The Delhi High Court dismissed Zeria Pharmaceutical Co. Ltd.’s (the ‘Appellant’) appeal against the Controller of Patents' (the ‘Respondent’) refusal order of a divisional patent application (3630/DLNP/2011). The ruling focused on a novel intermediate compound rejected for lack of inventive step and for failing to demonstrate enhanced therapeutic efficacy.

Case Background 

Zeria filed a divisional application 3630/DLNP/2011, claiming a methoxycarbonyl intermediate (Formula 5a) for synthesizing aminothiazole derivatives. The compound differed from the prior art by the substitution of a methoxycarbonyl group instead of an ethoxycarbonyl group. The Controller refused the subject application for lack of inventive step (citing D1: EP 0994108 A1; D2: US 5981557 A) and owing to it being a derivative lacking enhanced therapeutic efficacy.

Appellant’s Arguments: 

The Appellant argued that the Controller erroneously relied on document D1, classified as general state of the art (category "A" in ISR), which is irrelevant for inventive step and "teaches away" from the claimed compound (5a). The Appellant noted that D2 lacked specific disclosure of the methoxycarbonyl methyl ester, making its selection non-obvious over D1 and D2. The Appellant also contended that the Controller ignored an expert affidavit supporting inventive step, and erred in rejecting enhanced efficacy despite experimental data showing higher yield, shorter reaction time, and fewer impurities. 

Respondent’s submissions: 

The Respondent contended that the claimed intermediate compound was obvious due to the minor substitution of methoxy for ethoxy on known prior art, which is considered routine for skilled artisans. The Respondent asserted that no data demonstrated enhanced efficacy in the final pharmaceutical product compared to existing compounds, rendering it a mere new form lacking therapeutic efficacy. The Respondent further argued that the submitted evidence and affidavits failed to establish inventive step or therapeutic efficacy.

Court’s Analysis and Decision 

Patentability: 

The Delhi High Court held that an assessment under Section 3(d) of the Patents Act (the ‘Act’) (which deals with the patentability of new forms of known substances) is a primary consideration and must be assessed before other patentability criteria, while clarifying that novelty (under Section 2(1)(j) of the Act, does not exempt applications from Section 3(d) of the Act). The court found the claimed compound to be a mere derivative of the known compound in prior art D2. Since the Appellant admitted that it was not feasible to demonstrate therapeutic effect and failed to provide data showing enhanced therapeutic efficacy over the prior art, the invention fell within the ambit of Section 3(d) of the Act- as a mere derivative lacking enhanced efficacy.

Lack of inventive step under Section 2(1)(ja) of the Act:

The Court agreed with the Controller that substituting "ethoxy" with "methoxy" was an obvious modification for a person skilled in the art, based on prior art D1 and D2, and hence, the claimed compound lacked inventive step under Section 2(1)(ja) of the Act. The Court clarified that any trivial, routine changes without creativity does not constitute an inventive step.

Accordingly, the Court upheld the Controller’s refusal to grant the patent, and dismissed the appeal.