Regeneron perpetuated Eylea as a blockbuster by using its patents to block entry of lower-cost generics.  When those patents neared expiration, Regeneron launched a new formulation covered by at least one patent, namely, Eylea HD.  One of those patent only recently issued, but has already been challenged by at least one prospective generic in a Post-Grant Review (PGR) proceeding before the Patent Trial and Appeal Board of the Patent Office (PTAB).  Will that challenge succeed?