Protalix and Chiesi Announce European Commission Approval of Extended Dosing Regimen for Elfabrio^® in Fabry Disease

Key Highlights for Investors

• European Commission (EC) approves every-four-weeks (E4W) dosing regimen for Elfabrio^® (pegunigalsidase alfa) in adults with Fabry disease who are stable on enzyme replacement therapy (ERT).
• Protalix BioTherapeutics is entitled to a \$25 million regulatory milestone payment from Chiesi as a result of this approval.
• This approval is a significant reduction from the current two-week dosing schedule, potentially improving patient quality of life and reducing healthcare system burden.
• The new regimen applies only to the EU; the FDA-approved regimen in the US remains every two weeks.
• Strong support and positive outlook from patient advocacy groups and clinical leaders.
• Potential for increased market penetration, competitive positioning, and additional revenue streams for both Protalix and Chiesi.

Detailed Analysis of the Announcement

On March 9, 2026, Chiesi Global Rare Diseases and Protalix BioTherapeutics (NYSE American: PLX) announced that the European Commission has approved a new dosing regimen for Elfabrio^® (pegunigalsidase alfa), an enzyme replacement therapy for adults with Fabry disease who are stable on ERT. The new regimen allows for dosing every four weeks (2mg/kg), doubling the interval from the previous every-two-weeks schedule.

This regulatory milestone is significant for several reasons:

• Patient and Caregiver Benefit: The extended infusion interval is expected to reduce the treatment burden for eligible patients and their families, granting them greater flexibility and improving quality of life.
• Healthcare System Impact: By reducing the frequency of infusions, the new regimen may lessen the strain on healthcare resources, potentially translating into cost savings for payers and providers.
• Market Differentiation: Elfabrio^® now has a unique position among Fabry disease treatments in the EU, potentially increasing its competitive edge and uptake among eligible patients.

Financial Impact and Price Sensitive Developments

• Milestone Payment: Protalix is entitled to receive a \$25 million regulatory milestone payment from Chiesi upon this EC approval. This is a direct infusion of non-dilutive capital that could positively impact Protalix’s short-term cash flow and balance sheet.
• Ongoing Revenue Potential: The approval may lead to increased sales of Elfabrio^® in the EU by attracting patients seeking less frequent dosing, which could have a positive effect on future revenue streams and potentially the share price.
• US Market Unchanged: Investors should note that the dosing change applies only in the EU; the FDA-approved regimen in the US remains at 1mg/kg every two weeks, which may limit immediate global revenue upside but sets the stage for future US label expansion.

Clinical and Regulatory Details

The EC’s approval was based on data from the open-label, switch-over BRIGHT study, which evaluated the safety, efficacy, and pharmacokinetics of Elfabrio^® administered every four weeks in adults previously treated with other ERTs. Results from BRIGHT and its ongoing open-label extension study (CLI-06657AA1-03) supported the application for this new regimen.

Notably, the EU approval comes ahead of Fabry Disease Awareness Month in April, highlighting its timeliness and relevance to the patient community. The decision follows a positive recommendation from the European Medicines Agency’s Committee for Medicinal Products for Human Use (CHMP).

Statements from Leadership and Patient Advocates

“The European Commission approval for 2mg/kg body weight E4W dosing regimen for pegunigalsidase alfa represents a meaningful advancement for adults living with Fabry disease and their families,” said Giacomo Chiesi, Executive Vice President, Chiesi Global Rare Diseases. “By introducing an option that extends the infusion interval, we are offering families greater flexibility and the possibility to ease the overall burden of treatment.”

“This approval strengthens the treatment landscape for Fabry disease across the European Union by introducing an additional dosing approach that has the potential to enhance long-term care,” added Dror Bashan, President and CEO of Protalix BioTherapeutics.

“This approval allows for fewer infusion visits, helping reduce the ongoing burden on patients and families, allowing them to spend more time living their lives beyond treatment,” noted Mary Pavlou, President, Fabry International Network (FIN).

Safety Information and Clinical Profile

Investors should be aware that Elfabrio^® carries a boxed warning for hypersensitivity reactions, including anaphylaxis. In clinical trials, 14% of patients experienced hypersensitivity reactions and 3% had anaphylaxis. Infusion-associated reactions were common, and a case of glomerulonephritis was also reported. The most prevalent adverse events (≥15%) included infusion-associated reactions, nasopharyngitis, headache, diarrhea, fatigue, nausea, back pain, pain in extremity, and sinusitis.

The product’s safety profile and boxed warning may be relevant to market uptake and regulatory scrutiny in other jurisdictions.

Background on Fabry Disease and the Companies

• Fabry Disease: A rare, inherited lysosomal storage disorder caused by mutations in the GLA gene, leading to multi-organ involvement and significant morbidity. Early diagnosis and ERT are critical for management.
• Chiesi Group: A global, research-driven biopharma company with a strong focus on rare diseases, respiratory health, and sustainability initiatives.
• Protalix BioTherapeutics: A pioneer in plant cell-based expression systems (ProCellEx^®), with a track record of bringing innovative enzyme replacement therapies to market.

Investor Takeaways

• The EC approval of an every-four-weeks dosing regimen for Elfabrio^® is a major regulatory and commercial milestone for Protalix and Chiesi.
• The \$25 million milestone payment to Protalix is immediately value accretive and could drive positive sentiment and share price movement.
• The company’s continued innovation and regulatory momentum position it strongly in the rare disease ERT market.
• Investors should monitor future regulatory developments, especially potential changes to the US label.

Disclaimer: This article is for informational purposes only and does not constitute investment advice. Investors should conduct their own due diligence and consult with professional advisors before making investment decisions. All forward-looking statements are subject to risks and uncertainties as detailed in company filings with the US Securities and Exchange Commission.

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