EAGLE PHARM. INC., v. SLAYBACK PHARMA LLC, Appeal No. 2019-1924 (Fed. Cir. May 8, 2020).  Before O’Malley, Reyna, and Chen.  Appealed from D. Del. (Judge Connolly).  (Doctrine of Equivalents, Disclosure-Dedication Doctrine)


Eagle sued Slayback for infringing four patents covering Eagle’s brand name bendamustine pharmaceutical product, Belrapzo®.  The drug is used to treat chronic lymphocytic leukemia and indolent B-cell non-Hodgkin lymphoma.

The four asserted patents contain essentially the same written description.  Slayback stipulated to literal infringement of all limitations of the asserted claims, except for the limitation of “a pharmaceutically acceptable fluid comprising a mixture of polyethylene glycol and propylene glycol.”  Their formulations used ethanol instead of polyethylene glycol.  However, Eagle asserted this feature was infringed under the doctrine of equivalents because ethanol in Slayback’s formulation was insubstantially different from the propylene glycol (“PG”) in the claimed composition.

In defense, Slayback moved for a judgment of non-infringement on the pleadings, arguing that that disclosure-dedication doctrine barred Eagle’s claim of infringement under the doctrine of equivalents because the asserted patents disclose, but do not claim, ethanol as an alternative solvent to PG.  The district court agreed and granted the motion, finding that the written description of the asserted patents unambiguously and repeatedly identify ethanol as an alternative to PG.


Does the disclosure-dedication doctrine apply?  (continue reading)

Summary by:  Jason French

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