In Intendis GmbH v. Glenmark Pharmaceuticals Inc., USA, the Federal Circuit affirmed the district court decision that found infringement under the doctrine of equivalents. This case shows that the doctrine of equivalents still lives, that not every claim amendment will give rise to prosecution history estoppel, and that formulation patents can provide valuable protection for approved pharmaceutical products.

The Patent At Issue

The patent at issue was U.S. Patent No. 6,534,070, listed in the Orange Book for Finacea® Gel. The patent is owned by Intraserv GmbH & Co. and exclusively licensed to Intendis GmbH, both of whom were parties to the ANDA litigation.

Independent claim 1 recites:

A composition that comprises:
(i) azelaic acid as a therapeutically active ingredient in a concentration of 5 to 20% by weight,
(iii) at least one triacylglycerides in a concentration of 0.5 to 5% by weight,
(iv) propylene glycol, and
(v) at least one polysorbate, in an aqueous phase that further comprises water and salts,
and the composition further comprises
(ii) at least one polyacrylic acid, and
(vi) lecithin,
wherein the composition is in the form of a hydrogel.

Glenmark filed an Abbreviated New Drug Application (ANDA) seeking FDA approval of a generic version of Finacea® Gel that is formulated with isopropyl myristate instead of a triglyceride and lecithin.

The District Court Decision

The district court determined that Glenmark’s product infringed the ‘070 patent under the doctrine of equivalents. In particular, the court applied the function-way-result test and determined that the isopropyl myristate in Glenmark’s formulation performed substantially the same function as the triglyceride and lecithin in the claimed formulation.

The Federal Circuit Decision

The Federal Circuit decision was authored by Judge Moore and joined by Chief Judge Prost and Judge Taranto. As noted in the decision, “[e]ach prong of the function-way-result test is a factual determination” reviewed “for clear error.”

According to the Federal Circuit decision, the district court’s finding on the “function” prong was supported by expert testimony that the claimed excipients could act as penetration enhancers, that “nothing in the record” indicated they could not, and by “repeated statements” in Glenmark’s ANDA that both Glenmark’s excipient and the claimed excipients function as penetration enhancers.

Glenmark challenged the “same function” finding, emphasizing that the ‘070 patent does not disclose that lecithin and triglyceride act as penetration enhancers, and that Intendis described those components as “an emulsifier and an emollient, respectively” in its own submissions to the FDA. Glenmark also emphasized that “not a single literature reference in evidence identified lecithin or triglyceride as a penetration enhancer.”

The Federal Circuit rejected the first argument, noting “We have never held that a patent must spell out a claim element’s function, way, and result in order for the doctrine of equivalents to apply as to that element.”  Rather, “[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.”

Rejecting the second argument, the Federal Circuit stated:

Fatal to Glenmark’s argument is its own ANDA submission to the FDA repeatedly referring to the claimed excipients (triglyceride and lecithin) as penetration enhancers.

The Hypothetical Claim Analysis

Glenmark also challenged the finding of infringement on the basis that it enlarged the claims in a manner that would impermissibly encompass the prior art. The Federal Circuit acknowledged this limitation on the doctrine of equivalents, but determined that it was not violated.

The Federal Circuit noted that a “hypothetical claim analysis” can be used “to determine whether an equivalent would impermissibly ensnare the prior art,” but found that Glenmark was drafting its hypothetical claim too broadly. While the district court’s hypothetical claim “included the claimed excipients and Glenmark’s excipients,” Glenmark’s hypothetical claim included any penetration enhancer. The prior art reference cited by Glenmark disclosed an azelaic acid microemulsion having DMSO as a penetration enhancer, but did not disclose a composition having any of the penetration enhancers at issue.

The Federal Circuit approved of the scope of the district court’s hypothetical claim (which literally encompassed Glenmark’s product) and its finding that it did not read on the prior art.

The Prosecution History Estoppel Analysis

Glenmark also argued that prosecution history estoppel barred the finding of infringement under the doctrine of equivalents, because the applicants surrendered a lecithin-free composition during prosecution.

As stated by the Federal Circuit, “prosecution history estoppel can occur during prosecution in one of two ways, either (1) by making a narrowing amendment to the claim (“amendment-based estoppel”) or (2) by surrendering claim scope through argument to the patent examiner (“argument- based estoppel”).” The court also noted that “issues relating to the application of prosecution history estoppel” are reviewed de novo.

The Federal Circuit summarized the relevant prosecution history as follows:

[T]he examiner noted that two dependent claims, which recited a lecithin “concentration of up to 1%” and “concentration of up to 3%,” respectively, could include zero lecithin. Applicants responded that those range limitations clearly did not include zero because they “are only in claims dependent on independent claims, which clearly require [lecithin].” J.A. 4386–87 (noting that the examiner’s argument “is not well taken.”). Regardless, applicants amended the two dependent 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.”

The district court determined that the amendments at issue “were for clarification purposes,” and “‘not to disclaim formulations with zero lecithin,’” and so prosecution history estoppel did not bar the doctrine of equivalents. The Federal Circuit agreed:

Argument-based estoppel only applies when the prosecution history “evince[s] a clear and unmistakable surrender of subject matter.” …. Applicants’ clarifying statement … did not clearly and unmistakably disavow claim scope to distinguish prior art.

Amendment-based estoppel does not apply because the amendment was not a narrowing amendment made to obtain the patent. Rather, this record demonstrates that the amendment to the dependent claims was a clarifying amendment …. and it does not give rise to prosecution history estoppel.

Thus, the Federal Circuit affirmed the finding of infringement under the doctrine of equivalents.

A Non-Infringing Generic Product

While it is possible to have a non-infringing generic product, this case illustrates the importance of having a rationale for non-infringement that is consistent with representations made to the FDA during the approval process. Here, the Federal Circuit took Glenmark to task for the inconsistent positions taken before the FDA and the court:

In a strange turn of events, Glenmark argued at oral argument to this court that its statements in its FDA submissions about the claimed excipients (triglyceride and lecithin) functioning as penetration enhancers should be rejected and cannot be evidence to support the district court’s finding. It argued that “lecithin and triglycerides are not known to the art as penetration enhancers” and that its representation to the FDA that they do function as penetration enhancers was a “guess” and “wrong.” Oral Argument at 10:49–13:38, Intendis GmbH v. Glenmark Pharm. Inc., No. 2015-1902 (Fed. Cir. Jan. 8, 2016), available at These seemingly extemporaneous arguments do not persuade us that there is clear error in the district court’s decision that isopropyl myristate in Glenmark’s generic product and the claimed triglyceride and lecithin perform substantially the same function. No such arguments were made by Glenmark in any of its briefing to this court. And when asked whether Glenmark had notified the FDA of these purported inaccurate representations to the FDA, Glenmark’s counsel was unaware of such notification. Id. at 11:53 -12:25.