Spectrum Pharmaceuticals, Inc., University of Strathclyde, v. Sandoz, Inc., No. 2015-1407 (Fed. Cir. 2015)

Written By: David Youngkin

Spectrum appealed the district court’s holding that U.S. Patent 6,500,829 (“the ‘829 patent’”) was invalid as obvious and that claims were not infringed by Sandoz’s Abbreviated New Drug Application (“ANDA”).  The Federal Circuit affirmed the district court’s holding that a substantially pure compound would have been obvious over both the 50/50 mixture and pure isomer.  Additionally the Federal Circuit affirmed the district court’s decision that held Spectrum could not rely on the doctrine of equivalents because of prosecution history estopple.

Spectrum is the exclusive licensee of the ‘829 patent.  The ‘829 patent is directed to leucovorin which is used to treat folate deficiency and enhance the efficacy of a specific cancer treatment.  Leucovorin exists as 6S or 6R isomers with the 6S isomer being biologically active. 

Obviousness of Substantially Pure Compounds

One question before the court was “whether a substantially pure compound would have been obvious when both the 50/50 mixture and the pure compound were known in the art.”  Slip Op. at 11.   

The Federal Circuit agreed with the district court that there was clear motivation to modify the prior art 50/50 mix to make the claimed substantially pure mixture.  The court reasoned “[i]f it is known that the desired activity all lies in one isomer, surely, it is better, and there is generally motivation to try to obtain the purest compound possible.”  Id. at 11.  Conversely, the court reasoned that if the pure product was known, “no reason has been shown why one would want to have an impure material.”  Id. at 11.  In the end Spectrum simply did not provide any evidence of unexpected results for the substantially pure compound to overcome the evidence of obviousness.

Prosecution History Estopple Bars the Application of the Doctrine of Equivalents

The Federal Circuit also affirmed the district court decision that Sandoz’s ANDA did not infringe claims 5-9 of the ‘829 patent. Specifically the district court found that Sandoz’s ANDA product in vials of 175mg or 250mg would not meet the ‘829 patents claim limitation of at least two doses of 2000mg each.  The court found that during prosecution the applicant specifically disclaimed smaller dosage amounts and therefore Spectrum was unable to rely on the doctrine of equivalents to show infringement.

Full decision found here

© 2000-2022, Journal of the Patent & Trademark Office Society
Disclaimer & Privacy Policy