Prima Facie Infringement by Biosimilar Justifies Interim Injunction Despite Pending Post-Grant Opposition: Delhi High Court - 2025-09-19

Delhi High Court Restrains Zydus Lifesciences from Launching Biosimilar of Cancer Drug Nivolumab

New Delhi: In a significant ruling for pharmaceutical patent enforcement, the Delhi High Court, presided over by Justice Mini Pushkarna, has granted an interim injunction restraining Zydus Lifesciences Limited from manufacturing or launching its biosimilar version of the cancer drug Nivolumab. The Court found a prima facie case of patent infringement against Zydus, upholding the validity of the patent held by E. R. Squibb and Sons LLC & Ors.

The decision came in a quia timet action—a suit filed in anticipation of a future infringement—and reinforces the rights of patent holders against potential infringers, even when a post-grant opposition to the patent is pending.

Background of the Case

The lawsuit was initiated by E. R. Squibb and Sons against Zydus Lifesciences, alleging that Zydus was preparing to launch a biosimilar version of their patented drug Nivolumab, thereby infringing Indian Patent No. IN 340060 (IN ‘060). Nivolumab, marketed as Opdyta® in India, is a monoclonal antibody used in immunotherapy for various types of cancer. The patent is valid until May 2, 2026.

The plaintiffs became aware in 2022 that Zydus was conducting clinical trials for its biosimilar product, ZRC-3276, using Nivolumab as the reference drug. While Zydus initially claimed its activities were protected under the "Bolar Exemption" (Section 107A of the Patents Act), which permits research for regulatory approvals, the plaintiffs filed the suit upon receiving credible information in 2024 about Zydus's imminent commercial launch.

Key Arguments

Plaintiffs' Submissions:

* Senior Advocates Mr. Sandeep Sethi, Mr. P.S. Raman, and Mr. Amit Sibal, representing the plaintiffs, argued that the IN ‘060 patent is valid and subsisting, having survived four pre-grant oppositions.

* They established a prima facie case of infringement by demonstrating that Zydus's product, being a biosimilar of Nivolumab, must necessarily have the same amino acid sequences covered by the patent's claims.

* The plaintiffs contended that a pending post-grant opposition filed by Zydus's sister concern does not weaken the patent's enforceability, especially since the Opposition Board's recommendation for revocation is not binding on the Controller of Patents and is currently under judicial review.

Defendant's Submissions:

* Senior Advocates Mr. Harish Salve, Mr. Dushyant Dave, Mr. Rajiv Nayar, and Mr. Dayan Krishnan, appearing for Zydus, mounted a two-fold defense: non-infringement and invalidity of the patent.

* They argued that their product, ZRC-3276, does not infringe because the patent specifically claims an antibody that binds "specifically" to the PD-1 protein, whereas their product (and even the plaintiffs' own drug) also binds to other proteins.

* Zydus challenged the patent's validity, citing prior art (including one of the plaintiffs' own earlier patents) and arguing a lack of inventive step. They heavily relied on a favorable recommendation from the Opposition Board in the pending post-grant opposition.

Court’s Analysis and Findings

Justice Pushkarna conducted a detailed analysis, leading to a prima facie finding in favor of the plaintiffs on all key issues.

On Patent Validity: The Court held that Zydus failed to raise a "credible challenge" to the patent's validity. It noted:

"The defendant has not been able to show that Nivolumab was disclosed in the prior arts cited... Nothing has been brought before this Court to indicate that the documents... disclose the specific sequences of the antibody, as claimed in the suit patent."

The Court also observed that the patent had survived rigorous examination and four pre-grant oppositions. The reliance on the Opposition Board's non-binding recommendation was deemed insufficient to invalidate the patent at the interim stage, particularly since the matter is sub-judice.

On Infringement by the Biosimilar: The Court established a clear link between Zydus's biosimilar and the patented drug. Citing the Guidelines on Similar Biologics, 2016 , the judgment highlighted that a biosimilar must have the same target amino acid sequence as its reference biologic.

"Thus, it is clear that as per the aforesaid Similar Biologics Guidelines, the target amino acid sequence of the similar biologic should be confirmed and is expected to be the same for the reference biologic."

Since Zydus admitted its product is a biosimilar of Nivolumab, the Court concluded that it must contain the patented sequences, thus establishing prima facie infringement. The Court rejected Zydus's argument about non-specific binding, clarifying that the term "specifically" does not mean "exclusively" and that the patent specification itself allows for some cross-reactivity.

On 'Clearing the Way': The Court emphasized that Zydus was aware of the plaintiffs' patent rights, as evidenced by its sister concern's post-grant opposition. Despite this, Zydus proceeded towards a commercial launch without first seeking revocation of the patent or awaiting the outcome of the opposition. Citing precedent, the Court noted that a defendant who fails to "clear the way" before launching a potentially infringing product cannot claim the balance of convenience is in its favor.

Final Decision and Implications

The Court ruled that the plaintiffs had established a strong prima facie case, with the balance of convenience in their favor, and would suffer irreparable harm if the injunction was not granted.

The Court ordered: 1. Zydus and its affiliates are restrained from manufacturing, selling, importing, or otherwise dealing in any biosimilar of Nivolumab during the suit's pendency. 2. Zydus is further restrained from launching any infringing products manufactured during the patent's term, even after its expiry in 2026. 3. Zydus must file an affidavit disclosing the quantity of its manufactured biosimilar product within four weeks.

This judgment serves as a strong precedent for innovator pharmaceutical companies, affirming that a granted patent remains enforceable through an interim injunction even amidst ongoing validity challenges. It also clarifies that the regulatory pathway for biosimilars does not provide a shield against patent infringement.