Dr Jyoti Choithani Ramani analyses Taiho Pharmaceutical Co. Ltd. v. Controller of Patents & Anr., where the Delhi High Court set aside the rejection of Taiho’s patent. The Court clarified that for a valid Section 3(d) objection, the Patent Office must identify the ‘known substance with known efficacy’, explain how the claimed compound is a derivative or new form of it, and provide a reasoned efficacy comparison. This ruling reinforces procedural fairness and sets a precedent for a more rigorous and transparent examination by IPO for application of Section 3(d).
In an appeal against the order passed by the Assistant Controller of Patents and Designs in Taiho Pharmaceutical Co. Ltd. v The Controller of Patents & Anr., the Delhi High Court reversed the Controller of Patents’ (Controller) order refusing Taiho Pharmaceutical Co. Ltd.’s (Taiho) patent application.
Taiho’s patent application was for a novel piperidine compound with anti-cancer properties. The Controller had held that the claims lack inventive step and are non-patentable under section 3(d) of the Indian Patents Act, 1970.
Controller’s reasoning to refuse Taiho’s application:
- On lack of inventive step: The claimed substituted piperidine compounds of the application share the same core structure as those disclosed in the cited prior art D1, exhibiting Aurora A kinase inhibitory activity. Given that compounds 15 and 16 of D1 closely resemble the claimed compounds, a Person Skilled in The Art (PSITA) would consider them an obvious variation. Thus, the claims lack inventive step; and
- On non-patentability under Section 3(d): Taiho compared the activity of the claimed compounds with Paclitaxel, a type of chemotherapy medicine, which is unrelated in structure. The closest compounds are those disclosed in D1, sharing the same core structure responsible for the desired activity. The claimed compounds are thus considered derivatives of known substances from D1. The compound claimed in the application did not demonstrate enhanced therapeutic efficacy over known substances, as required under Section 3(d).
Taiho contended that:
- The prior art D1 does not clearly direct a PSITA to the claimed invention. Specifically, examples 15 and 16 of D1 lack a halogen or C1–C6 alkoxy group at the R2 (3-position), instead featuring X3 or lower alkyl groups. The claimed R2 substitution in the application enhances oral absorbability and therapeutic activity over D1;
- While raising an objection under Section 3(d), the Controller did not clearly identify the 'known substance' in prior art D1 as required;
- The Controller did not consider the enhanced efficacy data in Table 21 of the Complete Specification showing increased oral absorbability of the claimed compounds of the invention;
- The grant of corresponding patents in major jurisdictions supports the patentability of the application; and
- Reliance placed on the DS Biopharma Ltd. v. Controller of Patents & Designs (DS Biopharma) judgment in support where the Court set out the steps that the Indian Patent Office (IPO) must follow before applying Section 3(d) of the Patents Act.
The Court, in its detailed analysis, addressed several key aspects of the case:
- The Court referred to the Supreme Court judgement in Novartis AG v. Union of India and noted that Section 3(d) sets a higher threshold for patentability of pharmaceutical and chemical substances than the general standard under Section 2(1)(j). Section 3(d) is crucial in assessing the patentability of pharmaceutical or chemical substances, specifically focusing on the "new form of a known substance."
- The court referred to the DS Biopharma order, reiterating its relevant extracts:
- What is the specific 'known' substance in question?
- How and why the claimed molecule(s) or substance(s) is a derivative or is otherwise a new form of a known substance? and
- Basis to assert that the alleged 'known' substance and the claimed molecule or substance have the same 'known' efficacy?
The Court noted that the ratio of DS Biopharma is fully applicable in the facts and circumstances of the present case.
- The Court held that the Controller failed to identify any of the three elements, particularly the 'known' compound, thereby impairing Taiho’s ability to adequately respond to the objection and undermining its right to a fair opportunity to defend the application. In the absence of such identification, there exists no legal obligation to establish the efficacy of the claimed compound.
- When considered in its entirety, Taiho has not been afforded a sufficient opportunity to address the objection under Section 3(d), as the objection was raised for the first time in the hearing notice without any explanation as to how or why it was applicable to the claimed invention.
- The Court ruled that to sustain an objection under Section 3(d) of the Patents Act, the following factors have to be clearly identified by the Controller in the hearing notice, so as to afford a reasonable opportunity to the applicant to respond to it:
- The 'known substance' with 'known efficacy';
- Clear explanation as to how and why the claimed substance is a derivative or otherwise a new form of a 'known substance'; and
- An objective comparison between the therapeutic efficacy of the claimed invention and that of the known substance.
- The Court stated that the lack of inventive step objection, tied to D1, should be reconsidered together with the Section 3(d) issue, as both rely on proper identification of the 'known substance' and efficacy comparison.
- The Court also noted that any research data demonstrating enhanced therapeutic efficacy, if submitted by Taiho may also be duly considered while re-examining the inventive step and Section 3(d) objection.
Finally, the Court disposed of the appeal, setting aside the Controller’s order. The Court remanded the case to the IPO for fresh consideration and another hearing opportunity for Taiho.
