FDA Extends Review Date to April for US Approval of PRX-102

The U.S. Food and Drug Administration (FDA) has extended the review date by three months — to spring 2021 — for a biologics license application (BLA) seeking accelerated approval of PRX-102 (pegunigalsidase alfa) to treat adults with Fabry disease.

Protalix BioTherapeutics and Chiesi Global Rare Diseases, who are developing the investigational enzyme replacement therapy, had submitted the BLA in May 2020 through the FDA’s accelerated approval pathway program. That program allows medications that address an unmet need to rapidly obtain conditional approval if they show benefits in clinical trials.

The date for review for PRX-102, which had been previously set for Jan. 27, 2021, now will be April 27, 2021, Protaliz announced in a press release.

Notably, the FDA had already granted PRX-102 priority review designation and indicated that it is not currently planning to hold an advisory committee meeting to discuss the application.

Fabry disease is caused by a defect in the GLA gene, resulting in a lack of a functional alpha-galactosidase A, an enzyme responsible for breaking down some types of fat molecules that can accumulate in various cells throughout the body. The buildup of these fat molecules causes the progressive clinical signs and symptoms associated with the disease.

PRX-102 is a stabilized version of a man-made (recombinant) form of alpha-galactosidase A that can compensate for the lack of the naturally occurring enzyme. Made with Protalix’s plant-based ProCellEx platform, it has been chemically modified to last longer in the body — meaning that it requires less frequent infusions than existing enzyme replacement therapies.

The BLA submission included a comprehensive set of preclinical, clinical, and manufacturing data compiled from Protalix’s completed Phase 1/2 clinical trial of PRX-102 (NCT01678898) and its extension study (NCT01769001). In the extension, the 18 participants were given PRX-102 injections every two weeks.

The results showed that PRX-002 stayed active in the participants’ blood, decreasing the levels of disease biomarkers, improving kidney function, and slowing disease progression.

Also included in the BLA submission was data from the BRIDGE (NCT03018730) study, testing the safety and effectiveness of PRX-102 in patients previously treated with Replagal (agalsidase alpha), another enzyme replacement therapy. Safety data from ongoing trials in which patients are receiving a PRX-102 dosage of 1 mg/kg every other week also were submitted to the FDA.

Among these ongoing trials are an extension study (NCT01981720) for patients who successfully completed treatment in the previous Phase 1/2 study and its extension, and the BALANCE (NCT02795676) study, which is evaluating the effectiveness of PRX-102 in Fabry patients previously treated with Fabrazyme (agalsidase beta). Fabrazyme, also a replacement therapy, was the first developed specifically for Fabry disease.