Protalix BioTherapeutics said today it has granted Chiesi Farmaceutici exclusive U.S. rights to develop and commercialize the Phase III Fabry disease treatment PRX-102 (pegunigalsidase alfa), in an expansion of the companies’ partnership that could yield for Protalix an additional up-to-$805 million, plus royalties.

The extra money will raise to a total $95 million in upfront payments and development costs, plus $1 billion in milestones, what Chiesi could potentially spend under its agreements with Protalix toward developing PRX-102, a chemically modified version of the recombinant protein alpha-Galactosidase-A also known as CHF 6657.

PRX-102 showed strong positive safety and efficacy data in a Phase I/II clinical trial (NCT01678898), and is now under study in three Phase III trials now recruiting patients:

  • The BALANCE study evaluating the safety and efficacy of PRX-102 compared with Replagal® (Agalsidase Alfa) on renal function (NCT02795676).
  • The BRIGHT study assessing the safety, efficacy, and pharmacokinetics of 2 mg/kg of PR-102 administered every four weeks in Fabry disease patients (NCT03180840).
  • A study assessing the safety and efficacy of  PRX-102 in Fabry disease patients now treated with Replagal (NCT03018730).

Protalix said it anticipates being able to start reporting data from the Phase III trials in the first half of 2019.

The partnership was launched in October 2017, when the companies agreed exclusively to develop and commercialize PRX-102 for Fabry disease outside the U.S.

‘Significant Role’ Foreseen

“The more we work with Protalix and see the progress made in the development and the product’s characteristics, it becomes abundantly clear the significant role PRX-102 could have in the underserved Fabry market and to potentially change the treatment paradigm to the benefit of all stake holders,” Chiesi CEO Ugo Di Francesco said in a statement. “We believe this U.S. license agreement will bring many synergies in our fast-growing U.S. presence in rare diseases.”

Under the companies’ U.S. license and supply agreement, Chiesi agreed to pay Protalix $25 million upfront; up to $20 million in development costs, capped at $7.5 million per year; up to $760 million in payments tied to achieving regulatory and commercial milestones; and tiered royalties ranging from 15% to 40% on net sales as consideration for product supply.

“Taking into consideration a $25 million upfront payment and shared development expenses, we expect our cash runaway to take us through the read outs of all of the Fabry clinical trials,” Protalix President and CEO Moshe Manor said in a statement.

Protalix said it will continue to be the manufacturer of PRX-102 for clinical development and commercial purposes.

Based in Carmel, Israel, Protalix focuses on developing and commercializing recombinant therapeutic proteins expressed through its proprietary plant cell-based expression system, ProCellEx®.

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