Traws Pharma’s Ratutrelvir Cuts Adverse Events to 10% Versus 23.3% in 90-Patient Trial
Traws Pharma’s 90-patient Phase 2 trial shows ratutrelvir produced 10% adverse events versus 23.3% with nirmatrelvir/ritonavir, with no viral rebounds and faster symptom resolution in Paxlovid-ineligible patients (HR 1.31; p=0.018). Preclinical tivoxavir marboxil tablet achieved 30% higher exposure, predicting 28-day influenza protection despite an FDA IND hold.
1. Phase 2 Ratutrelvir Results
The 90-patient open-label Phase 2 study compared ratutrelvir 600 mg once daily for 10 days to standard nirmatrelvir/ritonavir dosing. Ratutrelvir demonstrated a 10% adverse event rate versus 23.3% for the comparator group, no viral rebounds and a statistically significant faster symptom resolution in patients ineligible for ritonavir (HR 1.31; p 0.018).
2. Tivoxavir Marboxil Preclinical Progress
A new tablet formulation of tivoxavir marboxil showed a 30% increase in drug exposure versus the earlier powder-in-capsule prototype. Pharmacokinetic modeling forecasts 28-day protective levels against seasonal and pandemic influenza variants, supporting a planned human influenza prophylaxis challenge study in the UK following an open IND submission in Australia.
3. FDA IND Hold Implications
The US IND for tivoxavir marboxil has been placed on clinical hold due to mutagenicity data concerns, with formal feedback and mitigation recommendations expected by March 16, 2026. This hold does not impede ongoing non-US studies, and the company is addressing data requirements to advance its BARDA strategic stockpile application.