Amendment from Method of Treatment to Product Claims Impermissible Under Section 59(1) of the Patents Act: Delhi High Court

“Changing an entire claim category from ‘method’ to ‘product’ cannot be a mere correction of an error”  - In a detailed and significant patent ruling on April 16, 2025, the Delhi High Court dismissed the appeal Against the refusal of their Indian Patent Application No. 201817047767 titled “ANTI-cMet ANTIBODY DRUG CONJUGATES AND METHODS FOR THEIR USE.” The decision, delivered by Justice Amit Bansal, reinforces the strict boundaries of Section 59(1) of the Patents Act, 1970, emphasizing that substantive amendments which enlarge the claim scope are impermissible.  

“The Appellants Are Seeking to Convert Method of Treatment Claims into Product Claims”

 The Court observed that the appellant originally filed a national phase application under the Patent Cooperation Treaty (PCT) in 2018, with claims exclusively directed to therapeutic methods using anti-cMet antibody-drug conjugates (ADCs) for treating cancers like non-small cell lung carcinoma (NSCLC). These method claims were non-patentable under Section 3(i) and failed to satisfy Section 2(1)(j) concerning industrial applicability.  

Upon receiving a First Examination Report, the appellants sought to amend the claims and filed a new set of eight claims, including a product claim for the anti-cMet ADC molecule.

 The Court held that:  

• “The appellant is seeking to convert the method of treatment Claims into

product Claims… The proposed amendments are not in the nature of correction or explanation or disclaimer… and are not permissible under Section 59(1) of the Act.”

“These Amendments Shift the Claimed Invention from Methods of

Treatment to Product/Composition – This Is Not a Mere Refinement”

 Rejecting the appellant’s submission that the product was inherently disclosed in the original claims and specification, the Court noted that:  

• “The as-filed specification… reflects that the original invention squarely resided in how to use these antibody-drug conjugates (ADCs) to achieve the therapeutic benefit, rather than attempting to protect the ADC molecules themselves as a separate patentable product.” The judgment critically emphasized that a standalone product claim introduces a substantially broader scope of protection and cannot be allowed at the amendment stage if it wasn’t claimed originally.

 “Even if the specification did contain the details… it was introduced primarily as a tool for treating cMet-expressing cancers. By recasting it as a general product claim, the appellant seeks a monopoly… far beyond the originally claimed method scope.”

“Allowance of Such Amendments Would Defy the Purpose of Section 59 of the Act”  

The Controller had refused the patent application on grounds that the amended claims conferred protection beyond the scope of the originally filed claims and thus violated the bar under Section 59(1).  

The Court upheld this reasoning, stating:  

• “Section 59 of the Act mandates that amendments must not introduce subject matter that extends beyond the content of the originally filed specification, nor enlarge the scope of the Claims.”

 Citing the Supreme Court’s verdict in Novartis AG v. Union of India, (2013) 6 SCC 1, the Court observed:  

• “The patent system should not develop along lines where the scope of the patent is determined not on the intrinsic worth of the invention but by the artful drafting of its claims.

 “Amendments Must Be by Way of Disclaimer, Correction or Explanation”  

The Court relied on its previous decisions in Nippon A & L Inc. v. Controller of Patents, 2022 SCC OnLine Del 1909 and Ovid Therapeutics v. Controller of Patents, 2024 SCC OnLine Del 875, reiterating that for an amendment to be valid under Section 59(1), it must:  

1. Be a disclaimer, correction, or explanation.

2. Incorporate an actual fact already disclosed.

3. Not introduce matter beyond the scope of original claims.  

4. Fall wholly within the original claim boundaries.

In contrast, the amendment by AbbVie introduced a new set of claims directed to a product and pharmaceutical compositions, which:

 “Were never previously pursued or disclosed as standalone inventions.”

“Allergan Case Distinguished: Amended Claims Here Do Not Retain

Disease Limitation”

The appellants had placed reliance on the High Court’s earlier decision in Allergan Inc. v. Controller of Patents, 2023 SCC OnLine Del 295, where method claims were successfully amended to product claims. But the Court distinguished it:

• “In Allergan… the amended claims pertained to the same disease as disclosed… In contrast, in the present case… the amended claims do not refer to any disease. Therefore… the amendments in the present case were broadening the scope.”

• The Delhi High Court ultimately held that:

• “The impugned order passed by the Controller refusing the subject patent application under Section 15 of the Act is upheld. There is no merit in the present appeal and the same is dismissed.”

• This judgment serves as a caution to patent applicants against using postfiling amendments to radically alter the nature of their claimed invention— especially from non-patentable subject matter (like therapeutic methods) to broader product protection.

Date of Decision: April 16, 2025