”

Phio is currently preparing to manufacture clinical supplies for the next planned study, which are expected to be available in the first quarter of 2027. In addition, the dosing phase of the company's nonclinical toxicology study has been completed. Final activities supporting the next phase of clinical development are expected to be completed during the first quarter of 2027.

About Phio Pharmaceuticals Corporation

Phio Pharmaceuticals Corp. (Nasdaq: PHIO) is a clinical-stage biopharmaceutical company advancing its proprietary INTASYL® siRNA gene silencing technology to eliminate cancer. Phio’s INTASYL compounds are designed to enhance the body’s immune cells to more effectively kill cancer cells. Phio’s lead clinical development program is an INTASYL compound, PH-762, that silences the PD-1 gene implicated in various forms of skin cancer. The Phase 1b trial (NCT# 06014086) evaluated PH-762 for the treatment of cutaneous squamous cell carcinoma, melanoma and Merkel cell carcinoma. PH-762 is a potential non-surgical treatment for skin cancers.

For additional information, visit the Company’s website, www.phiopharma.com.  

Forward Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements can be identified by words such as "intends," "believes," "anticipates," "indicates," "plans," "expects," "suggests," "may," "would," "should," "potential," "designed to," "will," "ongoing," "estimate," "forecast," "target," "predict," "could" and similar references, although not all forward-looking statements contain these words. Examples of forward-looking statements contained in this press release include, among others, the possibility that our INTASYL® siRNA gene silencing technology will make the body’s immune cells more effective in killing cancer cells, the potential for PH-762 to present a viable non-surgical alternative for skin cancer, our plans and expectations regarding FDA submissions and related interactions, including our intention to meet with the FDA to discuss potential next steps in the clinical trial design and development of PH-762, our belief that submission of our comprehensive briefing package to the FDA will support the next stage of clinical development of PH-762 and is an important step toward unlocking the PH-762 clinical potential in cutaneous squamous cell carcinoma, our belief that we will work with the FDA as we pursue the next phase of development of PH-762, our belief that activities supporting the next phase of clinical development of pH-762 are expected to be completed during the first quarter of 2027, and statements regarding our clinical strategy, development plans and timelines and other future events.   

 These statements are based only on our current beliefs, expectations and assumptions and are subject to inherent uncertainties, risks and changes in circumstances that are difficult to predict and many of which are outside of our control.  Our actual results may differ materially from those indicated in the forward-looking statements as a result of a number of important factors, including, but not limited to, the impact of future FDA interactions on the development of our product candidates; our ability to work with the FDA; the development of our product candidates, results from our nonclinical, preclinical and clinical activities, our ability to execute on business strategies, our ability to develop our product candidates with collaboration partners, and the success of any such collaborations, the timeline and duration for advancing our product candidates into clinical development, the timing or likelihood of regulatory filings and approvals, the success of our efforts to commercialize our product candidates if approved, our ability to manufacture and supply our product candidates for clinical activities, and for commercial use if approved, the scope of protection we are able to establish and maintain for intellectual property rights covering our technology platform, our ability to obtain future financing, market and other conditions and those risks identified in our most recent Annual Report on Form 10-K and subsequent Quarterly Reports on Form 10-Q under the caption “Risk Factors” and in other filings the Company periodically makes with the U.S. Securities and Exchange Commission. Readers are urged to review these risk factors and to not act in reliance on any forward-looking statements, as actual results may differ from those contemplated by our forward-looking statements. Phio does not undertake to update forward-looking statements to reflect a change in its views, events or circumstances that occur after the date of this release, except as required by law.   

Contact:

Phio Pharmaceuticals Corp. 

Jennifer Phillips: jphillips@phiopharma.com  

Corporate Affairs  

Filing Exhibits & Attachments

5 documents

Press Releases

• EX-99.1 EXHIBIT 99.1 11.7 KB

Other Documents

• EX-101 XBRL TAXONOMY EXTENSION SCHEMA 3.5 KB
• EX-101 XBRL TAXONOMY EXTENSION DEFINITION LINKBASE 11.5 KB
• EX-101 XBRL TAXONOMY EXTENSION LABEL LINKBASE 15.5 KB
• EX-101 XBRL TAXONOMY EXTENSION PRESENTATION LINKBASE 11.7 KB