Traws Pharma shares fall 20.30% intraday as FDA places tivoxavir marboxil on clinical hold over mutagenicity concerns.

Traws Pharma (NASDAQ: TRAW) fell 20.3% intraday after the FDA placed its influenza candidate tivoxavir marboxil on clinical hold due to concerns over mutagenicity data. The agency plans to outline specific concerns and mitigation steps by March 16, 2026. While the company also reported positive Phase 2 data for ratutrelvir—showing improved tolerability and faster symptom resolution versus PAXLOVID in COVID-19 patients—the regulatory setback for tivoxavir, a key antiviral development, dominated investor sentiment. The clinical hold raises uncertainty for tivoxavir’s advancement in the U.S., particularly for its potential inclusion in the strategic stockpile for avian influenza, overshadowing the positive ratutrelvir results.