Ongoing clinical results with ratutrelvir confirm a differentiated profile versus PAXLOVID® with fewer adverse events, no viral rebounds to date and faster time to sustained symptom resolution; results recapitulated in PAXLOVID®-ineligible patients, representing a significant population with few effective treatment options
Compressed tablets of tivoxavir marboxil predicted to provide 28-day protection from influenza against wide range of seasonal and pandemic-potential variants
Human influenza prophylaxis challenge study time slot secured for June 2026
NEWTOWN, Pa., Jan. 26, 2026 (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 the completion of enrollment in its ongoing 90-patient, open-label Phase 2 study of ratutrelvir, an investigational oral, ritonavir-free Mpro/3CL protease inhibitor, versus PAXLOVID®, in patients with mild-to-moderate COVID-19, together with a single arm in PAXLOVID®-ineligible subjects. Patients ineligible to receive PAXLOVID® are frequently at elevated risk for severe disease and require suitable, safe and effective treatment options. Ratutrelvir has the potential to address this gap in care and may be a valuable therapeutic option. The Company also provided an update on the progress of the tivoxavir marboxil program for influenza.
Ratutrelvir Update
The study, designed as an active-controlled comparator trial versus PAXLOVID® (nirmatrelvir/ritonavir), evaluated patient-reported symptom outcomes, safety, and real-world usability. A separate treatment arm was comprised of patients ineligible for ritonavir-boosted regimens due to contraindications or clinically significant drug–drug interactions.
Patients in the ratutrelvir arm received ratutrelvir 600 mg orally, once daily for 10 days, while patients in the comparator arm received oral PAXLOVID®, administered as nirmatrelvir 300 mg twice daily plus 100 mg ritonavir twice daily for 5 days, consistent with approved prescribing information.
“From a clinical perspective, the ongoing data analysis confirms previous reports 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 R. Redfield, MD, Chief Medical Officer of Traws Pharma. “The favorable tolerability profile, together with a shortened time to symptom resolution and the absence of viral rebound events in ratutrelvir-treated patients, encourages and supports the continued clinical evaluation of ratutrelvir in both acute COVID-19 and in studies designed to better understand its potential impact on longer-term outcomes.”
“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),” continued 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.”
Tivoxavir Marboxil Update
The Company additionally announced that it is progressing an additional indication for tivoxavir marboxil (TXM), a potential best in class CAP-dependent endonuclease inhibitor, as a single monthly oral tablet for the prophylactic treatment of seasonal influenza.
“In prior Phase 1 studies in healthy volunteers, an unformulated powder-in-capsule formulation provided blood levels exceeding 3X the EC50 against a basket of common seasonal influenza variants for up to 22 days after drug administration. A new compressed tablet formulation may provide 28 day coverage, enabling a once-a-month prophylactic treatment,” commented C. David Pauza, PhD, Chief Science Officer of Traws Pharma.
“Once a planned bridging healthy volunteer study has confirmed the extended exposure, we will progress TXM into a seasonal influenza virus prophylaxis Challenge Study in June 2026 at hVIVO, the pre-eminent CRO for such studies. Positive results will enable progression into registration studies,” continued Dr. Pauza.
“Collectively, the advancement of our antiviral portfolio provides a number of significant value inflection points and could provide needed treatment and prevention options for clinically important viral diseases,” commented Iain Dukes, MA, DPhil, Chief Executive Officer of Traws Pharma.
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 show 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 also 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.
About Tivoxavir Marboxil
Tivoxavir marboxil (TXM) is an investigational oral, small molecule CAP-dependent endonuclease inhibitor designed to be administered as a single-dose for the treatment of bird flu and the treatment or prophylaxis of seasonal influenza. It has shown potent in vitro activity against a range of influenza strains in preclinical studies, including a human isolate of the highly pathogenic avian flu H5N1 (bird flu). Consistent, positive preclinical data from three animal species indicate that a single dose of TXM demonstrated a therapeutic effect against H5N1 bird flu. Seasonal influenza represents an estimated multi-billion dollar antiviral market opportunity, largely driven by global health organizations, practice guidelines and government tenders and inclusion in drug stock piling initiatives4,5, with upside potential from potential pandemic flu outbreaks including H5N1 bird flu. We believe that these data support further development of TXM as a treatment for bird flu.
Source information
- https://ascpt.onlinelibrary.wiley.com/doi/pdf/10.1002/cpt.2646
- Carly Herbert et al. (2025) Clinical Infectious Diseases. https://pubmed.ncbi.nlm.nih.gov/39692474/
- Pfizer Inc. annual report on Form 10-K for the fiscal year ended December 31, 2024, filed with the U.S. Securities and Exchange Commission on February 27, 2025
- Per link
- TRAW data on file
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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-19 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”, “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 outcome of Traws’ IND filing with the FDA; the potential efficacy and tolerability of ratutrelvir for the treatment of COVID-19, including the potential to reduce the risk of COVID rebound and Long COVID; the success and timing of Traws’ clinical trials, including when Traws will report results of its studies of tivoxavir marboxil; the potential efficacy of tivoxavir marboxil to provide 28-day coverage against seasonal influenza variants; the potential for ratutrelvir or tivoxavir marboxil to gain market acceptance, if and when regulatory approval is obtained, or to 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; the extent of the spread and threat of the bird flu; the Company’s cash projections; 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
917-355-2395
jfraunces@lifesciadvisors.com
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