In the ongoing Immunex v. Sanofi patent litigation regarding Immunex’s claims of infringement against Sanofi and Regeneron’s Dupixent® (dupilumab) product, Immunex has filed a reply brief in support of its motion to stay the litigation pending Inter Partes Review of U.S. Patent No. 8,679,487 (“the ‘487 patent”), which Sanofi has opposed. Sanofi filed three IPR petitions on the ‘487 patent, IPR2017-01129, IPR2017-01879 and IPR2017-01884. Institution was denied in IPR2017-01129 on October 4, 2017. Trial was instituted in IPR2017-01879 and IPR2017-01884 on February 5, 2018. In support of its motion to stay, Immunex argues that “[i]n the absence of a stay, Immunex would be prejudiced because it would be forced to litigate overlapping validity issues in parallel proceedings, wasting its resources and those of the Court.” Sanofi opposed the stay arguing that it would delay the litigation. As we reported here, Sanofi has filed a motion for summary judgment of invalidity which is still pending.