Comment:Since Amgen's principal European patent related to filgrastim was due to expire in August 2006, the company launched a long acting formulation, a pegylated filgrastim (pegfilgrastim), under the brand name Neulasta in 2002. The move, part of Amgen's product lifecycle management strategy, resulted in Neulasta replacing Neupogen in major treatment centers. Amgen's US patent for Neupogen expired in December 2013. Neulasta's patent expired in December 2015 though it is subject to ongoing litigation