Protalix BioTherapeutics Completes Enrollment for PRX-102 Phase 3 Trial  

Patricia Inácio, PhD avatar

by Patricia Inácio, PhD |

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Protalix BioTherapeutics announced it has completed enrollment of its Phase 3 trial evaluating PRX-102 in Fabry disease patients previously treated with Shire’s Replagal (agalsidase alfa).

The BRIDGE trial (NCT03018730) is an open-label switch-over study that will assess the safety and efficacy of PRX-102 in 22 patients with Fabry disease treated with Replagal for at least two years and currently on a stable dose for at least six months.

After an initial three-month observation, where participants will continue to receive Replagal, patients will be switched to 1 mg/kg of PRX-102, administered into the bloodstream (intravenously) every two weeks for a year.

PRX-102 is an investigational enzyme replacement therapy (ERT) that compensates for the lack of the alpha-galactosidase A (αGAL-A) enzyme in Fabry patients. The absence of αGAL-A leads to the damaging accumulation of two fat molecules — Gb3 and lysoGb3 — in tissues such as the heart, kidneys, nervous system, eyes, and skin. PRX-102 is made with Protalix’s plant-based ProCellEx platform, which uses plant cells to produce therapeutic proteins in contrast to commonly used mammalian cells.

Preliminary findings of the BRIDGE trial showed that treatment with PRX-102 for six months greatly improved patients’ kidney function by reverting the decline in the glomerular filtration rate — a measure of how well the kidneys are cleaning the blood.

“In September 2018, we reported encouraging, positive interim results from the BRIDGE study and look forward to continue releasing additional data in 2019,” Moshe Manor, Protalix’s president and CEO, said in a press release.

“Based on the promising preliminary BRIDGE study results, and taking into account the newly issued guidance from the U.S. Food and Drug Administration (FDA), we plan to meet with the FDA during the first quarter of 2019 to discuss the most optimal regulatory path forward for PRX-102,” he said.

Protalix BioTherapeutics has two other ongoing Phase 3 trials, the BALANCE (NCT02795676) and the open-label BRIGHT (NCT03180840) studies. Patient enrollment is almost complete in the BRIGHT study (90 percent) and is approximately 70% in the BALANCE study.

The BALANCE trial is comparing Fabrazyme (agalsidase beta) with  PRX-102 in terms of kidney function and other clinical outcomes. The open-label BRIGHT trial is another switchover study for patients who have been taking either Fabrazyme or Replagal for three years.

“While we continue to enroll patients in the BRIGHT and BALANCE Fabry disease studies, we believe that with the patients enrolled across the studies included in our PRX-102 clinical program to date, there is a sufficient number of patients to support expedited review, including the potential for filing an application for accelerated approval,” Manor said.