By Kevin E. Noonan --
In its decision in a consolidated appeal, Eli Lilly & Co. v. Hospira, Inc. and Eli Lilly & Co. v. Dr. Reddy's Laboratories, Ltd., the Federal Circuit had the occasion to apply the Supreme Court's distinction regarding the limits of prosecution history estoppel on the doctrine of equivalents, regarding the effects on the estoppel of amendments made that are only tangentially related to patentability. In this case, this doctrine salvaged a decision in favor of the patentee Eli Lilly in both cases, keeping generic versions of Lilly's patented drug from FDA approval until Lilly's Orange Book-listed patent have expired.
The cases arose in ANDA litigation over Lilly's U.S. Patent No. 7,772,209 directed to "improved" methods for administering its anticancer drug Alimta® (pemetrexed disodium), a frequent target for generic drugmakers and the accompanying litigation (the opinion notes in a footnote that "[t]his is the fourth appeal we have decided concerning Alimta® and the third specifically concerning the '209 patent"). The drug itself, an antifolate metabolic inhibitor of thymidylate synthase, inhibits cell growth (normal and malignant) by interfering with production of DNA precursors and hence inhibiting replication. The anticancer efficacy for this drug (like many anticancer drugs) relies on the greater replicative activity of cancer cells compared with normal cells.
Pemetrexed, and its disodium salt, is not a new drug, being disclosed and claimed in U.S. Patent No. 5,344,932, and Lilly's licensed U.S. Patent No. 4,997,838, that disclosed a large genus of structurally related compounds that encompass pemetrexed but did not disclose the molecule. This reference also taught that "pharmaceutically acceptable bases," such as "alkali metals, alkali earth metals, non-toxic metals, ammonium, and substituted ammonium" could be prepared from the disclosed antifolate inhibitors.
Lilly's own investigations showed that Alimta® administration is nevertheless associated with significant side-effects, including "severe hematologic and immunologic side effects, resulting in infections, nausea, rashes, and even some deaths," which are not uncommon with antifolates according to the '209 patent specification. The '209 patent claims methods for pemetrexed administration supplemented with folic acid and a methylmalonic acid-lowering agent (including, e.g.,vitamin B12), "improved" to the extent that these side effects are reduced. Claim 12 is representative:
12. An improved method for administering pemetrexed disodium to a patient in need of chemotherapeutic treatment, wherein the improvement comprises:
a) administration of between about 350 μg and about 1000 μg of folic acid prior to the first administration of pemetrexed disodium;
b) administration of about 500 μg to about 1500 μg of vitamin B12, prior to the first administration of pemetrexed disodium; and
c) administration of pemetrexed disodium.
In a parent application to the '209 patent, broader claims directed to methods for reducing antifolate toxicity recited administration of a broad class of antifolates with methylmalonic acid lowering agents with or without folic acid. These claims were rejected as being anticipated by an earlier prior art reference or for being obvious over a combination of references. In response, Lilly amended the rejected claims to pemetrexed disodium and argued that the asserted art either did not recite the pemetrexed disodium or, for overcoming the obviousness rejection, that the art did not suggest vitamin supplementation.
The defendants in ANDA litigation did not request FDA approval for pemetrexed disodium but for a different salt -- the ditromethamine salt -– and argued to the agency that "their choice of the tromethamine cation was immaterial because pemetrexed dissociates from its counterion in solution" and that this salt was known to be safe for pharmaceutical use. At trial against Dr. Reddy's Laboratories, the District Court construed the term "administration of pemetrexed disodium" to mean "liquid administration of pemetrexed disodium," which "is accomplished by dissolving the solid compound pemetrexed disodium into solution." Using this construction, the District Court denied defendant's motion for summary judgment of noninfringement on the ground that Lilly was not precluded by prosecution history estoppel to assert that Dr. Reddy's ditromethamine pemetrexed salt was an equivalent to Lilly's claimed disodium salt. The Court reasoned that the amendment made during the earlier prosecution was only tangentially related to the differences in these salts, the amendment being made to distinguish different antifolate species and not different salt forms thereof. The Court also rejected defendant's "dedication to the public" argument with regard to the earlier known antifolate compounds disclosed in the '838 patent because that patent disclosed a large genus comprising thousands of compounds.
In litigation with Hospira, Eli Lilly argued both literal infringement as well as infringement under the doctrine of equivalents, based on Hospira's label that permitted pemetrexed ditromethamine to be reconstituted in saline. Hospira conceded (subject to appeal) that its product would infringe, and the District Court granted summary judgment against Hospira on both literal infringement and infringement under the doctrine of equivalents.
The Federal Circuit reversed-in-part and affirmed-in-part, in an opinion by Judge Lourie joined by Judges Moore and Taranto. Regarding literal infringement, the Court held that:
It 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 cannot be deemed pemetrexed disodium simply because some assortment of the ions in the solution consists of pemetrexed and two sodium cations. As Lilly acknowledges throughout its brief, pemetrexed disodium is a salt. . . . Once diluted, the salt's crystalline structure dissolves, and the individual ions dissociate. . . . In other words, pemetrexed disodium no longer exists once dissolved in solution, and, as a corollary, a different salt of pemetrexed dissolved in saline is not pemetrexed disodium [citations to the record omitted].
Because Hospira did not administer pemetrexed disodium, the panel reversed the District Court's finding of literal infringement.
Turning to the doctrine of equivalents, the opinion immediately cites Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushki Co., 535 U.S. 722, 733 (2002), in support of the principle that "[f]ew propositions of patent law have been so consistently sustained by the Supreme Court as the doctrine of equivalents." Having evinced the due measure of obeisance to the Court's jurisprudence, the panel then notes (somewhat in its own defense) that "the Supreme Court has also acknowledged that the doctrine of equivalents, 'when applied broadly, conflicts with the definitional and public-notice functions of the statutory claiming requirement,'" citing Warner-Jenkinson Co. v. Hilton Davis Chem. Co., 520 U.S. 17, 40 (1997), and that Federal Circuit law "emphasized . . . that the doctrine of equivalents is 'the exception, however, not the rule,' and not merely 'the second prong of every infringement charge, regularly available to extend protection beyond the scope of the claims,'" citing London v. Carson Pirie Scott & Co., 946 F.2d 1534, 1538 (Fed. Cir. 1991). In particular, countervailing doctrines that properly cabin the doctrine of equivalents are those of prosecution history estoppel and dedication of disclosed but not claimed embodiments to the public.
With regard to prosecution history estoppel, under Festo the question is whether the amendments made in the earlier patent from which the '209 patent claims priority were made for reasons related to patentability and do not fall within Supreme Court-recognized exceptions. As set forth on the opinion, Lilly did not dispute that its amendments satisfied the fundamental requirements of behavior that raises the estoppel: that "the amendment in question was both narrowing and made for a substantial reason relating to patentability." Nevertheless, Lilly relied on the exception that the rationale for its amendments "[bore] no more than a tangential relation to the equivalent in question," citing Festo. Hospira and Dr. Reddy's Laboratories colorfully argued that "the tangential exception is not a patentee's-buyer's-remorse exception" and that the tangential relationship exception should be construed narrowly. The Federal Circuit held that appellants had advanced a "too rigid" application of prosecution history estoppel. The Court agreed with the District Court's assessment that Lilly had narrowed the claims of the earlier, related application to overcome rejection based on treatment with methotrexate, and that "the particular type of salt to which pemetrexed is complexed relates only tenuously to the reason for the narrowing amendment," which was to avoid prior art directed to methotrexate administration.
Regarding prosecution of the '209 patent, the panel found no basis for Hospira's argument that claims were amended to recite pemetrexed disodium to avoid prior art asserted during that prosecution. Reiterating the "remorse" theme, Dr. Reddy's Laboratories "insists" that Federal Circuit case law has established that "an applicant's remorse at ceding more claim scope than necessary is not a reason for the tangential exception to apply, citing Lucent Techs., Inc. v. Gateway, Inc., 525 F.3d 1200, 1218 (Fed. Cir. 2008), and Schwarz Pharma, Inc. v. Paddock Labs., Inc., 504 F.3d 1371, 1377 (Fed. Cir. 2007). The panel countered that the exception itself "only exists because applicants over-narrow their claims during prosecution" and that "the reason for an amendment, where the tangential exception is invoked, cannot be determined without reference to the context in which it was made, including the prior art that might have given rise to the amendment in the first place." According to the panel, "[w]e do not demand perfection from patent prosecutors, and neither does the Supreme Court (citing Festo). Lilly's burden was to show that pemetrexed ditromethamine was 'peripheral, or not directly relevant, to its amendment . . . [a]nd as we concluded above, Lilly has done so." Finally, the panel refused to adopt Dr. Reddy's position as a bright-line rule, stating that "such a bright-line rule is both contrary to the equitable nature of prosecution history estoppel, [citing Festo], and inconsistent with the equitable spirit that animates the doctrine of equivalents, citing Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605, 608 (1950).
While the question of "whether prosecution history estoppel applies to bar a doctrine of equivalents claim is a question of law, . . . citing Regents of Univ. of Cal. v. Dakocytomation Cal., Inc., 517 F.3d 1364, 1371 (Fed. Cir. 2008) (citing Pharmacia & Upjohn Co. v. Mylan Pharm., Inc., 170 F.3d 1373, 1376 (Fed. Cir. 1999)," the decision in this case depends critically on the facts surrounding the amendments and the reasons for them. In a footnote, the opinion states that:
[I]n applying the Supreme Court's framework, we find the analogies to other cases less helpful than a direct consideration of the specific record of this case and what it shows about the reason for amendment and the relation of that reason to the asserted equivalent. This case-specific focus, within the governing framework, comports with the equitable nature of prosecution history estoppel.
The panel completes its analysis by rejecting Dr. Reddy's Laboratories' argument that the "disclosure-dedication" rule, Johnson & Johnston Assocs. Inc. v. R.E. Serv. Co., 285 F.3d 1046, 1054 (Fed. Cir. 2002) (en banc), prevented Lilly from asserting its claims under the doctrine of equivalents. The Federal Circuit agreed with Lilly that this doctrine does not apply where, as here, the patent does not disclose the specific embodiment at issue (here, pemetrexed ditromethamine) and thus could not have dedicated it to the public. Despite reference to earlier disclosure comprising about 50 antifolate compounds (none of them pemetrexed) and disclosure related to pharmaceutically acceptable salts thereof (but not ditromethamine), in the absence of express disclosure of pemetrexed ditromethamine "we see no reason why a skilled artisan would set out on DRL's winding path to cobble together pemetrexed ditromethamine" and thus held that the dedication-disclaimer rule did not preclude Lilly from asserting infringement under the doctrine of equivalents.
And on the merits, the Federal Circuit found no clear error in the District Court's determination that the methods for treating pemetrexed ditromethamine claimed by defendants was equivalent to Lilly's claimed methods for administering pemetrexed disodium. Thus, the Federal Circuit affirmed the District Court's grant in each case of summary judgment of infringement under the doctrine of equivalents.
Eli Lilly & Co. v. Hospira, Inc. (Fed. Cir. 2019)
Panel: Circuit Judges Lourie, Moore, and Taranto
Opinion by Circuit Judge Lourie
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