Traws Pharma’s Bird Flu Drug Candidate Presented at ICAR

Traws Pharma, Inc. recently announced that positive data supporting the potential for tivoxavir marboxil (TXM) as a bird flu treatment was presented yesterday in a poster at the International Society for Antiviral Research (ICAR 2025) held in Las Vegas, Nevada.

David Pauza, PhD, Chief Science Officer of Traws Pharma commented, “Bird flu has emerged as a potential threat to human health. Extensive spread in poultry and dairy farms have increased the exposure risk for agricultural workers. We believe an effective antiviral agent for bird flu needs to potently suppress native and resistant viruses and provide protection against mortality and viral disease, with good overall tolerability and ease of use. The positive data presented at ICAR, from laboratory, preclinical and Phase 1 studies, reinforce our view that TXM meets that target profile and has the potential to be a potent, effective and safe treatment for bird flu, with broad applicability to seasonal flu. Looking ahead, we plan to meet with the FDA to align on next steps, including the potential for an accelerated path to approval.”

“We were pleased to have the opportunity to share the promising TXM results in bird flu with the international antiviral community during the poster session at ICAR. We look forward to updating investors on Traws’ antiviral programs during a virtual event on Monday, March 31, 2025 at 10:00 AM ET, said Werner Cautreels, PhD, Chief Executive Officer of Traws Pharma.

Tivoxavir Marboxil Poster

Poster Title
Tivoxavir marboxil, an Influenza Inhibitor Targeting Cap-dependent Endonuclease: Results from a Phase I Trial Demonstrating Safety, Tolerability and Pharmacokinetics and Demonstrating Protection Against H5N1 Bird Flu in a Rodent Challenge Model

Data in the poster support potential use of single dose treatment of TXM in bird flu:

• Potent Preclinical Suppression of Resistant Virus: Laboratory studies showed that TXM potently suppressed influenza A, B and C viruses and baloxavir resistant flu viruses, with sub-nanomolar potency against H5N1/influenza A virus.
• Potent Antiviral Activity in Preclinical Challenge Model: Results from a rodent challenge model showed that 100% of mice treated with TXM survived, with no virus-induced weight loss and significant reductions in lung viremia, whereas all untreated animals succumbed by study day 6. These data are consistent with previously reported ferret data.
• Phase 1 data show potential for single treatment to maintain target drug levels: Results in healthy volunteers showed that a single dose of TXM maintained plasma blood levels at EC₉₀ for ~3 weeks, with good overall tolerability. The study incorporated a wide dose range in anticipation that bird flu would be more virulent and hard to treat.

The International Conference on Antiviral Research (ICAR, https://www.isar-icar.com/ICAR2025) is an international organization dedicated to bringing together scientists and clinicians from multiple disciplines to discuss the latest advances and breakthroughs in antiviral research.

Tivoxavir marboxil (TXM) is an investigational oral, small molecule CAP-dependent endonuclease inhibitor designed to be administered as a single-dose for the treatment of bird flu and seasonal influenza. Consistent, positive preclinical data from three species indicate that a single-dose of TXM demonstrated a therapeutic effect against H5N1 bird flu. Seasonal influenza represents an estimated multi-billion antiviral market opportunity, largely driven by global health organizations, practice guidelines and government tenders¹, with upside potential from potential pandemic flu outbreaks including H5N1 bird flu. We believe that these data support further development of tivoxavir marboxil as a treatment for bird flu.

Source information: 1. TRAW data on file; 2. Mostafa, A., Barre, R.S., Allue-Guardia, A., et al. (2025) Emerging Microbes and Infections, https://doi.org/10.1080/22221751.2024.2447614

Traws Pharma is a clinical stage biopharmaceutical company dedicated to developing novel therapies to target critical threats to human health in respiratory viral diseases. We strive to advance novel investigational antiviral agents that have potent activity against difficult to treat or resistant virus strains that threaten human health. Our product candidates are intended to be safe, with simple dosing regimen. We seek to utilize accelerated clinical trial strategies with a commitment to patients who are especially vulnerable.

The Company’s two antiviral programs are investigational oral small molecules targeting bird flu and seasonal influenza, and COVID-19. Tivoxavir marboxil is in development as a single dose treatment for bird flu and seasonal influenza, targeting the influenza cap-dependent endonuclease (CEN). Ratutrelvir is in development as a COVID treatment, targeting the Main protease (Mpro or 3CL protease), without the need for co-administration of ritonavir.