NEWTOWN, PA — Traws Pharma (NASDAQ: TRAW) said this week it is preparing additional toxicology data requested by U.K. regulators, delaying the planned launch of a Phase 2a human influenza challenge study for its experimental antiviral candidate tivoxavir marboxil (TXM) as the company works to advance a potential preventive treatment for seasonal flu.
The clinical-stage biotechnology company said the updated safety package is being assembled in response to information requirements from the United Kingdom’s Medicines and Healthcare Products Regulatory Agency (MHRA) and is expected to be resubmitted during the third quarter of 2026.
The regulatory request affects Traws’ planned influenza challenge study, in which healthy volunteers would be intentionally exposed to seasonal influenza under controlled conditions to evaluate the drug’s effectiveness as a preventive therapy.
Following resubmission, the company expects a formal response from the MHRA within 30 days, according to the announcement.
The development represents a regulatory hurdle for TXM, one of Traws’ lead pipeline candidates, as the company seeks proof-of-concept data supporting its use as an oral prophylactic treatment against influenza.
“Based upon recent feedback and further guidance from the MHRA, we believe our updated data package will support the proposed seasonal influenza Challenge study to be conducted in healthy volunteers and provide important proof of concept data for TXM’s use as an oral prophylaxis medicine,” Chief Executive Officer Iain D. Dukes said.
Traws said the additional toxicology work follows more detailed feedback from the MHRA after the company’s June 12 update regarding the program.
The company is developing TXM as a potential oral therapy designed to address seasonal influenza, which continues to generate substantial public health and economic burdens worldwide, particularly among older adults and immunocompromised patients.
According to Traws, laboratory testing has demonstrated activity across multiple seasonal influenza strains, while early pharmacokinetic data suggest the drug may be suitable for preventive use.
“TXM demonstrated broad in vitro efficacy across multiple strains of seasonal influenza and a pharmacokinetic profile consistent with its use as a chemoprophylactic agent,” Chief Science Officer C. David Pauza said.
Pauza added that the company also plans to evaluate additional molecules for potential inclusion in its influenza treatment program.
Chief Medical Officer Dr. Robert Redfield said influenza remains a significant health threat globally and noted that prevention strategies are particularly important for vulnerable populations at elevated risk of severe illness.
The company is focused on developing therapies targeting viral diseases and neuroplasticity-related disorders, including depression and post-traumatic stress disorder. The outcome of the MHRA review could determine the timeline for advancing TXM into the next stage of clinical development.
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