{"id":34797,"date":"2026-02-09T22:23:11","date_gmt":"2026-02-10T03:23:11","guid":{"rendered":"https:\/\/www.drugpatentwatch.com\/blog\/?p=34797"},"modified":"2026-02-10T22:08:31","modified_gmt":"2026-02-11T03:08:31","slug":"uncovering-the-success-patterns-in-modern-paragraph-iv-litigation","status":"publish","type":"post","link":"https:\/\/www.drugpatentwatch.com\/blog\/uncovering-the-success-patterns-in-modern-paragraph-iv-litigation\/","title":{"rendered":"Uncovering the Success Patterns in Modern Paragraph IV Litigation"},"content":{"rendered":"\n

Introduction: The High-Stakes Chess Match of Paragraph IV Litigation<\/strong><\/h2>\n\n\n\n
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In the world of pharmaceuticals, few events are as consequential as a Paragraph IV patent challenge. It is more than a legal proceeding; it is a strategic inflection point that can erase billions of dollars from a brand\u2019s market capitalization or create a multi-hundred-million-dollar opportunity for a generic challenger overnight. This is the high-stakes, high-reward chess match created by the Drug Price Competition and Patent Term Restoration Act of 1984, more commonly known as the Hatch-Waxman Act.1<\/sup><\/p>\n\n\n\n

Forty years ago, Congress struck a delicate and now-famous bargain. It sought to balance two competing, yet equally vital, public interests: incentivizing the monumental risk and investment required for pharmaceutical innovation, while simultaneously ensuring broad public access to affordable medicines through a robust generic market.1<\/sup> Before this landmark legislation, the generic drug industry was a pale shadow of its current self. Generic manufacturers faced the Herculean task of conducting their own expensive and time-consuming clinical trials to prove safety and efficacy, a barrier that kept the market share of generics to a mere 19% of all prescriptions.1<\/sup><\/p>\n\n\n\n

The Hatch-Waxman Act shattered this paradigm. It created the Abbreviated New Drug Application (ANDA) pathway, a streamlined process allowing generic companies to rely on the innovator\u2019s original safety and efficacy data.4<\/sup> This single change transformed the industry, and today, generic drugs account for over 90% of all prescriptions filled in the United States, saving the healthcare system hundreds of billions of dollars annually.6<\/sup><\/p>\n\n\n\n

At the heart of this system lies the Paragraph IV certification\u2014a declaration by a generic applicant that a brand\u2019s patent, listed in the FDA\u2019s \u201cOrange Book,\u201d is either invalid, unenforceable, or will not be infringed by their proposed product.5<\/sup> This is not a polite request; it is an audacious, calculated act of legal warfare. The filing of a Paragraph IV certification is deemed an artificial act of infringement, a legal trigger that allows the brand manufacturer to sue before the generic product even hits the market.8<\/sup><\/p>\n\n\n\n

The stakes are astronomical. For the brand company, a loss in Paragraph IV litigation means the premature collapse of a monopoly that protects billions in annual revenue.10<\/sup> For the generic challenger, a victory\u2014or even a favorable settlement\u2014can unlock the coveted 180-day period of market exclusivity granted to the first successful filer. This six-month window represents a temporary duopoly with the brand, a period of immense profitability that can define the commercial success of the generic product.13<\/sup><\/p>\n\n\n\n

But how are these victories won? What separates a successful challenge from a costly failure? The landscape of Paragraph IV litigation has evolved dramatically from a straightforward legal mechanism into a complex arena of sophisticated corporate strategy. Success is no longer just about finding a single piece of prior art; it\u2019s about understanding the subtle interplay of legal precedent, scientific evidence, regulatory nuance, and strategic timing.<\/p>\n\n\n\n

This report moves beyond a simple recitation of case law to provide a deep, analytical playbook for the modern Paragraph IV battlefield. We will dissect the statistical trends shaping the litigation landscape, revealing where the battles are fought and what “winning” truly means in a world where a courtroom loss can still be a market victory. We will deconstruct the most potent legal arguments\u2014from the workhorse of obviousness to the surgical precision of anticipation and the newly supercharged defenses of written description and enablement. Through in-depth analysis of recent, high-impact cases from 2022 through 2025, we will illuminate the specific patterns that lead to success.<\/p>\n\n\n\n

Finally, and most critically, we will translate these courtroom patterns into boardroom strategy. This report is designed for the skeptical, data-driven executive, attorney, and investor who demands actionable intelligence. We will explore how to leverage competitive intelligence platforms like DrugPatentWatch<\/strong> to identify vulnerabilities, select targets, and build resilient patent portfolios. Whether you are a generic challenger planning your next move or a brand manufacturer fortifying your defenses, this report provides the critical insights needed to navigate and win in the high-stakes world of Paragraph IV litigation.<\/p>\n\n\n\n

The Modern Paragraph IV Battlefield: A Statistical and Strategic Overview<\/strong><\/h2>\n\n\n\n

To understand the patterns of success in Paragraph IV challenges, we must first map the terrain. The modern litigation landscape is not a random field of skirmishes; it is a highly specialized arena shaped by powerful statistical trends, concentrated legal expertise, and a strategic calculus that often prioritizes market entry over a definitive legal victory. The data reveals a story of increasing sophistication, where both challengers and defenders are playing a more calculated, high-stakes game.<\/p>\n\n\n\n

Litigation Velocity and Venue: Where the Battles Are Fought<\/strong><\/h3>\n\n\n\n

The raw number of ANDA litigations filed has seen a notable shift over the past decade. After peaking in 2014 and 2015, case filings have generally trended downward.16<\/sup> This decline, which saw a 36% drop between 2017 and 2021, does not signal a retreat from patent challenges.17<\/sup> Instead, it reflects a maturing and consolidating generic industry that is becoming more selective, often focusing on more complex and profitable drug products rather than pursuing every possible target.16<\/sup> The recent data shows a slight rebound, with 312 complaints filed in 2024, up from 259 in 2023, indicating that the strategic importance of these challenges remains as high as ever.18<\/sup><\/p>\n\n\n\n

What is most striking is not the number of cases, but where they are filed. The world of Hatch-Waxman litigation is geographically concentrated to an extraordinary degree. The U.S. District Courts for the District of Delaware and the District of New Jersey are the undisputed epicenters, consistently handling the overwhelming majority of all ANDA cases filed nationwide.16<\/sup> In 2022, for instance, Delaware alone accounted for 63% of all ANDA patent cases.20<\/sup> This concentration is a direct result of corporate geography; a vast number of pharmaceutical companies are incorporated in Delaware or headquartered in New Jersey, making these districts the natural venues for litigation.18<\/sup><\/p>\n\n\n\n

This geographical focus has created a powerful feedback loop. A small cadre of judges within these two districts has developed deep and unparalleled expertise in the unique procedural and substantive complexities of pharmaceutical patent law. Judges like those in the District of Delaware are not just hearing their first or second Hatch-Waxman case; they are managing dockets with dozens of them.16<\/sup> This experience has led to the development of highly specialized local patent rules and case management procedures designed to handle these massive, multi-party disputes efficiently.21<\/sup><\/p>\n\n\n\n

For the players involved, this concentration represents a flight to quality and predictability. Generic companies, investing millions in a high-risk challenge, want their complex scientific arguments heard by a judiciary that understands the nuances of polymorph chemistry or antibody function. They cannot afford to have a case bogged down in a court unfamiliar with the territory. Likewise, brand companies benefit from a predictable process and judges who can efficiently manage discovery and trial schedules.<\/p>\n\n\n\n

The strategic implication is clear: the Paragraph IV battlefield is not just any court. It is a specialized arena where challengers must bring their A-game. The increasing trend of judges in these districts imposing strict limits on the number of asserted claims and prior art references early in the case\u2014a practice championed by judges like Judge Connolly in Delaware\u2014means that both sides must be prepared with their strongest arguments from day one.16<\/sup> The days of a scattergun approach are over. Today\u2019s challengers are more focused, better funded, and are entering a sophisticated legal environment where only the most well-crafted arguments will survive. For brand companies, this means every challenge must be treated as a serious threat from a well-prepared adversary.<\/p>\n\n\n\n

Deconstructing “Success”: Why a Courtroom Loss Can Still Be a Market Win<\/strong><\/h3>\n\n\n\n

If you were to look only at the final judgments from district court trials, you might conclude that generic challengers are fighting a losing battle. A 2024 analysis of terminated Hatch-Waxman cases found that innovator companies prevailed on the merits 20% of the time, whereas generic companies won a mere 2% of the time.18<\/sup> These statistics, however, are profoundly misleading because they ignore the single most important factor in Paragraph IV litigation: settlement.<\/p>\n\n\n\n

The vast majority of ANDA disputes never reach a final verdict. They are resolved through settlement agreements negotiated in the shadow of the courthouse.23<\/sup> When these settlements and other outcomes are factored in, the picture of “success” flips dramatically. One comprehensive analysis found that while generic firms win only about 48% of Paragraph IV trials that go to a final decision, their overall success rate\u2014which includes favorable settlements and cases where the brand drops the suit\u2014soars to a staggering 76%.26<\/sup><\/p>\n\n\n\n

How can this be? The answer lies in understanding the true strategic objective of the first-to-file generic challenger. The ultimate prize is not necessarily a judicial declaration that the brand\u2019s patent is invalid. The ultimate prize is securing early market entry to capitalize on the 180-day market exclusivity period. This six-month head start, during which the FDA will not approve any other generic versions of the drug, is the most profitable phase of a generic product’s lifecycle.14<\/sup> During this period, the first generic can price its product only moderately below the brand\u2014often just a 15-25% discount\u2014and capture significant market share, generating hundreds of millions of dollars in revenue on a blockbuster drug before multi-player competition drives prices down by 80-90% or more.6<\/sup><\/p>\n\n\n\n

This powerful financial incentive fundamentally redefines “winning.” The Paragraph IV litigation itself becomes a tool of leverage. By filing a credible challenge, the generic company creates a significant risk for the brand manufacturer. While the brand may be confident in its patents, there is always a non-zero chance\u2014the “tail risk”\u2014that a court will find them invalid, leading to a catastrophic and premature loss of all revenue. Faced with this possibility, the brand is often willing to come to the negotiating table.<\/p>\n\n\n\n

A common settlement outcome is a license agreement that allows the generic to enter the market on a specific date, often months or even years before the last patent is set to expire. For the generic company, this is a massive financial victory. They have avoided the immense cost and uncertainty of a full trial and secured a guaranteed entry date that allows them to monetize their 180-day exclusivity. For the brand company, it is a calculated business decision. They trade a few years of monopoly at the tail end of their patent life to eliminate the risk of losing everything immediately.<\/p>\n\n\n\n

Therefore, to analyze success patterns, we must look beyond the win-loss columns of court dockets. The key metric of success for a generic challenger is the delta between the patent expiry date and the negotiated market entry date. The legal arguments and litigation tactics are the means to that end. They are the weapons used to create enough pressure and uncertainty to force a favorable business outcome. This understanding is critical: the true battle is for market share and revenue, and the courtroom is simply the primary venue where that battle is waged.<\/p>\n\n\n\n

The Challenger’s Playbook: Deconstructing Winning Legal Arguments<\/strong><\/h2>\n\n\n\n

While the ultimate goal of a Paragraph IV challenge may be a strategic settlement, the path to that settlement is paved with strong legal arguments. A generic company cannot create leverage out of thin air; it must present a credible threat to the validity or enforceability of the brand’s patents. In recent years, a clear hierarchy of arguments has emerged, with challengers finding consistent success by focusing on specific, well-defined lines of attack. The modern challenger’s playbook is less about a single silver bullet and more about a sophisticated, multi-pronged assault on the weakest points of a brand’s patent fortress.<\/p>\n\n\n\n

The Obviousness Gambit (35 U.S.C. \u00a7 103): The Workhorse of Invalidation<\/strong><\/h3>\n\n\n\n

Of all the tools available to a patent challenger, the most versatile and consistently effective is the argument of obviousness. Data from litigated ANDA cases shows that when patents are invalidated at trial, obviousness is the most frequent reason.18<\/sup> This is because the legal standard for obviousness, particularly after the Supreme Court’s landmark decision in<\/p>\n\n\n\n

KSR International Co. v. Teleflex Inc.<\/em>, provides a flexible framework for attacking the incremental innovations that often make up the bulk of a drug’s patent portfolio.27<\/sup><\/p>\n\n\n\n

The KSR<\/em> decision fundamentally shifted the landscape by rejecting the rigid “teaching, suggestion, or motivation” (TSM) test that had previously dominated patent law.28<\/sup> Before<\/p>\n\n\n\n

KSR<\/em>, a challenger often had to find a prior art reference that explicitly suggested combining known elements. Post-KSR<\/em>, the inquiry is more expansive and grounded in common sense. The central question is whether a Person of Ordinary Skill in the Art (a “POSITA”), faced with a known problem, would have been motivated to combine known elements from the prior art to arrive at the claimed invention with a “reasonable expectation of success”.30<\/sup> This has opened the door to several powerful patterns of attack.<\/p>\n\n\n\n

Pattern 1: Attacking “Weaker” Secondary Patents<\/strong><\/h4>\n\n\n\n

The strongest patent in a brand’s portfolio is almost always the initial composition-of-matter patent covering the active pharmaceutical ingredient (API) itself. These patents are difficult to overcome. Consequently, savvy generic challengers rarely attack them head-on. Instead, they focus their firepower on the so-called “secondary” patents that brands file to extend their monopoly long after the core compound patent expires.33<\/sup> These patents often cover new formulations (e.g., extended-release versions), specific crystalline forms (polymorphs), or new methods of use and dosing regimens. While commercially valuable, these patents are often legally more vulnerable to an obviousness challenge.<\/p>\n\n\n\n

A prime example of this strategy is seen in ImmunoGen, Inc. v. Stewart<\/em> (2025). The patent at issue did not claim a new molecule, but a specific dosing regimen for an antibody-drug conjugate, calculated based on a patient’s “adjusted ideal body weight” (AIBW).36<\/sup> The challenger successfully argued that this was obvious. The court found that ocular toxicity was a known side effect of similar drugs, that mitigating side effects by adjusting dosage was a standard technique, and that AIBW was already a known method for dosing. Combining these known elements to solve a known problem was a predictable variation that a POSITA would have been motivated to try. The patent was invalidated.37<\/sup> This pattern is repeated across countless cases: a known drug, a known problem (e.g., side effects, poor stability), and a known solution from the pharmaceutical toolkit often equals obviousness.<\/p>\n\n\n\n

Pattern 2: The “Obvious to Try” with a Reasonable Expectation of Success<\/strong><\/h4>\n\n\n\n

The KSR<\/em> framework also breathed new life into the “obvious to try” argument. If the prior art reveals a known problem and identifies a finite number of predictable, potential solutions, it is likely obvious to pursue one of them. This is particularly potent in pharmaceutical cases where researchers are often optimizing known variables.<\/p>\n\n\n\n

The litigation surrounding Johnson & Johnson’s blockbuster prostate cancer drug, Zytiga\u00ae (abiraterone acetate), serves as a textbook case. The key secondary patent did not cover the drug itself, but its co-administration with the common steroid prednisone.38<\/sup> The challengers, led by Argentum Pharmaceuticals, argued that this combination was obvious. The Patent Trial and Appeal Board (PTAB) and the Federal Circuit agreed. The evidence showed that at the time of the invention, both abiraterone and prednisone were known to be effective in treating prostate cancer, and that combining anti-cancer agents with steroids to manage side effects was a standard and well-established practice in oncology.40<\/sup> A POSITA, therefore, would have been highly motivated to try the combination with a very reasonable expectation that it would work. The patent was invalidated, opening the door to generic competition and causing drug prices to plummet by as much as 98%.39<\/sup><\/p>\n\n\n\n

The Brand’s Defense: The Power of “Unexpected Results”<\/strong><\/h4>\n\n\n\n

The most powerful rebuttal to a prima facie case of obviousness is evidence of “unexpected results.” A brand can save an otherwise obvious-looking patent by demonstrating that the invention produced a surprising or superior outcome that a POSITA would not have predicted.42<\/sup> This is a high bar to clear. The brand must show not just that the results were good, but that they were unexpectedly good compared to the closest prior art.43<\/sup><\/p>\n\n\n\n

The credibility of this argument often hinges on the quality of the evidence and the narrative presented at trial. In Amgen Inc. v. Sandoz Inc.<\/em>, the court upheld a patent on a stereometrically pure version of apremilast because the inventor provided credible testimony and data showing it had a 20-fold higher potency than the racemic mixture, whereas a POSITA would have only expected a 2-fold increase.44<\/sup> In contrast, in<\/p>\n\n\n\n

Taiho Pharm. Co. v. Eugia Pharma Specialities Ltd.<\/em>, the court rejected an unexpected results argument for a twice-daily dosing regimen because the inventor’s testimony was vague, describing the results as “mystical” without a sound scientific explanation.44<\/sup><\/p>\n\n\n\n

The battle over obviousness is thus frequently a battle of competing narratives fought through expert witnesses and scientific data. The generic challenger aims to frame the invention as a logical, predictable, “common-sense” next step. The brand defender must counter with a compelling story of a surprising, counter-intuitive breakthrough. The side with the more credible and scientifically rigorous evidence usually prevails.<\/p>\n\n\n\n

Anticipation (35 U.S.C. \u00a7 102): The High-Stakes Surgical Strike<\/strong><\/h3>\n\n\n\n

If obviousness is the workhorse of patent invalidation, anticipation is the surgical strike. The legal standard for anticipation is exacting and unforgiving: a challenger must prove that a single<\/em> prior art reference discloses, either expressly or inherently, each and every element<\/em> of the claimed invention, arranged as in the claim.45<\/sup> There is no room for combining references or using “common sense” to fill in gaps. Because of this high bar, successful anticipation arguments are rarer than obviousness findings, but when they succeed, they are decisive.<\/p>\n\n\n\n

The core of an anticipation challenge is a microscopic focus on the “four corners” of a single prior art document. The goal is to demonstrate that the identical invention has already been described in its entirety. This makes the argument less about narrative and more about a direct, one-to-one mapping of claim limitations to the prior art disclosure.<\/p>\n\n\n\n

A crucial tool in this context, especially for pharmaceutical patents, is the doctrine of inherent anticipation<\/strong>. This doctrine applies when a prior art reference describes a process or composition that necessarily<\/em> results in the claimed invention, even if the authors of that reference did not recognize or appreciate that result at the time.46<\/sup> The classic example, established in<\/p>\n\n\n\n

Schering Corp. v. Geneva Pharmaceuticals<\/em>, is a situation where a previously known drug, when metabolized in the human body, necessarily produces a specific metabolite. A later patent claiming that metabolite as a new compound would be inherently anticipated by the prior art disclosure of the parent drug, because administering the parent drug would have been producing the metabolite all along.48<\/sup><\/p>\n\n\n\n

While no major, recent Paragraph IV victories have turned solely on a novel application of inherent anticipation, the principle remains a constant threat. For example, if a prior art reference describes a method for synthesizing a compound that, due to the laws of chemistry, necessarily produces a specific, previously unappreciated polymorph, a later patent claiming that polymorph could be inherently anticipated.<\/p>\n\n\n\n

The strategic value of an anticipation argument lies in its binary nature. Unlike the subjective balancing of factors in an obviousness analysis, anticipation is closer to a yes\/no question. This can make it a powerful argument at summary judgment, potentially ending a case before the immense expense of a full trial. For a generic challenger, unearthing a single, “killer” prior art reference through deep and meticulous research can be the most efficient path to victory. It is a high-risk, high-reward strategy that requires deep scientific expertise and exhaustive prior art searching, but its potential to deliver a swift, decisive victory makes it an essential part of the modern challenger’s playbook.<\/p>\n\n\n\n

The Post-Amgen Gauntlet (\u00a7 112): Winning with Written Description and Enablement<\/strong><\/h3>\n\n\n\n

For decades, invalidity arguments based on 35 U.S.C. \u00a7 112\u2014specifically the written description and enablement requirements\u2014were often viewed as secondary, “make-weight” arguments in Paragraph IV litigation. That era is definitively over. The U.S. Supreme Court’s unanimous 2023 decision in Amgen v. Sanofi<\/em> has elevated \u00a7 112 from a supporting player to a headline act, providing generic challengers with a powerful new weapon, particularly against patents covering biologics and other complex inventions.<\/p>\n\n\n\n

The law, under \u00a7 112, imposes a fundamental bargain: in exchange for a temporary monopoly, an inventor must provide a patent specification that fully discloses the invention to the public. This disclosure has two key components:<\/p>\n\n\n\n

    \n
  1. Written Description:<\/strong> The specification must demonstrate that the inventor was in “possession” of the full scope of what is being claimed at the time the application was filed.50<\/sup><\/li>\n\n\n\n
  2. Enablement:<\/strong> The specification must teach a POSITA how to make and use the full scope of the claimed invention without “undue experimentation”.53<\/sup><\/li>\n<\/ol>\n\n\n\n

    The Amgen<\/em> decision centered on the enablement requirement. Amgen held patents claiming a vast genus of antibodies defined by their function: binding to the PCSK9 protein and blocking it from binding to LDL receptors. Amgen’s patents provided examples of a few specific antibodies that performed this function and a “roadmap” for scientists to discover others. The Supreme Court declared this was not enough. It held that if you claim an entire class of compounds by their function, you must enable a POSITA to make and use the entire class<\/em>.53<\/sup> Providing a few examples and instructions for a trial-and-error research project does not satisfy the enablement requirement for millions of potential antibody candidates.53<\/sup><\/p>\n\n\n\n

    This ruling has sent shockwaves through the pharmaceutical industry and created a fertile new ground for Paragraph IV challenges. The new pattern of success is clear: attack overly broad claims that attempt to monopolize a functional result rather than a specific, well-defined structure.<\/p>\n\n\n\n

    We are already seeing the impact of this heightened scrutiny in the lower courts. In Biogen International GmbH v. Mylan Pharmaceuticals Inc.<\/em>, a district court invalidated a key patent for Biogen’s blockbuster multiple sclerosis drug, Tecfidera\u00ae. The patent claimed a method of treating MS with a specific 480 mg\/day dose of dimethyl fumarate (DMF). Mylan successfully argued that the patent failed the written description requirement.56<\/sup> The court found that the patent’s specification was overly broad, discussing a wide range of possible doses for general neurological diseases, and did not contain language that would lead a POSITA to specifically identify the 480 mg\/day dose as the effective treatment for MS. The specification did not demonstrate that the inventors were in “possession” of that specific invention at the time of filing.56<\/sup><\/p>\n\n\n\n

    Similarly, in the 2025 Federal Circuit case In re Xencor, Inc.<\/em>, the court invalidated claims for lack of written description support for a broad preamble claiming a “method of treating a patient”.36<\/sup> This demonstrates the court’s willingness to apply rigorous \u00a7 112 analysis to all aspects of a claim, not just the core elements.<\/p>\n\n\n\n

    The strategic implications are profound. For brand manufacturers, the game has changed. During patent prosecution, it is no longer sufficient to claim a functional outcome and provide a few examples. To build a resilient, defensible patent, the specification must be rich with structural details, data, and a sufficient number of representative examples to truly support the full scope of the claims. For generic challengers, the post-Amgen<\/em> landscape presents a golden opportunity. Every brand patent with broad, functional claims is now a potential target for a powerful \u00a7 112 invalidity challenge. This defense has become a primary weapon, forcing brands to justify the breadth of their monopoly and creating significant new leverage for generics in both litigation and settlement negotiations.<\/p>\n\n\n\n

    Anatomy of a Victory: In-Depth Case Studies (2022-2025)<\/strong><\/h2>\n\n\n\n

    To truly understand the patterns of success, we must move from analyzing legal doctrines in isolation to seeing how they are deployed in the crucible of actual litigation. The following case studies of recent, high-impact Paragraph IV challenges illustrate how the winning arguments discussed above are applied in practice. They provide a concrete look at the strategies that are succeeding in invalidating patents and accelerating generic market entry.<\/p>\n\n\n\n

    Before diving into the narrative details, the following table provides a high-level summary of key Paragraph IV outcomes from the 2022-2025 period, highlighting the recurring themes of targeting secondary patents and the dominance of obviousness as a winning argument.<\/p>\n\n\n\n

    Table 1: Key Paragraph IV Challenge Outcomes (2022-2025)<\/strong><\/p>\n\n\n\n

    Drug (Tradename\/Generic)<\/td>Brand Company<\/td>Generic Challenger(s)<\/td>Key Patent Type(s) Challenged<\/td>Core Winning Argument<\/td>Outcome\/Date<\/td><\/tr>
    Zytiga\u00ae<\/strong> (abiraterone acetate)<\/td>Janssen<\/td>Argentum, Mylan, Teva, et al.<\/td>Method of Use (Combination Therapy)<\/td>Obviousness<\/td>Patent invalidated by PTAB (2018), affirmed by Fed. Cir. (2019), leading to generic entry 38<\/sup><\/td><\/tr>
    Entyvio\u00ae<\/strong> (vedolizumab)<\/td>Takeda (vs. Roche patent)<\/td>Roche (Patentee)<\/td>Composition of Matter (Glycosylation)<\/td>Obviousness & Insufficiency (Ambiguity)<\/td>Roche’s patent revoked by UK High Court (2019) 58<\/sup><\/td><\/tr>
    Tecfidera\u00ae<\/strong> (dimethyl fumarate)<\/td>Biogen<\/td>Mylan<\/td>Method of Use (Dosing Regimen)<\/td>Lack of Written Description<\/td>Patent invalidated by District Court (2020), affirmed by Fed. Cir. 56<\/sup><\/td><\/tr>
    Vascepa\u00ae<\/strong> (icosapent ethyl)<\/td>Amarin<\/td>Hikma, Dr. Reddy’s<\/td>Method of Use (Cardiovascular Risk)<\/td>Obviousness<\/td>Patents invalidated by District Court (2020), affirmed by Fed. Cir. (2020) 61<\/sup><\/td><\/tr>
    Unnamed Dosing Regimen<\/strong><\/td>ImmunoGen<\/td>(Challenged at PTAB)<\/td>Method of Use (Dosing Regimen)<\/td>Obviousness<\/td>Claims found unpatentable by PTAB, affirmed by District Court and Fed. Cir. (2025) 36<\/sup><\/td><\/tr>
    Unnamed Antibody Treatment<\/strong><\/td>Xencor<\/td>(Challenged at PTAB)<\/td>Method of Use (Broad Preamble)<\/td>Lack of Written Description<\/td>Claims found unpatentable by Fed. Cir. (2025) 36<\/sup><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

    Case Study 1: Zytiga\u00ae (abiraterone acetate) \u2013 The Obvious Combination<\/strong><\/h3>\n\n\n\n

    The battle over Zytiga\u00ae stands as a quintessential example of a successful Paragraph IV challenge against a secondary, method-of-use patent. It perfectly illustrates how challengers can dismantle a blockbuster drug’s patent protection by arguing that the “innovation” was merely the application of standard medical practice.<\/p>\n\n\n\n