Protalix's Fabry Disease Treatment Hits the Mark in Phase III Switch-Over Study
Shares of Protalix Biotherapeutics were up nearly 7% in premarket trading after the company announced its Phase III BRIDGE study met key objectives in treating Fabry Disease. The announcement followed previous topline data from the study released in May.
The study assessed PRX-102 (pegunigalsidase alfa), a plant cell-expressed recombinant, PEGylated, cross-linked α-galactosidase-A product candidate in Fabry patients who switched from treatment with agalsidase alfa. After the switch from agalsidase alfa to PRX-102, researchers noted substantial improvement in patients’ renal function as measured by mean annualized estimated Glomerular Filtration Rate. In May, the company announced positive topline results for the BRIDGE study.
Fabry disease is a rare, X-linked inherited disease that results from abnormal deposits of a fatty substance in blood vessels. Fabry patients inherit a deficiency of the α-Galactosidase-A enzyme, which is normally responsible for the breakdown of globotriaosylceramide (Gb3). Patients with Fabry disease develop slowly progressive kidney disease, cardiac hypertrophy (enlargement of the heart), arrhythmias, stroke and early death. PRX-102 is a plant cell culture-expressed, and chemically modified stabilized version of the recombinant α-Galactosidase-A enzyme. In the U.S. there are two approved treatments for Fabry disease, Sanofi’s Fabrazyme and Amicus Therapeutics’ Galafold (migalastat). Takeda’s Replagal is approved in multiple countries, but not the United States.
In the Phase III BRIDGE study, 22 patients previously treated with Takeda’s Replagal (agalsidase alfa), received infusions of PRX-102 every two weeks. Study data showed substantial improvement in renal function in these patients. Twenty of 22 patients completed the 12-month treatment duration. Eighteen of the patients who completed the study opted to roll over to a long-term extension study and continue to be treated with PRX-102, Protalix said. Following the switch to PRX-102, there was a decrease in patients with progressing or fast progressing kidney disease, and most patients achieved a stable status post-switch.
PRX-102 was well-tolerated, with mostly mild or moderate adverse events. Two patients withdrew from the therapy due to a hypersensitivity reaction that was resolved, the company said.
"We are excited to have completed the final analysis of our Phase III BRIDGE study," Dror Bashan, Protalix's president and chief executive officer. "We anticipate that the BRIDGE study results will be used to support the filing of a Marketing Authorization Application (MAA) with the European Medicines Agency, and having completed the analysis, we have taken an important step in the preparations for the application."
Previously, Chiesi, an Italian rare disease-focused pharma company, acquired the rights to market the Protalix drug in the United States if it is approved by the U.S. Food and Drug Administration. In May 2020, Protalix and Chiesi submitted a Biologics License Application to the FDA for pegunigalsidase alfa for the proposed treatment of adult patients with Fabry disease after positive topline results were first announced in May. A decision is expected by April 27, 2021 under Priority Review.
The Phase III program for PRX-102 consists of three separate studies, BRIDGE, BRIGHT and BALANCE. The ongoing BALANCE study is an ongoing head-to-head study assessing PRX-102 against Sanofi’s Fabrazyme (agalsidase beta). The BRIGHT study is a switch-over study designed to evaluate a monthly dose of PRX-102, and to assess whether patients maintain clinical stability as measured by certain Fabry disease parameters after being switched to this regimen from an enzyme replacement therapy (ERT), agalsidase alfa or agalsidase beta, dosed every two weeks. Results from the BRIGHT study are expected in the first quarter of 2021 and interim results from the BALANCE study are expected in the first half of 2021.