“Merely Tangential” Exception to Prosecution History Estoppel Saved “Inartful” Amendment from Barring Infringement by Equivalents

In Eli Lilly and Co. v. Hospira, Inc., [2018-2126, 2018-2127] (August 9, 2019), the Federal Circuit reversed the district court’s finding of literal infringement in the Hospira Decision as clearly erroneous in light of the court’s claim construction of “administration of pemetrexed disodium,” but affirmed the district court’s finding of infringement under the doctrine of equivalents.

Lilly markets the compound pemetrexed in the form of a disodium salt as Alimta®, for treating certain types of non-small cell lung cancer and mesothelioma. This product was covered by U.S. Patent 7,772,209. Hospira and Dr. Reddy’s each filed ANDA applications to market competing

With respect to the finding of literal infringement, Hospira argued that it cannot literally infringe the claims of the ’209 patent because intravenous administration of pemetrexed ditromethamine dissolved in saline—a solution which contains pemetrexed and chloride anions alongside sodium and tromethamine cations—is not “administration of pemetrexed disodium.” The Federal Circuit agreed, finding that “[i]t was clearly erroneous for the district court to hold that the ‘administration of pemetrexed disodium’ step was met because Hospira’s pemetrexed ditromethamine product will be dissolved in saline before administration. A solution of pemetrexed and chloride anions and tromethamine and sodium cations can-not be deemed pemetrexed disodium simply because some assortment of the ions in the solution consists of pemetrexed and two sodium cations.” The Federal Circuit concluded that to literally practice the “administration of pemetrexed disodium” step under the district court’s claim construction, the pemetrexed disodium salt must be itself administered.

With respect to the Doctrine of Equivalaents, the main dispute was whether prosecution history estoppel prevented Lilly from claiming that the administration of pemetrexed ditromethamine was an infringing equivalent to administering pemetrexed disodium. During prosecution, Lilly amended the claims from “an antifolate” to “pemetrexed disodium.” Lilly conceded that this was a narrowing amendment, and that it was made for reasons of patentability. However, Lilly argued that the rationale of its amendment bore “no more than a tangential relation to the equivalent in question.”

Lilly argued that the district court properly held that the reason for its amendment was to distinguish pemetrexed from antifolates generally and that the different salt type is a merely tangential change with no consequence for pemetrexed’s administration or mechanism of action within the body. The Federal Circuit agreed with Lilly. Noting that “tangential” meant “touching lightly or in the most tenuous way,” the Federal Circuit said that the reason for the amendment was to distinguish methotrexate. Under these circumstances the particular type of salt to which pemetrexed is complexed relates only tenuously to the reason for the narrowing amendment, which was to avoid methotrexate . The Federal Circuit therefore held that Lilly’s amendment was merely tangential to pemetrexed ditromethamine because the prosecution history, in view of the ’209 patent itself, strongly indicates that the reason for the amendment was not to cede other, functionally identical, pemetrexed salts.

The Federal Circuit also found support in the prosecution record, noting that Lilly’s amendment, inartful though it might have been, was prudential in nature and did not need or intend to cede other pemetrexed salts. Because the references specifically mentioned pemetrexed the Federal Circuit saiad that narrowing “antifolate” to “pemetrexed disodium” could not possibly distinguish the art cited in the obviousness ground of rejection.

Lilly’s burden under Festo was to show that pemetrexed ditromethamine was “peripheral, or not directly relevant,” to its amendment, and the Federal Circuit concluded it had done so.

The Federal Circuit also rejected arguments that the disclosure-dedication rule prevented a finding of infringement under the docitrine of equivavlents, agreeing with Lilly that the ’209 patent does not disclose methods of treatment using pemetrexed ditromethamine, and, as a result, Lilly could not have dedicated such a method to the public.

Because neither prosecution history estoppel nor the disclosure-dedication rule bars Lilly from asserting infringement through equivalence, the Federal Circuit affirmed the judgement of infringement.

Function/Way/Result Test Causes Headaches in Chemical Cases; Substitute Insubstantial Differences Test

In Mylan Institutional LLC v. Aurpbindo Pharma Ltd., [2017-1645] (May 19, 2017), the Federal Circuit affirmed the grant of a preliminary injunction against the infringement of U.S. Patent 9,353,050 on a triarylmethane dye used to map lymph nodes.

The district court found that Aurobindo did not raise a substantial question of validity of the ’050 patent based on its arguments that the process patent is invalid: under §112, §102, and §103.  Regarding the §112 challenge, the Federal CIrcuit agreed that “by HPLC” was a
common and well-understood way of designating or determining purity, as seen in “numerous sources,” including other patents and the scientific literature.  Regarding the §103 challenge, the Federal Circuit agreed that it did not raise a substantial question regarding motivation to combine the
references or a reasonable expectation of success. Regarding the §102  challenge, the Federal Circuit agreed that the conflicting evidence did not raise a substantial question as to the patent’s validity.

On the likelihood of success, the Federal Circuit noted the unusual nature of a preliminary injunction issuing in the case of infringement under the doctrine of equivalents.  The Federal Circuit said that the law on the doctrine of equivalents as applied to chemical materials is not clear,
and its misapplication can lead to unsound results.  In particular the Federal Circuit noted that while the function/way/result tset may be suitable for analyzing mechanical devices, it often provides a poor framework for analyzing other products or processes — particular in the chemical arts.

In reviewing the district court’s equivalence analysis, the Federal Circuit found that either the did not address the “way” prong of the function/way/result test, or it did so incorrectly.  While the district court correctly found that manganese dioxide and silver oxide performed the same function, there is room for sufficient doubt as to whether silver oxide and manganese dioxide oxidize isoleuco acid in the same way so as to satisfy the “way” prong of the function/was/result test.

The Federal Circuit explained the headaches that can be caused using the function/way/result test (as opposed to insubstantial differences test) in chemical cases:

consider the well-known compounds aspirin and ibuprofen, which chemists would not usually consider to be structural equivalents under the insubstantial differences test. Chemical compounds are characterized
by their structures, and these two compounds differ substantially in structure (see appendix). However, the two compounds would seem to be substantial equivalents under the FWR test. They each provide analgesia and anti-inflammatory activity (“function”) by inhibiting
prostaglandin synthesis (“way”) in order to alleviate pain, reduce fevers, and lessen inflammation (“result”).

The Federal Circuit observed that a compound may appear to be equivalent under the function/way/result, but not under the substantiality of the differences test, and concluded that the substantial differences test may be more suitable than function/way/result for determining equivalence in the chemical arts.

Thus the Federal Circuit modified the preliminary injunction to eliminate the process patents as the basis for the preliminary injunction, but left the injunction intact as to the ‘050 product patent.  The Federal Circuit found no error in the district court’s courts conclusion that there was no substantial question about the validity of the patent, and agreed with the district court’s finding of irreparable harm.


Vitiation has not be Vitiated

In Power Integrations, Inc., v. Fairchild Semiconductor International, Inc, [2015-1329, 2015-1388] (December 12, 2016), a complicated action where each party claimed the other directly and indirectly infringed its patents,  the Federal Circuit: affirmed the jury’s verdict that the asserted claims of the ’876 patent were not anticipated;  vacated the jury’s verdict that Fairchild induced infringement of the asserted claims of the ’876 and ’851 patents; reversed the jury’s verdict that the asserted claims of the ’605 patent were not anticipated; and affirmed the district court’s construction of the ’972 patent.

An interesting aspect of the case was the use of vitiation to find no infringement under the doctrine of equivalents.  The Federal Circuit addressed Power Integrations’ claim vitiation argument, noting that under claim vitiation, “if a court determines that a finding of infringement under the doctrine of equivalents would entirely vitiate a particular claimed element, then the court should rule that there is no infringement under the doctrine of equivalents.” citing Lockheed Martin Corp. v. Space Systems/ Loral, Inc., 324 F.3d 1308, 1321 (Fed. Cir. 2003).  The Federal Circuit also quoted from Warner-Jenkinson Co., Inc. v. Hilton Davis Chem. Co.:

if a theory of equivalence would entirely vitiate a particular claim element, partial or

complete judgment should be rendered by the court.

The Federal Circuit agreed with Power Integrations that a finding of infringement under the doctrine of equivalents would vitiate the requirement that the claimed feedback signals be “distinct.” The Federal Circuit explained that the inventor of the ’972 patent detailed at trial the difficulty in designing a power supply with accurate primary-side control and the breakthrough he achieved by adding a second feedback signal specifically related to output current. The inventor went on to testify that having a second feedback signal—related to current—that is distinct from the first feedback signal—related to voltage—is what distinguished the claimed invention from the prior art.

Under these circumstances, allowing the doctrine of equivalents to read out the claim requirement for a second feedback signal in order to cover a system with a single feedback signal would impermissibly vitiate the claim element.