Protalix BioTherapeutics (PLX) Receives FDA CRL for Pegunigalsidase Alfa

Protalix BioTherapeutics, Inc. (NYSE: PLX) announced that they received a Complete Response Letter (CRL) from the U.S. Food and Drug Administration (FDA) regarding the Biologics License Application (BLA) seeking accelerated approval of pegunigalsidase alfa (PRX‑102) for the proposed treatment of adult patients with Fabry disease.

Protalix and Chiesi are studying the CRL to assess the most expedient regulatory approach to reach an understanding with the FDA on additional actions required to obtain approval of PRX‑102, and will provide an update soon.

"While disappointing, we remain confident in the strength of our data and in the depth of our program," said Dror Bashan, Protalix's President and Chief Executive Officer. "We remain committed to the program and to working with the FDA and Chiesi toward the approval of PRX‑102."

"Based on extensive clinical data including results from the Phase III BRIDGE clinical trial of PRX-102 for the proposed treatment of Fabry disease, we continue to feel strongly that PRX‑102 is an important option for the treatment of Fabry disease in adult patients, and we are continuing with our efforts to make this therapy available to patients," said Giacomo Chiesi, Head of Chiesi Global Rare Diseases. "We thank the patients and clinicians participating in our completed and ongoing clinical studies evaluating PRX-102. We are continuing to coordinate closely with the FDA to address and quickly resolve the deficiencies contained in the CRL."

Fabry disease is an X-linked inherited disease caused by deficient activity of the lysosomal α‑Galactosidase‑A enzyme, resulting in progressive accumulation of abnormal deposits of a fatty substance called globotriaosylceramide (Gb3) in the blood and blood vessel walls throughout the human body. Symptoms of Gb3 deposition range from episodes of pain, gastrointestinal (GI) symptoms, fatigue, angiokeratoma, and abnormal sweating to serious complications including cardiovascular, renal, and cerebrovascular events.

The PRX-102 BLA was initially submitted under the accelerated approval pathway and was granted Priority Review by the FDA. 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. The BLA submission for PRX‑102 included a comprehensive set of preclinical, clinical, and manufacturing data compiled from the completed Phase I/II clinical trial of PRX‑102, 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 Protalix's on-going clinical studies of PRX‑102 in patients receiving 1 mg/kg every other week.

We remain committed to the Phase III clinical program which is progressing, and patients continue to receive PRX‑102 treatment in the ongoing BALANCE study sponsored by Protalix and various long-term extension studies. In addition, Chiesi provides access to pegunigalsidase alfa through its Expanded Access Program (EAP) for Fabry disease patients in the United States who cannot be adequately treated with currently available FDA-approved drugs. The EAP is open to patients with a clinical diagnosis of Fabry disease who, in the opinion of the treating physician, have no comparable or satisfactory alternative treatment options with currently available FDA-approved therapies for Fabry disease. Other eligibility criteria apply. The Expanded Access Program is listed on ClinicalTrials.gov Identifier: NCT04552691 (https://clinicaltrials.gov/ct2/show/NCT04552691). Additional information on Chiesi's Expanded Access policy is available at https://www.chiesiusa.com/sustainability/expanded-access-programs/. Treating physicians must submit requests on behalf of their patients for consideration via the EAP request portal at https://chiesi.versaic.com. As originally planned, Chiesi will continue to coordinate with the European Medicines Agency (EMA) to file for regulatory approval of PRX‑102 in the European Union this year.

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