This Federal Circuit opinion details Celltrion's appeal of a preliminary injunction preventing them from launching a biosimilar version of Regeneron's EYLEA. The court affirms the district court's decision, finding that Celltrion did not demonstrate a substantial question of invalidity regarding Regeneron's patent. Key to the ruling was the patentable distinction found in the '865 patent's stability requirement compared to an earlier patent. The court also noted that previous appeals from other companies challenging similar injunctions were considered, with some arguments conceded by Celltrion based on those prior rulings.