Delhi High Court defines enhanced therapeutic efficacy in setting aside Indian Patent Office refusal order

In Ischemic LLC v The Controller of Patents, the Delhi High Court has set aside an Indian Patent Office (IPO) refusal order and remanded the matter back to it for reconsideration (2023 DHC 8496). The invention in question related to a specific isomer of a compound useful for treating ischemia (stoppage of blood flow to any organ in the body) and ischemia-reperfusion injuries (ie, injuries resulting from restoration of blood flow following an ischemic episode), which the IPO had held as non-patentable under Section 3(d) of the Patents Act. 

The appellant assailed the refusal on the grounds that the IPO’s order was unreasoned in its rejection under Section 3(d). The court’s attention was invited to the in vitro and in vivo data that was present in the specification and the clinical trial data submitted during the prosecution stage to demonstrate enhanced therapeutic efficacy of the claimed isomer. Additionally, it was impressed upon the court that the IPO had neither referred to, nor discussed, two experts’ findings, which had endorsed the view that the claimed isomer’s enhanced therapeutic efficacy was both surprising and unexpected. 

For its part, the IPO rebutted the plaintiff’s contentions and asserted that while some data had been submitted, the correlation between the data and the claim for enhanced therapeutic efficacy was unclear and not readily forthcoming from the submissions that were filed at a stage subsequent to the oral hearing proceedings.  

After perusing the data contained in the specification and hearing the parties at length, the court disagreed with the IPO’s position. Relying on the Supreme Court’s landmark judgment in Novartis AG v Union of India, the court held that:

Whenever any patent applicant wishes to place on record and demonstrate therapeutic efficacy, to satisfy the requirements laid down in Novartis AG (supra), the same has to be done precisely. The applicant must ensure that comparative tables and a clear explanation as to the manner in which the new form of the known substance has significant enhancement in therapeutic efficacy is placed before the patent office during prosecution. The same could be in the form of comparative tables in-vitro and in-vivo data as also clinical trial data.

The court also indicated that patent applications – at the time of filing – ought to contain some data that demonstrates enhancement of efficacy. However, if additional data becomes available at a later stage, it should be placed before the IPO prior to the date of the final hearing. Referring to AstraZeneca AB and Ors v Intas Pharmaceuticals Limited and Ors, the court held that data filed after the priority date of a patent application would be permissible, subject to it having a basis in the complete specification (2020 DHC 3125). Acknowledging the complexities and protracted process of drug development, as elaborated upon in the Calcutta High Court’s decision in Oyster Point Pharma Inc v The Controller of Patents and Designs, the court concluded that “clinical trial data can be submitted – but only to support the stand of the applicant in the specification to demonstrate a significant enhancement of the therapeutic efficacy” (MANU/WB/1544/2023).

This decision brings much-needed clarity to Section 3(d) of the Patents Act and ought to serve as a useful guide for the prosecution of future patent applications.