Eli Lilly early this month has sued Mumbai-based Sun Pharmaceutical Industries in a move to negate Para IV challenge against Lilly’s blockbuster anti-cancer drug Gemzar, generically known as Gemcitabine hydrochloride worth around US $ 586 million US sales in 2005 (source Eli Lilly Annual Report 2005). Sun, which recently filed an abbreviated new drug application with the US FDA under Para IV certification, claims Orange Book listed patents --- U.S. Patent # 4,808,614 (the ‘614 patent) expiring on November 15, 2010 and U.S. Patent # 5,464,826 (the ‘826 patent) expiring on May 07, 2013 --- to be invalid and non-infringed. Early in January 2006, Sicor Pharmaceuticals, Inc. (a subsidiary of Teva) submitted an abbreviated new drug application with the US FDA seeking marketing approval for generic version of Gemzar, claiming both Orange Book patents to be invalid and non-infringed. Subsequently in February 2006, Lilly filed a patent infringement lawsuit against Sicor in the U.S. District Court for the Southern District of Indiana. (Eli Lilly & Co. v. Sicor Pharmaceuticals, Inc. et al insdce 1:2006cv00238 2/15/2006).