The Delhi High Court, in the case of Osaka University vs Assistant Controller of Patents and Designs [C.A.(COMM.IPD-PAT) 390/2022], set aside the order passed by the Controller in application number 3495/DELNP/2012, entitled ‘Bridged Artificial Nucleoside and Nucleotide’. The subject application was refused by the Controller on the grounds of lack of inventive step and non-patentability under Section 3(d) of the Patents Act, 1970. The judgment essentially underscores that where the Controller relies on new prior art references or identifies a “known substance” under Section 3(d) only in the refusal order, the decision stands vitiated for breach of procedural fairness. It also emphasises the need for a coherent inventive step analysis.

The subject application concerned bridged artificial nucleosides and nucleotides having high binding affinity to single-stranded RNA and enhanced nuclease resistance, making them suitable for antisense and nucleic acid drugs.

The Appellant challenged the refusal contending that the impugned order suffered from analytical and procedural irregularities. It was argued that:

• the Controller’s reliance on prior art document D2 for rejecting the application on the ground of lack of inventive step was impermissible, as objection based on D2 were not raised in the First Examination Report (FER), the hearing notice, or even during the hearing;
• the comparison drawn between Table 6 of D2 and Example 13 of the specification was misplaced and based on an incorrect reading of the specification;
• the claimed compounds demonstrated a significant technical advance over the cited prior arts;
• the declaration from the inventor submitted before United States Patents and Trademarks Office (USPTO) during the US prosecution was not considered by the Controller.
• the rejection under Section 3(d) was made without establishing how the claimed invention was a derivative of a known substance.

Court’s Examination of the Objection on Inventive Step

Relying on Agriboard International LLC v. Deputy Controller of Patents and Designs [2022 SCC OnLine Del 4786], the Court reiterated that the Controller ought to consider:

• the invention disclosed in the prior art,
• the invention disclosed in the application, and
• the manner in which the subject invention would be obvious to a person skilled in the art (PSITA).

The Court noted that although four prior art documents (D1–D4) were cited, the impugned order failed to demonstrate how these documents, either individually or collectively, led to the claimed invention. Apart from a broad assertion that the claimed compounds were similar to known 2’,4’-bridged nucleoside analogues, no reasoning was provided as to why the specific amide-linked bridge claimed by the Applicant would be obvious.

A key infirmity identified by the Court was the Controller’s erroneous comparison of experimental data. To conclude that the claimed invention lacked technical advancement over document D2, the Controller compared Table 6 of D2 with Example 13 of the subject application. The Court held that this comparison was misplaced, as Example 13 related to serum stability, whereas Table 6 of D2 related to nuclease resistance.

The Court further observed that while documents D1 to D4 were cited in the hearing notice, the impugned order substantially relied only on D1 and D2, without any discussion of D3 and D4. There was no analysis explaining how these documents were to be read together or how their teachings would guide a PSITA towards the claimed invention. The absence of such reasoning, the Court held, rendered the inventive step analysis incomplete.

Additionally, the Court noted that the Controller violated principles of natural justice by introducing additional reasoning in the impugned order that did not form part of the FER or the hearing notice.

Objection on Non-Patentability under Section 3(d)

The Court found the refusal under Section 3(d) to be unsustainable for the following reasons:

• Neither the FER nor the hearing notice identified the derivative compound or the prior art from which the claimed invention was alleged to be derived. The reasoning appeared for the first time in the impugned order.
• In the absence of prior identification of the known substance, the Applicant had no opportunity to reply to the identified derivative of D2.

Relying on DS Biopharma Ltd. v. Controller of Patents [2022 SCC OnLine Del 3211], the Court reiterated that:

• invocation of Section 3(d) presupposes clear identification of the known substance, and
• the burden to demonstrate enhanced efficacy arises only after such identification.

In view of the foregoing, the Delhi High Court set aside the impugned order and remanded the matter to the Patent Office for fresh consideration.