Phio Pharmaceuticals Announces Patent Granted by USPTO, Strengthening the Company’s Intellectual Property Position in Treating Aging Skin and Skin Disorders

Phio Pharmaceuticals Corp. (Nasdaq: PHIO), a clinical stage biotechnology company whose proprietary INTASYL™ siRNA gene silencing technology is designed to make immune cells more effective in killing tumor cells, today announced that the United States Patent and Trademark Office (USPTO) has granted patent application 17/150,614 for two of its INTASYL Compounds, RXI-185 and RXI-231. The compounds treat age-related skin disorders including photo-aging and dermal hyperpigmentation, targeting the down-regulation of the Matrix metalloproteinase-1 (MMP1) and Tyrosinase (TYR) proteins.

Ultraviolet radiation (UVR) exposure is a known contributor to skin cancer and aging, inducing the hyperactivity of MMP1 which increases collagen breakdown and reduces collagen synthesis. RXI-185 is a potent silencer of MMP1 expression in the skin, interrupting UVR induced collagen breakdown, thereby, improving and/or slowing the progression for skin thickening, elasticity and wrinkles.

Various dermal pigmentation conditions including melasma and lentigines are notoriously difficult to treat. RXI-231 has been shown to penetrate the epidermal-dermal junction where tyrosinase-producing melanocytes reside and reduces the levels of tyrosinase (TYR) in the skin, resulting in detectable reductions of both melanin and pigmentation in nonclinical studies.

The Phio patent portfolio now consists of 81 issued patents, 77 of which cover our INTASYL siRNA gene silencing technology. The portfolio includes patents and applications broadly covering both the composition and methods of use of our INTASYL compounds targeting immune checkpoint, cellular differentiation, and metabolism targets for ex vivo cell-based cancer immunotherapies.

“We have a robust patent portfolio for Phio’s INTASYL siRNA technology,” said Robert Bitterman, CEO of Phio Pharmaceuticals. “The addition of this recent patent grant for treatment of photodamaged skin is complementary to our current initiative in treating skin cancer.”

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 use of RXI-231 and RXI-185 to treat aging and skin disorders. 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 Contact Michael Adams Bridge View Media [email protected]