Summary: The Calcutta High Court in a recent case clarified important aspects pertaining to inventive step assessment and the admissibility of post-filing data.
Introduction
In a significant decision, the Calcutta High Court in Takeda Pharmaceutical Co Ltd v. Deputy Controller of Patents & Designs & Ors. (decision dated 11.4.2025, IPDPTA/119/2023), clarified important aspects pertaining to inventive step assessment and the admissibility of post-filing data.
Brief background
The case involved Patent Application No. 3939/KOLNP/2010, which the Deputy Controller of Patents had rejected, on grounds of lack of inventive step, non-patentable subject matter, and insufficient disclosure under Sections 2(1)(ja), 3(d), and 10(4), respectively, of the Patents Act, 1970 ("Act"). Takeda ("appellant") appealed the rejection and the matter came before the Calcutta High Court.
The patent application related to a group of compounds defined by a Markush structure but was subsequently narrowed to a single compound, Brigatinib. Brigatinib is described as a potent anaplastic lymphoma kinase (ALK) inhibitor indicated for the treatment of ALK-positive non-small cell lung cancer (NSCLC). It was contended that Brigatinib exhibits enhanced selectivity for ALK over Ins-R (insulin receptor), thereby purportedly mitigating the risk of insulin resistance due to its substantially reduced binding affinity towards Ins-R. The application faced objections under Sections 2(1)(ja) and 3(d), citing lack of inventive steps and patentability. The appellant filed written submissions, amended claims, and an affidavit to establish the compound's advantageous characteristics. Subsequently, two pre-grant oppositions were filed, raising objections on grounds of novelty, prior publication, obviousness and insufficient disclosure.
Before the Patent Office, the appellant had argued that the subject of its application exhibited superior selectivity and therapeutic efficacy, and relied on post-filing data in support. However, this was disregarded by the Deputy Controller. Specifically, the Controller's order noted that the closest prior art compound, TAE684, differed from Brigatinib only in the substitution of a 'phosphoryl group' for a 'sulfonyl group'. Based on this similarity, the Controller held that replacing the 'sulfonyl group' with a 'phosphoryl group' would have been obvious due to bioisosterism between the two groups. (Bioisosterism is a strategic practice in medicinal chemistry where an atom, group, or chemical substituent is replaced with an atom or group of similar physicochemical properties, with the expectation that the resulting molecule will exhibit similar biological properties.) The Controller also refused to take on record the post-filing data and held that the appellant failed to demonstrate any technical advancement of the subject invention, rendering the claim non-allowable under Sections 2(1)(ja) and 3(d). Additionally, the Controller held that the specification lacked sufficient disclosure, citing the reason that the appellant was unaware of the technical advancements at the time of filing.
Each of these issues was discussed by the Calcutta High Court in its decision, as elaborated below.
Findings of the Court
Inventive Step
The Court noted that the Controller's order found Brigatinib's difference from TAE684 (phosphoryl vs sulfonyl group) obvious based on prior art (Zhao and Schneider) which disclosed bioisosterism between the two groups. However, the Court noted a critical oversight in inventive step assessment: the Controller's order failed to consider the applicant's argument that Zhao's teachings on bioisosterism were limited toherbicidal activityand did not extend to therapeutics, particularly those exhibiting selective activity. This omission is significant, as a person skilled in the art would not consider Zhao's references relevant to modifying TAE684 without evidence of therapeutic applicability.
The Court fell back on older decisions, notablyF. Hoffmann-La Roche Ltd. v. Cipla Ltd., 2015 SCC OnLine Del 13619, andAvery Dennison Corporation v. Controller of Patents and Designs (2022/DHC/004697),and noted that patent examiners must avoid hindsight bias when assessing inventive step.
The Court also noted that the invention should be considered as a whole; one cannot conclude that a claimed invention is obvious merely because individual parts of the claim taken separately are known or might be obvious or structurally similar to the claimed compound. Specifically, the Court observed that mere structural similarity between compounds of the prior art and the claimed invention does not make the entire invention obvious, something that the Deputy Controller had failed to demonstrate.
The Court therefore held that the Controller erred in disregarding the appellant's submissions and evidence aimed at refuting the obviousness objection.
Admissibility of post-filing data
Upon review of the Controller's order, it appears that the Controllerdid consider the post-filing datasubmitted by the appellant but refused to take them on record, characterizing it as "later accrued knowledge." The Controller reasoned that, as of the application's filing date, the appellant purportedly lacked awareness of whether Brigatinib exhibited any ALK inhibitory activity.
While the Court did not specifically address the issue whether the support for claimed technical advancement was present in the patent specification, the Court clarified that post-filing data, particularly in pharmaceutical inventions, is admissible to demonstrate therapeutic efficacy and technical advancement. Noting that drug development is a "lengthy process" and the data to demonstrate therapeutic efficacy can be filed after filing of specification, the Court confirmed that no statutory time bar exists against submitting additional documents after filing patent claims. It said that any evidence which shows technical advancement ought to have been considered in deciding the existence of technical effect. In this regard, according to the Court, the Deputy Controller's disregarding of post-filing data was erroneous.
Sufficiency of disclosure
The Court noted that the Deputy Controller had rejected application under Section 10(4) stating that there was no data to establish unexpected technical effects for inventive step and therapeutic efficacyand that the appellant was not aware if "Brigatinib" exhibits any ALK inhibitory activity. The Court held that for novel compound claims, to meet the requirement under Section 10(4), the disclosure of the compound's structure and preparation method is sufficient. The Court noted that Section 10(4) requires the applicants to fully and particularly describing the invention and its operation or use and the method by which it is to be performed; the provision does not require demonstrating any kind of data or efficacy which is not part of the claim.
Other observations
The Court also observed that the Deputy Controller had either ignored or not dealt at all with the data which would demonstrate the technical advancement and industrial acclaim attained by Brigatinib, including US FDA approvals, articles published in peer-reviewed journals of high impact factor, and expert evidence by way of affidavit.
Critically, the Court stated that the Deputy Controller had also failed to consider the universal assessment of inventive step across different patent jurisdictions, and the corresponding fact that the invention was registered in over 50 countries.
Key takeaways
The Court has reaffirmed that when assessing obviousness, conclusions must be based solely on prior art without hindsight. Prior art teachings should be considered as a whole, and any teachings that diverge from the patent claim suggest non-obviousness. A two-part test is required: identifying motivation to select and motivation to modify. Mere structural similarity between compounds is insufficient to establish obviousness; instead, there must be a clear teaching, suggestion, or motivation in the prior art to modify the lead compound. Additionally, factors like long-felt need, failure of others, industry recognition, and unexpected results can serve as objective evidence of non-obviousness.
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