The Federal Circuit in Intendis GmbH v. Glenmark Pharmaceuticals Inc., USA, No. 2015-1902 (Fed. Cir. May 16, 2016) affirmed the district court’s final judgment that Glenmark’s Abbreviated New Drug Application (ANDA) infringed claims 1-12 of U.S. Patent No. 6,534,070 (“the ’070 patent”) under the doctrine of equivalents (DOE) and that the ’070 patent is not invalid.

The ’070 patent, which is Orange Book listed, covers Finacea® Gel, a drug approved by the U.S. Food and Drug Administration for topical treatment of inflammatory papules and pustules of mild to moderate rosacea. Finacea® Gel is a hydrogel formulation containing 15% azelaic acid by weight and excipients including triglycerides and lecithin. Claim 1, the sole independent claim of the ’070 patent, reads:

  1. A composition that comprises:
    1. azelaic acid as a therapeutically active ingredient in a concentration of 5 to 20% by weight,
    2. at least one triacylglyceride in a concentration of 0.5 to 5% by weight,
    3. propylene glycol, and 
    4. at least one polysorbate, in an aqueous phase that further comprises water and salts, and the composition further comprises
    5. at least one polyacrylic acid, and
    6. lecithin,

wherein the composition is in the form of a hydrogel.

The generic version of Finacea® Gel sought by Glenmark substituted isopropyl myristate for the combination of lecithin and triglyceride. Despite Glenmark’s contention of noninfringement and invalidity of the ’070 patent, the district court found that the ’070 patent was not invalid for obviousness and was infringed under the DOE. Intendis GmbH v. Glenmark Pharm. Ltd., 117 F. Supp. 3d 549 (D. Del. 2015).

Specifically, the district court found DOE infringement under the function-way-result test. Based on expert testimony and Glenmark’s own ANDA submission, the district court found that isopropyl myristate in Glenmark’s proposed generic version performs substantially the same function as the claimed combination of lecithin and triglyceride: enhancing azelaic acid’s penetration of the skin. See Intendis GmbH v. Glenmark Pharm., Inc., No. 2015-1902, 2016 U.S. App. LEXIS 8907, at *4-6 (Fed. Cir. May 16, 2016). The district court also found that isopropyl myristate performed in substantially the same way as the claimed combination of lecithin and triglyceride, namely, “by disrupting the lipids in the skin’s outermost layer, known as the stratum corneum.” Id at *8. Further, the district court found that isopropyl myristate obtained substantially the same result as the claimed combination of lecithin and triglyceride, i.e., “a therapeutically effective azelaic acid composition that is able to penetrate the skin in order to deliver the active ingredient.” Id. at *9. In doing so, the district court further rejected Glenmark’s arguments that infringement under the DOE (1) would encompass the prior art and (2) was barred by prosecution history estoppel. Id. at *4-6, *19-20.

On appeal, Glenmark first argued that the district court erred in its application of the function prong of the function-way-result test under the DOE. Id. at *7. In particular, Glenmark argued that there is no affirmative evidence proving that the claimed combination of lecithin and triglyceride functions as a penetration enhancer in the claimed composition. In support of its argument, Glenmark contended that the ’070 patent itself is silent with respect to the claimed combination of lecithin and triglyceride as a skin penetration enhancer and that Finacea® Gel’s FDA filings and other reports identified the claimed lecithin and triglyceride as an emulsifier and an emollient, respectively. Id. at *9-10. But the Federal Circuit saw no clear error in the district court’s finding of DOE infringement. Id. at *10. Specifically, the Federal Circuit disagreed that the lack of disclosure of the claimed combination of lecithin and triglyceride as penetration enhancers in the ’070 patent is fatal to the infringement case. Instead of emphasizing the intrinsic record as the only source for the finding of a claimed element’s function, the Federal Circuit stated that “[t]he relevant inquiry is what the claim element’s function in the claimed composition is to one of skill in the art, and a fact finder may rely on extrinsic evidence in making this factual determination.” Id. at *11 (citing Zenith Labs., Inc. v. Bristol-Myers Squibb Co., 19 F.3d 1418, 1425 (Fed. Cir. 1994). Furthermore, the Federal Circuit indicated that Glenmark repeatedly referring to the claimed combination of lecithin and triglyceride as a penetration enhancer in its own ANDA submissions was fatal to Glenmark’s arguments. The Federal Circuit was not persuaded by Glenmark’s assertion during oral argument that its ANDA statements about the claimed combination of lecithin and triglyceride as a penetration enhancer were “a guess” and “wrong.” Id. at *12-13 (citation omitted).

Glenmark also challenged the district court’s determination that the scope of equivalency does not ensnare prior art. Id. at *13-15. Under the two-step analysis required by an ensnarement determination, the first step is “to construct a hypothetical claim that literally covers the accused device.” Next, prior art introduced by the accused infringer is assessed to “determine whether the patentee has carried its burden of persuading the court that the hypothetical claim is patentable over the prior art.” In short, [courts] ask if a hypothetical claim can be crafted, which contains both the literal claim scope and the accused device, without ensnaring the prior art.” Id. at *14. The district court concluded that the hypothetical claim was not anticipated by or rendered obvious over the cited art. The conclusion was based on expert testimony that (1) one of ordinary skill in the art would not have been motivated to substitute isopropyl myristate or triglyceride and lecithin for DMSO; and (2) the substitution would not have had reasonable expectation of success. Id. at *15. Glenmark argued that the hypothetical claim adopted by the district court was “inexplicably narrower” than Intendis’s range of equivalents. Id. at *15 According to Glenmark, the hypothetical claim should recite any penetration enhancer (thus ensnaring the art disclosing DMSO). Id.

The Federal Circuit disagreed with Glenmark. Id. Rather, the Federal Circuit agreed with the district court’s rejection of Glenmark’s proposed hypothetical claim as too broad, stating that “[t]he district court’s infringement finding was that the excipient in Glenmark’s product (isopropyl myristate) was equivalent to the claimed excipients (lecithin and triglycerides); it was not a finding that any penetration enhancer would be equivalent to the claimed excipients.” (citing Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605, 609 (1950) Id. at *16). Since Glenmark did not challenge the conclusion that the hypothetical claim would be patentable, the Federal Circuit found no error in the district court’s factual findings concerning the DOE infringement. Id at *16-17.

The Federal Circuit further rejected Glenmark’s argument on appeal that the doctrine of prosecution history estoppel barred the application of the DOE to the claims of the ’070 patent. Specifically, Glenmark argued that a lethicin-free composition was surrendered during prosecution of the ’070 patent. Id. at *18.

During prosecution of the ’070 patent, the examiner objected to two dependent claims for reciting a lecithin “concentration of up to 1%” and “concentration of up to 3%,” respectively, because they could include zero lethicin. Id. at *18. Applicants responded to indicate that those two dependent claims would not include a lethicin concentration as zero because their base claims clearly required lecithin. Id. Applicants regardless amended the two claims to recite a lecithin “concentration of from more than 0 to 1%” and “concentration of from more than 0 to 3%,” respectively, noting that they were amended to “expressly state what has already been made clear on the record.” Id. at *18-19.

The district court rejected Glenmark's argument for the surrender of lethicin-free composition. According to the district court, the amendments were made for clarification purposes and did not amount to the level of disavowing or disclaiming a composition without lecithin. Id. at *19-20. The Federal Circuit saw no error in the district court’s analysis and affirmed that the doctrine of prosecution history estoppel did not apply when claims were amended for clarification but not narrowed to obtain a patent. Id.

The Intendis case is a primer on the correct application of the DOE in patent cases, which is not always an easy task. The opinion covers common pitfalls such as determining “same” function, scope, and ensnarement of prior art, and prosecution history estoppel. The DOE may be enjoying a very modest resurgence, and opinions such as Intendis further clarify how infringement claims relying on this theory may succeed.