The refusal of a divisional application in India does not extinguish the parent patent, according to a decision handed down by the High Court of Delhi on April 24 2024. The existence of the parent patent is independent of the status of the divisional application. Furthermore, suppression of a fact that, if disclosed, would alter the outcome of the case can be regarded as a material fact.
The facts of the case
The patent in question is a compound with the molecular formula C28H36ClN5O3S and a chemical nomenclature of 5-chloro-N2-(2-isopropoxy-5-methyl-4-(piperidin-4-yl)phenyl)-N4-(2-(isopropylsulfonyl)phenyl)pyrimidine-2,4-diamine, also known as Ceritinib, a protein kinase inhibitor that is used in the treatment of non-small cell lung cancer. Novartis holds patent No. IN 276026 (IN'026) in India, related to "novel pyrimidine compounds and composition as protein kinase inhibitors".
Natco Pharma (Natco) filed a post-grant opposition to patent No. IN 276026 at the Indian Patent Office and launched Ceritinib capsules, in 2019, under the brand name “Noxalk” while its patent opposition was pending at the Indian Patent Office.
Novartis initiated an infringement action against Natco before the High Court of Delhi, in which the court observed that during the pendency of the post-grant opposition, the rights of a patentee subsist – though they may be crystallised once the opposition is decided. Thus, Natco ought to have waited for the decision in the post-grant opposition before launching its product.
Natco, in turn, challenged the validity of Novartis’s patent on the grounds of anticipation and obviousness. However, the court observed that the patent was prima facie valid.
Novartis granted an interim injunction
Natco was therefore enjoined, through an order dated January 9 2023, from selling/manufacturing Ceritinib by the High Court of Delhi, holding the patent infringement claim by Novartis to be valid. The court granted interim relief to Novartis due to the following reasons:
The court opined that obviousness from prior art was the determinative criterion based on which the court may ascertain whether the claim in the species patent was obvious from the teachings in the genus patent. The court approached this from the point of view of a person skilled in the art, with knowledge of the Markush formula, and considered the suggested substitutions and the properties of the product that the person skilled in the art desired to synthesise, having common general knowledge. And, based on that, whether they were in a position to arrive at the claim in the suit patent from the Markush formula in the genus patent.
The fact that even though the genus patent had remained in existence for a number of years, the species patent was not synthesised by anyone prima facie indicated that the species patent was not obvious from the teachings in the genus patent.
The court observed that Natco did not explain the reason to select a substituent from the several substitutions suggested in the prior art patent. Natco seems to have arrived at the molecular structure of Ceritinib by cherry-picking selected radicals from the several substituents suggested in the individual prior art patents of the Markush moiety claimed in each such cited prior art.
The inventive step as explained by Novartis was the feature of a tri-substituted N2-phenyl ring (linked to the core pyrimidine moiety by an amine linkage) in which one of the substitutions at R8 or R9 (as suggested in the Markush formula) is the pyrrolidinyl, piperidinyl, or azetidinyl ring, linked to the N2-phenyl ring by a carbon-to-carbon bond. None of the prior art patents cited by the defendant disclosed any linkage of a pyrrolidinyl, piperidinyl, or azetidinyl ring to the N2-phenyl ring by a carbon-to-carbon bond.
Natco moves to set aside the injunction
Instead of filing an appeal against the injunction order, Natco filed an interim application (IA 4636/2023) to set aside the interim relief granted to Novartis. In its application, it did not directly challenge the reasoning of the decision. However, it raised the ground that Novartis had filed a divisional application in respect of some of the claims in the suit patent. This was done as an objection was raised by the controller of patents regarding the unity of claims in the application for the suit patent.
Natco submitted that the objections raised by it, to contest the validity of the suit patent, were also raised by the Indian Patent Office in the first examination report (FER) objecting to the divisional application filed by the plaintiff, which was refused. Thus, it was incumbent on Novartis to disclose the filing of the divisional application and that it was refused. This aspect would seriously impact the ruling of the court and the interim injunction granted.
The court, however, refused Natco’s application to set aside the interim order, based on the following important factors:
The divisional application IN 5338/DELNP/2014 filed by Novartis was not rejected on the merits. There is no adjudication by the Indian Patent Office on the objections raised in the FER against the divisional application. The order passed in the divisional application was on the basis that “the applicant has not complied [with] objections and the applicant also stated that they do not wish to pursue the application”. Thus, it is clear that the divisional application was not rejected on the merits but because the applicant chose not to pursue the application.
Omitting, on the part of Novartis, to refer to the divisional application cannot, therefore, seriously impact the prima facie merits of the case.
Even assuming that the decision on the divisional application were to be regarded as on the merits, the court observed that the decision of the controller is not binding on the court. The court held that “when on an independent analysis on merits, this Court has found the suit patent not to be vulnerable to invalidity on any of the grounds envisaged in Section 64 of the Patents Act, the opinion of the Controller can hardly be cited as a ground for this Court to revisit, much less reverse, its decision.”
The court also noted that all the prior art cited by the controller in the FER against the divisional application had been considered while granting the interim injunction.
The ‘refusal’ of the divisional application does not, in fact or in law, extinguish the suit patent. The claim for a patent for Ceritinib stands granted in the suit patent, and until and unless the suit patent is invalidated, the patent remains valid.
