On March 13, 2025, the Federal Circuit decided in Merck Sharp & Dohme B.V. v. Aurobindo Pharma USA, Inc. (No. 2023-2254) how patent term extensions (PTEs) apply to reissued patents under the Hatch-Waxman Act. The court confirmed that PTE should be calculated based on the issue date of the original patent rather than the reissue date — a decision that has implications for pharmaceutical patent holders.
Under the Hatch-Waxman Act, a patentee can receive up to five years of PTE to compensate for regulatory delays in obtaining Food and Drug Administration (FDA) approval. 35 U.S.C. § 156. The formula for calculating PTE provides that “[t]he term of a patent … shall be extended by the time equal to the regulatory review period … occur[ring] after the date the patent is issued.” Id. at § 156(c). The dispute in this case centered on whether the reference to “patent” in subsection 156(c) is to the original patent or the reissue patent. Using the reissue date would usually result in shorter PTE because any regulatory review before the issue date does not affect PTE.
Merck’s original patent (U.S. Patent No. 6,670,340) covered the active ingredient in BRIDION® (“sugammedex”), a drug used to reverse neuromuscular blockade. During FDA review of Merck’s New Drug Application for BRIDION®, the patent was reissued as U.S. Patent No. RE44,733, which retained the original claims while adding narrower ones specific to the active ingredient. After FDA approved BRIDION®, Merck applied for PTE, which the U.S. Patent and Trademark Office (USPTO) granted based on the original patent’s issue date. Generic drug manufacturers challenged this calculation in District Court, arguing that the extension should be based on the reissue date, which would significantly reduce the extended term. The District Court agreed with the USPTO that § 156(c)’s reference to the “patent” refers to the original patent, not the reissued patent. In re Sugammadex, No. CV 20-2576 (CCC) (LDW), 2023 WL 3966146, at *16 (D.N.J. June 13, 2023).
The Federal Circuit affirmed the lower court’s ruling and held that PTE for a reissued patent should be calculated based on the original patent’s issue date. The court found that the meaning of the term “patent” as used in 35 U.S.C. § 156(c) was ambiguous but should be interpreted in a manner consistent with the Hatch-Waxman Act’s purpose of compensating patent owners for lost exclusivity due to regulatory delay. The Federal Circuit explained that a contrary interpretation would undermine the Act’s intent by arbitrarily shortening PTEs for patent holders who sought reissue, potentially discouraging valid reissues.
Takeaways
The court’s ruling has implications for pharmaceutical patentees and generic drug manufactures. For patentees seeking PTE for reissued patents, the ruling ensures that regulatory delays are accounted for from the issue date of the original patent that has claims covering the at-issue drug product, even when a patent undergoes reissuance. The decision also affirms the additional hurdles for generic drug manufacturers when challenging patent exclusivity because reissued patents maintaining claims to the at-issue drug maintain their full PTE period as calculated from the original patent issue date.
