Traws Pharma Reports Positive Interim Clinical Data with Ratutrelvir Versus PAXLOVID™, Shows Activity in PAXLOVID-Ineligible COVID-19 Patients

Rhea-AI Summary

Traws Pharma (NASDAQ: TRAW) reported interim Phase 2 data (Dec 17, 2025) showing its oral, ritonavir‑free Mpro inhibitor ratutrelvir had a differentiated clinical profile versus PAXLOVID™ in 37 patients (25 ratutrelvir; 12 PAXLOVID™) in a randomized, open‑label study. Ratutrelvir was dosed 600 mg once daily for 10 days and showed numerically comparable time‑to‑sustained symptom alleviation, fewer adverse events (most common: mild dyspepsia in 2 patients; 7.6%), and no viral rebounds observed to date versus one rebound in the PAXLOVID™ arm (1 of 12; 8.3%). Six ratutrelvir patients were PAXLOVID‑ineligible and showed similar symptom improvement. Final analysis expected January 2026.

Positive

• No viral rebounds observed in ratutrelvir-treated patients (n=25)
• Ratutrelvir cohort included 6 Paxlovid-ineligible patients
• Once-daily 600 mg oral dosing for 10 days
• Fewer adverse events versus PAXLOVID™ (7.6% vs 30%)

Negative

• Interim sample size only 37 patients (25 vs 12)
• More than 50% of planned 90-patient enrollment remains incomplete
• Not all patients completed the full 28‑day observation period
• No formal statistical comparisons performed in interim analysis

Argus Dec 17 session

-36.36% close to close Open Argus

Details

News Market Reaction – TRAW

On Dec 17, the day this news came out, TRAW closed 36.36% below the previous close.

Data tracked by StockTitan Argus for the Dec 17 session.

Key Figures

Interim sample size: 37 patients Ratutrelvir arm size: 25 patients PAXLOVID arm size: 12 patients +5 more

Interim sample size

37 patients

Patients included in interim Phase 2 analysis

Ratutrelvir arm size

25 patients

Patients treated with ratutrelvir in interim analysis

PAXLOVID arm size

12 patients

Patients treated with PAXLOVID™ comparator

Planned enrollment

90 patients

Planned Phase 2 trial population

Ratutrelvir dose

600 mg once daily for 10 days

Dosing regimen in Phase 2 trial

PAXLOVID dose

300 mg nirmatrelvir + 100 mg ritonavir BID for 5 days

Comparator regimen per label

PAXLOVID rebound rate

1 of 12 patients (8.3%)

Symptom/virologic rebound in comparator arm

Ratutrelvir dyspepsia

2 patients (7.6%)

Most common adverse event in ratutrelvir arm

Historical Context

5 past events · Latest: Nov 13

5 events

1. Nov 13

   Earnings update

   24h Move

   -17.3%

   Q3 2025 results, cash position, and ratutrelvir and flu program updates.

2. Oct 30

   CMC collaboration

   24h Move

   -5.0%

   Extended ChemDiv CMC support as ratutrelvir entered Phase 2 trials.

3. Oct 22

   Phase 2 support

   24h Move

   -10.1%

   Expert Systems backing Phase 2 with AI-driven pharmacology and design.

4. Oct 14

   First Phase 2 dosing

   24h Move

   +1.7%

   First patients dosed in two Phase 2 ratutrelvir COVID trials.

5. Oct 06

   Governance change

   24h Move

   -0.2%

   New independent director and formalized CEO/CFO roles to support trials.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Key Terms

mpro/3cl protease inhibitor, phase 2, randomized, open-label, drug–drug interactions, +4 more

8 terms

mpro/3cl protease inhibitor medical

"ratutrelvir, an investigational oral, ritonavir-free Mpro/3CL protease inhibitor"

mpro/3CL protease inhibitor is a type of antiviral drug designed to block a virus enzyme that acts like molecular scissors, cutting viral proteins into pieces the virus needs to replicate. Stopping that enzyme can halt viral replication, making these inhibitors candidate treatments for viral infections. Investors watch them because clinical trial results, safety and regulatory decisions determine whether such drugs can become approved medicines with significant commercial value.

phase 2 medical

"ongoing randomized, open-label Phase 2 clinical study in patients"

Phase 2 is the mid-stage clinical trial where a new drug or treatment is tested in a larger group of patients to see if it works and to keep checking safety after initial human testing. Think of it as a field test that proves whether a product actually delivers its promised benefit. Investors watch Phase 2 closely because its results strongly influence a medicine’s chances of reaching the market, the size of its potential sales, and the company’s valuation.

randomized, open-label medical

"ongoing randomized, open-label Phase 2 clinical study"

A randomized, open-label study is a clinical test in which participants are assigned to different treatments by chance (like flipping a coin) but both the patients and the researchers know which treatment each person receives. For investors, this matters because random assignment helps make comparisons fair, while the lack of secrecy can introduce bias or placebo effects, so results may be easier and faster to collect but require careful interpretation when judging a treatment’s true effect.

drug–drug interactions medical

"due to contraindications or clinically significant drug–drug interactions"

When two or more medications affect each other’s behavior in the body, altering effectiveness or causing unexpected side effects; one drug can make another stronger, weaker, or change how long it stays active. Investors care because these interactions can influence a drug’s safety profile, regulatory approval, labeling, market size and sales, or trigger additional studies and warnings — similar to how mixing ingredients can change a recipe’s outcome unpredictably.

flu-pro plus / covid-19 symptoms diary medical

"as assessed using the FLU-PRO Plus / COVID-19 Symptoms Diary"

A flu-pro plus / COVID-19 symptoms diary is a daily checklist or short journal that patients use to record presence, severity and duration of respiratory or related symptoms, medications taken, and any changes in condition. For investors, these diaries are important because they generate the patient-reported data that regulators and clinicians use to judge how well a treatment, vaccine or diagnostic works and to spot safety or usage trends that affect market approval, demand and commercial value.

virologic rebound medical

"No COVID-19 symptom or virologic rebound events have been observed"

A virologic rebound is when the amount of virus in a patient falls after treatment but then rises again, indicating the infection is not staying controlled. For investors, it matters because rebound can signal a drug or vaccine is less durable than hoped, which may prompt further testing, regulatory scrutiny, or weaker sales — similar to seeing weeds return after mowing and questioning whether the lawn care method really works.

long covid medical

"reducing post-acute sequelae of SARS-CoV-2 infection (Long COVID)"

A condition where symptoms from a viral infection persist or recur for weeks or months after the initial illness has cleared, often affecting energy, breathing, cognition or other body systems. It matters to investors because prolonged illness can change workforce availability, raise healthcare and insurance costs, shift demand for medical treatments and services, and influence regulatory and policy decisions—think of it as a lingering drag on productivity and expenses that can alter company performance.

post-acute sequelae of sars-cov-2 infection medical

"reducing post-acute sequelae of SARS-CoV-2 infection (Long COVID)"

Post-acute sequelae of SARS-CoV-2 infection, often called long COVID, describes a range of health problems that persist, recur or appear after the initial COVID-19 illness has passed. Investors care because these lingering symptoms can change healthcare needs, labor force productivity, insurance costs, and demand for treatments or diagnostics — think of it like a company dealing with ongoing fixes after a major outage that affect operations and expenses for months or years.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Ratutrelvir shows a differentiated profile versus PAXLOVID™ with fewer adverse events and no viral rebounds

Activity shown in Paxlovid^®-ineligible patients, representing a significant population with few effective treatment options

Final data analysis to be reported in January 2026

NEWTOWN, Pa., Dec. 17, 2025 (GLOBE NEWSWIRE) -- Traws Pharma, Inc. (NASDAQ: TRAW) (“Traws Pharma”, “Traws” or “the Company”), a clinical-stage biopharmaceutical company developing novel therapies to target critical threats to human health from respiratory viral diseases, today announced that interim data with ratutrelvir, an investigational oral, ritonavir-free Mpro/3CL protease inhibitor, demonstrated a differentiated clinical profile in a pre-specified interim analysis of an ongoing randomized, open-label Phase 2 clinical study in patients with mild-to-moderate COVID-19.

The study was designed as an active-controlled comparator trial versus PAXLOVID™ (nirmatrelvir/ritonavir) and evaluated patient-reported symptom outcomes, safety, and real-world usability. A separate treatment arm included patients ineligible for ritonavir-boosted regimens due to contraindications or clinically significant drug–drug interactions. To date, 37 patients have been included in the interim analysis, with 25 patients treated with ratutrelvir and 12 patients treated with PAXLOVID™. More than 50% of the planned 90-patient population has been enrolled.

Patients in the ratutrelvir arm received ratutrelvir 600 mg orally once daily for 10 days, while patients in the comparator arm received PAXLOVID™ administered as nirmatrelvir 300 mg plus ritonavir 100 mg twice daily for 5 days, consistent with approved prescribing information.

“From a clinical perspective, these interim data suggest that ratutrelvir may provide a meaningful benefit across a broader range of patients, including those who are unable to receive ritonavir-boosted therapy,” commented Robert Redfield, MD, Chief Medical Officer, Traws Pharma. “The favorable tolerability profile observed to date, together with the absence of viral rebound events in ratutrelvir-treated patients, is encouraging. While these findings are preliminary and descriptive, they support continued clinical evaluation of ratutrelvir in both acute COVID-19 and in studies designed to better understand its potential impact on longer-term outcomes.”

Efficacy Signal Seen in Broad COVID-19-Infected Population

Across the interim analysis, ratutrelvir-treated patients demonstrated time-to-sustained symptom alleviation and resolution that was numerically comparable to Paxlovid® -treated patients, as assessed using the FLU-PRO Plus / COVID-19 Symptoms Diary. Sustained alleviation was defined as self-reported alleviation of all COVID-19 symptoms for four consecutive days. At the time of analysis, not all patients had completed the full 28-day observation period, and no formal statistical comparisons were performed; findings are descriptive and non-inferential.

No COVID-19 symptom or virologic rebound events have been observed to date in ratutrelvir-treated patients. One rebound event was observed in the PAXLOVID™ comparator arm (1 of 12 patients; 8.3%), occurring shortly after completion of the standard 5-day dosing regimen.

Six patients (16.2% of the interim population; 24% of the ratutrelvir cohort) treated with ratutrelvir were ineligible for PAXLOVID™ due to contraindications or drug–drug interaction risk. These patients demonstrated patient-reported symptom improvement dynamics consistent with those observed in the broader ratutrelvir-treated cohort.

Favorable Tolerability Profile for Ratutrelvir versus PAXLOVID™

Ratutrelvir was well tolerated in the interim analysis, with fewer reported adverse events compared with the PAXLOVID™-treated cohort. The most commonly reported adverse event among ratutrelvir-treated patients was mild dyspepsia, reported in 2 patients (7.6%). No dysgeusia (a distorted sense of taste) or ritonavir-associated adverse effects were reported, and no treatment discontinuations due to adverse events were observed.

In contrast, adverse events commonly associated with PAXLOVID™, including dysgeusia, dizziness, and dyspepsia, were reported in 4 patients (30%) in the comparator arm, consistent with prior clinical trial and real-world experience.

Implications for Use of Ratutrelvir for Long-COVID Prevention and Treatment

“The combination of early and sustained symptom improvement, extended dosing duration, absence of viral rebound observed to date, and favorable tolerability supports the strategic hypothesis that ratutrelvir may have utility in reducing post-acute sequelae of SARS-CoV-2 infection (Long COVID)”, commented Dr. Redfield. “By enabling earlier and potentially more complete viral clearance without the limitations associated with ritonavir boosting, ratutrelvir may offer a differentiated approach to both acute COVID-19 treatment and prevention of longer-term complications, pending confirmation in dedicated clinical studies”.

“Collectively, we believe the interim data position ratutrelvir as a next-generation oral 3CL protease inhibitor with ritonavir-free administration, once-daily oral dosing, an improved tolerability profile, applicability to Paxlovid-ineligible populations, and potential relevance to long-COVID prevention strategies,” commented Iain Dukes, MA D Phil, Chief Executive Officer, Traws Pharma. “The study remains ongoing, and completion of enrollment and follow-up will be required to support statistically robust conclusions.”

About Ratutrelvir

Ratutrelvir is an investigational oral, small molecule Mpro (3CL protease) inhibitor designed to be a broadly acting treatment for SARS-CoV-2/COVID-19 that is used without ritonavir. It has demonstrated in vitro activity against a range of virus strains. Preclinical and Phase 1 studies show that ratutrelvir does not require co-administration with a metabolic inhibitor, such as ritonavir, which could avoid ritonavir-associated drug-drug interactions¹, and potentially enable wider patient use. Phase 1 data also showed that ratutrelvir’s pharmacokinetic (PK) profile demonstrated maintenance of target blood plasma levels approximately 13 times above the EC₅₀ using the target Phase 2 dosing regimen of 600 mg/day for ten days, which may reduce the likelihood of clinical rebound and, consequently, reduce the risk for Long COVID². Industry data indicate that COVID treatment represents a potential multi-billion dollar market opportunity³.

Source information:

	1.	https://ascpt.onlinelibrary.wiley.com/doi/pdf/10.1002/cpt.2646
	2.	Carly Herbert et al. (2025) Clinical Infectious Diseases. https://doi.org/10.1093/cid/ciae539
	3.	Pfizer Inc. 10K report 2024, Feb 27, 2025

Third-party products mentioned herein are the trademarks of their respective owners.

About Traws Pharma, Inc.

Traws Pharma is a clinical stage biopharmaceutical company dedicated to developing novel therapies to target critical threats to human health in respiratory viral diseases. Traws integrates antiviral drug development, medical intelligence and regulatory strategy to meet real world challenges in the treatment of viral diseases. We are advancing novel investigational oral small molecule antiviral agents that have potent activity against difficult to treat or resistant virus strains that threaten human health: COVID-19/Long COVID and bird flu and seasonal influenza. Ratutrelvir is in development as a ritonavir-independent COVID treatment, targeting the Main protease (Mpro or 3CL protease). Tivoxavir marboxil is in development as a single dose treatment for bird flu and seasonal influenza, targeting the influenza cap-dependent endonuclease (CEN).

Traws is actively seeking development and commercialization partners for its legacy clinical oncology programs, rigosertib and narazaciclib. More details can be found on Traws’ website at https://www.ir.trawspharma.com/partnering.

For more information, please visit www.trawspharma.com and follow us on LinkedIn.

Forward-Looking Statements

Some of the statements in this release are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, Section 21E of the Securities Exchange Act of 1934, as amended, and the Private Securities Litigation Reform Act of 1995, and involve risks and uncertainties including statements regarding the Company, its business and product candidates, including the potential opportunity, market size, benefits, effectiveness, safety, and the clinical and regulatory plans for ratutrelvir and tivoxavir marboxil, as well as plans for its legacy programs. The Company has attempted to identify forward-looking statements by terminology including “believes”, “estimates”, “anticipates”, “expects”, “plans”, “intends”, “may”, “could”, “might”, “will”, “should”, “potential”, “preliminary”, “encouraging”, “approximately” or other words that convey uncertainty of future events or outcomes. Although Traws believes that the expectations reflected in such forward-looking statements are reasonable as of the date made, expectations may prove to have been materially different from the results expressed or implied by such forward looking statements. These statements are only predictions and involve known and unknown risks, uncertainties, and other factors, including the success and timing of Traws’ clinical trials, including when Traws will report the final data analysis of the Phase 2 studies of ratutrelvir; the potential efficacy of ratutrelvir for the treatment of COVID-19, including for the treatment of PAXLOVID™-ineligible patients; the potential for ratutrelvir to gain market acceptance, if and when regulatory approval is obtained, or become the new standard of care; Traws’ interactions with the FDA, BARDA and similar foreign regulators; collaborations; market conditions; regulatory requirements and pathways for approval; the ongoing need for improved therapy to reduce the frequency of clinical rebound and the concomitant risk for Long COVID; Traws’ ability to raise additional capital when needed; and those discussed under the heading “Risk Factors” in Traws’ filings with the U.S. Securities and Exchange Commission (SEC). Any forward-looking statements contained in this release speak only as of its date. Traws undertakes no obligation to update any forward-looking statements contained in this release to reflect events or circumstances occurring after its date or to reflect the occurrence of unanticipated events, except to the extent required by law.

Traws Pharma Contact:
Charles Parker
Traws Pharma, Inc.
cparker@trawspharma.com
www.trawspharma.com

Investor Contact:
John Fraunces
LifeSci Advisors, LLC
917-335-2395
jfraunces@lifesciadvisors.com

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What interim Phase 2 results did TRAW report on December 17, 2025?

Traws reported interim data from 37 patients showing ratutrelvir had comparable symptom alleviation, fewer adverse events, and no viral rebounds to date versus PAXLOVID™.

How many patients received ratutrelvir in the TRAW Phase 2 interim analysis?

Twenty-five patients received ratutrelvir 600 mg once daily for 10 days in the interim analysis.

Did ratutrelvir show activity in Paxlovid-ineligible patients in the TRAW study?

Yes; six patients who were ineligible for ritonavir‑boosted regimens were treated with ratutrelvir and showed similar symptom improvement dynamics.

Were any viral rebound events observed with ratutrelvir in the interim data?

No viral rebound events were reported in ratutrelvir‑treated patients in the interim analysis.

When will Traws release the final analysis of the ratutrelvir study?

Traws indicated the final data analysis is expected to be reported in January 2026.

How did adverse event rates compare between ratutrelvir and PAXLOVID™ in the interim report?

Adverse events were reported in 7.6% of ratutrelvir patients (most common: mild dyspepsia) versus 30% in the PAXLOVID™ comparator arm.