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Shionogi & Genentech v. Norwich Pharma — Baloxavir Marboxil ANDA Settlement | PatSnap
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Case ID1:23-cv-00161
FiledFeb 2023
ClosedJul 2025
Patent Litigation

Shionogi, Roche & Genentech v. Norwich: Baloxavir ANDA Settled After 891 Days

Shionogi, Hoffmann-La Roche, and Genentech brought a Hatch-Waxman infringement action in Delaware against Norwich Pharmaceuticals and Alvogen, asserting eight patents covering baloxavir marboxil (Xofluza), the cap-dependent endonuclease inhibitor flu antiviral. The parties reached a negotiated settlement in July 2025, with Norwich enjoined from launching its generic 40 mg and 80 mg tablets until a confidential contractual entry date.

Resolution time
891days
891 days — longer than the median ANDA case in Delaware, suggesting contested patent validity or complex licensing terms
Patents asserted
8
US8927710, US8987441, US9815835, US10392406, US10633397, US10759814, US11261198, US11306106 — 8 baloxavir marboxil composition and process patents asserted
Outcome
Case Terminated
Negotiated settlement; Norwich enjoined and admits ANDA filing constituted infringement under 35 U.S.C. § 271(e)(2)(A)
Cost ruling
No Cost Award
Stipulation expressly provides no costs, disbursements, or attorneys’ fees awarded to any party
Published by PatSnap Insights Team · Verified by PatSnap Eureka Data
Case overview

A High-Stakes ANDA Battle Over Xofluza’s Eight-Patent Fortress

Filed on 13 February 2023 in the District of Delaware before Judge Maryellen Noreika, this Hatch-Waxman action brought by Shionogi Inc., Hoffmann-La Roche Inc., and Genentech Inc. targeted Norwich Pharmaceuticals and Alvogen Pb Research & Development LLC. The plaintiffs asserted eight U.S. patents spanning compositions, crystalline forms, and manufacturing processes for baloxavir marboxil — the active ingredient in Xofluza, a first-in-class cap-dependent endonuclease inhibitor approved for influenza treatment.

The case closed on 23 July 2025 when the parties filed a stipulated settlement order. Under its terms, Norwich admitted that filing ANDA No. 217449 constituted infringement of all eight asserted patents under 35 U.S.C. § 271(e)(2)(A), and consented to an injunction barring commercial launch of its generic 40 mg and 80 mg baloxavir marboxil tablets until the earlier of a confidential contractual ‘Entry Date’ or expiration of the latest-expiring asserted patent, including any pediatric exclusivities. The 30-month regulatory stay was simultaneously terminated.

At 891 days, the case ran longer than typical Hatch-Waxman matters that resolve quickly on motion, suggesting the parties negotiated substantive licensing terms — likely a future authorized-generic or royalty arrangement — rather than achieving an early capitulation. The confidential Entry Date remains undisclosed in the public record, leaving the actual competitive timeline for a generic Xofluza uncertain. Norwich retains its Paragraph IV certifications, preserving a limited pathway to challenge patent validity in future proceedings.

Case at a glance
Case no.1:23-cv-00161
CourtDelaware
JudgeMaryellen Noreika
FiledFebruary 13, 2023
ClosedJuly 23, 2025
Duration891 days
OutcomeCase Terminated
Verdict causeInfringement Action
BasisCase Terminated
Prior Art Intelligence
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Case data sourced from PACER / Delaware District Court via PatSnap Eureka Litigation Intelligence Explore similar cases ↗
Case timeline

Filing to Case Terminated in 891 days

891 days — longer than the median ANDA case in Delaware, suggesting contested patent validity or complex licensing terms

Case timeline: Complaint filed FEB 13 2023, MAY–JUN — 891 days total Horizontal timeline showing the three key events in Shionogi, Inc. v NORWICH PHARMACEUTICALS, Inc. from filing to resolution. Source: PACER, Delaware District Court. FEB 13 2023 Complaint filed Pre-trial proceedings JUL 23 2025 Case Terminated 891 DAYS TOTAL
Settlement terms

Negotiated settlement: what the stipulated order means for both sides

Legal mechanism

Stipulated settlement order under Hatch-Waxman framework

The parties resolved the dispute through a consent order entered by the court. Norwich admitted ANDA-based infringement under 35 U.S.C. § 271(e)(2)(A) for all eight asserted patents, triggering an injunction tied to either a private contractual Entry Date or patent expiry. The 30-month FDA stay was lifted by agreement. All remaining claims were dismissed without prejudice, preserving future litigation rights over different products.

Dismissed without prejudice
Patent holder outcome

Xofluza franchise protected; entry date kept confidential

Shionogi, Roche, and Genentech secured a court-entered injunction blocking Norwich’s generic launch until a privately negotiated Entry Date — likely granting a controlled market exclusivity runway. The infringement admission by Norwich strengthens the enforceability record of all eight asserted patents against any future ANDA challenger. Pediatric exclusivities are expressly preserved in the injunction scope.

Patent portfolio reinforced
Generic challenger outcome

Norwich admits infringement but secures a future launch right

While Norwich’s immediate commercial ambitions are blocked, the settlement almost certainly includes a confidential licensed Entry Date giving Norwich a defined path to market. Norwich retains its Paragraph IV certifications under 21 U.S.C. § 355(j)(2)(A)(vii)(IV), preserving its legal standing to challenge patent validity in future proceedings. The dismissal without prejudice also leaves other product-related claims open.

Future launch right preserved
Commercial implications

Eight-patent barrier raises the cost of generic Xofluza entry

The settlement signals that Xofluza’s IP estate — spanning composition, crystal form, and process patents — presents a formidable challenge for any ANDA filer. With Norwich’s infringement admission now on record, subsequent generic challengers face a stronger enforceability baseline. The confidential Entry Date structure is consistent with an authorized-generic or royalty arrangement, a commercially common resolution in high-value antiviral ANDA disputes.

High entry barrier confirmed
Legal analysis based on PACER docket records for case 1:23-cv-00161 and PatSnap Eureka litigation intelligence Search PatSnap Eureka ↗
Parties and representation

Full party and counsel information

RoleNameTypeDetail
PlaintiffShionogi, Inc.CompanyPharmaceutical patent holders — Shionogi, Roche & Genentech, collectively holding 8 baloxavir marboxil patentsSearch in Eureka ↗
Co-PlaintiffHoffmann-La Roche, Inc.CompanySearch in Eureka ↗
Co-PlaintiffGenentech, Inc.CompanySearch in Eureka ↗
DefendantNORWICH PHARMACEUTICALS, Inc.CompanyNorwich Pharmaceuticals and Alvogen: generic drug applicants seeking FDA approval via ANDA No. 217449Search in Eureka ↗
Co-DefendantAlvogen Pb Research & Development, LLCCompanySearch in Eureka ↗
Plaintiff counselCameron Paul ClarkAttorneyCounsel for Shionogi, Inc.Search in Eureka ↗
Plaintiff counselJack B. BlumenfeldAttorneyCounsel for Shionogi, Inc.Search in Eureka ↗
Plaintiff counselKaren JacobsAttorneyCounsel for Shionogi, Inc.Search in Eureka ↗
Plaintiff law firmMorris, Nichols, Arsht & Tunnell LLPLaw FirmRepresenting Shionogi, Inc.Search in Eureka ↗
Defendant counselEdward M. MathiasAttorneyCounsel for NORWICH PHARMACEUTICALS, Inc.Search in Eureka ↗
Defendant counselEmily DiBenedettoAttorneyCounsel for NORWICH PHARMACEUTICALS, Inc.Search in Eureka ↗
Defendant counselJason T. MurataAttorneyCounsel for NORWICH PHARMACEUTICALS, Inc.Search in Eureka ↗
Defendant counselKaren Elizabeth KellerAttorneyCounsel for NORWICH PHARMACEUTICALS, Inc.Search in Eureka ↗
Defendant counselNathan Roger HoeschenAttorneyCounsel for NORWICH PHARMACEUTICALS, Inc.Search in Eureka ↗
Defendant counselRoss E. BlauAttorneyCounsel for NORWICH PHARMACEUTICALS, Inc.Search in Eureka ↗
Defendant law firmShaw Keller LLPLaw FirmRepresenting NORWICH PHARMACEUTICALS, Inc.Search in Eureka ↗
Presiding judgeJudge Maryellen NoreikaJudgeDelaware District CourtSearch in Eureka ↗
Official verdict

Official order — verbatim text

“The Parties in the above-captioned Actions, have agreed to terms and conditions representing a negotiated settlement and have set forth those terms and conditions in a Settlement Agreement (the “Settlement Agreement”). Now the Parties, by their respective undersigned attorneys, hereby stipulate and consent to entry of a Stipulation and Order in these Actions as follows: IT IS this ___ day of _________, 2025: ORDERED, ADJUDGED AND DECREED as follows: 1. This District Court has jurisdiction over the subject matter of the above Actions and has personal jurisdiction over the parties. 2. As used in this Stipulation and Order, (i) the term “Norwich Product” shall mean the generic 40 milligram and 80 milligram generic baloxovir marboxil tablet drug products sold, offered for sale or distributed pursuant to Abbreviated New Drug Application No. 217449 in the form, subject to amendments as FDA might require, as tentatively approved by FDA on September 13, 2023, and does not include any new or different dosage form, route of Case 1:23-cv-00161-MN Document 123 Filed 07/23/25 Page 1 of 4 PageID #: 2551 2 administration, dosage strength, or active ingredient(s); and (ii) the term “Affiliate” shall mean, with respect to a Party, any entity or person that, directly or indirectly through one or more intermediaries, controls, is controlled by, or is under common control with such Party. For purposes of this definition, “control” means (a) ownership, directly or through one or more intermediaries, of (i) fifty percent (50%) or more of the shares of stock entitled to vote for the election of directors, in the case of a corporation, or (ii) fifty percent (50%) or more of the equity interests in the case of any other type of legal entity or status as a general partner in any partnership, or (b) any other arrangement whereby an entity or person has the right to elect a majority of the board of directors or equivalent governing body of a corporation or other entity or the right to direct the management and policies of a corporation or other entity. 3. Except as specifically authorized pursuant to the Settlement Agreement, Defendants and any of their Affiliates, successors and assigns, and all other persons in active concert or participation with any of them, are enjoined from manufacturing, using, offering to sell, or selling within the United States, or importing into the United States, the Norwich Product until the earlier of (a) the Entry Date as defined in the Settlement Agreement, or (b) the expiration date of the latest-expiring of United States Patent Numbers 8,927,710, 8,987,441, 9,815,835, 10,392,406, 10,633,397, 10,759,814, 11,261,198, 11,306,106 and 12,064,438 (the “Asserted Patents”), including any extensions or exclusivities and pediatric exclusivities. 4. For purposes of these Actions with respect to the Norwich Product only, Defendants admit that, unless and until the Asserted Patents are held invalid or unenforceable and in the absence of a license or other authorization from Plaintiffs, (a) the submission of ANDA No. 217449 to the FDA for the purpose of obtaining regulatory approval to engage in the commercial manufacture, use, and/or sale of the Norwich Product within the United States Case 1:23-cv-00161-MN Document 123 Filed 07/23/25 Page 2 of 4 PageID #: 2552 3 before the expiration of the Asserted Patents was an act of infringement of the Asserted Patents under 35 U.S.C. § 271(e)(2)(A), and (b) the Asserted Patents would be infringed by the unlicensed manufacture, use, sale, offer to sell, importation or distribution of the Norwich Product in or for the United States. Nothing set forth herein shall prevent Defendants from maintaining their Paragraph IV certifications to the Asserted Patents pursuant to 21 U.S.C. § 355(j)(2)(A)(vii)(IV) or pursuant to 21 C.F.R. § 314.94(a)(12). Each Party acknowledges and agrees that the 30- month stay under 21 U.S.C. § 355(j)(5)(B)(iii) with respect to approval of Norwich’s ANDA No. 217449 for the Norwich Product is hereby terminated. 5. This Stipulation and Order is without prejudice to any claim, defense, or counterclaim in any possible future action regarding a product other than the Norwich Product. 6. Compliance with this Stipulation and Order may be enforced by Plaintiffs and Defendants, and their successors in interest, or assigns, as permitted by the terms of the Settlement Agreement. 7. This District Court retains jurisdiction over Plaintiffs and Defendants to enforce or supervise performance under this Stipulation and Order. 8. All other claims, counterclaims, affirmative defenses and demands in these actions are hereby dismissed without prejudice and without costs, disbursements or attorneys’ fees to any party. 9. The Clerk of the Court is directed to enter this Stipulation and Order forthwith in these Actions.”
Source: PACER Docket, Case 1:23-cv-00161, Delaware District Court

The stipulated order is notable for the breadth of Norwich’s admission: it concedes infringement of all eight asserted patents under § 271(e)(2)(A) without any carve-outs or invalidity findings. The injunction is keyed to the ‘latest-expiring’ asserted patent, meaning the full portfolio must run its course before generic launch is permitted absent the Entry Date trigger. The without-prejudice dismissal of all other claims preserves both parties’ rights in any future dispute over different products or dosage forms, while the express retention of Paragraph IV certifications keeps patent validity contestable.

PACER case 1:23-cv-00161 · Public docket record Explore in Eureka ↗
Patent at issue

US8927710 and 7 further patents — baloxavir marboxil compositions, processes & forms

Publication No.US10392406B2
Application No.US15/569191
Patent details
ProductBaloxavir marboxil tablet compositions — substituted polycyclic pyridone derivatives
Cited in actionFebruary 13, 2023

Publication No.US10633397B2
Application No.US16/221733
Patent details
ProductBaloxavir marboxil compositions and prodrugs — polycyclic pyridone derivatives
Cited in actionFebruary 13, 2023

Publication No.US10759814B2
Application No.US16/323580
Patent details
ProductBaloxavir marboxil tablet compositions — substituted polycyclic pyridone derivatives
Cited in actionFebruary 13, 2023

Publication No.US11261198B2
Application No.US16/310897
Patent details
ProductBaloxavir marboxil crystalline forms and manufacturing processes
Cited in actionFebruary 13, 2023

Publication No.US8987441B2
Application No.US13/824723
Patent details
ProductBaloxavir marboxil core compositions — substituted polycyclic pyridone derivatives
Cited in actionFebruary 13, 2023

Publication No.US9815835B2
Application No.US15/252791
Patent details
ProductBaloxavir marboxil crystalline polymorph and process
Cited in actionFebruary 13, 2023

Publication No.US11306106B2
Application No.US16/937877
Patent details
ProductBaloxavir marboxil prodrug formulations — carbamoylpyridone derivatives
Cited in actionFebruary 13, 2023

Publication No.US8927710B2
Application No.US13/378334
Patent details
ProductBaloxavir marboxil foundational composition patents
Cited in actionFebruary 13, 2023

The eight asserted patents collectively define the intellectual property fortress around baloxavir marboxil, the active ingredient in Xofluza. The portfolio spans multiple technical layers: core composition claims covering the substituted polycyclic carbamoylpyridone scaffold (US8927710, US8987441), prodrug design protecting the marboxil ester form (US9815835, US11306106), crystalline form claims (US10759814), and formulation and process patents (US10392406, US10633397, US11261198). Application dates range from 2011 to 2020, creating a staggered expiry ladder characteristic of life-cycle management strategies in branded pharmaceutical portfolios.

Baloxavir marboxil operates by a distinct mechanism — cap-dependent endonuclease inhibition — differentiating it from neuraminidase inhibitors like oseltamivir. This mechanistic novelty supported a broad patenting strategy. For any generic or biosimilar developer operating in the influenza antiviral space, this eight-patent estate represents a high-cost invalidation challenge: each patent must be independently addressed in ANDA Paragraph IV certifications, IPR petitions, or litigation. The admission of infringement by Norwich further reinforces the enforceability baseline of the entire portfolio.

Patent data sourced from USPTO via PatSnap Eureka patent database Search patent records in Eureka ↗
Freedom to operate

Should you run an FTO against Xofluza’s baloxavir marboxil patent estate?

Any company developing generic baloxavir marboxil products, cap-dependent endonuclease inhibitor antivirals, or structurally related polycyclic pyridone compounds should treat an FTO analysis as mandatory before filing an ANDA or advancing a candidate into clinical development. The eight-patent portfolio spans compositions, prodrugs, crystal forms, and processes — meaning a narrow design-around on one claim family may not clear the others. Norwich’s infringement admission across all eight patents in this case illustrates the breadth of the risk.

PatSnap Eureka’s FTO Search Agent can map each of the eight asserted patents against your compound structure, synthesis route, and formulation approach simultaneously — identifying which claim families pose the highest risk and which are most vulnerable to prior art challenges. Eureka’s claim-level analysis and patent expiry tracking give R&D and IP teams a structured view of the Xofluza estate before committing to an ANDA filing strategy.

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Related litigation

Similar Hatch-Waxman ANDA cases: influenza antiviral patents in Delaware

Cases involving Hatch-Waxman ANDA infringement actions over influenza antiviral patents litigated in the District of Delaware.

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Strategic implications

What this case signals for the influenza antiviral IP landscape

The Xofluza settlement illustrates how layered patent portfolios can extend exclusivity well beyond any single patent’s expiry.

Eight-patent stacking is a deliberate Hatch-Waxman shield

Asserting eight patents simultaneously — covering composition, crystal forms, prodrug structure, and manufacturing — forces any ANDA challenger to invalidate or design around every layer. Norwich’s infringement admission across all eight patents confirms the strategy worked. Generic developers should budget for multi-patent FTO analysis before filing any ANDA against Xofluza or structurally similar cap-dependent endonuclease inhibitors.

Confidential entry dates create opacity for follow-on generic filers

When lead ANDA filers settle with a private Entry Date, subsequent generics gain no public signal on competitive timing. This creates uncertainty for any company in the pipeline behind Norwich. Monitoring settlement filings and FDA tentative approval dates for ANDA No. 217449 is now essential intelligence for Xofluza competitors seeking to estimate market entry windows.

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Frequently asked questions

Shionogi v NORWICH — key questions answered

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Monitor the Xofluza patent estate and ANDA activity in real time

Use PatSnap Eureka to track expiry dates, IPR filings, and new ANDA challenges across all eight baloxavir marboxil patents. Set automated alerts on Norwich’s Paragraph IV certifications and any follow-on generic activity to stay ahead of market entry risk.

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