Exhibit 99.1

Phio Pharmaceuticals Announces Appointment of Mr. David H. Deming to the Position of Lead Independent Director

King of Prussia, Pennsylvania - (Newsfile Corp. – Oct 31, 2025) — 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 is pleased to announce that David Deming has been appointed Lead Independent Director of the Board of Directors of Phio Pharmaceuticals.

Mr. Deming brings over 30 years of experience in investment banking and asset management to his new role as Lead Independent Director. He was with JP Morgan for over 27 years, both in M&A and leading the Health Group in investment banking for his last 12 years there. Mr. Deming was appointed to the Phio Board of Directors in February 2025 and serves as a member of the Board's Nominating Committee.

“Mr. Deming's extensive experience in the biopharma sector, both through his investment banking career and service on a number of corporate boards, provides a valuable resource to Phio as we advance our gene silencing technology with the goal of eliminating cancer,” said Robert Bitterman, CEO and Chairman of the Board.

About Phio Pharmaceuticals Corp.

Phio Pharmaceuticals Corp. (Nasdaq: PHIO) is a clinical-stage siRNA biopharmaceutical company advancing its INTASYL® gene silencing technology focused on immuno-oncology therapeutics. Phio’s INTASYL compounds are designed to enhance the body’s immune cells to more effectively kill cancer cells. Phio’s lead clinical program is an INTASYL compound, PH-762, that silences the PD-1 gene implicated in various forms of skin cancer. The on-going Phase 1b trial (NCT# 06014086) is evaluating 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, our expectations with respect to the continued safety results of our clinical trial, our expectations with respect to the potential of a well-tolerated treatment for cutaneous carcinomas, and statements regarding our commercial and 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 to our business and operations by inflationary pressures, rising interest rates, recession fears, the development of our product candidates, results from our 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 identified in our 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 SEC. 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  

Phio Pharmaceuticals Corp. 8-K