PRX-102 Effectively Treats Fabry Disease in Phase 3 Data

The final results of the BRIGHT phase 3 clinical trial were announced by Protalix BioTherapeutics and Chiesi Global Rare Diseases. The trial evaluated PRX-102 (pegunigalsidase alfa) as treatment for individuals with Fabry disease.

The study successfully achieved safety, efficacy and pharmacokinetic objectives. All participating patients enrolled in the extension study following the completion of the trial.

When patients with Fabry disease were treated with 2 mg/kg of PRX-102 by intravenous (IV) infusion every 4 weeks, the results showed that their condition was stable. To assess stability, investigators estimated glomerular filtration rate (eGFR) slope and plasma lyso-Gb3 concentration.

The Trial and Treatment

Fabry disease is an X-linked inherited rare disease that occurs in 1 per 40,000-60,000 people. Patients with the disease inherit a deficient α‑Galactosidase‑A enzyme resulting in progressive accumulation of abnormal deposits of a fatty substance called globotriaosylceramide (Gb3) in blood vessel walls throughout a person's body.

PRX-102 is a plant cell-expressed recombinant, PEGylated, cross-linked α‑galactosidase‑A product candidate. Patients with Fabry disease can't properly breakdown the abundance of GB3 that accumulates in the blood vessels on their own, leading to episodes of pain, impaired peripheral sensation, and end-organ failure.

The multicenter, multinational open-label, switch-over study administered a total of 14 infusions to patients in 4 week intervals. The 30 adults who began the trial had previously received an approved enzyme replacement therapy (ERT) for at least three years on a stable dose administered every two weeks (agalsidase alfa – Replagal® or agalsidase beta – Fabrazyme®).

The Results

Of the 30 patients, 1 patient deterred from the intended regimen by switching to 1 mg/kg of PRX-102 every 2 weeks per protocol at the 11th infusion, and 28 received the intended regimen every 4 weeks for the entire study.

The outcome measures show that plasma lyso-Gb3 concentrations remained stable throughout the trial, displaying a mean change of 3.01 nM from baseline to week 52. By the final week, mean eGFR values and eGFR slope also indicated stability.

With 33 total treatment-emergent adverse events (TEAEs) reported in 9 (30%) patients, all were mild or moderate in severity. The majority of them were resolved by the conclusion of trial. No serious or severe treatment-related TEAEs were observed, and none led to death or withdrawal from the study.

"We are excited to share the final data from the BRIGHT study, an important milestone in the progress of our PRX-102 clinical program," Dror Bashan, President and CEO, Protalix said in a statement. "The availability of this data for review by the U.S. Food and Drug Administration, the European Medicines Agency and other regulators is another step forward towards the anticipated approval of PRX-102 as a potential good alternative for adult Fabry patients in both the regular 1 mg\kg every two weeks as well as the 2 mg\kg every four weeks regimen."