Trial for CF treatment BX004 nears top-line results in Europe
FDA concerns with third-party nebulizer device keeps US trial on hold
Despite a recent hold by the U.S. Food and Drug Administration (FDA) on a BX004 clinical trial in the U.S., the experimental cystic fibrosis (CF) lung infection treatment is still advancing in Europe. According to BX004’s developer Biomx, top-line results are expected in early 2026.
“Patient enrollment and dosing in Europe have progressed faster than expected, and the BX004 Phase 2b trial remains on track to report top-line results in the first quarter of 2026,” Jonathan Solomon, CEO of BiomX, said in a company press release.
Biomx said it is also currently working to address the FDA’s concerns related to the trial. The FDA recently provided new feedback, highlighting how the therapy may help fill unmet medical needs and offering guidance on future development, Biomx added.
“We are encouraged by the FDA’s perspective recognizing persistent unmet need in this patient population and by the constructive guidance on potential development pathways,” Solomon said. “We believe this feedback can help us optimize study design and potentially broaden the clinical relevance of BX004, subject to future data from the Phase 2b trial, regulatory alignment, and resources.”
Targeting the cause of CF lung issues
CF is a genetic disorder characterized by thick, sticky mucus that builds up in the lungs and other organs. This mucus creates a perfect environment for infectious bacteria, making lung infections a common problem for people with CF.
BX004 aims to eliminate infectious bacteria using bacteriophages — viruses, often shortened to phages, that can infect and kill bacterial cells. The experimental therapy contains a cocktail of several phages that can target Pseudomonas aeruginosa, a specific type of bacteria that often causes problematic lung infections in CF patients.
BX004 is designed to be delivered into the lungs using a nebulizer, which is manufactured by a third party. The FDA recently put a hold on the U.S. portion of a Phase 2b clinical trial (NCT06998043) testing the therapy, citing concerns with the nebulizer.
Biomx said it has been working with the nebulizer’s manufacturer to address the FDA’s concerns. The companies provided “a comprehensive package of data and analyses” to answer the FDA’s questions. After reviewing that data, the FDA “issued an additional request for limited technical clarifications related to the nebulizer’s performance … which are narrow in scope and pertain solely to the nebulizer device,” Biomx said.
The company added it has already submitted responses it believes fully address the FDA’s questions and is hoping the agency will soon lift its hold on the clinical trial. Biomx stressed the FDA has not raised any concerns about the BX004 therapy itself.
“We believe the information provided appropriately addresses the FDA’s questions and look forward to continuing our dialog with the FDA to support a potential lifting of the clinical hold in the U.S. in the near term,” Solomon said.
In addition to asking for further clarifications about the nebulizer, the FDA offered Biomx guidance about how the therapy might be further developed — including considerations for a potential Phase 3 trial. The FDA’s feedback also emphasized that treating bacterial lung infections in CF patients remains an area of unmet medical need.
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