Reinforcing Section 3(d): Intermediates Must Demonstrate Therapeutic Efficacy

In a defining patent ruling, Zeria Pharmaceutical Co. Ltd. v. The Controller of Patents, the Hon’ble Delhi High Court reaffirmed the stringent threshold for patentability, especially concerning pharmaceutical intermediate compounds. The case, centred on critical interpretations of patentability under Sections 2(1)(ja) and 3(d) of the Patents Act, 1970 (hereinafter referred to as “the Act”).

Factual Background

Zeria Pharmaceutical (Appellant) filed a patent application no. 3630/DELNP/2011 titled “A COMPOUND REPRESENTED BY FORMULA (5a)”, on May 13, 2011, as a divisional patent application out of patent application no. 1090/DELNP/2007. The Controller (Respondent) refused the application on October 20, 2016, on the grounds that the subject application does not fulfil the criteria envisaged under Section 2(1)(ja), since the invention therein lacked novelty and inventive step in view of prior arts D1 and D2, and under Section 3(d).

Contentions of the Appellant

The Appellant argued that D1 “teaches away” from the claimed invention since it teaches a reaction wherein a compound of formula (5a) is avoided. It was further contended that the prior art D2 does not discloses the claimed methyl ester having the methoxycarbonyl group, and emphasized that selecting the methoxycarbonyl group required a non-obvious choice among multiple options. The Appellant also submitted that the impugned order is flawed, as the Controller failed to consider expert affidavit data demonstrating improved yield, purity, and reduced reaction time.

Finally, the Appellant contended that Section 3(d) ought not to apply to intermediates, since therapeutic efficacy is irrelevant in their context and process-related improvements should suffice.

Contentions of the Respondent

The Respondent contended that the claimed compound only differed from the known compound disclosed in D2 by having a methoxy group instead of an  ethoxy group, an obvious substitution for the person skilled in the art (PSITA). Further, the Respondent submitted that D1 and D2 are from the same applicant which suggests an attempt to extend protection of known compounds without substantial innovation.

Regarding Section 3(d), the Respondent submitted that the claimed compound has no enhanced efficacy, and that the data provided by the Appellant pertains to the process used for the preparation of hydrochloride form of the claimed compound rather than the claimed compound.

Hon’ble Court’s analysis and findings

While placing reliance on Novozymes v. Assistant Controller of Patents & Designs and Novartis Ag v. Natco Pharma Ltd., the Hon’ble Court held that the objection under Section 3(d) of the Act must first be assessed, followed by an examination of patentability under Sections 2(1)(j) and 2(1)(ja). Accordingly, the Court proceeded to analyse the following:

Section 3(d)- Enhanced Efficacy Requirement

The Hon’ble Court underscored that under Section 3(d), any new form of a known substance must demonstrate enhanced “therapeutic efficacy”. While the Appellant argued improved process, yields and purity, the Hon’ble Court held that these benefits do not equate to enhanced therapeutic efficacy, citing the Hon’ble Supreme Court’s landmark decision in Novartis v. Union of India. The Hon’ble Court also noted that the Appellant itself stated that since the claimed compound is an intermediate, it is not possible to determine the “therapeutic efficacy”.

Section 2(1)(ja)- Inventive Step

The Hon’ble Court affirmed that the claimed methyl ester compound was an obvious variant of compounds disclosed in D2. The substitution of methoxy for ethoxy was a predictable change for PSITA. The “teaches away” argument was also rejected, as D1’s alternative reaction did not explicitly discourage the claimed modification (Astrazeneca AB v. Torrent Pharmaceuticals).

Conclusion

The Delhi High Court dismissed the appeal, upholding the refusal under Sections 2(1)(ja) and 3(d). The Court emphasized that intermediates must show enhanced therapeutic efficacy.

This ruling reinforces the strict standards for pharmaceutical patentability in India, and highlights the judiciary's commitment to curbing evergreening.

Nandini Mittal 

Associate

nandini.mittal@iprattorneys.com