Biosimilar infringement disputes in India are still a comparatively new but growing field of pharmaceutical patent law. The Delhi High Court's Order dated 18 July 2025 in E.R. Squibb and Sons LLC & Ors v. Zydus Lifesciences Ltd.[1] (2025) (‘Squibb’) is a turning point in the developing field. The Court granted an-interim injunction restraining Zydus from manufacturing, clearing or dealing its biosimilar version of the cancer medication Nivolumab until 2026 i.e., until the expiry of the Indian Patent No. 340060. A biosimilar is a biologic drug developed to closely replicate an already approved biologic, called the reference product. It matches the original drug in terms of safety, efficacy, and quality, but is produced by a different manufacturer once the reference product’s patent has expired. While not identical, it is highly comparable in clinical performance. In India, their approval is governed by regulatory authorities like the Central Drugs Standard Control Organization (CDSCO), which evaluate pharmacokinetic and pharmacodynamic equivalence for therapeutic use. However, bio similarity is a regulatory standard, not an infringement determination.
Zydus has subsequently preferred an appeal against the said order before the Division Bench (two-judge Bench) of the Delhi High Court. The Division Bench by Order dated 24 July 2025[2] recorded the consent of both parties to decide the matter finally instead of adjudicating request for relief of any interim orders in the appeal. The matter is now scheduled for final hearing in the appeal on 13 August 2025.
Factual and procedural background
The Plaintiffs, E.R. Squibb and its Indian licensee BMS, are owners of a composition and process patent pertaining to Nivolumab, the Indian Patent No. 340060, titled, ‘Human Monoclonal Antibodies to Programmed Death 1 (PD-1) for use in treating Cancer’. The Plaintiffs instituted a suit claiming that Zydus Lifesciences was on the verge of commercially launching a biosimilar product of Nivolumab prior to expiration of their Indian patent on 2 May 2026. However, prior to initiating litigation, the Plaintiffs issued a cease-and-desist notice to Zydus. In reply, Zydus categorically denied any ongoing or imminent unauthorized activity and stated that their biosimilar was still undergoing clinical trials. On this basis, the Plaintiffs initially did not apprehend immediate infringement. However, subsequent emergence of an anonymous third-party email suggesting imminent launch shifted the Plaintiffs’ position.
Even though Zydus had not marketed the product when the suit was filed, the Plaintiffs used its publicly stated regulatory filings, and disclosures regarding clinical trials to allege an imminent threat of infringement. In its interim order dated 8 May 2025, the Delhi High Court noted that while Zydus was conducting clinical trials for its proposed biosimilar of Nivolumab, there was no direct evidence of launch or marketing. The Court, therefore, allowed certain activities to continue but cautioned Zydus against any commercial exploitation pending further proceedings.
Legal considerations
A. Evidentiary standard for quia timet relief
Indian Courts have been cautious in dealing with quia timet injunctions and held that where reasonable apprehension of imminent infringement likely to cause irreparable harm exists, Courts are empowered to grant interim relief even before actual infringement occurs, if a strong prima facie case is established. The doctrinal foundation for quia timet relief originates in common law, particularly cases such as Connaught Laboratories Ltd. v. SmithKline Beecham Pharma Inc.,[3] where courts recognized the need to prevent harm before it materializes, provided there is credible and immediate threat of infringement. In E.R. Squibb, the Court granted quia timet relief primarily based on internal communications, regulatory filings, and a third-party anonymous email. While the Plaintiff argued these constituted indicators of an imminent launch, whether such evidence is sufficient is the question that Courts will be required to analyze. One aspect to consider is that despite Zydus’s undertakings denying any intent to launch, the Court held that imminence for a quia timet action was established.
B. Blending regulatory and patent frameworks
Central to the Court's analysis is its implied identification of bio similarity under regulatory law with infringement of a patent. Bio similarity, as a determination made by regulatory agencies like the Central Drugs Standard Control Organization (CDSCO), is essentially focused on pharmacokinetic and pharmacodynamic similarity for clinical safety and effectiveness.[4] Patent infringement, on the other hand, involves a comparison between the patent claim- with the product alleged to infringe.
The Court noted that Zydus's own application for its product, ZRC-3276, identified the Plaintiffs' Nivolumab (Opdivo®) as the reference biologic. Under India's Similar Biologics Guidelines, a bio-similar is expected to have the same target amino acid sequence as the reference product. This, the Court reasoned, was a de facto admission that Zydus's product would have the same patented sequences. By treating Zydus’s regulatory filings and bio similarity claims as indicative of infringement, the Court appears to have deviated from an earlier precedent in the case of F. Hoffmann-La Roche Ltd. & Others v. Drugs Controller General of India & Others,[5] decided on 11 September 2023, where the absence of an infringing product and the failure to establish claim mapping precluded the grant of quia timet relief. In that instance, the Delhi High Court refused to infer infringement merely from bio similarity filings, emphasizing the need for a direct comparison between patent claims and the allegedly infringing product. In Squibb, however, no such claim-product mapping was conducted; the Court instead relied on the International Non-proprietary Name (INN) ‘Nivolumab’ and regulatory disclosures to infer potential infringement.
Zydus argued its product did not infringe because, unlike the patent's claim of an antibody that ‘binds specifically’ to the PD-1 protein, their product also bound to other proteins. The Court rejected this, clarifying that ‘specifically’ does not mean ‘exclusively’. The Court referred to the patent's complete specification, which allows for cross-reactivity and only mandates a lack of substantial binding to other receptors, a condition both products appeared to meet based on Zydus's own test results.
The Court also rejected Zydus's claim of delay in filing the suit, accepting the Plaintiffs' timeline of action which was triggered by the recent apprehension of a commercial launch, not the earlier clinical trial application which was covered by the Bolar Exemption.
Take on Bolar Exemption
Section 107A permissively allows third parties to utilize patented inventions without liability towards the development and filing of information with a regulatory authority. This provision is commonly called the Bolar exemption and is meant to facilitate market entry by generics and bio similars in a timely manner at the time of patent expiry.
In Squibb, the Court did not concur with Zydus's reliance on this exemption, questioning whether the company had sufficiently shown that its conduct was confined to regulatory objectives. The Court held that any infringing products manufactured, offered for sale or sold, etc., during the life/term of the patent, do not gain credibility. Thus, the Court held that manufacture of infringing goods and stockpiling them during the said period, to release it/flood the market, would also amount to infringement. The Court held that any use and sale of any products manufactured during the said period, in violation of a patent, is also liable to be restrained.
Concerns over patent linkage
The Court's use of Zydus's regulatory submissions and bio similarity claims as surrogates for infringement also creates concerns about an indirect patent linkage. Patent linkage is a system where approval is made dependent on patent resolution, a model India has deliberately shunned in its drug regulatory system.[6]
In Bayer v. Union of India,[7] the Delhi High Court confirmed that Indian drug regulators do not have to analyse patent questions in approving drugs. The rationale in Squibb seems to transfer this burden to the Courts, effectively permitting regulatory measures to act as proof of possible infringement. Though short of formal linkage, this would arguably be functionally equivalent, changing the balance between patent and regulatory regimes in a way that is not necessarily reflected in the legislative intent.
Invalidity challenge
The Court further considered and rejected Zydus’ invalidity challenge to Patent No. IN 340060, primarily on the grounds that the cited prior art did not anticipate or render the claimed invention obvious. Zydus had relied on prior disclosures, including EP 1537878 B1 (WO 2004/004771), WO 2001/014557, and WO 2002/079499, arguing that they anticipated the claimed monoclonal antibody sequence. However, the Court found that none of the cited documents disclosed the precise Complementarity-Determining Regions (CDRs) or variable region sequences that were central to the plaintiff’s patented invention.
Zydus heavily relied on several prior art documents, most notably a European patent, EP '878 (corresponding to WO 2004/004771), which also belonged to the Plaintiffs. They asserted that this earlier patent family (referred to as D3) already claimed Nivolumab, making the suit patent an attempt at ‘evergreening’. However, the Court dismantled this argument. After examining the prior art, the Court concluded that while documents like D3 disclosed the use of an anti-PD-1 antibody for cancer treatment, they did not disclose the specific, unique amino acid sequences that define the Nivolumab antibody claimed in the suit patent. The Court emphasized the distinction between a process patent (as the prior arts appeared to be) and the suit patent, which is a product patent for a specific, artificially created monoclonal antibody. The Court highlighted that ‘while the prior art as cited, provided the target, the suit patent provides the actual product’.
The Court also referred to the 2013 Guidelines for Examination of Biotechnology Applications for Patent, which stated that for a sequence to be anticipated by prior art, it must be an exact match. Zydus failed to demonstrate such a match.
Zydus also placed significant weight on a recommendation from the Opposition Board (OBR) which, in a pending post-grant opposition proceeding, had opined that the patent was invalid and should be revoked. The Court was not persuaded, pointing out several flaws in this reliance. Firstly, it noted that the OBR is merely a recommendatory body whose opinion is not binding on the Controller of Patents. Secondly, the legal validity of this specific OBR was under challenge before the High Court of Madras. Emphasizing the non-binding nature of such recommendations, the Court noted that the OBR had already been set aside and remanded by the Madras High Court for fresh consideration,[8] thereby stripping it of any legal conclusiveness. Lastly, the very prior art (EP '878) that the OBR relied upon had already been considered and dismissed by the Controller of Patents during the pre-grant opposition stage, where the Controller had explicitly found the invention to be new and novel.
Ultimately, the Court held that Zydus had failed to raise a ‘credible challenge’ to the patent's validity, a necessary threshold for denying an interim injunction. The Court pointed to the fact that the patent was granted after surviving four pre-grant oppositions and has been granted in over 50 countries without revocation.
Conclusion
The E.R. Squibb v. Zydus Order, while is an important decision, it remains to be seen whether Courts will continue this line of reasoning, especially in the context of assessing prima facie infringement pertaining to biosimilars.
[The author is an Associate in IPR practice at Lakshmikumaran & Sridharan Attorneys]
[1] CS(COMM) 376/2024 & I.A. 10533/2024
[2] FAO(OS) (COMM) 120/2025
[3] 7 F. Supp. 2d 477 (D. Del. 1998)
[4] Central Drugs Standard Control Organization (CDSCO), Guidelines on Similar Biologics: Regulatory Requirements for Marketing Authorization in India, Revised 2016, Ministry of Health and Family Welfare, Government of India, available at: https://cdsco.gov.in/opencms/export/sites/CDSCO_WEB/Pdf-documents/biotech/Guidelines_on_Similar_Biologics.pdf
[5] 2023 SCC OnLine Del 5615
[6] Bayer Corporation v. Union of India, 2009 SCC OnLine Del 3519, paras 60 to 65
[7] 2009 SCC OnLine Del 3519
[8] In W.A. No. 1697/2024 vide Order dated 10th January 2025
