On March 13, 2025, the Federal Circuit issued a decision in Merck Sharp & Dohme B.V. v. Aurobindo Pharma USA, Inc., No. 23-2254 (Fed. Cir. 2025) that clarifies how patent term extension (PTE) is calculated for reissue patents. PTE was established under the Hatch-Waxman Act as a mechanism by which the term of a patent may be extended for up to five years to compensate for delays in obtaining regulatory approval for certain products such as pharmaceuticals and medical devices.[1] PTE therefore can be an important mechanism for extending exclusivity for valuable products in the life sciences. Notably, the amount of PTE available for any given patent depends upon the issue date of the patent, which is the subject that the Court addressed in this decision.
The case involves Merck’s U.S. Patent No. RE44,733 (“the RE’733 patent”), which includes claims directed to “sugammadex,” the active ingredient in Merck’s BRIDION® drug for reversing neuromuscular blockades. The RE’733 patent is a reissue of U.S. Patent No. 6,670,340 (“the original patent”), which included claims directed to sugammadex. The RE’733 patent retains the claims of the original patent and also includes 12 additional, narrower claims directed to sugammadex.[2] After regulatory approval of sugammadex, the U.S. Patent and Trademark Office (USPTO) awarded five years of PTE to RE’733 based on the issue date of the original patent.[3]
Merck asserted the RE’733 patent against defendant-appellants (collectively “Aurobindo”), who sought regulatory approval to sell generic versions of BRIDION®. Aurobindo argued at trial that the USPTO miscalculated the PTE award of the RE’733 patent in view of the plain text meaning of 35 U.S.C. § 156(c).[4] 35 U.S.C. § 156(c) provides that:
The term of a patent eligible for extension under subsection (a) shall be extended by the time equal to the regulatory review period for the approved product which period occurs after the date the patent is issued…
(emphasis added). Aurobindo argued that the plain text of 35 U.S.C. § 156(c) required the USPTO to calculate PTE using the issue date of the reissued RE’733 patent, not the issue date of the original patent.[5] Under this reasoning, Aurobindo asserted that the RE’733 patent was entitled to only 686 days of PTE, not the five years awarded by the USPTO, and that the term of the RE’733 patent had therefore expired.[6] The district court interpreted “the patent” in 35 U.S.C. § 156(c) as referring to the original patent, finding that the RE’733 patent was entitled to the five years of PTE awarded by the USPTO.[7]
On appeal, the Federal Circuit agreed with the district court that the RE’733 patent was entitled to five years of PTE based on the issue date of the original patent.[8] The Court considered the specific context of the use of “the patent” in 35 U.S.C. § 156(c) and the broader purpose of the Hatch-Waxman Act.[9] The Court reasoned that construing “the patent” as used in 35 U.S.C. § 156(c) as meaning the original patent was the only construction that comported with the purpose of the Hatch-Waxman Act, which is to compensate “patent owners who were actually disabled from benefiting from patent protection during the pendency of regulatory review.”[10] The Court noted that their decision is consistent with how the USPTO has handled such cases and that Section 2766 of the USPTO’s Manual of Patent Examining Procedure was consistent with this statutory interpretation.[11]
Under the Federal Circuit’s construction, Merck is compensated “for the period of exclusivity lost due to regulatory delay”—the period of time after the original patent issued during which Merck was unable to commercially market BRIDION® due to regulatory review.[12] Under Aurobindo’s proposed construction of “the patent,” which the court rejected, the calculus should be tied to the issue date of the RE’733 patent, which naturally would occur later than the issue date of the original patent, and therefore would have resulted in less compensation for the period of exclusivity that Merck lost due to regulatory review.[13]
The Federal Circuit held that “in the context of reissued patents, ‘the patent’ in [35 U.S.C. § 156(c)] refers to the original patent that includes claims that are directed to a drug product.”[14] In this case, the original patent included claims directed to sugammadex, and therefore the patent was entitled to the five years of PTE awarded by the USPTO.
Two footnotes in the opinion suggest how courts could address other factual scenarios not raised in the current case. In one instance, the Court commented that if the original patent included claims directed to a drug product subject to regulatory review, and those claims were canceled during reissue, the canceled claims would no longer be PTE eligible regardless of whether they were canceled before or after regulatory review.[15] In another instance, the Court noted that the case did not address the situation “where the original patent did not include any claims directed to the drug product and was later reissued to include broader claims directed to such product,”[16] suggesting such situation could turn on factors such as whether the reissued patent was issued before or after regulatory review.
The reissue process can be used to strengthen patents by adding additional claims or modifying existing claims. In view of this case, patentees need not per se avoid seeking reissue on patents that may serve as a basis for PTE. However, given the limited factual scenario presented and the suggestion that other scenarios may be treated differently, patentees should use caution in considering the types of claim amendments presented in reissue for patents that may be subject to PTE.
[1] See 35 U.S.C. § 156.
[2] Merck Sharp & Dohme B.V. v. Aurobindo Pharma USA, Inc., No. 23-2254 (Fed. Cir. 2025) at 6.
[3] Id. at 4.
[4] Id. at 8.
[5] Id.
[6] Id.
[7] Id. at 8-9.
[8] See id. at 17.
[9] Id. at 11-12.
[10] Id. at 14.
[11] Id. at 16; see M.P.E.P. § 2766 (“With respect to calculating the amount of extension to which the reissued patent is entitled to receive, so long as the original patent claimed the approved product and the reissued patent claims the approved product, the original patent grant date would be used to calculate the extension to which the reissued patent would be entitled.”)
[12] Id. at 13.
[13] See id.
[14] Id. at 17.
[15] See id. at Footnote 10 (“If the original patent included claims directed to a drug product subject to regulatory review and the patent owner subsequently cancels those claims, section 156 of course would not apply, whether the cancellation occurred before or after regulatory review. This is because cancelled claims are treated as void ab initio. Fresenius, 721 F.3d at 1346.”)
[16] Id. at Footnote 11.
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