N-Zyme Biomedical, a clinical-stage company headquartered in Delaware, announced the initiation of a Phase II trial of fosamprenavir for laryngopharyngeal reflux (LPR), marking the first clinical test of a pepsin inhibitor in reflux disease and a direct challenge to the decades-long dominance of acid suppression as the therapeutic paradigm for this condition.
The significance lies in the molecule's mechanism: while proton pump inhibitors (PPIs) and potassium-competitive acid blockers (P-CABs) reduce gastric acid, they do not address pepsin, the proteolytic enzyme that research increasingly implicates as a primary driver of tissue damage in LPR and other extraesophageal reflux manifestations. Fosamprenavir, the molecule N-Zyme is repurposing, is a well-characterized antiretroviral prodrug with an established human safety profile from its prior use in HIV therapy - marketed by ViiV Healthcare/GSK as Lexiva/Telzir. After identifying its function as a pepsin inhibitor, N-Zyme has recently secured patents from both the US Patent and Trademark Office and the Japan Patent Office covering its use in reflux indications. The trial is led by Dr. Nikki Johnston at the Medical College of Wisconsin, who has published extensively on pepsin's role in LPR pathology.
Competitive context
The reflux treatment landscape is currently being reshaped by the P-CAB class. Phathom Pharmaceuticals' Voquezna (vonoprazan) is approved in the US for erosive GERD, non-erosive GERD, and H. pylori eradication, while Sebela Pharmaceuticals' tegoprazan has an NDA under FDA review with a decision anticipated in January 2027 following positive Phase III TRIUMpH data. Both agents, however, share the same fundamental limitation as PPIs: they suppress acid without targeting pepsin, leaving a subset of patients — particularly those with LPR — without adequate symptom control. Cross-trial comparisons are limited by differences in patient populations and endpoint definitions, but N-Zyme's pepsin-directed approach is mechanistically distinct from all current approved therapies and any known late-stage pipeline program.