. . . In this case, the district court was confronted with just such a situation. There was no dispute that the asserted '356 patent had the same priority date as the later filed '001 and '709 patents, yet the '356 patent had a significantly longer term. . . .
Introduction
In Allergan USA, Inc. v. MSN Laboratories, No. 2024-1061 (Fed. Cir. Aug. 13, 2024) ("Decision"), the United States Court of Appeals for the Federal Circuit addressed key issues related to the judicially-created doctrine of obviousness-type double patenting ("ODP") and written description under 35 U.S.C. § 112. Allergan appealed the District of Delaware's invalidation of its patent claims covering the drug eluxadoline, marketed under the brand name Viberzi®, which is used to treat irritable bowel syndrome with diarrhea ("IBS-D"). Specifically, the district court had held that claim 40 of U.S. Patent No. 7,741,356 ("the '356 patent") was invalid under ODP and that the asserted claims of U.S. Patents Nos. 11,007,179 ("the '179 patent"), 11,090,291 ("the '291 patent"), 11,160,792 ("the '792 patent"), and 11,311,516 ("the '516 patent") were invalid for lack of written description.
The Federal Circuit reversed the district court on both issues. With respect to ODP, the court held that the district court erred in invalidating the '356 patent based on later-filed and later-issued patents that, although sharing the same priority date, expired before the '356 patent. The term of the '356 patent was longer because it was extended by the patent office's grant of "Patent Term Adjustment" ("PTA") due to prolonged prosecution of the patent application, whereas expiration of the related patents was not. The Federal Circuit emphasized that as the first-filed and first-issued patent in its family, the '356 patent could not be invalidated by later-issued patents simply because it expired later due to PTA.
In addition, the Federal Circuit rejected the district court's conclusion that the asserted claims of the '179, '291, '792, and '516 patents lacked written description support. The district court had erroneously found that the patents' specification did not support the asserted claims to formulations without a "glidant," an inactive ingredient that appeared in all of the detailed embodiments described in the patents' specifications. The Federal Circuit clarified that the proper inquiry is whether a person of ordinary skill in the art would have understood from the patents' disclosure that the inventors were in possession of the claimed formulations, even without an explicit statement in the specification that a glidant was an "optional" component of the invention.
Background
This case arose under the Hatch-Waxman Act, which provides a specific framework for adjudicating patent issues where a drug company seeks FDA approval to market a generic version of an approved pharmaceutical product. Under 35 U.S.C. § 271(e)(2)(A), the act of filing an Abbreviated New Drug Application ("ANDA") seeking approval of a generic pharmaceutical product together with a "Paragraph IV certification" is deemed an act of patent infringement. This so-called "artificial" act of infringement allows the patent litigation to commence while FDA reviews the ANDA and potentially be resolved in time to inform an orderly launch of the generic drug product consistent with the adjudicated patent rights.
Here, MSN filed an ANDA, seeking FDA approval to market a generic version of Viberzi®. MSN's ANDA submission included a Paragraph IV certification, asserting its position that, notwithstanding Allergan's patents directed to Viberzi®, FDA could immediately approve the ANDA because the patents are invalid, unenforceable, or not infringed by MSN's generic drug product. As required by the Hatch-Waxman Act, MSN concurrently sent a notice of its ANDA submission to Allergan, including a statement of reasons supporting its Paragraph IV certification that Allergan's patents are invalid, unenforceable, or not infringed.
Allergan responded by filing a lawsuit in the District of Delaware under 35 U.S.C. § 271(e)(2)(A), asserting that MSN's ANDA filing was an infringement of its patents. Prior to trial, MSN stipulated that its generic drug product would infringe all asserted claims, if those claims were found to be valid. Decision at 8. As a result, the trial focused solely on the validity of Allergan's asserted patent claims. Id.
Following a three-day bench trial, the District of Delaware ruled in favor of MSN. Id. at 9-11. The court ruled that asserted claim 40 of the '356 patent was invalid under the doctrine of obviousness-type double patenting. The '356 patent, issued in 2010, claimed eight chemical compounds, including eluxadoline. The district court found that claim 40 of the '356 patent directed to eluxadonline was invalid for ODP because, as Allergan conceded, it was not patentably distinct from later-filed, later-issued, but earlier-expiring claims in U.S. Patents No. 8,344,011 ("the '011 patent") and 8,609,709 ("the '709 patent"). Id. at 9. The ODP issue arose in the case because the term of the '356 patent was extended by PTA, extending its expiration beyond that of the '011 and '709 patents.
The district court further ruled that the claims of the '179, '291, '792, and '516 patents were invalid for lack of written description. Those patents shared a common specification and had claims directed to pharmaceutical formulations of eluxadoline. The district court concluded that the patents failed to meet the written description requirement because they claimed, but did not adequately disclose, formulations of the drug product without a glidant, e.g., colloidal silica. Id. at 10. Specifically, the district court held, that "[f]or all the formulations disclosed in the patent specification, a glidant is used without any indication that it was not required to practice the invention." Id.
Allergan appealed both rulings to the Federal Circuit. Id.
Federal Circuit's Analysis
Obviousness-Type Double Patenting
The Federal Circuit began its ODP analysis with a historical overview of the doctrine. The court explained that the judicially-created ODP doctrine is rooted in the principle that under 35 U.S.C. § 101, "an inventor may obtain 'a patent' (i.e., a single patent) for an invention." Decision at 11. The doctrine is designed to prevent a patentee from extending a patent's exclusivity beyond the legally prescribed patent term by obtaining multiple patents for the same invention or obvious variations thereof. Id. at 11-12 (citing In re Zickendraht, 319 F.2d 225, 232 (CCPA 1963) ("assumption that upon expiration of the patent, [the public] will be free to use not only the invention claimed in the patent but also any modifications or variants thereof which would have been obvious. . . .")). In practice, patentees avoid ODP by filing a "terminal disclaimer" with the patent office for any patents issuing with claims that are patentably indistinct from subject matter claimed in an earlier issued patent. Decision at 13. By doing so, a patentee disclaims any part of the later-issued patent term that extends beyond expiration of the earlier-issued patent. Id.
The Federal Circuit explained how changes in the way patent term is calculated have affected the way courts apply the ODP doctrine. For example, before the 1994 Uruguay Round Agreements Act ("URAA"), a patent's term was calculated from its issuance date and generally lasted for 17 years. See Decision at 12. Thus, in calculating a patent's term, the "issuance dates and expiration dates were inextricably intertwined." Id. By definition, therefore, a later issuing patent would have a longer term than an earlier issued patent in the same patent family.
Since the URAA, a patent's term is determined by adding 20 years to the patent's earliest effective filing date, which is either the filing date of the application itself or the filing date of a related application upon which it relies for priority. Id. The Federal Circuit commented that "[i]n many cases, this means that, post-URAA, there is little risk of an unjustified extension of term subject to ODP because all patents to an invention that share a priority date are expected to expire on the same day. Id. at 12-13 (citing In re Fallaux, 564 F.3d 1313, 1318 (Fed. Cir. 2009)). Nevertheless, "a common priority date does not always guarantee a common expiration date," particularly where patents with the same priority date may have different expiration dates due to PTA or its related "Patent Term Extension" rules. Decision at 13. PTA, for example, compensates patentees for delays in the prosecution of their patent applications, which can result in a patent term that extends beyond the standard 20-year term. See id. (citing 35 U.S.C. § 154(b)).
In this case, the district court was confronted with just such a situation. There was no dispute that the asserted '356 patent had the same priority date as the later filed '001 and '709 patents, yet the '356 patent had a significantly longer term. Moreover, there was no terminal disclaimer limiting the term of the '356 patent to that of its related and later-issued patents. Under those circumstances, the district court "felt itself bound by" a recent Federal Circuit decision that appeared to involve essentially the same facts, In re Cellect, 81 F.4th 1216, 1229 (Fed. Cir. 2023).
The patents at issue in Cellect all derived from the same priority application but had different expiration dates due to PTA. And the patentee had not terminally disclaimed any of the longer-running patent terms. There, the Federal Circuit expressly held that "ODP for a patent that has received PTA, regardless of whether or not a terminal disclaimer is required or has been filed, must be based on the expiration date of the patent after PTA has been added." Cellect, 81 F.4th at 1299 (emphasis added).
True to its reading and understanding of Cellect, the district court invalidated the '356 patent because its effective term, including PTA, ran longer than its related '001 and '709 patents that indisputably claimed patentably indistinct subject matter. This literal application of Cellect would suggest that PTA is rendered meaningless in cases involving multiple related patents with patentably indistinct claims, as patentees may be forced to file terminal disclaimers to avoid ODP invalidation, effectively surrendering the benefit of any PTA.
Avoiding this problem, the Federal Circuit found that the district court misread Cellect and failed to appreciate the nuanced effects of the underlying facts. According to the Federal Circuit, "Cellect answered a different question than that at issue here." Decision at 15. The question left unanswered is which of the issued patents is the proper reference for applying ODP—the first-issued '356 patent or the later-issued '001 and '709 patents? Stated differently, which of the three patents "sets the maximum period of exclusivity for the claimed subject matter and any patentably indistinct variants." Id. at 17.
In answering that question, the Federal Circuit looked to its precedent that directs application of ODP to a "'second, later expiring patent for the same invention.'" Id. (quoting Abbvie Inc. v. Mathilda & Terence Kennedy Institute of Rheumatology Trust, 764 F.3d 1366,1373 (Fed. Cir. 2014) (emphasis in original)). Echoing that precedent, the Federal Circuit emphasized that the purpose of the ODP doctrine "is to prevent patentees from obtaining a second patent on a patentably indistinct invention to effectively extend the life of a first patent to that subject matter." Decision at 16 (emphasis in original) (citing Miller v. Eagle Mfg. Co., 151 U.S. 186, 198 (1894) ("[T]he power to create a monopoly is exhausted by the first patent . . . a new and later patent for the same invention would operate to extend or prolong the monopoly beyond the period allowed by law")).
The Federal Circuit concluded that "[t]he '356 patent is undoubtedly the 'first' patent to cover eluxadoline, whether we measure by filing date or by issuance date." Decision at 16. As the first-filed and first-issued patent, therefore, the '356 patent was not a "second, later expiring patent" and therefore set the outer limits for exclusivity—its extended term due to PTA did not unjustly extend Allergan's monopoly. Id. at 17. Arguably, therefore, the later issued '001 and '709 patents, if eligible, could have been awarded PTA extensions up to and including the term of the '356 patent without offending the ODP doctrine.
In responding to MSN's defense of the district court's ruling, the Federal Circuit noted that MSN "places its stock in our holding in" Gilead Sciences, Inc. v. Natco Pharma Ltd., 753 F.3d 1208 (Fed. Cir. 2014). Decision at 18. "And taken on its face, we can understand why." Id. In Gilead, the Federal Circuit had held that a later-issued but earlier-expiring patent, such as the '001 and '709 patents, could serve as an ODP reference to invalidate an earlier-issued but later-expiring patent, such as the '356 patent. However, the Federal Circuit distinguished Gilead on grounds that it involved a very different factual scenario. In that case, the challenged patent was filed after but issued before the ODP reference patent and, importantly, claimed a different priority date—its own filing date. The challenged patent therefore expired 20 years from its own filing date, long after the ODP reference patent which had a much earlier priority date.
The Federal Circuit explained that "the court in Gilead, . . . focused its inquiry only on whether issuance dates should remain the most relevant benchmark for evaluating ODP post-URAA." Decision at 18 (citing Gilead, 753 F.3d at 1214-15). Absent from the Gilead court's analysis was any consideration of "the role of filing dates." Id. Unlike the challenged patent in Gilead, "claim 40 of the '356 patent was filed before, shares a priority date with, and issued before the reference claims of the '011 and '709 patents." Id. at 19. Against that backdrop, the Federal Circuit concluded that because "the '356 patent was the first patent in its family to be filed and to issue, it does not extend any period of exclusivity on the claimed subject matter." Id. (emphasis in original).
Apparent from the court's analysis is that application of the ODP doctrine will remain a heavily fact-intensive exercise. Perhaps sensitive to the innumerable possible factual scenarios, the Federal Circuit took care to narrowly articulate its holding in this case—"We therefore hold that a first-filed, first-issued, later-expiring claim cannot be invalidated by a later-filed, later-issued, earlier-expiring reference claim having a common priority date." Decision at 17. Despite that narrow holding, the one generalized addition of this case to the ODP analysis is the invitation to analyze not only patent issuance dates but also patent priority dates when applying the ODP doctrine—suggesting that ODP may require a broader analysis of the full factual context in future cases.
Written Description Requirement
The Federal Circuit began its analysis of the written description issue by noting that "this is not a typical written description case." Decision at 21. Ordinarily, these cases involve situations where the patent claims recite a specific species of the invention, but the specification only disclosed a broad genus, or where the patentee attempted to claim broadly what was disclosed only narrowly in the patent's specification. By contrast, the issue in this case came down to a single inactive ingredient, a so-called "glidant," that was discussed throughout the patents' specification but appeared nowhere in their claims. The court characterized the asserted claims as "essentially picture claims to a particular pharmaceutical formulation," with narrow limitations specifying exact ingredients and amounts—which were indisputably disclosed with exacting precision in the patents' specification. Decision at 21-22.
Unlike typical written description cases, therefore, the issue was not whether the inventors had possession of the claimed drug formulation—the court emphatically affirmed, "that question answers itself." Id. at 22. Instead, the precise issue framed by the district court was whether the inventors had adequately disclosed whether a glidant was merely an "optional" component of the invention. Id. Specifically, the district court concluded that "'the specification . . . fails to show that the patentee was in possession of a formulation in which the inclusion of the glidant was optional.'" Id. at 23 (quoting Allergan USA, Inc. v. MSN Lab'ys Priv. Ltd., 694 F. Supp. 3d 511, 524 (D. Del. 2023)).
In reaching that conclusion, the district court had relied heavily on the Federal Circuit's prior decision in ICU Medical, Inc. v. Alaris Medical Systems, Inc., 558 F.3d 1368 (Fed. Cir. 2009). Decision at 26. The patent at issue in ICU Medical disclosed a medical device comprising, among other components, a valve consisting of "a body, a seal, and a spike." Decision at 27. According to the patent's specification, the spike performed a specific function, "piercing a seal inside the valve." Id. However, the patent claims asserted by the patentee in that case "recited a valve comprising only a body and a seal"—a so-called "spikeless" or "spike-optional" valve. Id. The Federal Circuit held that the "spikeless" patent claims were invalid for the singular reason that "'the specification describe[d] only medical valves with spikes,' [and] [t]he inventor therefore did not possess a medical valve that operated without a spike." Id. (quoting ICU Medical, 558 F.3d at 1378).
The Federal Circuit distinguished this case from ICU Medical for two reasons. First, although not expressly described as "optional," the patents' disclosure here, unlike ICU Medical, at least suggested formulations of eluxadonline made without a glidant. While it is true that all detailed embodiments described in the patents include a glidant, their general description of the invention includes two instances where the drug formulation is described as comprising eluxadoline "and an inert ingredient selected from" a list of inactive ingredients—some of which are glidants and others that are not. Id. at 24 (quoting patent specification) (emphasis in original). In other words, the drug formulation need only include eluxadoline and one additional inactive ingredient—which may or may not be a glidant. The Federal Circuit therefore was satisfied that the patents "contemplate a formulation that both includes and does not include a glidant." Id. Addressing the district court's specific concern, the Federal Circuit expressly held that the patents "contemplate a formulation in which a glidant is optional." Id.
Second, the Federal Circuit noted that "the specification in ICU Medical attributed a particular function to the spike—piercing a seal inside the valve—that could not be accomplished without a spike." Id. at 27. Here, although a glidant was included in each of the detailed embodiments disclosed in the patents, they "attribute[] no particular function or significance to the glidant." Id. Moreover, the fact that the patents generally describe formulations of eluxadoline both with and without a glidant was enough to "indicate[] that it is optional, regardless of whether the inventors expressly described it as 'optional.'" Id. (citing Lockwood v. Am. Airlines, Inc.,107 F.3d 1565, 1572 (Fed. Cir. 1997) ("exact terms need not be used in haec verba")).
Having rejected the district court's ruling that the patents' specification failed to disclose that a glidant was optional, the Federal Circuit likewise rejected the district court's reliance on expert testimony that a person of ordinary skill in the art "'would understand that using a glidant in a [disclosed] formulation would be a signal that it was necessary in order to achieve sufficient flow properties.'" Decision at 28 (quoting Allergan, 694 F. Supp. 3d at 524-25). The Federal Circuit found no fault in the district court's use of expert testimony to guide its inquiry into the specification's disclosure. Id. at 29 ("Reliance on such testimony, untethered to the inventors' own description of the invention, would improperly take the written description inquiry outside the four corners of the specification"). However, the Federal Circuit viewed this expert testimony as little more than evidence that a glidant may be necessary in some formulations but not as proof that "the inventors did not possess a formulation in which it was not necessary." Id. (emphasis in original).
Finally, the Federal Circuit cautioned against the intermingling of the utility and enablement requirements with the written description analysis. Specifically, the Federal Circuit explained that for purpose of written description, "a claimed invention need successfully operate only to some limited degree." Id. "So, although a formulation without a glidant may not flow as well as a formulation with a glidant, that does not mean that the formulation would not 'work' without a glidant, as the district court found." Id.
For these and other reasons, the Federal Circuit concluded that the district court "clearly erred" in finding that the patents' disclosure failed to convey that "the inventors had possession of a formulation without a glidant." Id. The Federal Circuit therefore reversed "the district court's conclusion that the asserted claims of the '179, '291, '792, and '516 patents are invalid under 35 U.S.C. § 112 for lack of written description." Id. at 29-30.
Conclusion
The Federal Circuit's decision in Allergan USA Inc. v. MSN Laboratories reinforces important principles of patent law regarding written description and obviousness-type double patenting. In reversing the district court's ruling on written description, the Federal Circuit clarified that a patent's specification need not expressly label every component as "optional" or necessary to meet the written description requirement, provided that a person of ordinary skill in the art would understand the invention as disclosed. On the issue of obviousness-type double patenting, the court issued a narrow holding that a first-filed, first-issued patent cannot be invalidated by later-issued patents in the same family merely because they expire earlier. However, while the holding is specific to the facts of this case, the court's analysis hints at broader implications. Stated more broadly, ODP now appears to depend on the entirety of the facts and circumstances of each case—a fertile field for patent practitioners.
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