U.K. regulators have issued a “negative review” of Traws Pharma’s planned human influenza challenge study, forcing the biotech to defer a phase 2a trial tied to $20 million in funding.
In April, Traws tasked hVIVO with testing its prophylactic antiviral candidate, tivoxavir marboxil (TXM), in about 150 healthy people intentionally infected with seasonal flu. The trial, which Traws scheduled for this month, offered the company a faster way to generate TXM data than field studies. Traws embarked on the strategy after the FDA knocked back its plans to develop TXM for bird flu based on animal data.
Yet the challenge trial plan ran into problems with another regulatory agency. Traws’ statement lacks a direct explanation for why the U.K. Medicines and Healthcare Products Regulatory Agency’s (MHRA) review of the challenge trial was negative, although its discussion of the next steps offers some clues.
Drawing from its portfolio of back-up antiviral compounds, Traws is “actively advancing candidates with TXM’s long-duration pharmacokinetic and antiviral profile and devoid of any mutagenic potential.” The alternative antiviral candidates will “exclude potential regulatory concerns,” Traws CEO Iain Dukes said in a statement. The FDA previously put a planned TXM trial on hold over mutagenicity data concerns.
The biotech faces time pressures. Traws’ cash runway extends into the first quarter of next year, and the financing deal it struck in April is tied to the delayed challenge trial. The agreement includes $10 million tied to MHRA approval for the challenge study and a further $10 million linked to the announcement of data from the trial.
Traws’ influenza program remains a priority, Robert Redfield, M.D., the company’s chief medical officer, said in a statement. Redfield joined Traws in 2024, about three years after ending a stint as director of the CDC that began in 2018.