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Federal Circuit Upholds Application of Dedication-Disclosure Doctrine at the Pleading Stage

On May 8, 2020, the Court of Appeals for the Federal Circuit affirmed the District of Delaware’s application of the disclosure-dedication doctrine in granting a motion for judgment on the pleadings in Eagle Pharmaceuticals Inc. v. Slayback Pharma LLC, No. 19-1924.  The district court’s judgment held that under the disclosure-dedication doctrine, the asserted patents disclosed – but did not claim – a particular solvent, and that Slayback’s use of that disclosed but unclaimed solvent could therefore not infringe under the doctrine of equivalents.

Plaintiff Eagle Pharmaceuticals Inc. holds a New Drug Application (NDA) No. 205580 for BELRAPZO®, a drug with the active ingredient bendamustine approved by the FDA to treat patients with chronic lymphocytic leukemia and indolent B-cell non-Hodgkin lymphoma.  After defendant Slayback Pharma LLC submitted an NDA for a bioequivalent drug, Eagle filed suit in the United States District Court for the District of Delaware asserting that Slayback infringed Eagle’s U.S. Patent Nos. 9,265,831, 9,572,796, 9,572,797, and 10,010,533.  All four asserted patents shared essentially the same written description, and the independent claims recited essentially the same limitations: a pharmaceutical composition consisting of (i) bendamustine or a pharmaceutically acceptable salt thereof; (ii) a pharmaceutically acceptable fluid that contains some combination of two solvents (propylene glycol and polyethylene glycol); and (iii) a stabilizing amount of an antioxidant.

Slayback conceded that its bioequivalent drug literally infringed all limitations except for the “pharmaceutically acceptable fluid” limitation because it used ethanol and not propylene glycol or polyethylene glycol.  Eagle argued that because the use of ethanol is insubstantially different from propylene glycol and polyethylene glycol, Slayback infringed under the doctrine of equivalents. 

Slayback moved for judgment on the pleadings pursuant to Federal Rule of Civil Procedure 12(c), arguing that Eagle was barred from asserting infringement under the doctrine of equivalents because the asserted patents had dedicated the use of ethanol as a solvent to the public by disclosing the use of ethanol in the specification, but not claiming the use of ethanol in any issued claim.  Eagle opposed, asserting that the claimed embodiment did not disclose ethanol as an alternative solvent, and that the specification only discussed ethanol in conjunction with unclaimed embodiments that contain a chloride salt.  Eagle also submitted expert testimony opining that a skilled artisan would not understand the disclosure of the use of ethanol as a solvent with chloride salt formulations to be applicable to the claimed embodiments.  Unpersuaded by Eagle’s arguments, the district court granted Slayback’s motion, concluding that it had “sufficient context to decide a question of law – i.e., that the disclosure-dedication doctrine applies to bar Eagle’s claims for infringement under the doctrine of equivalents.”

On appeal, Eagle first argued that the district court erred in its finding that the asserted patents disclosed, but did not claim, ethanol as a solvent.  Eagle contended that the asserted patents disclosed three types of formulations: (i) chloride salt formulations; (ii) antioxidant formulations; and (iii) dimethyl sulfoxide formulations, and that the specification only disclosed ethanol with unclaimed chloride salt formulations.  Further, Eagle posited that a skilled artisan would recognize that these are three independent formulations with different ingredients, and a solvent that works in conjunction with chloride salt would not be a suitable alternative in the claimed formulations.  The Federal Circuit rejected these arguments, reasoning that the disclosure-dedication doctrine does not require a specification to disclose a dedicated subject matter in an embodiment that matches the claimed embodiment.  Instead, this doctrine only requires that the specification disclose the unclaimed subject matter as an alternative to the relevant claim limitation.  The Federal Circuit noted that the specifications of the asserted patents unequivocally identified ethanol as an alternative pharmaceutically acceptable fluid, and nothing in the specifications indicated that the use of ethanol was limited to certain formulations.

Additionally, Eagle argued that the district court erred in applying a judgment of law on the pleadings when a factual dispute still remained – namely, whether a skilled artisan would have understood the specifications to disclose ethanol as an alternate pharmaceutically acceptable fluid.  According to Eagle, the district court failed to draw all reasonable inferences in Eagle’s favor when it neglected to consider Eagle’s expert testimony.  The Federal Circuit disagreed, noting that district courts have discretion to decide whether to consider extrinsic evidence and convert a motion for judgment on the pleadings into one for summary judgment.  Upon reviewing Eagle’s expert testimony, the district court determined that it was an attempt to manufacture a factual dispute.  Further, Eagle conceded that it would have been improper for the court to consider expert testimony at the pleadings stage.  Thus, the Federal Circuit held that the district court did not abuse its discretion, and affirmed.

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Thomas H. Wintner is an intellectual property and commercial litigator at Mintz. Tom handles cases in trial and appellate courts, counseling clients in life sciences, health care, education, real estate, and other sectors. He has extensive experience with patent litigation and other IP matters.
Adam P. Samansky is an intellectual property litigator at Mintz. He primarily serves pharmaceutical, medical, high tech, and defense industry clients. Adam handles patent, trademark, and trade secret matters for innovators and investors, and he has a successful record in Hatch-Waxman litigation.

Nana Liu


Nana Liu is a Mintz attorney who focuses on intellectual property litigation for life sciences companies. She handles cases in federal courts, the US Court of Appeals for the Federal Circuit, and the International Trade Commission (ITC), as well as Hatch-Waxman pharmaceutical cases.