Patentees in the pharmaceutical industry can breathe a sigh of relief following the Federal Circuit’s holding in Allergan. 

Recently, the relationship and intersection between obviousness-type double patenting (ODP) and any awarded Patent Term Adjustment (PTA) and/or Patent Term Extension (PTE) has received significant attention. The United States Court of Appeals for the Federal Circuit held in In re Cellect, 81 F.4th 1216 (Fed. Cir. 2023), that PTA and PTE, being codified in separate statutes, are treated differently for the purposes of determining the requisite expiration dates in an ODP analysis.

The Federal Circuit’s recent holding in Allergan USA, Inc. v. MSN Laboratories Private Ltd., No. 2024-1061, 2024 WL 3763599 (Fed. Cir. Aug. 13, 2024), raises the issue of when a claim can be used as a reference claim in an ODP analysis. In particular, the court addressed the question of whether “a first-filed, first-issued, later-expiring claim [can] be invalidated by a later-filed, later-issued, earlier-expiring reference claim having a common priority date”. Id. at *4.

Background

The Patent Family

The patents at issue relate to the drug compound eluxadoline, marketed as Viberzi by Allergan for the treatment of irritable bowel syndrome with diarrhea. Janssen is the assignee of U.S. Patent No. 7,741,356 (’356 patent), filed March 14, 2005, and assigned Serial No. 11/079,647 (’647 application). The ’647 application issued as the ’356 patent on June 22, 2010. The ’356 patent was awarded 1,107 days of PTA to compensate for delays during prosecution. Janssen disclaimed all but 467 days in applying for PTE following FDA approval.

The ’647 application has a number of continuing applications that claim the benefit of the earlier priority date of the ’647 application. Of interest are U.S. Patent Nos. 8,344,011 (’011 patent) and 8,609,709 (’709 patent).

The ’011 patent is a divisional of U.S. Patent No. 7,786,158, which is a continuation of the ’356 patent.[1] The ’011 patent, issued January 1, 2013, did not receive any PTA. Claim 33 of the ’011 patent recites methods of treatment via administering any one of the same eight specific compounds of claim 40 of the ’356 patent, including eluxadoline.

The ’709 patent is a continuation of the ’011 patent and was issued December 17, 2013. Similarly, the ’709 patent did not receive any PTA. Claim 5 of the ’709 patent recites a compound having the specific chemical formula of eluxadoline. The ’709 patent is subject to a terminal disclaimer over the ’356 patent.

Excluding the awarded PTE, the ’356 patent would expire on June 24, 2026. Claim 40 of the ’356 patent is at issue and recites the formulae of eight specific chemical compounds, including that of eluxadoline. The ’011 and ’079 patents would each expire on March 14, 2025, 20 years from the filing date of the ’647 application to which priority is claimed.

Procedural History

Sun Pharmaceutical Industries Limited, in seeking to market a generic version of Viberzi, filed an Abbreviated New Drug Application (ANDA) in July 2019, making a Paragraph IV certification under the Hatch-Waxman Act, thereby asserting that the claims of ’356 patent are invalid and would not be infringed by the generic drug.[2] Allergan subsequently sued Sun, alleging that Sun’s ANDA infringes claim 40 of the ’356 patent.

Following discovery, the parties stipulated that Sun’s ANDA would infringe the asserted claims provided that they were valid. Thus, the only outstanding issues pertain to the validity of the asserted claims. Sun had asserted that claim 40 of the ’356 patent, reciting eight specific chemical structures including that of eluxadoline and having a later expiration date due to the award of PTA, was invalid under ODP as being patentably indistinct over claim 33 of the ’011 patent and claim 5 of the ’709 patent, each of which expire earlier than the ’356 patent.[3]

The district court agreed with Sun, holding claim 40 of the ’356 patent invalid for ODP. Allergan appealed.

The Federal Circuit’s Decision

In support of its position, Sun argued that the holding of In re Cellect is controlling. In particular, Sun asserted that an earlier-filed, earlier-issued and later-expiring claim can be invalidated under ODP by a later-filed, later-issued and earlier-expiring reference claim. Sun further analogized the situation to that of Gilead Sciences, Inc. v. Natco Pharma Ltd., 753 F.3d 1208 (Fed. Cir. 2014), in which a later-issued and earlier-expiring patent could serve as an ODP reference to invalidate an earlier-issued and later-expiring patent.

Allergan argued that claim 40 of the ’356 patent, being the first to be filed and first to issue, should not be subject to ODP over the later-filed and later-issuing reference patents.

The Federal Circuit reversed the district court’s finding that claim 40 of the ’356 patent was invalid under ODP. In its holding, the court distinguished the instant situation from Cellect. While the court agreed that Cellect established the rule that the calculation of an expiration date in an ODP analysis for a patent awarded PTA includes the PTA, the court noted that Cellect did not address the question of when a claim may be used as a reference claim in an ODP analysis.

In holding that the claims of the ’011 and ’709 patents were not applicable as references in an ODP analysis, the court reiterated the rationale behind ODP, which is to prevent a patentee from obtaining a second patent on patentably indistinct subject matter, thereby unjustifiably extending the term of the first patent. Allergan, 2024 WL 3763599, at *6 (“[T]he 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.”) (emphasis in original) (citing Miller v. Eagle Mfg. Co., 151 U.S. 186, 198 (1894)); Cellect, 81 F.4th at 1226 (“A crucial purpose of ODP is to prevent an inventor from securing a second, later-expiring patent for non-distinct claims”) (emphasis added).

There is no question that the ’356 patent is the first patent covering eluxadoline because the applications leading to the alleged reference ’011 and ’709 patents were not filed until after the ’356 patent issued. To hold said first-ever patent covering eluxadoline invalid under ODP on the grounds that it “extends Allergan's period of exclusivity to the subject matter claimed in the ’011 and ’709 continuation patents simply because it expires later … is antithetical to the principles of ODP.” Allergan, 2024 WL 3763599, at *6.

In particular, the ’356 patent, being the first and foundational patent in the patent family, establishes the maximum period of the limited monopoly for the claimed subject matter and other patentably indistinct variants of the patent family. The ’356 patent is not a second patent that seeks to prolong and unjustifiably extend the term of the monopoly.

The court also distinguished the instant situation from Gilead in dismissing Sun’s arguments and reliance on the same. While the court acknowledged a later-issued and earlier-expiring patent could serve as an ODP reference to invalidate an earlier-issued and later-expiring patent, the challenged patent and reference patent in Gilead did not share a priority date, resulting in the earlier-issued and later-expiring patent, claiming a patentably indistinct variant, having a later priority date and later-expiring patent term. In contrast, the ’356 patent was the first-filed and first-issued patent within the patent family such that its full term would not extend any period of exclusivity to the claimed subject matter.

Therefore, the court held 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.” Id. at *7.

Conclusion and Practice Points

In its opinion, the Federal Circuit also acknowledged the patent life cycle of a pharmaceutical drug patent family in which prosecution of the first-filed application directed to a genus of compounds is likely to take longer and be more drawn out and would, more likely than not, result in an award of PTA that extends the term of the first-filed patent beyond the statutory patent term. See id. at *8. Prosecution may be more expedient in subsequent child applications, claiming, for example, methods of treatment, whose issued patents may or may not receive an award of PTA and would expire no later than the parent. Thus, allowing a later-filed, later-issued and earlier-expiring child patent to be used to invalidate the first-filed, first-issued patent in the family having received an award of PTA via ODP would force patentees, in maintaining validity of the parent patent, to disclaim any term beyond that of the reference child patent, thereby running afoul of the intent of Congress to permit a patentee to enjoy the guaranteed patent term.

Patentees in the pharmaceutical industry can breathe a sigh of relief following the Federal Circuit’s holding in Allergan. The first-filed, first-issued patents in a pharmaceutical drug family, often covering a genus of novel drug compounds, cannot be invalidated by the claims of a second or subsequent patent claiming additional subject matter such as methods of treatment, dosing and formulations utilizing said compounds, as often leveraged by challengers in invalidity defenses based on ODP. The holding also strengthens the portfolio of patentees whose first-filed and first-issued patents have both an award of PTA and PTE, as the PTA cannot be invalidated through an ODP analysis relying on later-filed, later-issued child patents as reference patents. Moreover, patentees will no longer face the conundrum of holding a patent with invalid claims due to ODP but a valid grant of PTE.

Knowing that the claims of a first-filed, first-issued patent with PTA in a family is immunized against ODP, the emphasis on strategy becomes even more important. Applicants should still seek to protect their most valuable asset in the first filing, often the novel drug compounds or a genus of compounds, such that the first-filed, first-issued foundational patent of the family establishes the period of exclusivity. Pharmaceutical patentees may seek to further extend the patent term of this foundational patent in applying for PTE following FDA approval with the knowledge that ODP based on the claims of a later-filed, later-issued may not be used to invalidate the foundational patent. However, pharmaceutical applicants must take care to ensure that each family member shares a common priority date. Additionally, to maximize PTE, pharmaceutical applicants will want to obtain issuance of the first-filed patent prior to starting clinical trials. Thus, it continues to be beneficial to include and sufficiently describe the subject matter of the later-filed child applications directed to methods of treatment, methods of administration and formulations in the initial filing of the application to be issued as the foundational patent.

Further, considering the subject matter claimed in ‘709 patent claim 5 and ‘356 patent claim 40―namely a specific compound and eight compounds including the specific compound, respectively―had Sun prevailed in invalidating ‘356 patent claim 40 on the basis of the later-issuing claim 5 of the ‘709 patent (as to which there is a terminal disclaimer over the ‘356 patent), it would mean a significant change in patent practice. For instance, in situations where an earlier-issued patent provides a reference claim (e.g., ‘356 patent claim 40) as to a later pending claim (e.g., ‘709 patent claim 5), when faced with an ODP rejection as to the earlier-issued patent claim, the applicant would need to not only file a terminal disclaimer as to the patent of the reference claim, but also file a terminal disclaimer in the patent of the reference claim as to the application of the pending claim, thereby possibly resulting in forfeiture of appropriately earned PTA. The Federal Circuit’s decision keeps intact present patent practice where in the scenario described, only a terminal disclaimer in the application as to the earlier patent is all that is required to overcome ODP.

For More Information

If you have any questions about this Alert, please contact Thomas J. Kowalski, Vicki G. Norton, Ph.D., Brandon A. Chan, Ph.D., any of the attorneys in our Intellectual Property Practice Group. any of the attorneys in our Life Sciences and Medical Technologies Industry Group or the attorney in the firm with whom you are regularly in contact.

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