Protalix BioTherapeutics, Inc. filed an 8-K press release on November 9, 2026, announcing the presentation of individual participant pharmacokinetic and pharmacodynamic data from the Phase 1 single ascending dose study of PRX-115 at the American College of Rheumatology Convergence 2026 in Orlando, Florida.

Key Highlights

  • Poster presented at ACR 2026: Individual participant PK/PD data from the 18 mg, 24 mg, and 36 mg cohorts of the Phase 1 PRX-115 study were presented on November 10, 2026, in Poster Session C (Abstract 2652).
  • Six participants per cohort received a single infusion and were followed for 85 days, according to the filing.
  • Uric acid target met for up to 12 weeks: At 36 mg, mean plasma uric acid stayed below the 6.0 mg/dL target for up to 12 weeks after a single infusion, the company disclosed.
  • PRX-115 plasma levels measurable for up to 85 days: New individual patient data show the effect associated with PRX-115 plasma levels remaining measurable for up to 85 days, per the filing.
  • Phase 2 RELEASE study design: The study tests a fixed 36 mg dose across five treatment arms of 30 patients each, including dosing every 4, 6, or 8 weeks with and without methotrexate, and placebo.
  • Top-line results expected second half of 2027: The company stated it anticipates top-line results from the Phase 2 RELEASE study (NCT07280156) in the second half of 2027.
  • Safety profile from Phase 1: PRX-115 was described as generally well tolerated, with mostly mild to moderate and transient related adverse events and one anaphylactic reaction that resolved; no other serious adverse events were reported.

PRX-115 Phase 1 Findings and the Phase 2 RELEASE Study Design

Protalix BioTherapeutics (NYSE American:PLX) disclosed that the analysis presented at ACR Convergence 2026 covers the 18 mg, 24 mg, and 36 mg cohorts of its Phase 1 single ascending dose study of PRX-115, a plant cell-expressed recombinant PEGylated uricase in development for uncontrolled gout. According to the filing, PRX-115 exposure increased with dose and persisted longer at higher doses, and participants with prolonged measurable PRX-115 concentrations kept plasma uric acid levels below the therapeutic target longer, while declining concentrations matched gradual plasma uric acid recovery.

The company disclosed that at the 36 mg dose level, mean plasma uric acid levels stayed below the 6.0 mg/dL target for up to 12 weeks after a single infusion. The filing noted that PRX-115 plasma levels remained measurable for up to 85 days. The safety data, previously presented at ACR 2024, showed PRX-115 was generally well tolerated, with mostly mild to moderate and transient related adverse events; one anaphylactic reaction occurred six minutes into an infusion after exposure to about 5% of the planned dose, resolved completely, and no other serious adverse events were reported, according to the filing.

The Phase 2 RELEASE study (NCT07280156) is described in the filing as a double-blind, placebo-controlled study testing a fixed 36 mg dose in five treatment arms of 30 patients each: PRX-115 every 4 weeks without methotrexate; PRX-115 every 4, 6, or 8 weeks with methotrexate; and placebo. The primary endpoint, according to the filing, is the proportion of patients who demonstrated a reduction in serum uric acid levels to below 6.0 mg/dL for at least 80% of the time during Month 6. The company stated that top-line results are expected in the second half of 2027. The filing noted that all statements regarding future outcomes are forward-looking and subject to the company's cautionary language under the Private Securities Litigation Reform Act of 1995.

What Was Disclosed

Protalix BioTherapeutics disclosed Phase 1 PK/PD data for PRX-115 at ACR Convergence 2026, covering three dose cohorts followed for 85 days. The data support the dosing intervals being tested in the ongoing Phase 2 RELEASE study, with top-line results expected in the second half of 2027.