Legal Infirmities In Refusal Of A Patent: Calcutta High Court Rules Remand Inevitable

It is known that if the Appeal Court finds that the Controller has not followed the principle of natural justice while refusing a patent, such an order is most likely to be set aside and returned for reconsideration. This happened again in a case heard by the Calcutta High Court, where Respondent 2 refused the patent application relating to a group of compounds defined by a Markush structure but was subsequently narrowed to a single compound, Brigatinib.

In Takeda Pharmaceutical Co Ltd vs Deputy Controller of Patents & Designs & Ors. (IPDPTA/119/2023) (11.4.2025), the Calcutta High Court was called upon to find whether the Controller ignored the submissions and evidence relied on by the appellant in pronouncing the order of refusal of a patent, and whether this amounted to a violation of the principle of natural justice. Another critical issue for the Court was to clarify what the legally accepted important aspects are pertaining to inventive step assessment and the admissibility of post-filing data.

Legal Issues before the Court

1. Whether the claimed invention, specifically the compound Brigatinib, involves an inventive step and is not obvious to a person skilled in the art?
2. Whether the patent application complies with the sufficiency of disclosure requirement under section 10(4) of the Patents Act, 1970?
3. Whether the impugned order rejecting the patent application was passed in accordance with the principles of natural justice, considering all evidence and submissions by the appellant?

Factual Matrix

Patent Application No. 3939/KOLNP/2010 was examined and FER was issued, stating the objections relating to lack of inventive step, non-patentable subject matter, and insufficient disclosure under Sections 2(1)(ja), 3(d), and 10(4). The hearing was offered, and the appellant was allowed to argue and to give written submissions to present his case. Subsequent to the filing of the said written submissions, two pre-grant oppositions were filed against the application for a patent. Interestingly, both of the pre-grant oppositions raised similar objections of lack of novelty and prior publication under Section 25(1)(b), prior public knowledge or public use in India under Section 25(1)(d), obviousness and lack of inventive steps under Section 25(1)(e) of the Act. On April 12, 2023, Respondent 2 passed an order refusing the patent on the grounds of lack of inventive steps under section 2 (1) (ja), being non-patentable under Section 3(d) and insufficient description under Section 10(4) of the Patents Act 1970. Takeda preferred an appeal against the impugned order.

Case of the Appellant

1. Respondent No. 2 ignored the submissions and the evidence relied on by the appellant.
2. The impugned order was passed without any application of mind and is based on mere assumptions and an incorrect understanding of the invention as well as the prior arts.
3. It was further alleged that the impugned order was passed in violation of the principles of natural justice and is devoid of reason.
4. The respondent erred in not considering the supplementary experimental data and subsequent affidavits, which would demonstrate the improved selectivity of Brigatinib for ALK over Ins-R, technical advancement and enhanced therapeutic efficacy possessed by Brigatinib over the closest compounds known in the art.
5. The supplementary data did not present any new or additional features of the claimed invention, as has been held by respondent No. 2.

Argument of the Appellant

The appellant argued that the respondent ventured into a hindsight search for similar-looking structures and placed the "Sulfonyl Group" without assigning any reason as to why the said particular group ought to be replaced from TAE-684. Further, the respondent failed to appreciate that a single functional group can drastically alter a compound's properties. The appellant submitted that the subject application exhibited superior selectivity and therapeutic efficacy, and they relied on post-filing data to substantiate this claim. However, this evidence was disregarded by Respondent 2, stating it as "later accrued knowledge."

Respondent's Defence

The Controller submitted 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. The respondent contended that the claimed invention differs in the presence of a 'phosphoryl group' to get compound 'Brigatinib' instead of a 'sulfonyl group' of the prior arts. The technical advancement in the present case may be regarded as an 'increase in the selectivity' of 'Brigatinib' for ALK over InS-R.

The respondent submitted that the appellant failed to furnish any evidence of technical advancement, nor of the effectiveness of the compound 'Brigatinib' at the time of filing the complete specification. The respondent submitted that, since the appellant was unaware of the technical advancements at the time the specifications were filed, the invention lacked sufficient disclosure under section 10(4).

Subject Invention

The original claimed invention of this patent application was for a group of compounds defined by a Markush structure. During the FER response, it was narrowed to a single compound, Brigatinib. In the specification, Brigatinib is described as a potent anaplastic lymphoma kinase (ALK) inhibitor indicated for the treatment of ALK-positive non-small cell lung cancer (NSCLC). Appellant 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.

Court's Analysis and Decision

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 the inventive step assessment. Firstly, Respondent 2 failed to consider the appellant's argument that Zhao's teachings on bioisosterism were limited to herbicidal activity and 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. Secondly, Respondent 2 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.

On Inventive Step Analysis

The Court gleaned through various case laws in India, which laid down the guiding principles that ought to have been followed by the Controller for assessment of Inventive step in this case. Citing the legal position relating to assessment of inventive step as established through the judicial precedence the Court stated that, in F. Hoffmann-La Roche Ltd. vs Cipla Ltd., 2015 SCC OnLine Del 13619, (Guidelines to avoid hindsight reconstruction and criteria for assessing inventive step including motivation to select and modify lead compounds) and in Avery Dennison Corporation vs Controller of Patents and Designs (2022/DHC/004697) (Principles for determining inventive step and lack of obviousness including various approaches such as "obvious to try," problem/solution, could-would, and TSM test).

Citing Bishwanath PrasadRadhey Shyam v. Hindustan Metal Industries [(1979) 2 SCC 511], the Court emphasised that the objective and strict assessment of "obviousness" requires the need to consider the invention as a whole. The Court noted that an inventive step must not be concluded based on isolated components but on the overall invention. By applying the aforesaid principles, the Court concluded that in order to inquire into obviousness, a two-fold inquiry is required to be conducted, i.e., motivation to select and motivation to modify, and mere structural similarity cannot form the basis for selection of a lead compound in the prior art.

The legal position is well settled that potent and promising activity in the prior art trumps mere structural similarity. There must be teaching, suggestions or motivation in the prior art document in order to modify the lead compound. Besides the primary consideration as noted, the objective indicia of non-obviousness include secondary considerations such as (i) a long-felt need; (ii) failure of others; (iii) industry acclaim; and (iv) unexpected results. The Court noted that (ii) Respondent 2 had failed to consider the legal assessment of inventive as established across different cited cases.

On Technical Advancement

Speaking on the findings of Respondent 2 relating to lack of technical advancement, the Court noted that the applicant had filed specifications which disclosed the effectiveness of a few exemplified compounds which demonstrate the IC50 value less than 1nM. The appellant brought diverse evidence on record to demonstrate that Brigatinib is identified to exhibit increased selectivity for ALK, over Ins-R, due to substantially decreased binding affinity towards Ins-R as reflected by increased IC50 value, which consequently resulted in superior therapeutic efficacy, resulting in reduced competitive binding to Ins-R, and consequently decreased deleterious side effects that are caused by disruption of normal functions due to non-targeted binding to Ins-R, which seriously affects the patient's health. The Court found that all such technical and scientific evidence has been ignored and has not even been considered by Respondent 2 in the impugned order.

On the Permissibility of Post-Filing Data

Citing Oyster Point Pharma Inc vs Controller of Patents and Designs & Anr, 2023 SCC Online Cal 1214 and Astrazeneca vs Intas Pharmaceuticals Ltd, 2020 SCC Online Del 2765, the Court reminded that submission of post-filing evidence in pharmaceutical patent prosecution is permissible. In these cases, it was held that there is no statutory bar on submitting additional data after filing, relevant for considering technical advancement and efficacy. In recognition of post-filing evidence in patent proceedings, the Court ruled that evidence of technical advancement can be submitted after filing the patent specification.

The Court ruled that in the present case, Respondent 2 erred in disregarding the post-filing evidence. The Court noted that respondent no.2 also erred in not considering the post-filing experimental data, written submissions, industrial acclaims and also by refusing to accept any further data during the process of hearing before passing the impugned order. No reasons were discussed for rejecting the subsequent experimental data. The Court ruled that the non-consideration is not only in violation of the provisions of the Act but also contrary to the principles of natural justice.

OnSufficiency of Disclosure

The Court agreed with the appellant that the European Patent Office had granted a patent for the same compound without objection to sufficiency, and the respondent did not consider this fact. The Court noted that, on the contrary, 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. The Court found that in the impugned order Respondent 2 has made contradictory findings in concluding that even though the appellant has disclosed a process for preparation of "Brigatinib" since the subject matter relates to a compound by displaying a process (only) for preparation of the said drug the same did not fulfil the requirements of Section 10(4) of the Act and that the appellant was not aware if "Brigatinib" exhibits any ALK inhibitory activity.

The Court noted that Brigatinib was selected while narrowing down the claims at the time of prosecution of the subject invention from the class of compounds claimed as a Markush structure. Further, in a claim relating to a novel compound, the requirement of sufficiency of disclosure is satisfied if the structure of the compound and the method for the preparation of said compound are disclosed, as it enables a person skilled in the art to perform the invention. The Court ruled that Respondent 2 failed to apply the correct approach required to evaluate the matter for the requirement of sufficiency of disclosure under Section 10(4) of the Act, which ought to have been applied. 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 describe the invention and its operation or use and the method by which it is to be performed, and this provision does not require demonstrating any kind of data or efficacy which is not part of the claim.

Decision of the Court

In view of such infirmities found in the impugned order, the Court set aside with directions to the respondents to consider it afresh after giving an adequate opportunity of hearing to all the parties and, upon consideration, all the materials on record and the experimental data. The Court made it clear that all points are left open for adjudication in accordance with the law.

Key Takeaways

The Court, in this decision, 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. 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. This case also reconfirms that with so many legal infirmities in the refusal order relating to a patent, the remand by the Court is inescapable.

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