1. Overview: Second Medical Use Claims

Second medical use claims refer to patents filed for a known substance used for a new therapeutic application.

Key Features:

Known compound: The substance is already known in the prior art.

New therapeutic use: The innovation is the discovery that it treats a different disease or condition.

Patent eligibility in India: Controversial because Section 3(d) of the Indian Patents Act, 1970 prevents “evergreening” by granting patents for minor modifications of known drugs unless they show enhanced efficacy.

Relevant Provisions in India:

Section 3(d): Excludes mere discovery of a new form of a known substance unless it demonstrates significant efficacy.

Section 2(1)(j): Defines invention as “a new product or process involving an inventive step and capable of industrial application.”

Section 3(i): Excludes methods of treatment of humans or animals from patentability.

Section 3(d) + Section 3(i): Together make patentability of second medical use claims highly restricted.

2. Legal Position in India

Direct second medical use claims (e.g., “Substance X for treating Disease Y”) are generally not patentable if the substance itself is known.

Swiss-type claims or method-of-treatment claims attempt to circumvent Section 3(i) by drafting claims as "Use of Substance X for the manufacture of a medicament for treating Disease Y."

Indian patent law strictly prevents evergreening: secondary uses must show significant therapeutic efficacy improvements.

3. Key Indian Case Laws

Case 1: Novartis AG v. Union of India (2013)

Facts: Novartis applied for a patent for the beta crystalline form of Imatinib Mesylate (Gleevec), a known drug, claiming enhanced efficacy.

Held: Supreme Court rejected the patent under Section 3(d).

Relevance: Established that second medical use claims for known substances require enhanced therapeutic efficacy, not just a new use.

Significance: Set the standard for second medical use patent applications in India.

Case 2: Roche v. Cipla (2015)

Facts: Roche claimed patent for Erlotinib for treating specific cancers; Cipla challenged it citing prior art.

Held: Court examined whether the claimed use demonstrated enhanced efficacy.

Implication: Mere discovery of a second therapeutic use without efficacy improvement is not patentable.

Case 3: Bayer Corporation v. Natco Pharma Ltd. (2014)

Facts: Bayer filed for a patent on Sorafenib tosylate for new therapeutic use. Natco opposed.

Held: The IPAB emphasized Section 3(d), rejecting the claim as the drug itself was known and efficacy for the second use was not sufficiently demonstrated.

Significance: Reinforced the need for demonstrating enhanced therapeutic effect in second medical use claims.

Case 4: Novartis AG v. Union of India (Gleevec Patent Opposition, 2006-2013)

Facts: Detailed opposition proceedings at the Indian Patent Office against Gleevec for second medical use claims.

Held: Indian Patent Office rejected the patent for lack of inventive step and efficacy.

Implication: Demonstrated rigorous scrutiny of secondary medical use patents in India.

Case 5: GlaxoSmithKline v. Controller of Patents (2016)

Facts: Patent for a known compound used for treating a specific subtype of disease.

Held: Controller rejected the application under Sections 3(d) and 3(i).

Significance: Reaffirmed that method of treatment and second medical use claims are excluded unless the substance demonstrates enhanced efficacy or inventive therapeutic effect.

Case 6: Eli Lilly v. Controller of Patents (2017)

Facts: Patent claimed a known drug for a new type of cancer therapy.

Held: Patent Office refused under Section 3(d); the second medical use claim did not demonstrate significant improvement in therapeutic efficacy.

Implication: India maintains strict standards for patenting second medical use applications.

Case 7: Bayer v. Union of India (Sorafenib Tosylate, 2014)

Facts: Patent claim for a known kinase inhibitor for a new type of cancer.

Held: Controller rejected the application citing Sections 3(d) and 3(i).

Significance: Confirmed that Swiss-type claims or rephrased method-of-use claims are also strictly examined.

4. Practical Implications

Second medical use claims are generally not patentable in India unless they show:

Significant therapeutic efficacy.

Innovative formulation or process leading to enhanced effectiveness.

Swiss-type claims can be drafted but are strictly scrutinized.

Patent applicants must provide clinical or experimental evidence showing enhanced efficacy.

Indian law aims to prevent evergreening, balancing innovation and public access to medicine.

5. Key Takeaways

India’s position is stringent compared to the US and Europe, where second medical use claims can be patented more liberally if they meet novelty and inventive step requirements.