Protalix BioTherapeutics, Chiesi Global Announce BLA Acceptance of Pegunigalsidase Alfa

Protalix BioTherapeutics together with its development and commercialization partner Chiesi Global Rare Diseases, a unit of Chiesi, announced the U.S. Food and Drug Administration (FDA) has accepted the Biologics License Application (BLA) and granted Priority Review designation for pegunigalsidase alfa for the proposed treatment of adult patients with Fabry disease. The BLA was submitted via the FDA's Accelerated Approval pathway. Pegunigalsidase alfa is the Company's purposefully designed, long-acting recombinant, PEGylated, cross-linked α-galactosidase-A investigational product candidate. The FDA set an action date of January 27, 2021, under the Prescription Drug User Fee Act (PDUFA). The FDA also indicated in the BLA filing communication letter that it is not currently planning to hold an advisory committee meeting to discuss the application.

Priority Review is granted to therapies that the FDA determines have the potential to provide significant improvements in the treatment, diagnosis or prevention of serious conditions. This designation shortens the FDA review period following the acceptance of the BLA to six months compared to 10 months under standard review. Pegunigalsidase alfa was granted Fast Track designation by the FDA in January 2018.

The BLA submission includes a comprehensive set of preclinical, clinical and manufacturing data compiled from the Company's completed Phase I/II clinical trial of pegunigalsidase alfa, including the related extension study succeeding the Phase I/II clinical trial, interim clinical data from the Phase III BRIDGE switch-over study and safety data from the Company's on-going clinical studies of PRX–102 in patients receiving 1 mg/kg every other week.

"The FDA's acceptance of the BLA and grant of priority review for PRX-102 are significant achievements for Protalix and Chiesi, and represent a crucial step forward as we look to establish a new treatment option to the Fabry patient community," said Dror Bashan, Protalix's President and Chief Executive Officer. "Based on the encouraging results for PRX-102 we have seen to date, we are eager to continue discussions with the FDA and to continue our other development efforts for PRX-102, as marketing approval of PRX-102 is our top priority."

"PRX-102 represents an important advance in research with the potential to deliver significant advantages to patients with Fabry disease," said Giacomo Chiesi, Head of Global Rare Diseases. "We are very encouraged by the strong interest in this therapy among both patients and clinicians and we look forward to the prospect of making it available to patients around the world who can benefit from treatment."

Fabry disease is an X-linked inherited disease that results from deficient activity of the lysosomal 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. Fabry disease occurs in one person per 40,000 to 60,000. Fabry patients inherit a deficiency of the α–Galactosidase–A 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.

Pegunigalsidase alfa (PRX–102) is an investigational, plant cell culture-expressed, and chemically modified stabilized version of the recombinant α-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, PRX–102 has been observed to have a circulatory half-life of approximately 80 hours. The Company designed PRX–102 to potentially address the continued unmet clinical need in Fabry patients.