Delhi High Court clarifies scope of product-by-process claims in landmark pharma ruling

The Delhi High Court has adjudicated on the complexities associated with the assessment and infringement of so-called ‘product-by-process’ claims. On 24 July 2023 the court dismissed interim injunction applications filed by Vifor International against the defendants: MSN Laboratories, Dr Reddy’s Laboratories, Corona Remedies and Virchow Biotech (CS(COMM) 261/2021).

Vifor filed three separate suits, seeking interim injunctions to prevent the defendants from infringing its patent (221536) called “Water Soluble Iron Carbohydrate Complex and a Process for Producing Water Soluble Iron Carbohydrate Complex”, which relates to ferric carboxymaltose (FCM).

Vifor sought protection for a product using FCM – used for intravenous treatment of iron-deficiency anaemia. It asserted that while Claim 1 of the suit patent was a product per se claim for FCM, the process elements used to describe the end product that formed the claim’s subject matter were not limiting. In particular, the patent contained Claim 1 in the product-by-process format in addition to dependent claims, some of which were directed to the process to prepare the product, which did not limit the claim to mandate the use of the process. Vifor said that it had acquired the exclusive right under Section 48 of the Patents Act 1970 to prevent third parties from making or using the FCM product obtained directly from the process that the suit patent protects – or any other process.

Conversely, the defendants contended that they arrived at an entirely different process. Therefore, the use of such a process to produce FCM would not amount to infringement.

The court’s findings

The court held in favour of the defendants and refused to grant an interim injunction, stating that the process of the defendants did not infringe Vifor’s patent.

Assessment of patentability of product-by-process claims

The court referred to the Guidelines for Examination of Patent Application in the Field of Pharmaceuticals and negated Vifor’s stand that the concept of a product-by-process claim is unknown in patent law and practice in India. Holding that the Indian Patent Office recognises the existence of such claims and has laid down the pre-requisites for assessment of novelty, the court concurred with the defendants and asserted that the patentability of a product-by-process claim depends upon the product itself if it does not depend upon the production method, which highlights that ‘process’ terms in such claims are limitations but not additional features of the concerned product.

Principles of claim construction to determine scope of claims

On the issue of understanding the principles of claim construction and the scope of the claims, the court referred to the preamble of Claim 1 of the suit patent, which recited “water-soluble iron carbohydrate complexes” and the phrase “obtainable from” in the transition phase. The court rejected Vifor’s contention that the use of the words ‘obtainable from’ was a description of one way that FCM can be produced. It noted that the limitation to the product by the process is prima facie evident and that the Claim 1 of the patent does not cover any or all processes that may be used to obtain FCM.

Understanding the scope of infringement of a product-by-process claim

Further, to assess whether the suit patent claims were infringed by the defendants, the court compared Vifor’s process to that of the defendants. Defendants MSN and Dr Reddy’s Laboratories were claiming for a process of manufacturing FCM by using oxone, an oxidising agent different from aqueous hypochlorite – as used by Vifor. The court also noted that Corona Remedies claimed to have used starch hydrolysate with a dextrose equivalent value greater than 20 as a starting material, which is different from Vifor’s starting material: maltodextrin with a dextrose equivalent value of less than 20.

Finding that the defendants’ process was different to Vifor’s product-by-process claim, the court concluded that the defendants’ process did not trespass onto the scope of Claim 1 of the suit patent, which is limited by a particular process.

On the issue of balance of convenience, the court ruled in favour of the defendants. The court permitted the defendants to launch their FCM product with the caveat that they cannot use a process or set of processes covered under the suit patent.

Looking ahead

This judgment is the first of its kind in terms of a limited assessment of infringement of a product-by-process patent. The patent community is looking toward a more detailed order after the trial.   

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