PHIO Phio Pharmaceuticals Corporation

Phio Pharmaceuticals Corp. (Nasdaq: PHIO), a clinical stage biotechnology company whose proprietary INTASYL™ RNAi platform technology is designed to make immune cells more effective in killing tumor cells, today announced the presentation of new preclinical data at the 38th Annual Meeting of the Society for Immunotherapy of Cancer (SITC). The event is scheduled to take place in San Diego, California, from November 1-5, 2023. Phio’s innovative preclinical study data highlights the benefit of intratumoral injection (IT) of an INTASYL compound targeting CTLA-4 (27790) in conjunction with systemic anti-PD-1 antibody therapy.

Preclinical studies have demonstrated:

• The combination of INTASYL compound 27790 with systemic anti-PD-1 antibody therapy significantly enhanced the efficacy of anti-PD-1 mAb therapy in vivo.
• The combination of INTASYL compound 27790 and anti-PD-1 elicited complete regression of ~40% of IT treated tumors in a mouse model.
• Additionally, INTASYL compound 27790 appeared to improve the efficacy of anti-PD-1 therapy toward those tumors not treated directly with 27790.
• INTASYL compound 27790 increased the percentage of reactive CD8+ T cells in the tumor while decreasing immunosuppressive/pro-tumor macrophages in the treated tumor micro-environment.

“These data underscore the potential of Phio’s INTASYL™ RNAi platform technology to offer a strategy to enhance the effectiveness of immune checkpoint inhibition therapies,” said Phio’s President & CEO Robert Bitterman, “and further demonstrate the flexibility and capabilities of the INTASYL platform.”

Presentation Details are as follows:

Title:	Intratumoral CTLA-4-targeting INTASYL™ self-delivering RNAi enhances tumor control in combination with systemic anti-PD-1 antibody therapy in vivo suggesting a strategy to mitigate irSAEs
Presenting Author:	Melissa Maxwell
Date and Time:	9:00 am - 8:30 pm PST on Saturday, November 4, 2023
Location:	Exhibit Halls A and B1 – San Diego Convention Center
The poster presentation will be accessible in person and will also be made available on the "Investors – Events and Presentations" section of the Company's website (click here).

About Phio Pharmaceuticals Corp.

Phio Pharmaceuticals Corp. (Nasdaq: PHIO) is a clinical stage biotechnology company whose proprietary INTASYL™ RNAi technology is designed to make immune cells more effective in killing tumor cells. INTASYL is the only self-delivering RNAi technology focused on immuno-oncology therapeutics. INTASYL drugs precisely target specific proteins that reduce the body’s ability to fight cancer, without the need for specialized formulations or drug delivery systems.

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. 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. Examples of forward-looking statements include statements regarding the combination of an INTASYL compound targeting CTLA-4 and a systemic anti-PD-1 antibody to demonstrate enhanced tumor 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.ir@phiopharma.com

PR ContactMichael AdamsBridge View Mediaadams@bridgeviewmedia.com