NEWTOWN, PA — Traws Pharma, Inc. (NASDAQ: TRAW) said interim results from a mid-stage clinical trial suggest its experimental COVID-19 treatment ratutrelvir may offer a differentiated alternative to Paxlovid, with fewer side effects and no viral rebound observed to date.
The findings come from a pre-specified interim analysis of an ongoing Phase 2, randomized, open-label study comparing ratutrelvir with Paxlovid in patients with mild-to-moderate COVID-19. The trial also includes a separate cohort of patients who are ineligible for ritonavir-boosted therapies, a population with limited treatment options due to drug interactions or contraindications.
Ratutrelvir is an investigational oral antiviral designed to inhibit the SARS-CoV-2 main protease without the need for ritonavir boosting. In the interim analysis, data from 37 patients were evaluated, including 25 treated with ratutrelvir and 12 treated with Paxlovid. More than half of the planned 90-patient enrollment has been completed.
Patients receiving ratutrelvir were dosed once daily for 10 days, while the comparator group received the standard five-day Paxlovid regimen. According to the company, patient-reported symptom outcomes were numerically comparable between the two groups, based on standardized symptom diaries. The analysis was descriptive, with no formal statistical testing conducted.
Notably, no symptom or virologic rebound events were reported among ratutrelvir-treated patients. One rebound event occurred in the Paxlovid arm, representing 8.3 percent of that cohort. Viral rebound following treatment has been a concern among clinicians and patients using existing oral antivirals.
The interim data also highlighted a more favorable tolerability profile for ratutrelvir. Mild dyspepsia was the most commonly reported adverse event, occurring in two patients. No treatment discontinuations were reported, and adverse effects commonly associated with Paxlovid, such as taste disturbance and dizziness, were not observed in the ratutrelvir group.
Six patients in the ratutrelvir arm were ineligible for Paxlovid due to contraindications or drug–drug interaction risks. These patients showed symptom improvement patterns similar to those seen in the broader ratutrelvir-treated population, suggesting potential utility in a group often excluded from antiviral therapy.
Company executives said the absence of viral rebound, combined with extended dosing and improved tolerability, supports further evaluation of ratutrelvir not only for acute COVID-19 but also for its potential role in reducing the risk of long COVID. Final data from the study are expected to be reported in January 2026.
Traws Pharma said enrollment and follow-up are ongoing and emphasized that larger datasets will be required to draw definitive conclusions about efficacy and long-term outcomes.
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