The complaint

AstraZeneca Pharmaceuticals LP v. Hetero USA Inc., No. 1:26-cv-01437 (D. Del.), is a 13-page complaint filed November 6, 2026 under the Hatch-Waxman provisions of 35 U.S.C. 271(e)(2). The plaintiffs are AstraZeneca Pharmaceuticals LP, which holds New Drug Application No. 213756 for KOSELUGO (selumetinib) capsules; Alexion Pharma International Operations Limited and Array BioPharma Inc., which the complaint identifies as assignees of the four patents in suit; KuDOS Pharmaceuticals Limited; and MSD International Business GmbH. The defendant is Hetero USA Inc., which the complaint describes, on information and belief, as a Delaware corporation with a place of business in Piscataway, New Jersey.

The ANDA

The complaint alleges that Hetero submitted Abbreviated New Drug Application No. 221857 seeking approval to market generic versions of KOSELUGO 10 mg and 25 mg capsules before the patents expire. It alleges that KOSELUGO is used to treat neurofibromatosis type 1 in patients with symptomatic, inoperable plexiform neurofibromas. According to the complaint, Hetero's notice letter dated September 25, 2026 stated that the ANDA contains a Paragraph IV certification that the patents are invalid, unenforceable, and/or will not be infringed, and the plaintiffs filed within 45 days of receiving it.

The complaint says the notice letter included an offer of confidential access, that the plaintiffs proposed revisions on October 28, 2026, and that Hetero declined on October 29 and again on November 4 to provide meaningful access to the full ANDA. It alleges on information and belief that the proposed product uses a formulation covered by one or more claims of the patents and that the FDA has not yet approved the ANDA.

The patents

According to the complaint, all four patents are titled Pharmaceutical Composition, are listed in the Orange Book for NDA No. 213756, and issued on these dates:

  • U.S. Patent No. 11,813,246, issued November 14, 2023.
  • U.S. Patent No. 12,220,403, issued February 11, 2025.
  • U.S. Patent No. 12,318,367, issued June 3, 2025.
  • U.S. Patent No. 12,364,684, issued July 22, 2025.

The counts and relief

Counts I through IV each allege that the ANDA submission infringes under 35 U.S.C. 271(e)(2), and allege on information and belief that Hetero will infringe and induce or contribute to infringement under 35 U.S.C. 271(b) and (c) upon approval. The complaint asks for an order under 35 U.S.C. 271(e)(4)(A) setting the effective date of any approval no earlier than the expiration of the patents plus any exclusivity, a permanent injunction, a declaration that the case is exceptional under 35 U.S.C. 285 with attorneys' fees, and costs.

The early filings

The docket shows the ANDA form, the patent report to the Commissioner, magistrate consent forms, five Rule 7.1 disclosure statements, and an issued summons, all entered November 9, 2026.

What to watch next

Watch for the judge assignment, Hetero's answer and any counterclaims, and a scheduling order.