Phio Pharmaceuticals Announces Key Tumor Response Data from all Cohorts in Intratumoral PH-762 Dose Escalation Cutaneous Carcinoma Trial

Rhea-AI Summary

Phio Pharmaceuticals (NASDAQ: PHIO) reported pathology and safety results from its Phase 1b intratumoral PH-762 dose‑escalation trial in cutaneous carcinomas on January 20, 2026. Across five cohorts, 22 patients completed treatment and excision; among 20 cSCC patients, 14 were pathologic responders (70% overall response): 10 complete responses (100% clearance), 2 near‑complete (>90%), and 2 partial (>50%). One metastatic Merkel cell patient had a partial (>50%) response. No dose‑limiting toxicities or clinically relevant treatment‑emergent adverse events were observed through the reported follow‑up. Drug concentration was escalated 20‑fold from first to final cohort. Extended safety follow‑up is expected in Q2 2026 and follow‑on trial design is underway.

Positive

• Pathology overall response rate of 70% in cSCC patients
• 10 cSCC patients achieved complete pathologic clearance (100%)
• No dose‑limiting toxicities or clinically relevant treatment‑emergent adverse events

Negative

• Small trial size: only 22 treated patients total
• 7 patients had responses under 50% (6 cSCC, 1 melanoma)
• Extended safety data pending; full follow‑up expected in Q2 2026

News Market Reaction

-5.26% 1.7x vol

8 alerts

-5.26% News Effect

+2.5% Peak Tracked

-14.3% Trough Tracked

-$729K Valuation Impact

$13M Market Cap

1.7x Rel. Volume

On the day this news was published, PHIO declined 5.26%, reflecting a notable negative market reaction. Argus tracked a peak move of +2.5% during that session. Argus tracked a trough of -14.3% from its starting point during tracking. Our momentum scanner triggered 8 alerts that day, indicating moderate trading interest and price volatility. This price movement removed approximately $729K from the company's valuation, bringing the market cap to $13M at that time. Trading volume was above average at 1.7x the daily average, suggesting increased trading activity.

Data tracked by StockTitan Argus on the day of publication.

Key Figures

Overall response rate: 70% Patients treated: 22 patients cSCC patients: 20 patients +5 more

8 metrics

Overall response rate 70% Pathologic responses in squamous cell carcinomas in Phase 1b trial

Patients treated 22 patients Completed treatment across five cohorts in Phase 1b trial

cSCC patients 20 patients Cutaneous squamous cell carcinoma subset in trial

Pathologic responders 14 patients Responders among 20 cSCC patients

Complete responses 10 patients 100% clearance in cSCC responders

Near/major responses 2 patients >90% clearance in cSCC responders

Dose escalation range 20-fold increase Drug concentration from first to final cohort

Dosing schedule 4 injections Weekly intratumoral PH-762 doses per protocol

Market Reality Check

Price: $1.04 Vol: Volume 128,327 is well be...

low vol

$1.04 Last Close

Volume Volume 128,327 is well below the 20-day average 379,351 (relative volume 0.34). low

Technical Price $1.14 is trading below the 200-day MA at $1.93, despite positive clinical data.

Peers on Argus

PHIO gained 0.88% ahead of this positive PH-762 update, while close peers showed...

1 Down

PHIO gained 0.88% ahead of this positive PH-762 update, while close peers showed mixed moves (e.g., PHGE up 2.68%, ADAP down 17.57%, BCTX down 4.67%). Momentum scanner only flagged XTLB, down 10.87% without news, supporting a stock-specific rather than sector-wide move.

Historical Context

5 past events · Latest: Jan 15 (Positive)

Pattern 5 events

Date	Event	Sentiment	Move	Catalyst
Jan 15	Investor conference	Positive	+0.9%	Announcement of Sidoti Micro-Cap conference presentation and PH-762 trial update access.
Dec 23	Development update	Positive	-6.4%	FDA acceptance of PH-762 nonclinical protocol and interim Phase 1b results from 18 patients.
Nov 25	Clinical trial milestone	Positive	+3.5%	Completion of enrollment and positive early response plus safety data for PH-762 Phase 1b.
Nov 17	Scientific presentation	Positive	+1.5%	Announcement of an Advanced Therapies USA podium talk on INTASYL and PH-762 platform.
Nov 13	Earnings and update	Negative	-9.5%	Q3 2025 net loss with financing details alongside PH-762 cohort responses and runway guidance.

Pattern Detected

PHIO has generally reacted positively to PH-762 development updates but showed at least one notable selloff on prior positive trial progress, indicating occasional divergence between news tone and price.

Recent Company History

Over the last few months, PHIO has repeatedly highlighted progress for its INTASYL lead PH-762. In November 2025, it reported encouraging early Phase 1b tumor clearance data and completed enrollment in the trial, with modest positive price reactions. An earnings update on Nov 13, 2025 combined clinical progress with financing activity but saw a -9.49% move. The Dec 23, 2025 development update on PH-762 coincided with a -6.36% decline. Today’s more complete pathology dataset extends those earlier results with higher responder numbers and continued clean safety.

Regulatory & Risk Context

Active S-3 Shelf · $24.5 million

Shelf Active

Active S-3 Shelf Registration 2025-11-20

$24.5 million registered capacity

An effective S-3 resale registration filed on Nov 20, 2025 covers up to 11,763,800 shares issuable upon exercise of outstanding warrants. Existing stockholders, not the company, may resell these shares. Phio would receive up to $24.5 million in cash only if all such warrants are exercised, with proceeds expected to support working capital and PH-762 development.

Market Pulse Summary

The stock moved -5.3% in the session following this news. A negative reaction despite favorable Phas...

Analysis

The stock moved -5.3% in the session following this news. A negative reaction despite favorable Phase 1b data would fit PHIO’s history where at least one positive PH-762 update coincided with a -6.36% move. The trial results again showed a 70% overall response rate and no dose-limiting toxicities, but prior financings and the S-3 resale registration for up to 11,763,800 warrant shares with potential proceeds of $24.5 million may weigh on sentiment and contribute to volatility around otherwise constructive clinical milestones.

Key Terms

intratumoral, siRNA, neoadjuvant, pathologic responders, +4 more

8 terms

intratumoral medical

"intratumoral PH-762 dose escalation clinical trial with the INTASYL compound"

"Intratumoral" describes something that occurs or exists within a tumor, which is an abnormal growth of tissue. For investors, understanding intratumoral is important because it relates to medical treatments or research aimed at targeting the tumor directly, potentially leading to more effective therapies. Think of it as focusing treatment straight into the problem area, much like fixing a leak by working directly on the pipe itself.

siRNA medical

"clinical-stage siRNA biopharmaceutical company developing therapeutics"

Small interfering RNA (siRNA) is a short strand of genetic material that binds to and destroys the messenger RNA that carries instructions for making a specific protein, effectively switching that gene off. Investors care because siRNA is a platform for precise medicines: successful trials or approvals can create high-value drugs, while delivery challenges, manufacturing complexity, patent positions and regulatory risk can sharply affect a biotech company's prospects.

neoadjuvant medical

"evaluate the safety and tolerability of neoadjuvant use of intratumoral PH-762"

"Neoadjuvant" describes treatments or interventions that are given before the main or primary procedure, such as surgery or a major decision. It’s like preparing the ground before planting seeds, aiming to improve the final outcome. For investors, understanding neoadjuvant approaches can provide insight into how companies enhance results or effectiveness in their processes or products.

pathologic responders medical

"14 patients were determined to be pathologic responders, including 10 patients"

Pathologic responders are patients whose tumors show clear signs of shrinkage or disappearance when examined under a microscope after a treatment, typically surgery following drug therapy. For investors, this is a tangible measure of a therapy’s effectiveness—like inspecting an engine after repairs—and higher rates of pathologic response can signal better clinical benefit, stronger chances of regulatory approval, and greater commercial potential for a drug.

dose-limiting toxicities medical

"There were no dose-limiting toxicities or clinically relevant treatment-emergent"

Dose-limiting toxicities are the harmful side effects seen in early clinical trials that are severe enough to stop researchers from raising a drug’s dose. Like a car’s speed limiter marking the safe top speed, DLTs define the maximum tolerable dose, and they matter to investors because they determine whether a medicine can reach effective levels, influence development timelines, costs, and regulatory chances, and thus affect a drug’s commercial prospects.

treatment-emergent adverse effects medical

"or clinically relevant treatment-emergent adverse effects in any patients"

Adverse effects that first appear or worsen after a patient begins a therapy or enters a clinical study; they capture any new symptoms or health problems that are linked in time to the treatment. Investors watch these because they reveal a drug’s safety profile—like spotting warning lights on a dashboard—and can affect regulatory approval, prescribing decisions, liability risk, and ultimately a company’s revenue and stock value.

cutaneous squamous cell carcinoma medical

"patients with cutaneous carcinomas... Among the 20 patients with cSCC"

A common form of skin cancer that starts in the thin, outer layer of the skin and can grow or, in some cases, spread to nearby tissue or organs. For investors, it matters because diagnosis rates, available treatments, and regulatory approvals shape demand for therapies, influence clinical trial results, and affect potential revenue for companies developing drugs, devices, or diagnostics — like spotting a stubborn weed that may require different tools to remove.

Merkel cell carcinoma medical

"A single patient with metastatic Merkel cell carcinoma had a partial response"

Merkel cell carcinoma is a rare, fast-growing form of skin cancer that starts in cells near the base of the skin and often spreads quickly to nearby tissues and organs. For investors, it matters because treatments for this aggressive disease can create high-value opportunities or risks: successful drugs or tests can unlock significant revenue and partnerships, while failed trials or regulatory setbacks can sharply affect a biotech company’s prospects — like a single critical test determining whether a new product succeeds or stalls.

AI-generated analysis. Not financial advice.

Pathology data indicate 70% overall response rate for squamous cell carcinomas: 100% clearance in 10 out of 14 responders

Favorable safety and tolerability at all dose escalations

King of Prussia, Pennsylvania--(Newsfile Corp. - January 20, 2026) - 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 announced today a summary of the pathology results and safety outcomes across all cohorts in its Phase 1b dose escalation clinical trial with the INTASYL compound PH-762 for the treatment of skin cancer.

A total of 22 patients with cutaneous carcinomas completed treatment across five cohorts in the Phase 1b trial and underwent excision of the treated lesional site. Among the 20 patients with cSCC, 14 patients were determined to be pathologic responders, including 10 patients with complete response (100% clearance), 2 patients with major/near clear response (greater than 90% clearance), and 2 patients with partial response (greater than 50% clearance). A single patient with metastatic Merkel cell carcinoma had a partial response with greater than 50% clearance. Six cSCC patients and one melanoma patient had responses of less than 50%, however, none of the patients experienced a progression of the disease.

There were no dose-limiting toxicities or clinically relevant treatment-emergent adverse effects in any patients who received intratumoral PH-762 in this trial. PH-762 has been well tolerated in all enrolled patients in each of the five dose escalating cohorts, increasing drug concentration 20-fold from the first to the final cohort. Safety data through an extended follow-up period is expected to be reported in the second quarter of 2026.

"The pathology data is remarkable with an overall response rate of 70%, complemented by a favorable safety data. With this data in hand, we are now actively beginning the follow-on clinical trial design in the next step in the regulatory development pathway," said Robert Bitterman, CEO and Chairman of the Board, Phio Pharmaceuticals.

The Phase 1b clinical trial is designed to evaluate the safety and tolerability of neoadjuvant use of intratumoral PH-762 in Stages 1, 2 and 4 cSCC, Stage 4 melanoma, and Stage 4 Merkel cell carcinoma. Per the trial's protocol, patients received four injections of PH-762 at weekly intervals and pathologic response was assessed 2 weeks following the final injection of PH-762.

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, a potent silencer of PD-1 gene implicated in various forms of skin cancer. The ongoing 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, the potential for PH-762 to present a viable non-surgical alternative for skin cancer, expectations regarding timing of enrollment, the expectations that we have sufficient capital to complete the treatment phase of our ongoing Phase 1b clinical trial, and statements regarding our 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, results from our preclinical and clinical activities, our ability to execute on business strategies, the timing or likelihood of regulatory filings and approvals, 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

To view the source version of this press release, please visit https://www.newsfilecorp.com/release/280906

FAQ

What were the reported PH-762 pathology results in Phio's January 20, 2026 release?

Phio reported a 70% overall pathologic response in cSCC: 10 complete clearances, 2 >90%, and 2 >50%.

How many patients were treated in the PH-762 Phase 1b cutaneous carcinoma trial (PHIO)?

A total of 22 patients completed treatment across five dose‑escalation cohorts.

What safety outcomes did Phio report for intratumoral PH-762 (PHIO)?

No dose‑limiting toxicities or clinically relevant treatment‑emergent adverse effects were observed in any treated patients.

What dose escalation was used for PH-762 in the Phase 1b trial (PHIO)?

Drug concentration was escalated 20‑fold from the first cohort to the final cohort.

When will Phio report extended safety follow‑up for PH-762 (PHIO)?

Extended safety follow‑up is expected to be reported in Q2 2026.

What is Phio's next step after the PH-762 Phase 1b results (PHIO)?

Phio said it is actively beginning design of the follow‑on clinical trial in the regulatory development pathway.