Traws Pharma's Interim Data For Ratutrelvir Demonstrated A Differentiated Clinical Profile In Pre-specified Interim Analysis Of An Ongoing Open-label Phase 2 Study For Mild-to-moderate Covid-19, Final Data Analysis Expected In January 2026

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."