Bendamustine - USA

On May 09, 2019 Delaware Court granted Slayback’s motion for judgment on pleadings that its NDA does not infringe Eagle’s patents under Doctrine of Equivalents (DOE).

Eagle is the holder of NDA for BALRAPZO® (bendamustine) that was approved by FDA to treat patients with chronic lymphocytic leukemia and indolent B-cell non-Hodgkin lymphoma. Eagle sued Slayback Pharma alleging infringement under the doctrine of equivalents of four patents: U.S. Patent Nos. 9,265,831, 9,572,796, 9,572,797 and 10,010,533 (all expiring on 01/28/2031). Eagle initiated this lawsuit in response to Slayback's submission of NDA No. 212209 for approval to manufacture and sell before the four asserted patents expire. All the independent claims of the patents require the presence of three limitations in the claimed pharmaceutical composition: (I) bendamustine or a pharmaceutically acceptable salt thereof; (2) a pharmaceutically acceptable fluid that contains some combination of two solvents: propylene glycol and polyethylene glycol; and (3) a stabilizing amount of an antioxidant.

Slay back's motion focuses on the second claim limitation-a pharmaceutically acceptable fluid that contains some combination of propylene glycol and polyethylene glycol. Slayback's proposed bendamustine drug contains polyethylene glycol, but instead of propylene glycol it uses another, second solvent. Eagle alleges that Slayback's drug infringes the solvent limitation under the doctrine of equivalents. Slayback had moved to dismiss on the ground that the so-called disclosure-dedication doctrine bars application of the doctrine of equivalents to the solvent limitation.

Court’s analysis:

The sole issue was whether, under the disclosure-dedication doctrine, the asserted patents' disclosure of Slayback' s second solvent as an alternative to propylene glycol bars Eagle from claiming that Slayback's drug infringes the solvent limitation under the doctrine of equivalents. Court said that under the disclosure-dedication doctrine, a patentee can disclaim an equivalent by disclosing the equivalent in the written description but not claiming it. [SanDisk Corp. v. Kingston Tech. Co., 695 F.3d 1348, 1363 (Fed. Cir. 2012)]. Furthermore, "before unclaimed subject matter is deemed to have been dedicated to the public, that unclaimed subject matter must have been identified by the patentee as an alternative to a claim limitation."[Pfizer, Inc. v. Teva Pharm. USA, Inc., 429 F.3d 1364, 1379 (Fed. Cir. 2005)].

Court said that the written description of the asserted patents explicitly and repeatedly identifies Slayback's second solvent as an alternative to propylene glycol in embodiments of the patented invention:

“In other aspects of the invention, the bendamustine containing compositions include a) a pharmaceutically acceptable fluid which contains one or more of propylene glycol, ethanol, polyethylene glycol, benzyl alcohol and glycofurol, and b) a stabilizing amount of a chloride salt”.

Despite these disclosures, Eagle made two arguments against applying the disclosure-dedication doctrine. First, it contends that the Federal Circuit's decision in “Nalco Co. v. Chem-Mod, LLC, 883 F. 3d 1337 (Fed. Cir. 2018)” prohibits application of the disclosure-dedication doctrine at the Rule 12(c) stage. Second, Eagle argues that it would be inappropriate to grant Slayback's motion at this time because Slayback has not shown that a person of ordinary skill in the art (POSITA) would understand the patents' written description to teach the use of Slayback's second solvent as an alternative to propylene glycol in the claimed formulation.

Court denied both the arguments. With respect to first argument court said that, Nalco does not prohibit the Court from applying the Disclosure-Dedication Doctrine at the Rule 12(c) stage because Nalco did not address the disclosure-dedication doctrine & Nalco did not hold that all "questions over the proper interpretation of a patent's intrinsic record are 'not suitable' and 'particularly inappropriate' for resolution on a motion to dismiss."  With respect to second argument court said that, Eagle's attempt to confine the disclosure-dedication doctrine to cases where an alleged infringer's exact formulation is disclosed in the written description, however, is contrary to established Federal Circuit precedent. Under Federal Circuit law, the disclosure-dedication doctrine applies to unclaimed subject matter that is "identified by the patentee as an alternative to a claim limitation." In this case, the solvent limitation is the claim limitation at issue, and the written description of the asserted patents repeatedly identifies Slayback's second solvent as an alternative to one of the two solvents recited in that limitation (i.e., propylene glycol).

Court thus finally held that it would be clear to a POSITA that the asserted patents disclose Slayback's second solvent as an alternative to propylene glycol, a claim limitation found in each of the independent claims. Therefore, Eagle is barred by the disclosure-dedication doctrine from alleging, based on Slayback's substitution of Slayback's second solvent for propylene glycol, that Slayback's proposed bendamustine drug product infringes the solvent claim limitation under the doctrine of equivalents.