Cancer immunotherapy patents sit at the sharpest intersection of innovation incentive, patient access, and the limits of judicial inference – and few disputes have illustrated this as vividly as a recent contest over an anti-cancer biosimilar that the patent holder’s own data may not have clearly excluded from the market.<\/p>\n
E.R. Squibb and Sons, LLC (\u201cE.R. Squibb\u201d or \u201cSquibb\u201d) is the registered holder of Indian Patent No. IN\u00a0340060 (\u201cIN\u2019060\u201d or \u201csuit patent\u201d), titled \u201cHuman Monoclonal Antibodies to Programmed Death\u00a01 (PD-1) for use in treating Cancer.\u201d The patented molecule, the 5C4 antibody, is marketed globally as Opdivo and in India under the brand Opdyta. PD-1 is a protein on T-cells that, when bound by ligands on cancer cells, deactivates the immune system’s ability to destroy those cells. Nivolumab (the International Nonproprietary Name, or INN, assigned to 5C4) blocks this pathway, allowing the immune system to attack cancer cells. The two principal claim features in IN\u2019060 are: first, that the antibody binds specifically to human PD-1; and second, that it contains specified amino acid sequences in its heavy and light chains.<\/p>\n
Zydus Lifesciences Limited (\u201cZydus\u201d) developed ZRC\u00a03276, a biosimilar of Nivolumab, and declared that treatment using its product would cost approximately 70% less than Opdyta. Before ZRC\u00a03276 could reach the market, E.R. Squibb filed an anticipatory suit before the Delhi High Court, asserting that the imminent commercial launch would infringe IN\u2019060. A Single Judge granted an interim injunction restraining Zydus from manufacturing or releasing ZRC\u00a03276. Zydus appealed. On January\u00a012, 2026, a Division Bench of the Delhi High Court modified the impugned order by vacating the injunction and directing Zydus instead to maintain and file audited accounts of its revenue from sales of ZRC\u00a03276 with the Court Registry, with advance copies to E.R. Squibb, until the suit patent’s expiry on May\u00a02, 2026.<\/p>\n
The court observed that Section\u00a048 of the Patents Act confers on a patentee the exclusive right to prevent others from making, using, offering, selling, or importing \u201cthat product\u201d – the product defined in the granted claims. The court found that \u201cmapping,\u201d though not a term of art, simply means demonstrating that the defendant’s product is the product the plaintiff holds the patent over. The essential features of the patented claim, the court noted, must be identified in the allegedly infringing product; minor workshop improvisations do not escape infringement, but neither does a product escape the inquiry because it resembles another marketed product. The court further observed that where direct product-to-claim mapping is absent, collateral material must be overwhelming and must form a continuous, unbroken chain of circumstances before a court can draw the inference of infringement.<\/p>\n
The court found that the Single Judge’s \u201cindirect mapping\u201d approach rested on three sequential steps: that 5C4 maps onto Nivolumab; that ZRC 3276 is a biosimilar of Nivolumab; and that biosimilars necessarily share identical amino acid sequences. The court observed that the first step was circular: Nivolumab is the INN assigned to the 5C4 antibody itself, so mapping 5C4 onto Nivolumab amounts to mapping the patent onto its own exemplified molecule, which is self-evident and advances the infringement analysis not at all. On the third step, the court found that the Similar Biologics Guidelines require biosimilars to be \u201csimilar in terms of quality, safety and efficacy,\u201d with no requirement of amino acid identity. The impugned judgment itself, the court noted, had acknowledged that biosimilars would be \u201cchemically different\u201d from their reference biologics; a concession that fatally undermined the basis for the indirect mapping conclusion.<\/p>\n
The court’s analysis on the meaning of \u201cspecifically\u201d proved particularly decisive. The court observed that during pre-grant opposition proceedings before the Patent Office, E.R. Squibb had argued that prior art antibodies were distinguishable from its claim because they demonstrated statistically significant binding to non-PD-1 CD-28 proteins, with the threshold for statistical significance set at a \u2018p\u2019 value of less than 0.05. ZRC\u00a03276’s \u2018p\u2019 value for cross-binding was 0.0001, the court found, a figure Squibb’s own prosecution benchmark would characterize as highly statistically significant. The court held that a patentee who secures registration by representing a particular technical criterion to the Patent Office cannot ignore that criterion in subsequent infringement proceedings. The learned Single Judge had entirely failed to consider this argument despite it being squarely raised by Zydus. That omission, the court stated, was fatal to the impugned order. The court further observed that the impugned judgment’s infringement finding rested on product-to-product mapping rather than product-to-claim mapping, and that even on its own terms, such a comparison could not establish infringement under Section\u00a048.<\/p>\n
The court observed that both the protection of valid patents and the availability of life-saving medicines represent pre-eminent components of public interest, and that neither consideration automatically overrides the other. The court noted that a clear and well-established case of infringement, supported by product-to-claim mapping and an unchallenged patent, must be protected by injunction, without compromise. However, the court held that where the technical questions raised are genuinely complex and would require expert evidence, where product-to-claim mapping has not been performed, and where the product in question is a life-saving cancer drug priced 70% below its competitor, public interest requires the court to err in favour of continued patient access while securing the patentee’s economic interests through alternate means. With the suit patent set to expire on May 2, 2026, only four months after the judgment, An absolute injunction would deny patients access to affordable treatment for a commercially negligible residual period.<\/p>\n
In view of the observations and the arguments presented by both the parties, the Delhi High Court held that:<\/p>\n