Novartis v. Hetero & MSN: Federal Circuit Splits on Entresto® Patents
Novartis AG pursued appellate enforcement of four patents protecting Entresto® (sacubitril/valsartan) against generic challengers Hetero and MSN. The Federal Circuit issued a mixed ruling — affirming some patent claims while reversing others — across a 529-day appeal that reshapes the generic entry landscape for one of cardiology’s top-selling drugs.
Federal Circuit delivers split verdict on Entresto® patent fortress
Novartis AG filed this Federal Circuit appeal on July 31, 2023, challenging a district-level outcome involving four patents — US8101659, US8796331, US9388134, and US8877938 — that collectively protect the composition, formulation, and use of Entresto® (sacubitril and valsartan), the blockbuster heart-failure therapy sold in 24/26 mg, 49/51 mg, and 97/103 mg dosage strengths. The defendants — Hetero USA Inc., Hetero Labs Limited, MSN Pharmaceuticals Inc., MSN Laboratories Private Ltd., and MSN Life Sciences Private Ltd. — are generic pharmaceutical manufacturers whose ANDA filings triggered the underlying infringement action.
The Federal Circuit closed the case on January 10, 2025, issuing a ruling of ‘Affirmed in Part, Reversed in Part,’ with the appeal also dismissed in part on procedural grounds. This mixed outcome means Novartis prevailed on certain patent claims or validity findings while the challengers secured a reversal on others — each side retaining meaningful wins. The partial dismissal suggests some discrete issues were resolved without reaching the merits, consistent with standing, mootness, or jurisdictional deficiencies on those portions.
A 529-day appeal duration is notable and suggests the complexity of multi-patent, multi-defendant ANDA litigation at the Federal Circuit. The split disposition is commercially significant: it leaves Entresto® patent protection intact on some axes while opening partial pathways for generic entry, the precise scope of which depends on which specific claims were affirmed versus reversed — information not fully detailed in the public docket. What remains unknown is whether the reversal pertains to validity, infringement, or claim scope, and whether either party will seek en banc rehearing or certiorari.
Filing to Appeal Dismissed in Part in 529 days
529-day appeal — above the Federal Circuit median for ANDA-related patent disputes
Federal Circuit affirms in part, reverses in part: what the mixed ruling means
What ‘Affirmed in Part, Reversed in Part’ means at the Federal Circuit
A split Federal Circuit disposition means the appellate panel found no reversible error in some lower-court determinations but identified legal or factual error in others. ‘Affirmed’ portions stand as final — the lower court’s findings on those issues are upheld. ‘Reversed’ portions nullify specific lower-court holdings, potentially reopening those claims to different outcomes on remand or granting the appellant relief on those discrete issues.
Partial merits adjudicationNovartis retains protection on affirmed claims — reversal limits full enforcement
Where the Federal Circuit affirmed, Novartis’s patent positions on those claims survive the challenge intact, reinforcing Entresto® exclusivity on those dimensions. However, the reversal on other portions weakens the overall patent fortress, potentially enabling generic manufacturers to design around or enter on the reversed claims. Novartis may seek en banc rehearing or certiorari to contest the reversed portions.
Partial patent survivalHetero and MSN secure a partial win — generic path partially opened
The reversal in favour of the generic challengers (Hetero and MSN group) means at least one lower-court finding against them was incorrect in the Federal Circuit’s assessment. On reversed issues, generic entry may become viable subject to any remand proceedings. Affirmed portions, however, continue to block generic launch on those patent claims, meaning the challengers face a mixed competitive picture rather than a clear path to market.
Partial generic pathwayEntresto® generic timeline remains uncertain after split Federal Circuit ruling
For the broader cardiovascular pharmaceutical sector, a split Federal Circuit ruling on a multi-patent drug franchise signals continued complexity in ANDA patent litigation strategy. The affirmed claims suggest the Entresto® composition and method patents carry substantial weight; the reversal suggests not all claims in a layered patent portfolio will withstand appellate scrutiny. Companies building or challenging similar patent estates should expect granular claim-by-claim analysis at the Federal Circuit level.
Cardiovascular IP risk elevatedFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Novartis, AG | Company | Global pharmaceutical innovator — holder of US8101659, US8796331, US9388134 & US8877938 covering Entresto®Search in Eureka ↗ |
| Defendant | Hetero USA, Inc. | Company | Generic pharmaceutical manufacturers (Hetero USA, Hetero Labs, MSN group) seeking ANDA approval for sacubitril/valsartanSearch in Eureka ↗ |
| Co-Defendant | Hetero Labs Limited | Individual | Search in Eureka ↗ |
| Co-Defendant | Hetero Labs Limited | Individual | Search in Eureka ↗ |
| Co-Defendant | MSN Pharmaceuticals, Inc. | Company | Search in Eureka ↗ |
| Co-Defendant | MSN Laboratories Private, Ltd. | Company | Search in Eureka ↗ |
| Co-Defendant | MSN Life Sciences Private, Ltd. | Company | Search in Eureka ↗ |
| Plaintiff counsel | Christina A. L. Schwarz | Attorney | Counsel for Novartis, AGSearch in Eureka ↗ |
| Plaintiff counsel | Deanne Maynard | Attorney | Counsel for Novartis, AGSearch in Eureka ↗ |
| Plaintiff counsel | Nicholas Nick Kallas | Attorney | Counsel for Novartis, AGSearch in Eureka ↗ |
| Plaintiff counsel | Seth W. Lloyd | Attorney | Counsel for Novartis, AGSearch in Eureka ↗ |
| Plaintiff law firm | Morrison & Foerster LLP | Law Firm | Representing Novartis, AGSearch in Eureka ↗ |
| Plaintiff law firm | Venable LLP | Law Firm | Representing Novartis, AGSearch in Eureka ↗ |
| Defendant counsel | Dmitry Shelhoff | Attorney | Counsel for Hetero USA, Inc.Search in Eureka ↗ |
| Defendant counsel | Edward D. Pergament | Attorney | Counsel for Hetero USA, Inc.Search in Eureka ↗ |
| Defendant counsel | Julia S. Kim | Attorney | Counsel for Hetero USA, Inc.Search in Eureka ↗ |
| Defendant counsel | Kenneth Canfield | Attorney | Counsel for Hetero USA, Inc.Search in Eureka ↗ |
| Defendant law firm | Pergament & Cepeda LLP | Law Firm | Representing Hetero USA, Inc.Search in Eureka ↗ |
| Defendant law firm | Shelhoff Canfield & Chin LLC | Law Firm | Representing Hetero USA, Inc.Search in Eureka ↗ |
| Presiding judge | Judge N/A | Judge | Court of Appeals for the Federal CircuitSearch in Eureka ↗ |
Official order — verbatim text
The Federal Circuit’s disposition — ‘Affirmed in Part, Reversed in Part,’ with the appeal also dismissed in part — reflects a nuanced multi-claim, multi-patent review applying de novo review to claim construction and substantial evidence review to underlying fact findings. The partial dismissal suggests certain issues lacked jurisdiction or were rendered moot. The split outcome is commercially significant: affirmed holdings provide Novartis finality on those claims, while reversed holdings may enable targeted generic entry or require remand proceedings to determine downstream relief.
US8101659, US8796331, US9388134 & US8877938 — Entresto® sacubitril/valsartan patent estate
The four patents in suit — US8101659, US8796331, US9388134, and US8877938 — form the core intellectual property estate protecting Entresto® (sacubitril/valsartan), Novartis’s angiotensin receptor-neprilysin inhibitor (ARNi) therapy approved for heart failure with reduced ejection fraction. The patents span application dates from 2008 through 2014, covering compound compositions, combination formulations, crystalline forms, and therapeutic use methods across three commercially available dose strengths (24/26 mg, 49/51 mg, 97/103 mg). Together they represent a layered ‘patent fortress’ strategy typical of blockbuster cardiovascular drugs.
Entresto® generated over $6 billion in annual global sales at peak, making its patent estate a high-value target for generic ANDA challengers. The multi-patent structure — covering chemistry, formulation, and method-of-use dimensions — is designed to provide overlapping exclusivity extending beyond any single patent’s expiry. The Federal Circuit’s mixed ruling in this case suggests that while some layers of this estate are robust, others are legally vulnerable, creating asymmetric risk for both the innovator and generic competitors seeking to time their market entry.
Should your team run an FTO against the Entresto® patent estate?
Any company developing sacubitril-containing compounds, valsartan combination therapies, ARNi drug products, or fixed-dose cardiovascular tablets should treat this Federal Circuit ruling as a trigger for updated freedom-to-operate analysis. The partial reversal means the patent landscape has shifted — some claim scope is now narrower or invalidated, while affirmed claims retain full enforceability. R&D and regulatory affairs teams advancing ANDA or NDA filings in this space need claim-level FTO clarity, not portfolio-level generalisation.
PatSnap Eureka’s FTO Search Agent can map your compound or formulation against each of the four asserted patents — US8101659, US8796331, US9388134, and US8877938 — identifying which claim families were affirmed (blocking) versus reversed (potentially cleared). The agent cross-references prosecution history, Federal Circuit claim construction rulings, and related continuation filings to give your team an actionable clearance map before your next regulatory submission deadline.
Run a freedom-to-operate analysis on US8101659 to assess your product’s exposure
Run FTO in Eureka →Similar Federal Circuit ANDA patent appeals in cardiovascular pharma
Cases involving Federal Circuit appeals of ANDA infringement actions over cardiovascular compound and formulation patents — comparable technology complexity and multi-defendant structure to Case 23-2221.
What this case signals for the pharmaceutical ANDA IP landscape
A split Federal Circuit ruling on a four-patent drug franchise underscores the limits of layered patent protection and the value of granular appellate strategy.
Multi-patent ANDA estates face claim-by-claim appellate scrutiny
The Federal Circuit’s willingness to reverse discrete portions of a multi-patent ruling signals that patent holders cannot rely on portfolio breadth alone. Each claim family must independently withstand validity and infringement analysis. For Entresto®-class assets, this means structural and method claims may have different appellate durability than formulation claims.
Generic challengers can extract partial wins even against dominant drug patents
Hetero and MSN’s partial reversal demonstrates that even commercially dominant pharmaceutical patents are vulnerable to targeted appellate challenges. Generic companies investing in selective invalidity or non-infringement arguments on specific claim sets — rather than broad challenges — may achieve commercially useful partial wins that create ANDA approval pathways.
Novartis v Hetero — key questions answered
The Federal Circuit issued a mixed ruling in Case 23-2221: ‘Affirmed in Part, Reversed in Part,’ with the appeal also dismissed in part. This means Novartis prevailed on some patent claims while Hetero and MSN secured a reversal on others. The case closed on January 10, 2025, after 529 days on appeal.
Novartis asserted four patents: US8101659, US8796331, US9388134, and US8877938. These patents collectively cover the composition, formulation, crystalline forms, and therapeutic use of Entresto® (sacubitril/valsartan) in its three commercial dose strengths: 24/26 mg, 49/51 mg, and 97/103 mg.
A split Federal Circuit ruling means generic entry is partially blocked and partially potentially enabled. Claims that were affirmed continue to prevent generic launch on those dimensions. Claims that were reversed may open a pathway for Hetero and MSN to seek ANDA approval on those specific aspects, subject to any remand proceedings. The precise commercial impact depends on which specific claims were reversed.
The ‘dismissed in part’ component of the Federal Circuit’s disposition typically indicates that certain issues within the appeal lacked the requisite jurisdiction, were rendered moot by other proceedings, or failed to meet standing requirements. The public record does not detail which specific issues were dismissed, but this is consistent with multi-issue ANDA appeals where some claims resolve before full merits adjudication.
The case demonstrates that even heavily-defended blockbuster drug patent estates — with four overlapping patents covering compound, formulation, and use dimensions — are not fully impervious to Federal Circuit challenge. The split ruling suggests generic challengers can extract partial appellate wins through targeted invalidity or non-infringement arguments, while innovators retain meaningful protection on affirmed claims. This pattern is likely to influence ANDA litigation strategy for other ARNi and combination cardiovascular therapies.
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