Protalix, Chiesi Launch Expanded Access Program for PRX-102 in the US

Protalix BioTherapeutics and Chiesi Global Rare Diseases have launched an expanded access program (EAP) in the U.S. for PRX-102 (pegunigalsidase alfa), an investigational enzyme replacement therapy (ERT) to treat adults with Fabry disease.

The EAP (NCT04552691) is open to patients who, in the opinion of their physician, have no satisfactory alternative treatment options with therapies currently approved by the U.S. Food and Drug Administration (FDA), and/or cannot participate in other  ongoing trials of Fabry.

Patients participating in the EAP will receive PRX-102 infusions every two weeks at a dose of 1 mg/kg body weight. Limited efficacy data and related adverse events (side effects) will be collected from all participants.

Additional information on Chiesi’s expanded access policy is available here. To be considered for the program, treating physicians must submit requests on behalf of their patients through the company’s portal. 

“The launch of this Expanded Access Program for [PRX-102] is another example of Chiesi’s and Protalix’s shared commitment to support patients whose condition cannot be adequately treated by currently available FDA-approved therapies for Fabry disease,” Marcel van Kuijck, PhD, global head of Medical Affairs at Chiesi, said in a press release.

“We are excited that a broader group of physicians and patients beyond those in our Phase III program will have access to [PRX-102] and that such support to Fabry patients in the U.S. is available prior to FDA’s final review,” said Raul Chertkoff, MD, vice president and chief medical officer at Protalix.

PRX-102 is a stabilized version of a man-made (recombinant) form of the enzyme alpha-galactosidase A. Like other ERTs, PRX-102 replenishes the levels of alpha-galactosidase A, which is missing in patients with Fabry. That helps cells break down the fatty molecule globotriaosylceramide (Gb3), and preventing it from building up in different tissues, including those of the kidneys, heart, and blood vessels in the brain. 

The FDA recently accepted a biologics license application (BLA) from the companies seeking approval for PRX-102 through its accelerated approval program. That program allows medications that address an unmet need to rapidly obtain conditional approval, provided they have shown some benefits in a clinical trial. The FDA’s decision is expected no later than Jan. 27.

In addition to the EAP, Protalix is evaluating PRX-102 in three Phase 3 trials — BALANCE (NCT02795676), BRIGHT (NCT03180840), and BRIDGE  (NCT03018730) — and other related open-label studies.

BALANCE is assessing the effectiveness of PRX-102 at preventing kidney function decline in patients with Fabry who previously had been treated with Fabrazyme (agalsidase beta), an approved ERT marketed by Sanofi Genzyme. Interim results from the study are expected in the first half of 2021.

The open-label BRIGHT trial will evaluate the safety and effectiveness of PRX-102, when administered once-a-month at a dose of 2 mg/kg, in patients previously treated with Fabrazyme or Replagal (agalsidase alfa), another approved ERT, developed by Shire, which now is owned by Takeda. Final results are expected by the end of the year.

BRIDGE is an open-label switch-over study that will assess the safety and effectiveness of PRX-102 in patients previously treated with Replagal for at least two years, who remained on a stable dose regimen for at least six months. Following a three-month screening period, patients will be switched to receive infusions containing 1 mg/kg of PRX-102 every two weeks for 12 months.

Early data from BRIDGE suggested PRX-102 was well-tolerated and effectively slowed the progression of kidney disease.

“The National Fabry Disease Foundation and the Fabry community are very excited about the launch of Chiesi’s expanded access program for [PRX-102] for the treatment of Fabry disease,” said Jerry Walter, founder and president of the National Fabry Disease Foundation. 

“As the number of people diagnosed with Fabry disease continues to exceed predictions, access to treatment through expanded access programs can play an important role in helping as many eligible patients as possible access the treatment they need,” he added.