Phio Pharmaceuticals Presents Preclinical Data Demonstrating Synergy-Enhanced in vivo Anti-Tumor Efficacy of PD-1/CTLA-4 Dual-Targeting INTASYL - Data to be presented at American Association for Cancer Research (AACR) An

Phio Pharmaceuticals

Presents Preclinical Data Demonstrating Synergy-Enhanced in vivo Anti-Tumor Efficacy of PD-1/CTLA-4 Dual-Targeting INTASYL

- Data to be presented at American Association

for Cancer Research (AACR) Annual Meeting 2023 -

MARLBOROUGH, Mass., April 18, 2023 /PRNewswire-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 that in vivo data from a mouse model of colon cancer demonstrates

target synergy-enhanced anti-tumor efficacy from a novel dual-targeting mouse PD-1 and CTLA-4 of an INTASYL coformulation.

Intratumoral administration of the PD-1/CTLA-4 INTASYL improved tumor

control compared to either single targeting formulation, at an identical total dose. The dual-targeting formulation was well tolerated.

"The synergistic effects of dual inhibition of PD-1 and CTLA-4

in enhancing tumor response are clinically recognized, however, a high rate of immune-related adverse events limits the utility of systemic

use of this combination of products," said Dr. Mary Spellman, Phio's Acting Chief Medical Officer. "Intratumoral administration

of dual-targeting PD-1/CTLA-4 INTASYL may provide an effective treatment option, with an improved safety profile."

Presentation Details:

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 dual-targeting PD-1/CTLA-4 INTASYL's potential to provide an

effective treatment option with improved safety profiles. 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 the

ongoing coronavirus pandemic, military conflict between Ukraine and Russia, 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.