Protalix's PRX-115 Shows Promise in Phase I Gout Trial with Extended Dosing Potential

Protalix BioTherapeutics has announced promising results from its completed Phase I clinical trial of PRX-115, a novel PEGylated uricase designed to treat severe gout. The trial results, presented at the American College of Rheumatology (ACR) annual meeting, demonstrate favorable safety outcomes and suggest potential advantages in dosing frequency over current standard treatments.

Phase I Trial Design and Results

The double-blind, placebo-controlled study enrolled 64 subjects with elevated urate levels (>6.0 mg/dL) across eight cohorts. Participants received a single intravenous infusion and were monitored for 85 days, with subjects randomized in a 3:1 ratio between PRX-115 and placebo. The trial was conducted at New Zealand Clinical Research under the oversight of the New Zealand Medicines and Medical Devices Safety Authority.

Safety data showed PRX-115 to be generally well-tolerated, with 25% of treated subjects (12/48) reporting study drug-related adverse events. While one subject in cohort 2 experienced an anaphylactic reaction immediately post-infusion, the reaction resolved completely, and no other serious adverse events were reported throughout the study period.

Potential Therapeutic Advantages

A significant finding from the trial suggests that PRX-115 may enable reduced infusion frequency compared to currently approved treatments. This potential advantage is particularly noteworthy when compared to Krystexxa, the FDA-approved treatment for chronic gout, which requires biweekly intravenous infusions.

Development Pipeline and Next Steps

Building on these encouraging Phase I results, Protalix is advancing PRX-115 to the next development stage. The company is currently planning a Phase II trial, with design details expected to be announced in the coming quarters and trial initiation targeted for the second half of 2025.

Broader Company Portfolio

PRX-115 is part of Protalix's expanding development portfolio, which includes two globally approved products: Elfabrio and Elelyso. The company's proprietary plant-based expression system offers potential advantages in manufacturing, including reduced risk of viral contamination compared to traditional mammalian cell production methods.

The company is also developing PRX-119, a PEGylated recombinant human DNase I product candidate, for NETs-related diseases, with preclinical studies showing promising results in both sepsis and ARDS models.