IP Law Daily, PATENT—Fed. Cir.: Pharmaceutical company fails to secure mandatory ITC stay in achondroplasia patent dispute, (Mar 27, 2026)

By Ravindra Kumar Singh, B.L.

A district court correctly found that the pharmaceutical company could not reset the statutory deadline for a mandatory stay by dismissing and refiling its patent action.

The U.S. Court of Appeals for the Federal Circuit has affirmed a federal district court’s denial of a mandatory stay under 28 U.S.C. § 1659(a)(2), holding that a pharmaceutical company developing a treatment for achondroplasia was not entitled to such relief because it attempted to circumvent the statute’s 30-day deadline. The company tried to get around the time limit by voluntarily dismissing and refiling its declaratory judgment action against a competing drug manufacturer. The court further held that any error in treating the motion as moot was harmless, as the plaintiffs were substantively ineligible for a mandatory stay (Ascendis Pharma A/S v. Biomarin Pharmaceutical Inc., No. 26-1026 (Fed. Cir. Mar. 26, 2026)).

Background. The plaintiff/appellant, Ascendis Pharma A/S and related entities, are pharmaceutical companies developing therapies for growth disorders. The defendant/ appellee, BioMarin Pharmaceutical Inc., is another drug manufacturer specializing in treatments for rare genetic conditions. The asserted U.S. Patent No. RE48,267 (the ’267 patent) is owned by BioMarin and covers certain C-type natriuretic peptide (CNP) variants, including BioMarin’s FDA-approved drug Voxzogo®, used to treat achondroplasia.

The dispute began when Ascendis filed a New Drug Application with the FDA for its competing product, TransCon® CNP. Shortly thereafter, BioMarin initiated proceedings before the U.S. International Trade Commission (ITC), alleging that Ascendis’s activities infringed the ’267 patent. In response, Ascendis filed a declaratory judgment action in the Northern District of California, asserting non-infringement and invoking the safe harbor provision under 35 U.S.C. § 271(e)(1).

However, Ascendis did not seek a mandatory stay within the statutory 30-day period. After BioMarin moved to dismiss or stay the case, Ascendis voluntarily dismissed its complaint and refiled a nearly identical action, intending to reset the statutory clock and request a mandatory stay under § 1659(a)(2). The district court denied the request for a mandatory stay as moot and instead granted a discretionary stay. Ascendis appealed, challenging the denial of the mandatory stay.

Standing. The Federal Circuit first addressed whether Ascendis had Article III standing to pursue the appeal. Applying the standard articulated in Spokeo, Inc. v. Robins, 578 U.S. 330, 338 (2016), the court found that Ascendis had demonstrated a concrete and imminent injury. BioMarin had indicated that it might seek to lift the discretionary stay and pursue a preliminary injunction upon FDA approval of Ascendis’s product. This created a sufficient threat of parallel litigation.

Further, the court relied on Grit Energy Solutions, LLC v. Oren Technologies, LLC, 957 F.3d 1309, 1320 (Fed. Cir. 2020), where prior litigation between the parties supported standing due to the risk of renewed enforcement. Similarly, the possibility of renewed district court proceedings here was neither speculative nor remote.

Collateral order doctrine. The court next held that it had jurisdiction under the collateral order doctrine, citing Cohen v. Beneficial Industrial Loan Corp., 337 U.S. 541 (1949). It concluded that all three requirements were satisfied.

First, the district court conclusively determined the issue by denying the mandatory stay despite recognizing that the statutory criteria were met. Second, the issue was separate from the merits of the underlying patent dispute, which concerned non-infringement. Third, the denial was effectively unreviewable after final judgment because the purpose of § 1659 is to prevent simultaneous proceedings, a right that would be irretrievably lost if not immediately reviewed.

The court also relied on In re Princo Corp., 478 F.3d 1345, 1357 (Fed. Cir. 2007), emphasizing that the statutory right to a stay cannot be vindicated after litigation has already occurred.

Mootness and harmless error. Turning to the merits, the Federal Circuit rejected the district court’s conclusion that the mandatory stay request was moot. It clarified that a discretionary stay, which can be lifted, is not equivalent to a mandatory stay under § 1659(a)(2), which remains in place until ITC proceedings conclude. Nevertheless, the court held that this error was harmless because Ascendis was not entitled to a mandatory stay in any event.

Statutory interpretation and refiling. The central issue was whether Ascendis could restart the 30-day statutory period by dismissing and refiling its complaint. The court answered in the negative, holding that the phrase “the district court action is filed” in § 1659(a)(2) refers to the original action, not a refiled one.

The court grounded its reasoning in common-law principles prohibiting litigants from using procedural tactics to circumvent statutory requirements. It cited Russ v. Standard Insurance Co., 120 F.3d 988, 990 (9th Cir. 1997), where a plaintiff was barred from dismissing and refiling to cure a procedural defect. Applying this principle, the court found that Ascendis’s conduct, voluntarily dismissing and refiling an identical complaint solely to reset the deadline, fell squarely within the prohibited category of procedural manipulation.

Statutory and legislative arguments. Ascendis argued that the statutory text did not expressly prohibit refiling and that Congress could have included such language, as it did in other statutes, such as 28 U.S.C. § 1446(b). The court rejected this argument, finding it unpersuasive and overly speculative. The court further relied on legislative history, noting that Congress imposed strict deadlines in § 1659 to “avoid abuse” and “encourage prompt adjudication.” Allowing refiling to reset the deadline would undermine these objectives.

Conclusion. Thus, the Federal Circuit concluded that Ascendis could not use voluntary dismissal and refiling to evade the statutory deadline for seeking a mandatory stay under § 1659(a)(2). Because Ascendis failed to timely request the stay in its original action, it was not entitled to mandatory relief. Accordingly, the appellate court affirmed the district court’s decision.

The Case is No. 26-1026.

Judge: Stoll, K.

Attorneys: Gabriel K. Bell (Latham & Watkins LLP) for Ascendis Pharma A/S. Edward R. Reines (Jones Day) for BioMarin Pharmaceutical Inc.

Companies: Ascendis Pharma A/S; BioMarin Pharmaceutical Inc.

Cases: Patent FedCirNews GCNNews