Date: 14-May-2020

ProtalixBioTherapeutics Announces Positive Results From BRIDGE Phase III Trial Of Pegunigalsidasealfa To Treat Fabry Disease

ProtalixBioTherapeuticsInc, a biopharmaceutical company focused on the development, production and commercialization of recombinant therapeutic proteins, announced positive topline results from its phase III BRIDGE clinical trial of pegunigalsidasealfa, or PRX-102.

Pegunigalsidasealfa is the company's plant cell-expressed recombinant, PEGylated, cross-linked a-galactosidase-A product candidate under development for the treatment of Fabry disease.

The BRIDGE study was a phase III 12 month open-label, single arm switch-over study evaluating the safety and efficacy of pegunigalsidasealfa, 1 mg/kg infused every two weeks, in up to 22 Fabry patients previously treated with agalsidasealfa, marketed by Takeda Pharmaceutical Company Limited (Shire Plc) as Replagal, for at least two years and on a stable dose for at least six months.

Topline results of the data generated in the study 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 agalsidasealfa to PRX-102. Consistent with previously announced interim data, PRX-102 was found to be well tolerated, with all adverse events being transient in nature without sequelae.

Twenty-two patients were enrolled in the study; two of those patients withdrew early from the study due to hypersensitivity reaction, and 20 of the patients successfully 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.

In the study, the mean annualized eGFR slope of the study participants improved from 5.90 mL/min/1.73m2/year while on agalsidasealfa 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.

Baseline characteristics of the patients, ranging from ages 24 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 19.55nM (32.35%) in males and 4.57nM (29.81%) in females.

"The final analysis of the BRIDGE Study in Fabry patients previously treated with agalsidasealfa demonstrate a positive potential benefit of pegunigalsidasealfa on renal function," said Dr. Ales Linhart of Charles University in Prague, Czech Republic, a principal investigator in the BRIDGE study.

"The completion of our phase III BRIDGE study and its subsequent analysis mark a significant milestone towards our goal to establish PRX-102 as a new treatment option for Fabry disease," said DrorBashan, Protalix's president and chief executive officer. "We are encouraged that the BRIDGE study successfully met its main objectives for safety and efficacy, and we are further motivated to continue our work in progressing pegunigalsidasealfa."

"Our BRIDGE study, together with our other two ongoing fully enrolled phase III clinical trials, the BALANCE study and the BRIGHT study, represents what we believe to be the most comprehensive and robust phase III clinical program for Fabry disease currently in progress," continuedBashan. "As the first of our three studies to complete phase III, we believe the BRIDGE study findings support that PRX-102 has the potential to be an important enzyme replacement therapy for the treatment of Fabry disease."

The ongoing BALANCE study is a fully enrolled, randomized, double blind, head-to-head, active control study which aims to demonstrate PRX102's superiority in renal function as measured by the comparison of the mean annualized change (slope) in estimated glomerular filtration rate (eGFRCKD-EPI) between treatment groups over 24 months of treatment as compared to agalsidase beta, marketed by Sanofi Genzyme as Fabrazyme.

The BRIGHT study is a fully enrolled open-label, switch-over study designed to evaluate the safety, efficacy and pharmacokinetics of PRX102, 2 mg/kg dosed once every 4 weeks, 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), agalsidasealfa or agalsidase beta, dosed every two weeks.

"We previously announced positive interim results from 16 Fabry patients after six and twelve months in the BRIDGE study. These final results not only indicate that our findings are durable and consistent with previous analyses, but also demonstrate the important potential benefit of pegunigalsidasealfa on renal function for Fabry patients," said Einat Brill Almon, Ph.D, Protalix's senior vice president, Product Development. "We look forward to the continued findings from our other ongoing phase III studies of PRX102, with the final results from the BRIGHT study expected in the fourth quarter of 2020, and interim results from the BALANCE study expected in the first half of 2021."

As previously announced, the company and its collaboration partner for PRX102, ChiesiFarmaceuticiS.p.A., or Chiesi, plan the submission of a BLA for PRX-102 via the US FDA's Accelerated Approval pathway in the second quarter of 2020. The company and Chiesi have experienced minor delays in completing the submission due to the novel coronavirus disease (COVID-19) outbreak and other reasons, and the Company anticipates providing further updates regarding the planned submission by the end of the current month.

Fabry disease is an X-linked inherited disease that results from deficient activity of the lysosomal aGalactosidaseA enzyme resulting in progressive accumulation of abnormal deposits of a fatty substance called globotriaosylceramide (Gb3) in blood vessel walls throughout a person's body. Fabry disease occurs in one person per 40,000 to 60,000.

Fabry patients inherit a deficiency of the aGalactosidaseA enzyme, which is normally responsible for the breakdown of Gb3. The abnormal storage of Gb3 increases with time and, accordingly, Gb3 accumulates, primarily in the blood and in the blood vessel walls. The ultimate consequences of Gb3 deposition range from episodes of pain and impaired peripheral sensation to end-organ failure – particularly of the kidneys, but also of the heart and the cerebrovascular system.

Pegunigalsidasealfa (PRX102) is an investigational, plant cell culture-expressed, and chemically modified stabilized version of the recombinant a-Galactosidase-A enzyme. Protein sub-units are covalently bound via chemical cross-linking using short PEG moieties, resulting in a molecule with unique pharmacokinetic parameters. In clinical studies, PRX102 has been observed to have a circulatory half-life of approximately 80 hours. The Company designed PRX102 to potentially address the continued unmet clinical need in Fabry patients.