Therapeutic Efficacy: A Requirement Under Section 3(d), Not Section 3(e) of the Indian Patents Act

The Hon’ble High Court at Calcutta has recently passed an Order allowing an Appeal from the Order of the Controller refusing an application on the grounds of Section 2(1)(ja)- lack of inventive step and Section 3(e) [Order dated July 4, 2025, in IPDPTA/8/2022]. The case arose from a second round of litigation involving the same patent application.

The first refusal was challenged by way of a Writ Petition before the Calcutta High Court, which, by its Order dated June 18, 2019, remanded the matter back to the Controller for fresh consideration. The Hon’ble Writ Court in its order dated June 18, 2019, was pleased to observe that – “The impugned order proceeds on the basis of section 3(d) of the Act of 1970 while considering the application for grant of Patent. The notice which the authorities issued was under section 3(e) read with section 2(1)(ja) of the Act of 1970”.

On remand, Learned Controller, without referring to the elements of section 3(d), while dealing with section 3(e) in the Order –

• Sustained the objection under Section 3(e).
• Held that enhancement of bioavailability alone does not establish synergism and requires therapeutic efficacy for the purpose of overcoming Section 3(e).
• Incorrectly linked the need to show therapeutic efficacy [a Section 3(d) criterion] with the assessment under Section 3(e).
• Conflated pharmacokinetic properties (like bioavailability) with synergistic effects, which are required to overcome a Section 3(e) objection.

LEGAL DISTINCTION BETWEEN THE PROVISIONS

It is important to understand the distinction between Sections 3(d) and 3(e)

Key elements of Section 3(d): New Forms of Known Substances

• Purpose: To prevent evergreening of patents, especially in pharmaceuticals.

• Scope: Applies to new forms of known substances (e.g., salts, esters, polymorphs).

• Patentability Condition: The new form must demonstrate enhanced efficacy over the known substance.

• Key Focus: Therapeutic efficacy in pharmaceuticals; now also interpreted to include biochemical substances.

Example: A new crystalline form of a known drug must show better therapeutic effect, not just improved stability or bioavailability.

Key elements of Section 3(e): Mere Admixture of Substances

• Purpose: To prevent patents on simple mixtures that do not result in a synergistic effect.

• Scope: Applies to compositions or combinations of known substances.

• Patentability Condition: The composition must show a synergistic effect— i.e., the combined effect must be greater than the sum of individual effects.

• Key Focus: Compositional synergy, not just physical or chemical combination.

Example: A mixture of two known enzymes must show a combined effect that is significantly better than each enzyme alone.

Fundamental Differences

It has to be understood that objective of Section 3(d) is to prevent the grant of a patent on an invention directed to the new forms of a known substances, while the objective of Section 3(e) to prevent the grant of patent on an invention directed to mere admixtures of two or more substances.

Coming to the test of patentability in case of 3(d), it is to be understood that the derivatives of known substances have enhanced efficacy and in case of pharmaceutical inventions, therapeutic efficacy. Primarily 3(d) is tool in law to prevent ever-greening of patent protection of known substances. On the other hand, the test of patentability in case of section 3e is to examine whether there is synergy between the ingredients of the composition / combination where they are mixtures of two or more substances.

In the Order of the Controller which has been set aside by the High Court, the ‘efficacy’ component of section 3(d) was read into section 3(e) and that is the main error in the Order passed by the Controller. If synergism leads to better bioavailability of the mixture as compared to the bioavailability of individual components of the mixture in isolation when added separately, it is a good case for the grant of a patent, if the better bioavailability is unpredictable, unexpected and surprising having regard to the known properties of the individual substances.

THE FINDINGS OF THE COURT

The Court found that the Controller misapplied Section 3(e) by requiring demonstration of enhancement of therapeutic efficacy, which is not relevant under this section. The Hon’ble Court found that the Controller’s finding that bioavailability alone cannot establish synergism was incorrect. Further there is a mix-up of Section 3(d) and 3(e) based on a misconception of law in requiring therapeutic efficacy for the purpose of overcoming an objection under Section 3(e).

The rejection on the ground of lack of inventive step under Section 2(1)(ja) was also held to be unsustainable.

CONCLUSION

This Order of the High Court clarifies an important jurisprudential distinction in Indian Patent Law:

1. Synergism (Section 3(e)) and therapeutic efficacy (Section 3(d)) must be evaluated independently.
2. A misapplication of these provisions can render the Controller’s order vulnerable to reversal.

Authored By: Mr. Mitul Dasgupta, Advocate and Mr. Dominic Alvares, Patent Agent and Advocate

Mr. Mitul Dasgupta, works as an Advocate and Mr. Dominic Alvares, works as a Patent Agent and Advocate at S MAJUDAR & CO. cal@patentindia.com