NEWTOWN, PA — Traws Pharma, Inc. (Nasdaq: TRAW) announced completion of a 90-patient Phase 2 study evaluating its investigational COVID-19 treatment ratutrelvir against PAXLOVID® and provided an update on development of its influenza candidate tivoxavir marboxil.
The open-label Phase 2 trial compared ratutrelvir, an oral Mpro/3CL protease inhibitor administered without ritonavir, to PAXLOVID® in patients with mild-to-moderate COVID-19. A separate treatment arm included patients ineligible for ritonavir-boosted regimens because of contraindications or significant drug interactions.
Patients receiving ratutrelvir who were ineligible for PAXLOVID® reported three treatment-related adverse events among 30 subjects, or 10%, compared with seven events among 30 subjects, or 23.3%, in the PAXLOVID® arm. The company said symptom resolution occurred more quickly in ratutrelvir-treated patients who were ineligible for PAXLOVID®, citing a hazard ratio of 1.31 (95% CI, 0.78-2.20; p=0.018).
According to the company, no viral rebound events were observed in ratutrelvir-treated patients in the study.
Robert R. Redfield, M.D., chief medical officer, said the analysis “confirms that ratutrelvir may provide a meaningful benefit across a broader range of patients, including those who are unable to receive ritonavir-boosted therapy.”
Redfield added that the “absence of viral rebound events” and shortened time to symptom resolution support continued evaluation of ratutrelvir in acute COVID-19 and in studies assessing longer-term outcomes.
Traws Pharma also reported progress with tivoxavir marboxil, a CAP-dependent endonuclease inhibitor under development as a once-monthly oral tablet for prevention of seasonal influenza.
The company said preclinical analysis of a tablet formulation showed a 30% increase in drug exposure compared with a prototype formulation. Modeling suggests the tablet could provide 28-day coverage in humans.
C. David Pauza, Ph.D., chief science officer, said, “Modelling of these data suggests that the tablet formulation should provide 28-day coverage, enabling a once-a-month prophylactic treatment.”
The company submitted a pharmacokinetic study of compressed tivoxavir marboxil tablets under an open investigational new drug application in Australia and is preparing for a human influenza prophylaxis challenge study in the United Kingdom.
Separately, Traws Pharma said the U.S. Food and Drug Administration placed its U.S. IND for tivoxavir marboxil on clinical hold because of concerns related to the mutagenicity data package. The FDA intends to communicate its concerns and suggested mitigation steps by March 16, 2026, the company said.
Redfield said the clinical hold does not directly affect ongoing or planned studies outside the United States and that the company is working to address the FDA’s concerns within its clinical development plan.
Traws Pharma is a clinical-stage biopharmaceutical company developing antiviral therapies targeting respiratory viral diseases, including COVID-19 and influenza.
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