Celgene & BMS v. Natco Pharma: Consent Judgment Blocks Generic Azacitidine
Celgene, Bristol-Myers Squibb, and Celgene International sued Indian generic manufacturer Natco Pharma in the Delaware District Court over its ANDA for 200 mg and 300 mg azacitidine tablets, the active ingredient in Onureg®. The parties resolved the dispute in 254 days via a consent judgment imposing an injunction on Natco until expiry of both asserted patents.
Hatch-Waxman Standoff Over Onureg® Ends in Agreed Injunction
Filed on 18 September 2023 before Judge Jennifer L. Hall in the Delaware District Court, this Hatch-Waxman infringement action was brought by Celgene Corp., Celgene International SARL, and Bristol-Myers Squibb Company against Natco Pharma Ltd. The plaintiffs asserted US Patent Nos. 8,846,628 and 11,571,436, which cover oral azacitidine tablet formulations marketed as Onureg®, an FDA-approved treatment for acute myeloid leukaemia. Natco had filed ANDA No. 218696 seeking approval for generic 200 mg and 300 mg azacitidine tablets referencing NDA 214120.
The case closed on 29 May 2024 — 254 days after filing — through a stipulated consent judgment. Under its terms, Natco is enjoined from making, importing, selling, or distributing its ANDA product in the United States until both patents-in-suit expire, unless specifically authorised by plaintiffs. All claims and counterclaims were dismissed with prejudice, with no costs or attorneys’ fees awarded to either party. The FDA is not restricted from approving ANDA 218696, and Natco retains its Paragraph IV certification rights and its safe-harbour research exemption under 35 U.S.C. § 271(e)(1).
A 254-day resolution is notably swift for Hatch-Waxman litigation, suggesting the parties reached commercial alignment well before trial became imminent. The consent judgment’s carve-outs — preserving Natco’s Paragraph IV certification and FDA approval pathway — indicate that Natco has not conceded patent validity and may revisit market entry after patent expiry or through future challenge proceedings. The public record does not disclose whether any royalty, licensing fee, or authorised generic arrangement forms part of the parties’ private agreement.
Filing to Consent Judgment in 254 days
254-day resolution — faster than the median Hatch-Waxman Paragraph IV case in Delaware
Consent judgment entered: what the agreed injunction means for both parties
Consent judgment: an agreed injunction without admission
A consent judgment is a court-ordered resolution negotiated by both parties and entered as a binding judicial order. Here, Natco accepted an injunction blocking U.S. commercialisation of its ANDA product until both patents expire — without the court adjudicating infringement or validity on the merits. All claims were dismissed with prejudice, making the injunction immediately enforceable while preserving Natco’s right to contest patents in future proceedings.
Dismissed with prejudiceBMS and Celgene secure patent exclusivity through expiry
The consent judgment delivers the primary commercial objective for Celgene and Bristol-Myers Squibb: Onureg® faces no generic competition from Natco until both US8846628 and US11571436 expire. The injunction covers all forms of commercial activity — manufacture, import, sale, and distribution — and extends to third-party assistance. Plaintiffs retain enforcement rights and the court retains jurisdiction to resolve any breach, providing a durable enforcement mechanism.
Exclusivity preservedNatco retains ANDA and future challenge rights
Despite accepting the injunction, Natco preserved meaningful optionality. Its ANDA No. 218696 remains intact and the FDA is explicitly permitted to approve it. Natco retains its Paragraph IV certification against both patents, keeping open the possibility of a future IPR or validity challenge. The safe-harbour exemption under § 271(e)(1) is also preserved, allowing continued research activity. No admission of infringement or invalidity appears in the public record.
ANDA and § IV rights retainedOral azacitidine market remains protected — for now
The consent judgment reinforces BMS’s and Celgene’s control over the oral azacitidine segment. Other generic filers seeking to challenge Onureg® will face a strengthened enforcement precedent: plaintiffs have already demonstrated willingness to litigate and secure court-ordered relief. The preserved Paragraph IV and IPR pathways suggest the validity of US8846628 and US11571436 has not been tested in adversarial proceedings, leaving that question open for future challengers.
Generic entry deferredFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Celgene, Corp. | Company | Pharmaceutical innovator — holder of US8846628B2 and US11571436B2 covering Onureg® azacitidineSearch in Eureka ↗ |
| Co-Plaintiff | Bristol‑Myers Squibb Company | Company | Search in Eureka ↗ |
| Co-Plaintiff | Celgene International, SARL | Individual | Search in Eureka ↗ |
| Defendant | Natco Pharma, Ltd. | Company | Indian generic drug manufacturer seeking U.S. market entry via ANDA for azacitidine tabletsSearch in Eureka ↗ |
| Plaintiff counsel | Amy K. Wigmore | Attorney | Counsel for Celgene, Corp.Search in Eureka ↗ |
| Plaintiff counsel | Andrew J. Danford | Attorney | Counsel for Celgene, Corp.Search in Eureka ↗ |
| Plaintiff counsel | Brian E. Farnan | Attorney | Counsel for Celgene, Corp.Search in Eureka ↗ |
| Plaintiff counsel | David Mlaver | Attorney | Counsel for Celgene, Corp.Search in Eureka ↗ |
| Plaintiff counsel | Gerard A. Salvatore | Attorney | Counsel for Celgene, Corp.Search in Eureka ↗ |
| Plaintiff counsel | Heather M. Petruzzi | Attorney | Counsel for Celgene, Corp.Search in Eureka ↗ |
| Plaintiff counsel | Joseph J. Farnan , Jr. | Attorney | Counsel for Celgene, Corp.Search in Eureka ↗ |
| Plaintiff counsel | Li-tsung A. Chen | Attorney | Counsel for Celgene, Corp.Search in Eureka ↗ |
| Plaintiff counsel | Michael J. Farnan | Attorney | Counsel for Celgene, Corp.Search in Eureka ↗ |
| Plaintiff counsel | Nora Q.E. Passamaneck | Attorney | Counsel for Celgene, Corp.Search in Eureka ↗ |
| Plaintiff law firm | Farnan LLP | Law Firm | Representing Celgene, Corp.Search in Eureka ↗ |
| Defendant counsel | Andrew O. Larsen | Attorney | Counsel for Natco Pharma, Ltd.Search in Eureka ↗ |
| Defendant counsel | Christopher J. Sorenson | Attorney | Counsel for Natco Pharma, Ltd.Search in Eureka ↗ |
| Defendant counsel | James S. Green , Jr. | Attorney | Counsel for Natco Pharma, Ltd.Search in Eureka ↗ |
| Defendant counsel | Jason M. Wiener | Attorney | Counsel for Natco Pharma, Ltd.Search in Eureka ↗ |
| Defendant law firm | Seitz Van Ogtrop & Green PA | Law Firm | Representing Natco Pharma, Ltd.Search in Eureka ↗ |
| Presiding judge | Judge Jennifer L. Hall | Judge | Delaware District CourtSearch in Eureka ↗ |
Official order — verbatim text
The consent judgment is a stipulated court order — not a merits adjudication. The court did not rule on infringement or validity; instead, both parties agreed to entry of the injunction and dismissal with prejudice. The ‘with prejudice’ designation bars relitigation of the claims asserted here, but critically does not preclude Natco from challenging patent validity in separate inter partes review proceedings at the USPTO. The carve-outs in paragraphs 8–10 reflect standard Hatch-Waxman settlement practice, preserving the regulatory and research safe harbours that Natco would need to remain in the generic drug development pipeline.
US8846628B2 & US11571436B2 — Oral Azacitidine Tablet Formulations
US8846628B2 (application US12/466213) and US11571436B2 (application US17/533033) both protect oral azacitidine tablet technology underlying Onureg®, an FDA-approved agent for maintenance therapy in acute myeloid leukaemia. Azacitidine was historically delivered only by injection; the patents reflect Celgene’s development of a stable oral formulation suitable for outpatient use. US11571436 issued from a more recent application filed in November 2021, suggesting continuation or improvement claims that may extend the effective exclusivity period beyond the earlier ‘628 patent.
From a competitive standpoint, these two patents collectively form the core IP barrier to generic oral azacitidine entry in the U.S. market. The dual-patent structure is characteristic of Celgene’s and BMS’s approach to lifecycle management in oncology: layering a composition or formulation patent with a later-issued method-of-use or improvement patent to extend the commercially relevant exclusivity window. Any generic manufacturer, biosimilar developer, or combination-therapy company operating in the AML maintenance space should treat these patents as a primary FTO consideration.
Should your team run an FTO against US8846628 and US11571436?
If your R&D pipeline includes oral azacitidine formulations, azacitidine combination products, or any ANDA referencing NDA 214120, a freedom-to-operate analysis against US8846628B2 and US11571436B2 is not optional — it is a prerequisite. The consent judgment confirms that BMS and Celgene will litigate promptly in Delaware, and the dual-patent structure means that designing around one patent may not clear the other. This analysis is equally relevant for companies developing hypomethylating agent alternatives in the AML or MDS space.
PatSnap Eureka’s FTO Search Agent can map your product’s technical features against the claims of both asserted patents simultaneously, identify prior art that may inform a validity challenge, and flag related continuation applications in the Celgene/BMS portfolio that could affect your go-to-market window. Use Eureka to model patent expiry scenarios for both the ‘628 and ‘436 patents and identify whether any claim scope differences create a defensible design-around opportunity.
Run a freedom-to-operate analysis on US11571436B2 to assess your product’s exposure
Run FTO in Eureka →Similar Hatch-Waxman Azacitidine & Oral Oncology Patent Cases
Explore Paragraph IV patent infringement cases involving oral oncology formulations litigated in the Delaware District Court with comparable ANDA enforcement postures.
Related patent case — similar technology
Comparable case in the same technology domain. Patent holder and defendant reached resolution after proceedings.
SettledRelated infringement action — same court
Comparable Onureg®200 mg and 300 mg tablets of azacitidine-adjacent infringement action. Patent enforcement dynamics analysed in depth.
Active · District CourtRelated invalidity challenge — appellate outcome
Combined invalidity and infringement action in the same technology space. Decided after substantive proceedings.
DecidedCelgene, Corp.’s broader IP enforcement history
Celgene, Corp.’s full litigation history covering prior enforcement, licensing activity, and inter partes review proceedings.
Portfolio viewWhat this case signals for the oral oncology Hatch-Waxman IP landscape
A swift consent judgment in a Paragraph IV action over a key AML therapy carries implications beyond the two named parties.
Consent judgments are the dominant Hatch-Waxman exit in Delaware
This case resolved in under nine months without a merits ruling — consistent with a broader pattern of early negotiated exits in Delaware Paragraph IV litigation. For generic filers, the commercial calculus often favours a negotiated delay over the cost and uncertainty of full trial, particularly when the innovator holds a portfolio of layered patents as seen here.
Preserved Paragraph IV certification signals the validity fight is unfinished
Natco’s retention of its § 355(j) Paragraph IV certification is a material carve-out. It signals that Natco — or a third party acquiring its ANDA — could mount a future IPR challenge to US8846628 or US11571436. Companies monitoring the oral azacitidine space should track post-grant proceedings at the USPTO alongside this case.
US11571436’s 2021 priority date creates a vulnerability window worth assessing
US11571436B2 issued from application US17/533033, filed in late 2021. Its relatively recent priority date may expose it to a richer prior art landscape than the earlier ‘628 patent. Generic challengers and FTO analysts should model the expiry differential between the two patents and assess whether the ‘436 patent represents the more vulnerable exclusivity pillar.
BMS portfolio concentration in oral AML therapy elevates competitive monitoring priority
BMS/Celgene’s dual-patent assertion strategy in a single ANDA case reflects a layered enforcement posture typical of blockbuster oncology assets. Companies operating in the AML or myelodysplastic syndrome treatment space — including those developing azacitidine combination regimens — should conduct a full FTO review against the broader Celgene/BMS oral formulation portfolio before advancing clinical-stage programs.
Celgene v Natco — key questions answered
The consent judgment enjoins Natco from making, importing, selling, offering to sell, or distributing its ANDA 218696 azacitidine tablet product in the United States until US8846628 and US11571436 both expire. Natco also cannot assist third parties in infringing these patents in connection with any azacitidine product referencing NDA 214120. All claims were dismissed with prejudice and no costs were awarded to either party.
The plaintiffs asserted US Patent No. 8,846,628 (application US12/466213) and US Patent No. 11,571,436 (application US17/533033). Both patents cover oral azacitidine tablet technology underlying Onureg®, BMS/Celgene’s FDA-approved oral azacitidine product for acute myeloid leukaemia maintenance therapy.
No. Paragraph 9 of the consent judgment explicitly states that nothing therein restricts the FDA from approving ANDA No. 218696 or the Natco ANDA product. However, even if the FDA grants approval, Natco would remain enjoined from commercialising the product in the United States until the patents-in-suit expire, unless Celgene and BMS specifically authorise it.
The consent judgment preserves Natco’s Paragraph IV certification under 21 U.S.C. § 355(j)(2)(A)(vii)(IV) against both patents. While the dismissal with prejudice bars relitigation of the specific claims in this action, it does not on its face preclude a separate inter partes review petition at the USPTO. Whether estoppel or contractual provisions in any private settlement agreement further limit Natco’s challenge options is not disclosed in the public record.
The case closed in 254 days — a relatively fast resolution for a Delaware Paragraph IV action, which typically proceeds on a 24–30 month statutory timeline toward trial. The rapid consent judgment suggests the parties reached a commercial understanding early, possibly reflecting Natco’s assessment of the strength of BMS/Celgene’s dual-patent position, the cost of extended litigation, or undisclosed licensing or authorised-generic arrangements not reflected in the public court record.
Track Generic Entry Risk Across Your Oral Oncology Portfolio
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