claim amendments : CAFC Alert

A case for importing limitation from specification into the claim

| April 6, 2019

Forest Laboratories, LLC v. Sigmapharm Laboratories, LLC

March 14, 2019

Before Prost, Dyk, and Moore (Opinion by Moore)


A district court’s narrowing claim interpretation that read a limitation from the specification into the claim may have helped a patent about an antipsychotic drug survive invalidity challenges. The Federal Circuit agreed with the district court’s claim interpretation, reasoning that repeated emphasis on the limitation in the specification and prosecution history supports the reading of the limitation into the claim. The Federal Circuit also agreed that, as a solution to an unrecognized problem, the claimed invention may not be obvious, particularly when there were no alternate, independent bases on which the prior art could be combined to make the claimed invention. Unfortunately, the district court’s lack of express findings on an unrelated proffered motivation to combine prompted the Federal Circuit to nevertheless vacate the district court’s nonobviousness determination and remand the case.


Forest Laboratories, LLC makes and sells the drug, SAPHRIS®, for treating bipolar disorders and schizophrenia. The active ingredient in SAPHRIS® is the compound, asenapine. This compound is the subject matter of U.S. Patent No. 5,763,476 (“476 patent”), also owned by Forest Laboratories.

SAPHRIS® on average costs almost $1,500 for 60 tablets, and there are currently no generic alternatives. When a group of drug makers sought approval from the FDA to make generic versions of SAPHRIS®, Forest Laboratories accused them of infringing the 476 patent.

For our purpose, claim 1 of the 476 patent is of particular interest:

1. A pharmaceutical composition comprising as a medicinally active compound: trans-5-chloro-2-methyl-2,3,3a,12b-tetrahydro-1H-dibenz[2,3:6,7]oxepino[4,5,-c]pyrrole  or a pharmaceutically acceptable salt thereof; wherein the composition is a solid composition and disintegrates within 30 seconds in water at 37°C.

It is worth noting that claim 4 of the 476 patent recites a “method for treating tension, excitation, anxiety, and psychotic and schizophrenic disorders, comprising administering sublingually or buccally” the asenapine.

Among the issues on appeal, the Federal Circuit’s discussions on claim construction and nonobviousness of claim 1 are informative.

As to claim construction, the question was whether claim 1 should be limited to sublingually or buccally administered compositions, or as the accused infringers would argue, should cover any composition that meets the claimed disintegration profile.

The district court determined that claim 1 should be limited to sublingual or buccal compositions. And the Federal Circuit agreed.

Unlike claim 4, claim 1 does not expressly recite “sublingual or buccal” administrations. The original claim 1 did recite “[a] sublingual or buccal pharmaceutical composition…suitable for use in sublingual or buccal compositions”, but all the “sublingual or buccal” language was removed during prosecution. 

At first glance, then, the district court’s claim interpretation would seem to contradict not only the plain language of the claims, and also the intrinsic evidence vis-à-vis the prosecution history.

However, both the district court and the Federal Circuit were able to draw for their claim interpretation from the specification and prosecution history of the 476 patent.

The 476 patent specification repeatedly uses “sublingual or buccal” to modify the “invention”. For example, the 476 patent is titled “sublingual or buccal pharmaceutical composition”, and statements like “the invention relates to a sublingual or buccal pharmaceutical composition” are peppered throughout the specification. The 476 patent also extolls sublingual and buccal treatments, and criticizes conventional peroral or oral treatments.

The Federal Circuit noted that “[w]hen a patent…describes the features of the ‘present invention’ as a whole, this description limits the scope of the invention” (quoting Verizon Servs. Corp. v. Vonage Holdings Corp., 503 F.3d 1295, 1308 (Fed. Cir. 2007). In addition, both the district court and the Federal Circuit cited UltimatePointer, LLC v. Nintendo Co., 816 F.3d 816 (Fed. Cir. 2016) to support their claim interpretation. In UltimatePointer, the court limited the claim term “handheld device” to a “direct-pointing device” (for example, a Wiimote), even though the claim language did not expressly contain such a limitation. “[T]he repeated description of the invention as a direct-pointing system, the repeated extolling of the virtues of direct pointing, and the repeated criticism of indirect pointing clearly point to the conclusion that the ‘handheld device’…is limited to a direct-pointing device.” Id. at 823-24. 

The prosecution history of the 476 patent likewise repeatedly used “sublingual or buccal” to modify the claimed composition. Most notably, in interpreting the original claim 1, the Examiner took the position that the language “‘suitable for sublingually or buccal administration,’ does not result in a structural difference between the claimed invention and the prior art,” and the “the composition as claimed may be used for either mode of administration (sublingually or orally, rectally, etc.).” In response, the patentee amended claim 1 to define “suitability” to mean that “the composition is a solid composition and disintegrates within 30 seconds in water at 37°C”. This feature distinguished the claimed invention over the prior art:

The Office Action indicated that any composition whose physical characteristics make the composition unique to sublingual or buccal administration…would be allowable. Applicants submit that the distinguishing feature of disintegration time is exactly such a characteristic…It is this feature of rapid disintegration which distinguishes a sublingual composition from a peroral one and which makes the compositions of the present invention suitable to avoid the adverse effects observed with peroral administration….

To obtain the good effects of the compositions of the present invention, it is necessary that the medicine be delivered by sublingual or buccal administration.

The district court inferred from those statements the inventors’ intention to limit the claims to sublingual or buccal compositions. The Federal Circuit reached the same conclusion even without considering the prosecution history. Looking only at the specification, and in a rather attenuated logic, the Federal Circuit determined that since the specification describes the claimed disintegration time as defining “rapid disintegration”, and also describes “rapid disintegration” as a feature of sublingual/buccal composition, the claimed disintegration time must therefore limit the claim to “sublingual or buccal” compositions.

Based on the above interpretation, the district court and the Federal Circuit agreed that claim 1 of the 476 patent was not obvious.

Even though asenapine, the use of asenapine to treat schizophrenia, and sublingual and buccal administrations of drugs were separately known in the art, there was no motivation to combine the prior art to arrive at the 476 patent’s sublingual or buccal formulation.

The Federal Circuit noted a “problem/solution” basis for finding nonobviousness. “[W]here a problem was not known in the art, the solution to that problem may not be obvious”. “[S]olving an unrecognized problem in the art can itself be [a] nonobvious patentable invention, even where the solution is obvious once the problem is known.”  

Here, the invention grew out of concerns over severe cardiotoxic side effects of oral asenapine, which caused cardiac arrest in some patients. This prompted the inventors to consider alternative routes of administration. However, the dangers of oral asenapine were unknown in the art at the time of invention. Large-scale clinical studies were even being conducted with conventional oral asenapine tablets.

In addition, the inventors found that the cardiotoxicity of oral asenapine was likely due to accumulation of unmetabolized asenapine. However, sublingual or buccal administrations were expected to produce more, not less, unmetabolized asenapine.

The district court found, and the Federal Circuit accepted, that since nothing in the prior art indicated that oral asenapine had problems, the person skilled in the art would not have been motivated to change the route of administration.  Moreover, “it would not have been predictable or expected that sublingual administration would provide a solution to the problem of cardiotoxic effect.”

The accused infringers attempted to argue, as an alternate motivation to combine, the benefit of having more treatment options. However, the Federal Circuit dismissed this argument, because “a generic need for more antipsychotic treatment options did not provide a motivation to combine these particular prior art elements.”

The Federal Circuit did disagree with the district court on one thing—unexpected results. The district court found it unexpected that sublingual administrations of asenapine lacked the cardiotoxicity of the oral formulations, because the skilled person would have expected the contrary. However, if the problem was not known, then how could the solution to the problem be “unexpected”? There would have been no expectations. As the Federal Circuit explained, “[A] person of ordinary skill could not have been surprised that the sublingual route of administration did not result in cardiotoxic effects because the person of ordinary skill would not have been aware that other routes of administration do result in cardiotoxic effect”.

The fight, however, is not completely over. The accused infringers offered a different “motivation to combine” argument, based on whether sublingual or buccal administration would have addressed patient compliance problems. The Federal Circuit did not think the district court made sufficient express findings on this proffered motivation to combine, and for this reason, vacated the district court’s nonobviousness determinations and remanded the case.

The district court and the Federal Circuit’s “problem/solution” approach to nonobviousness in this case raised an interesting question. How does that approach reconcile with the established case law that any need or problem known in the field of endeavor at the time of invention and addressed by the patent can provide a reason for combining the prior art? The whole of MPEP 2144(IV) is dedicated to explaining how the motivation to combine can be for a purpose or problem different from that of the inventor.

The Federal Circuit answered that question in a recent, non-precedential decision in In re Conrad (Fed. Cir., March 22, 2019): “[C]ases found that the inventor’s discovery of and solution to an unknown problem weighed in favor of non-obviousness because the proffered reason to modify the prior art did not present a specific, alternate basis that was unrelated to the rationale behind the inventor’s reasons for making the invention.” Where the person skilled in the art would combine the prior art “for a reason independent from solving the problem identified by [the inventor]”, the fact that the invention solved an unrecognized problem may not lend as much patentable weight as it did in Forest Laboratories.


In this case, the narrower interpretation worked to the patentee’s advantage, particularly because the accused infringers had already conceded on the question of infringement. But such narrowing of the claim scope after the fact may not always be desirable. One may have preserved the validity of the patent, but is left with a negligible pool of potential infringers against whom to assert the patent.

Be mindful of how the invention is defined in the specification and during prosecution. Be careful with scope-limiting language such as “The present invention is…”, and absolute language such as “necessary”, “essential”, and “the distinguishing feature”.

Question the Examiner’s rationale for combining prior art. I have on several occasions seen Examiners use “more options” to rationalize a proposed combination of prior art. This may be a cop-out, because the Examiner may not have a specific, alternate basis for combining the prior art that is unrelated to the inventor’s reasons for making the invention. In that case, the nonobviousness of the invention may be formulated as the discovery of a solution to the “recognition of an unknown problem”.

Don’t Keep Limitations Not Needed To Distinguish the Prior Art

| November 6, 2013

Integrated Technology Corporation v. Rudolph Technologies, Inc.

November 4, 2013

Moore (author), Rader, and Clevenger


The CAFC reversed the denial of Rudolph’s motion for JMOL that its accused no-touch products do not infringe under the doctrine of equivalents.  The CAFC found that prosecution history estoppel (preventing ITC from recapturing through the doctrine of equivalents the subject matter that ITC surrendered during prosecution) presumptively applies, and that ITC failed to rebut the presumption because it failed to establish one of three exceptions by a preponderance of the evidence.

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