FDA Accepts BLA for Pegunigalsidase Alfa for Fabry Disease

Dror Bashan

Protalix BioTherapeutics, in coordination with Chiesi Global Rare Diseases, has announced that the FDA accepted its biologics license application (BLA) and granted priority review designation to pegunigalsidase alfa, also known as PRX-102, for the proposed treatment of adult patients with Fabry disease.¹

The FDA has scheduled PRX-102 a prescription drug user fee act (PDUFA) date for January 27, 2021. The BLA is supported by a comprehensive set of data compiled from the company’s completed phase 1/2 clinical trial as well as the related extension study succeeding the phase 1/2 clinical trial, interim data from the phase 3 BRIDGE switch-over study, and safety data from the 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," Dror Bashan, president and chief executive officer, Protalix, said in a statement.

Pegunigalsidase alfa is an investigational, plant cell culture-expressed, and chemically modified stabilized version of the recombinant α-Galactosidase-A enzyme. The treatment is designed to covalently bound protein sub-units via chemical cross-linking using short PEG moieties, resulting in a molecule with unique pharmacokinetic parameters.

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The phase 3 BRIDGE trial (NCT03018730) is an open-label, single-arm study designed to assess the safety and effectiveness of the therapy in adult patients with Fabry disease, aged 24 to 60 years, who previously were receiving a stable dose of the approved enzyme replacement therapy (ERT) agalsidase alfa (Replagal; Shire) for at least 2 years.²

Topline results from BRIDGE, announced in May, showed a 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 PRX-102. Additionally, the drug was consistent with previously announced interim data and was found to be well tolerated with all adverse events (AEs) being transient in nature without sequelae.

In the 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.

In total, 20 patients successfully 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 PRX-102.

Data from other ongoing phase 3 studies of PRX-102 could be on the way soon as well. At the time of the announced topline data, Einat Brill Almon, PhD, senior vice president, Product Development, Protalix, said he expects final results from the BRIGHT study to be released in the fourth quarter of 2020 and interim results from the BALANCE study in the first half of 2021. BALANCE will assess PRX-102’s safety and ability to prevent renal function decline in patients with Fabry disease who switched from agalsidase beta (Fabrazyme; Sanofi).

Bashan went on to say, “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.”

REFERENCES

1. Protalix BioTherapeutics and Chiesi Global Rare Diseases announce US food and drug administration acceptance of biologics license application (BLA) for pegunigalsidase alfa for the proposed treatment of Fabry disease and grants priority review. News release. Carmiel, Israel. Protalix BioTherapeutics. Published August 11, 2020. Accessed August 11, 2020. https://www.prnewswire.com/il/news-releases/protalix-biotherapeutics-and-chiesi-global-rare-diseases-announce-us-food-and-drug-administration-acceptance-of-biologics-license-application-bla-for-pegunigalsidase-alfa-for-the-proposed-treatment-of-fabry-disease-and-grants--301109844.html

2. Protalix BioTherapeutics announces positive topline results from the BRIDGE phase 3 open-label, switch-over clinical trial evaluating pegunigalsidase alfa for the treatment of Fabry disease. News release. Carmiel, Israel. Protalix BioTherapeutics. Published May 11, 2020. Accessed August 11, 2020. https://www.biospace.com/article/releases/protalix-biotherapeutics-announces-positive-topline-results-from-the-bridge-phase-iii-open-label-switch-over-clinical-trial-evaluating-pegunigalsidase-alfa-for-the-treatment-of-fabry-disease/