• Intratumoral PH-762 has encouraging safety profile in the initial cohort

• Escalation to proceed to next dose concentration

Marlborough, Massachusetts–(Newsfile Corp. – May 28, 2024) – 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 a Safety Monitoring Committee (SMC) reviewed safety data from the first dose cohort treated in the Phase 1b clinical trial with Phio's lead compound PH-762. Based on these findings, the SMC recommended the escalation to the next dose concentration.

Phio's ongoing Phase 1b clinical study (NCT 06014086) is designed to evaluate the safety and tolerability of neoadjuvant use of intratumoral PH-762 in Stages 1, 2 and 4 cutaneous squamous cell carcinoma, Stage 4 melanoma and Stage 4 Merkel cell carcinoma.

There have been no dose-limiting toxicities, or clinically relevant treatment-emergent adverse events in the initial cohort receiving intratumoral PH-762. The intratumoral injections have been well tolerated. The SMC has recommended dose escalation and enrollment of the next planned cohort in the clinical study.

"Safety and efficacy data from our clinical trial will establish the roadmap for continued development of PH-762," said Mary Spellman MD, Phio's acting Chief Medical Officer. "We are pleased with continued interest in the potential therapy and look forward to continued enrollment in the clinical study."

About Phio Pharmaceuticals Corp.

Phio Pharmaceuticals Corp. (Nasdaq: PHIO) is a clinical stage biotechnology company whose proprietary INTASYL siRNA gene silencing 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

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Contact:
Phio Pharmaceuticals Corp.
ir@phiopharma.com

PR Contact
Michael Adams
Bridge View Media
adams@bridgeviewmedia.com

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