Delhi HC Quashes IPO's Patent Rejection of Taiho Pharma's Cancer Drug, Orders Re-evaluation
Delhi High Court
New Delhi: In a ruling impacting pharmaceutical patent jurisprudence in India, the Delhi High Court has set aside the Indian Patent Office's (IPO) rejection of Japanese drugmaker Taiho Pharmaceutical Co. Ltd.'s application for a novel anti-cancer compound and directed the Patent Controller to reconsider the application afresh.
The Court held that the IPO failed to properly identify the 'known substance' and did not give the applicant a fair opportunity to demonstrate enhanced efficacy, as required under Section 3(d) of the Patents Act, 1970.
The Court, in its May 15, 2025 ruling observed;
“By not identifying any particular ‘known substance’ in the hearing notice, the appellant was not afforded a fair opportunity to respond to the same, by demonstrating, through comparative research data, that the claimed compound possesses enhanced therapeutic efficacy,”
The case involved Taiho’s patent application (No. 7283/DELNP/2014) for a novel piperidine compound with Aurora A kinase inhibitory activity, indicated for cancer therapy. The IPO had rejected the application citing Section 2(1)(ja) (lack of inventive step) and Section 3(d) (new form of known substance without enhanced efficacy), referencing prior art D1.
However, the Court found that the Patent Office had not followed the necessary steps laid down by legal precedent for applying Section 3(d):
“In order to sustain an objection under Section 3(d) of the Act, the following factors have to be clearly identified by the Controller:
(i) the 'known substance' with 'known efficacy';
(ii) clear explanation as to how and why the claimed substance is a derivative or otherwise a new form of a 'known substance';
(iii) an objective comparison between the therapeutic efficacy of the claimed invention and that of the known substance.”
The High Court cited its own earlier judgment in DS Biopharma Ltd. v. Controller of Patents & Designs, emphasizing that procedural lapses such as vague hearing notices and lack of specific compound references deprive applicants of their right to be heard fairly.
“The hearing notice only refers to D1 as the closest prior art and makes a general observation regarding structural similarity... The appellant cannot be expected to infer a ‘known substance’ and furnish efficacy data based on such inference,” the order stated.
Further, the Court held that the inventive step analysis under Section 2(1)(ja) was closely linked to the Section 3(d) findings and therefore required reconsideration:
“Since the reasoning under Section 2(1)(ja)... is closely intertwined with the assessment under Section 3(d), the objection... also warrants reconsideration upon proper identification of the ‘known substance’ from the closest prior art and comparison of the enhanced efficacy data thereof by the appellant.”
Accordingly, the Court remanded the matter back to the Patent Office for fresh evaluation, instructing the Controller to issue a new hearing notice and afford the appellant a fresh opportunity to respond with relevant data.
“The Controller would afford a fresh opportunity of hearing before deciding the subject patent application, after giving a hearing notice to the appellant.”
The matter has now been referred back for compliance and further action, with the Patent Office directed to examine all technical and legal submissions afresh.
To view the original judgement, click on the link below:
