E. R. Squibb and Sons, LLC & Ors. Vs. Zydus Lifesciences Limited

Quia Timet Action and Patent Protection in the Biologics Sector

Introduction:  The intersection of biopharmaceutical innovation and patent law stands at the heart of the recent judgment delivered by the Hon'ble High Court of Delhi in E. R. Squibb and Sons, LLC & Ors. v. Zydus Lifesciences Limited. This decision is significant for its detailed analysis of patent claim construction, the scope of patent infringement in biosimilar development, and the jurisprudence surrounding interim relief in quia timet actions. The matter concerns Indian Patent No. IN 340060 (hereinafter "suit patent") which claims the monoclonal antibody Nivolumab, an anti-PD-1 antibody used in cancer immunotherapy. With the defendants poised to launch a biosimilar product allegedly infringing the suit patent, the plaintiffs sought a pre-emptive injunction, prompting a thorough judicial evaluation of patent validity, claim construction, prior art, and the credibility of apprehended infringement.

Factual Background: The suit patent IN 340060 titled “Human Monoclonal Antibodies to Programmed Death 1 (PD-1) for use in treating Cancer” was filed as a national phase application from PCT/JP2006/309606, claiming priority from U.S. provisional applications dating back to 2005. Granted in India on 1 July 2020, the patent claims a 20-year term expiring on 2 May 2026. The invention relates to the monoclonal antibody known as Nivolumab (also referred to as 5C4), which binds to the PD-1 receptor on T-cells, thereby modulating immune responses against cancer cells.

Nivolumab is marketed globally under the brand name Opdivo® and is sold in India as Opdyta®. The patent was granted after rejection of four pre-grant oppositions, and a post-grant opposition filed by Zydus Healthcare Limited, a sister concern of the defendant, is currently pending. An Opposition Board Recommendation (OBR) dated 31 January 2023 opined that the suit patent lacked novelty and inventive step, which was subsequently set aside by the High Court of Madras. The matter was remanded to the Single Judge for fresh adjudication.

Plaintiffs became aware in April 2022 that the defendant had sought regulatory approval for clinical trials of a biosimilar to Nivolumab. Although the defendant responded by claiming protection under the Bolar exemption (Section 107A, Patents Act, 1970), further investigation revealed registration of clinical trials under the name ZRC-3276, with Opdivo® listed as the reference product.

Procedural Background: The plaintiffs issued a cease-and-desist letter in May 2022, to which the defendant responded by asserting that it was only conducting clinical trials and had not yet launched the product. Based on this assurance and the clinical trial stage of development, the plaintiffs did not pursue legal action at the time.

In April 2024, the plaintiffs received inquiries from medical professionals and distribution networks indicating that the defendant may be preparing for a commercial launch. Upon discovering that the defendant had applied for marketing authorisation for ZRC-3276, the plaintiffs initiated a quia timet suit for permanent injunction and filed I.A. 10533/2024 under Order XXXIX Rules 1 and 2 CPC seeking interim relief. On 8 May 2024, the Delhi High Court granted an ad interim injunction restraining the defendant from launching the biosimilar without court approval. The order remained in force till final adjudication of the interim application, which was decided vide judgment dated 18 July 2025.

Core Dispute: The central issue was whether the plaintiffs were entitled to an interim injunction against the defendant’s potential commercial launch of its biosimilar version of Nivolumab on grounds of patent infringement. The dispute also involved determining whether the plaintiffs had made out a prima facie case of infringement, whether the suit patent was prima facie valid despite the post-grant opposition and prior art cited, and whether the plaintiffs had approached the Court with delay, thereby disentitling them to interim relief.

Discussion on Judgments: The plaintiffs relied on Jay Switches India Pvt. Ltd. v. Sandhar Technologies Ltd., 2024 SCC OnLine Del 8434, to underscore the importance of claim construction in determining patent infringement. The Court in Jay Switches emphasised that interpreting the scope of the claims is the primary step in adjudicating infringement actions, particularly in complex technologies like antibodies.

The plaintiffs also cited Bishwanath Prasad Radhey Shyam v. Hindustan Metal Industries, (1979) 2 SCC 511, where the Supreme Court stressed that the claims in a patent must be read with the complete specification, and that claim construction must be rooted in the technical disclosures of the patent.

Further, reliance was placed on Novonordisk v. Union of India, 2022 SCC OnLine Del 1944, which held that the Opposition Board Recommendation under Section 25(3) of the Patents Act is not binding on the Controller and is merely recommendatory. This case was cited to negate the defendant's reliance on the OBR recommending revocation of the patent.

The defendants countered by citing prior art documents including WO 2001/014557, WO 2002/079499, and EP 1537878 B1 (WO 2004/004771), arguing that the suit patent lacked novelty and inventive step. They further contended that the plaintiffs had admitted in foreign patent filings that Nivolumab was developed under an earlier patent family, thereby invalidating the suit patent.

Reasoning and Analysis of the Judge: The Court, on the issue of delay,  accepted the plaintiffs’ explanation that they initially refrained from filing the suit in 2022 due to the defendant’s reliance on the Bolar exemption. The Court observed that a fresh cause of action arose only in 2024 when credible information regarding imminent commercial launch surfaced.

Regarding the question of infringement, the Court held that Nivolumab (also known as 5C4 antibody) was clearly claimed in Claims 1, 3, and 7 of the suit patent, which were defined by specific amino acid sequences in the CDR regions and variable chains. Since the defendant was developing a biosimilar using the plaintiffs’ product as a reference, it was prima facie covered by the scope of the claims.

On validity, the Court found that the prior art documents relied on by the defendant did not disclose the specific amino acid sequences claimed in the suit patent. D3 (EP '878) was held to pertain only to the use of anti-PD-1 antibodies in general, not to the precise structure of Nivolumab. Further, D1 and D2 were dismissed for failing to disclose any antibody sequences. The Court relied on the Guidelines for Examination of Biotechnology Applications for Patent, 2013, which state that unless the prior art matches the claimed sequence exactly, it cannot be deemed anticipatory.

The Court also dismissed the defendant’s reliance on the Opposition Board’s adverse recommendation, noting its recommendatory nature and the pending adjudication in the Madras High Court.

Final Decision:  The High Court of Delhi granted interim relief in favour of the plaintiffs, continuing the injunction against the defendant from launching or commercially exploiting its biosimilar product ZRC-3276 without court approval until the expiry of the patent or final adjudication of the suit. The Court held that the plaintiffs had made out a strong prima facie case of infringement, that the balance of convenience lay in their favour, and that irreparable harm would be caused if the injunction was denied.

Law Settled in This Case:  This judgment reinforces the jurisprudence on quia timet actions in patent infringement suits, particularly in the biopharmaceutical context. It clarifies that the apprehension of infringement, if supported by credible evidence, can sustain an injunction even before actual launch. The case also reaffirms that prior art must disclose specific elements of the claimed invention—such as amino acid sequences in the case of biologics—for a credible challenge to novelty or inventive step. Furthermore, the judgment affirms that the recommendation of an Opposition Board is not binding and cannot by itself undermine a patent’s validity. Lastly, it underlines that reference to a patented product in biosimilar development may constitute prima facie infringement if claim mapping is established.

Case Title: E. R. Squibb and Sons, LLC & Ors. Vs. Zydus Lifesciences Limited

Date of Order: 18 July 2025

Case Number: CS(COMM) 376/2024 

Neutral Citation: 2025:DHC:5802

Name of Court: High Court of Delhi

Name of Judge: Hon’ble Ms. Justice Mini Pushkarna

Disclaimer: The information shared here is intended to serve the public interest by offering insights and perspectives. However, readers are advised to exercise their own discretion when interpreting and applying this information. The content herein is subjective and may contain errors in perception, interpretation, and presentation.

Written By: Advocate Ajay Amitabh Suman, IP Adjutor [Patent and Trademark Attorney], High Court of Delhi