Interesting bit of news, but not exactly unexpected, or worrying really.
The Protalix corporate presentation presented Amicus's Galafold (Migalastat) as a competitor as this was already approved by the EU in 2016. So not unexpected to see the FDA albeit somewhat delayed, following-suit.
Also not particularly concerned with this as Galafold (again as mentioned on the Protalix corporate presentation) is relevant only to about 30% of the Fabry population, i.e. those with amenable mutations. This is because Galafold's job is to bind to particular forms of mis-folded alpha-galactosidase A, then once bound chaperones the relevant amenable a-GalA into the lysosome to help carry-out it's function there. Not only is this relevant only to amenable mutations, but also only works effectively in severe patients.
By comparison, Protalix's Pegunigalsidase (PRX-102), is the actual enzyme that the the patient's need and therefore is open for use for the total Fabry population. Also it has an active time-frame of 14 days, compared to Fabryzyme's 1/2 a day.
Galafold by comparison has to be taken once every 2 days. And it's effective elimination half-life is 3 - 5 hours after dosing. Not exactly a great drug.
So dependent on PRX-102 approval it will be a choice between:
1. Fabryzyme: Relevant to the total Fabry population, but incredibly expensive and very short active time-frame (1/2 day)
2. Galafold: Relevant to about 30% of the Fabry population and has to be taken every 2 days, but with an even shorter elimination half life of 3-5 hours. Convenience of being orally bioavailable.
3. PRX-102: Probably very expensive too and delivered intravenously, but relevant to the total Fabry population, and with a hugely significantly longer active time-frame of 14 days (28 times longer activity than Fabryzyme, and 70 times longer than Galafold).
If Protalix's Pegunigalsidase is approved, it's clear it would be the better treatment.
