Traws Pharma Defers Phase 2a Influenza Challenge Trial After MHRA Negative Review; FDA Hold Remains on Bird Flu Development
Key Insights
Traws Pharma (search) postponed its phase 2a human influenza (search) challenge study of tivoxavir marboxil after receiving a negative regulatory review from the UK's MHRA.
The deferred trial was tied to $20 million in financing, with $10 million contingent on MHRA approval and $10 million linked to data readout.
The FDA separately placed the U.S. IND application on hold in January due to concerns about mutagenicity in the toxicology data package.
Traws Pharma (search) (TRAW) has deferred its planned phase 2a human influenza (search) challenge study for its lead antiviral candidate, tivoxavir marboxil (TXM), following a negative review from the United Kingdom's Medicines and Healthcare products Regulatory Agency (MHRA). The decision, announced after market close on Friday, sent shares down approximately 28% in after-hours trading.
The challenge trial, which was slated to begin this quarter, would have enrolled approximately 150 healthy volunteers who would receive either TXM or placebo before being exposed to a controlled strain of seasonal influenza (search) virus. The study was designed to assess whether the drug could prevent infection, offering a faster route to generating clinical data compared to traditional field studies.
Dual Regulatory Setbacks
The MHRA's negative review compounds an earlier regulatory hurdle in the United States. In mid-January, the U.S. Food and Drug Administration placed Traws' Investigational New Drug (IND) application for tivoxavir marboxil on clinical hold. The FDA's concerns centered on the toxicology data package, specifically regarding the potential for the compound to cause genetic changes.
Traws had pivoted to the UK challenge trial strategy after the FDA declined to allow development of TXM for bird flu based solely on animal data. Now, with both regulatory pathways blocked, the company is reassessing its development approach.
Financial Implications
The deferred trial carries significant financial consequences. In April, Traws secured a financing agreement that included $10 million tied to MHRA approval for the challenge study and an additional $10 million linked to the announcement of data from the trial. The company stated its cash runway extends into the first quarter of 2027.
Backup Candidates and Strategic Pivot
Traws is now turning to its portfolio of backup influenza (search) antiviral compounds. According to CEO Iain Dukes, the company is "actively advancing candidates with TXM's long-duration pharmacokinetic and antiviral profile and devoid of any mutagenic potential." These alternative candidates are designed to "exclude potential regulatory concerns" that have plagued the lead compound.
Chief Science Officer David Pauza emphasized that tivoxavir marboxil demonstrated potent efficacy in three animal models of highly pathogenic avian influenza (search) and possesses a pharmacokinetic profile consistent with use for bird flu treatment and prevention. "The product candidate retains potential for emergency use in a bird flu outbreak and for prevention in high-risk populations," Pauza said.
Chief Medical Officer Robert R. Redfield acknowledged the setback while reaffirming the program's importance: "While we have had a setback in the development of our lead compound for influenza (search), the program continues to be a high priority."
Analyst and Retail Sentiment
Despite the regulatory challenges, both analysts covering TRAW maintain a "Buy" rating on the stock, with an average 12-month price target of $5.50 — implying a potential upside of over 300% from the stock's last close. On Stocktwits, retail sentiment shifted from "bearish" to "neutral" territory, with some users characterizing the after-hours decline as "overblown."