Protalix BioTherapeutics (PLX), Chiesi Global Rare Diseases Present Key Clinical Data of Pegunigalsidase Alfa for the Treatment of Fabry Disease

Protalix BioTherapeutics, Inc. (NYSE American: PLX) (TASE: PLX), a biopharmaceutical company focused on the development, production and commercialization of recombinant therapeutic proteins produced by its proprietary ProCellEx® plant cell-based protein expression system, and Chiesi Global Rare Diseases, a business unit of Chiesi Farmaceutici S.p.A., an international research-focused healthcare Group (Chiesi Group), today announced that final results from the Phase III BRIDGE clinical trial (NCT03018730) of pegunigalsidase alfa (PRX–102), an investigational therapy in development for the potential treatment of Fabry disease, will be presented at the 17th Annual WORLDSymposium™ 2021, a research conference dedicated to lysosomal diseases being held virtually February 8–12, 2021

The final results, which were first announced in December 2020, will be presented in both an oral and a poster presentation by Prof. Ales Linhart, MD, Charles University, Praha, Czech Republic, a principal investigator in the Phase III clinical trials of PRX–102 for the potential treatment of Fabry disease. The Company has already announced the schedule of the presentations.

The BRIDGE clinical trial was a Phase III 12 month open label, single arm switch over study evaluating the safety and efficacy of pegunigalsidase alfa, 1 mg/kg infused every two weeks, in up to 22 Fabry patients previously treated with agalsidase alfa, marketed by Takeda Pharmaceutical Company Limited (formerly Shire Plc) as Replagal®, for at least two years and on a stable dose for at least six months. Replagal is not approved in the United States.

The data to be presented by Prof. Linhart showed substantial improvement in renal function as measured by mean annualized estimated Glomerular Filtration Rate (eGFR slope) in both male and female patients who were switched from agalsidase alfa to pegunigalsidase alfa.

Twenty of twenty-two patients completed the 12-month treatment duration, 18 of which opted to roll over to a long-term extension study and continue to be treated with pegunigalsidase alfa.

In the BRIDGE study, the mean annualized eGFR slope of the study participants improved from -5.90 mL/min/1.73m2/year while on agalsidase alfa to -1.19 mL/min/1.73m2/year on PRX-102 in all patients. Male patients improved from -6.36 mL/min/1.73m2/year to –1.73 mL/min/1.73m2/year and female patients improved from -5.03 mL/min/1.73m2/year to –0.21 mL/min/1.73m2/year. Following the switch to pegunigalsidase alfa there was a decrease in patients with progressing or fast progressing kidney disease, and the majority of patients achieved a stable status post-switch.

An immunogenicity assessment indicated that four out of 20 patients (20%) developed persistent antidrug antibodies over the course of the study, of which two had neutralizing activity.

Baseline characteristics of the 20 patients that completed the study, ranging from ages 28 to 60 years, were as follows: mean eGFR 75.87 mL/min/1.73m2 in males, and 86.14 mL/min/1.73m2 in females and plasma lyso-Gb3 mean levels were 51.81 nM and 13.81 nM in males and females, respectively. While lyso-Gb3 levels remain slightly high, particularly within the male cohort, continuous reduction in lyso-Gb3 levels was observed of 19.55 nM (32.35%) in males and 4.57 nM (29.81%) in females.

"The final analysis of the BRIDGE Study in Fabry patients previously treated with agalsidase alfa demonstrates a potential benefit of pegunigalsidase alfa on renal function," said Prof. Linhart.

Pegunigalsidase alfa was well tolerated in the study, with all adverse events being transient in nature without sequelae. Among the 22 patients enrolled in the BRIDGE study, the majority of treatment emergent adverse events were mild or moderate in severity (96.9%), with two patients (9.1%) withdrawing from the therapy due to hypersensitivity reaction that was resolved. The most common moderate treatment emergent adverse events were nasopharyngitis, headache and dyspnea.

Additional details can be found on the WORLDSymposium website at https://worldsymposia.org/. Copies of the presentation materials will be made available on Protalix's website under the Presentations tab in the Investors section at the time of the poster session.

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