Clarifying 'Coverage' vs. 'Disclosure' in Patent Infringement: Novartis v. Natco Pharma Limited

Introduction

The Delhi High Court adjudicated a significant patent infringement case titled Novartis Ag And Another Plaintiffs v. Natco Pharma Limited on January 9, 2023. The dispute centered around Indian Patent IN 276026 ("IN'026"), titled “Novel Pyrimidine Compounds and Compositions as Protein Kinase Inhibitors”, held by Novartis. Novartis alleged that Natco Pharma Ltd. infringed upon this patent by manufacturing and distributing Ceritinib tablets without authorization. Ceritinib, a second-generation ALK inhibitor used in the treatment of ALK-positive advanced non-small cell lung cancer (NSCLC), was specifically claimed in the suit patent. The crux of the case revolved around the validity of the patent, its novelty, inventive step, and whether Natco's actions constituted infringement.

Summary of the Judgment

The Delhi High Court initially granted an ad interim injunction restraining Natco from manufacturing Ceritinib, pending the outcome of patent validity challenges. Subsequently, the Drugs Controller General of India (DCGI) revoked IN'026 on grounds of lacking novelty. Novartis appealed this revocation to the Intellectual Property Appellate Board (IPAB), which stayed the controller's revocation and reinstated the patent, thereby maintaining the injunction against Natco. Natco further contested the IPAB's decision through a pending writ petition. The High Court ultimately upheld the validity of the suit patent, dismissing Natco's contentions that the patent was anticipated or obvious in light of prior art, and reinforced the distinction between "coverage" and "disclosure" in patent law.

Analysis

Precedents Cited

The judgment extensively referenced established legal precedents to substantiate its rulings. Notably, the Supreme Court's decision in Novartis AG v. U.O.I. clarified that "coverage" of a patent does not inherently imply "disclosure". Other significant cases include Roche v. Cipla (2016), which emphasized the importance of claim construction in infringement analyses, and Dr. Reddy's Laboratories v. Eli Lilly, which elaborated on the determination of inventive steps and obviousness. These cases collectively influenced the court's approach in distinguishing between mere coverage of prior art and actual disclosure that invalidates a patent.

Legal Reasoning

The core legal issue addressed was whether Natco's actions infringed upon IN'026 and whether the patent itself was valid in light of prior art. Natco argued that the patent lacked novelty and inventive step, citing prior patents including IN'653, IN'560 (both held by Novartis), AstraZeneca's US'964, and Rigel Pharmaceuticals' patents US'276, US'430, US'204, and US'112. However, the court found that while these prior patents featured broad Markush structures encompassing numerous compounds, they did not specifically disclose or enable the synthesis of Ceritinib or the exact Markush structure claimed in IN'026. The court emphasized the distinction between "coverage" and "disclosure". It determined that although prior patents might cover the general chemical framework, they did not provide sufficient teaching or enablement for a person skilled in the art to synthesize Ceritinib without foreknowledge of its specific structure. Therefore, the suit patent was deemed novel and inventive, meeting the criteria set out in Sections 2(1)(j) and 2(1)(ja) of the Patents Act, 1970. Additionally, the judgment addressed Natco's argument that listing prior art patents in New Drug Applications (NDAs) and the Orange Book constituted an admission of disclosure. The court dismissed this by explaining that "reading on" a compound via Markush claims does not equate to its disclosure unless specifically enabled.

Impact

This judgment reinforces the necessity for patents to not only claim a broad range of compounds but also to ensure that specific inventions within those claims are adequately disclosed and enabled. It sets a precedent in Indian patent law by clarifying that mere inclusion within the coverage of prior Markush claims does not render a patent invalid; specific disclosure and enablement are essential for anticipation. For pharmaceutical companies, this underscores the importance of detailed patent specifications that clearly enable the synthesis of claimed compounds. It also provides clarity on the defense mechanisms available against broad prior art claims, ensuring that inventive steps are recognized and protected.

Complex Concepts Simplified

Markush Structure

A Markush structure is a way of representing a group of related chemical compounds in patent claims. It allows for various substitutions at specific positions, covering a wide array of similar compounds within a single patent.

Coverage vs. Disclosure

Coverage refers to the range of compounds or methods included within the scope of a patent claim. Disclosure means that the patent provides enough information for someone skilled in the field to replicate the invention. In patent law, coverage alone does not invalidate a patent unless the specific invention is also adequately disclosed in prior art.

Inventive Step

An inventive step means that the invention is not obvious to someone with ordinary skills in the relevant field. It is one of the key criteria for patentability, ensuring that patents are granted only for genuine innovations.

Interlocutory Injunction

An interlocutory injunction is a temporary court order that restrains a party from taking a particular action until the final decision of the case is made.

Conclusion

The Delhi High Court's decision in Novartis v. Natco Pharma Limited serves as a pivotal clarification in Indian patent jurisprudence, particularly concerning the differentiation between "coverage" and "disclosure" in patent infringement cases. By affirming that broad Markush claims do not inherently invalidate a patent without specific disclosure, the court has reinforced the protection of genuine innovations in the pharmaceutical industry. This judgment not only upholds the validity of Novartis' patent but also provides a clear framework for future patent litigations, ensuring that inventive steps are duly recognized and enforced.