Boehringer Ingelheim Pharma GmbH & Co. KG & Anr. filed multiple suits before the Delhi High Court against various Indian pharmaceutical companies, including Vee Excel Drugs and Pharmaceuticals Pvt. Ltd., seeking a permanent injunction to restrain the defendants from infringing Indian Patent No. IN 243301. The case, CS(COMM) 239/2019 and connected matters, was adjudicated by Hon’ble Mr. Justice Amit Bansal, with the judgment reserved on 27th January 2023 and delivered on 29th March 2023. The neutral citation for the judgment is 2023:DHC:2272. The plaintiffs contended that the defendants were manufacturing and selling Linagliptin-based pharmaceutical products, thereby infringing their patent covering "8-(3-AMINOPIPERIDIN–1–YL)-XANTHINE COMPOUNDS." They argued that the patent was validly granted and that their rights under Section 48 of the Patents Act, 1970, entitled them to an exclusive monopoly over Linagliptin formulations in India. The plaintiffs had previously obtained an interim injunction restraining the defendants from manufacturing and selling Linagliptin tablets.
The defendants countered that the plaintiffs' patent IN 243301 was an attempt at "evergreening," as Linagliptin had already been claimed in an earlier genus patent, IN 227719, which expired on 21st February 2022. They asserted that the plaintiffs were attempting to extend their monopoly beyond the permissible twenty-year patent term by obtaining a species patent that covered the same invention as the genus patent. The defendants also challenged the validity of the plaintiffs' patent under multiple provisions of the Patents Act, including Section 64(1)(a) (prior claiming), Section 64(1)(f) (lack of inventive step), and Section 3(d) (mere discovery of a new form of a known substance). They argued that Linagliptin, as a Markush structure, was already disclosed and protected under the earlier patent, and thus, any attempt to extend its exclusivity was impermissible.
The plaintiffs, in response, submitted that Linagliptin was specifically claimed only in the species patent IN 243301 and was distinct from the broader genus patent IN 227719. They contended that the suit patent had been successfully enforced in multiple jurisdictions, including China, and that no pre-grant or post-grant oppositions had been filed against it. They further argued that once a patent was granted, the onus was on the defendants to demonstrate its invalidity with cogent evidence. The plaintiffs relied on the judgment in FMC Corporation & Anr. v. Best Crop Science LLP & Anr., (2021) 87 PTC 217, to argue that merely raising a challenge was insufficient to deny an injunction unless the challenge was credible. They also cited National Research Development Corp. of India v. Delhi Cloth & General Mills, (1979 SCC OnLine Del 206), to claim that old patents with established commercial success should be presumed valid for interim relief purposes.
The defendants, on the other hand, relied on AstraZeneca AB & Anr. v. Intas Pharmaceuticals Ltd., (2021) 87 PTC 374 (DB), to argue that the suit patent was vulnerable to revocation due to prior claiming and evergreening. They contended that the plaintiffs had admitted in multiple proceedings worldwide that Linagliptin was covered under IN 227719. They emphasized that Linagliptin was the only commercial embodiment of both patents, as evidenced by the plaintiffs' identical Form 27 working statements for IN 227719 and IN 243301.
The court analyzed whether an older patent should be presumed valid for granting an interim injunction. Referring to Bishwanath Prasad Radhey Shyam v. Hindustan Metal Industries, AIR 1982 SC 1444, the court reaffirmed that Section 13(4) of the Patents Act does not warrant the validity of a patent merely because it has been granted. The court also rejected the six-year rule discussed in National Research Development Corp. (supra), stating that in India, the presumption of validity does not arise merely due to a patent's age or commercial success. The judgment in F. Hoffmann-La Roche & Anr. v. Cipla Ltd., ILR(2009)Supp.(2)Delhi 551, was cited to emphasize that even patents that survive pre-grant and post-grant oppositions can still be challenged on new grounds in revocation proceedings.
The court then examined the issue of prior claiming under Section 64(1)(a). It noted that a species patent could be invalidated if the genus patent had already claimed the same subject matter. A comparative analysis of the claims of IN 227719 and IN 243301 showed substantial structural similarity, leading to the conclusion that Linagliptin was indeed covered by the genus patent. The court also referred to the International Search Report (ISR) of the PCT application for IN 243301, which categorized the genus patent as an ‘X’ reference, indicating that Linagliptin lacked novelty and inventive step. The court found this persuasive evidence that the plaintiffs’ claim of Linagliptin being separately patentable was untenable.
On the issue of evergreening under Section 3(d), the court analyzed whether the plaintiffs had demonstrated any enhanced efficacy of Linagliptin over the broader genus patent. The court cited Novartis AG v. Union of India, (2013) 6 SCC 1, where the Supreme Court held that mere discovery of a new form of a known substance without improved therapeutic efficacy is not patentable. The plaintiffs failed to show any significant enhancement in efficacy, leading the court to conclude that the suit patent was vulnerable under Section 3(d).
The court held that the defendants had established a credible challenge to the validity of the suit patent. Following the standard laid down in F. Hoffmann-La Roche v. Cipla (supra), it ruled that a credible challenge at the interim stage is sufficient to deny an injunction. The court found that the balance of convenience lay in favor of the defendants, as the plaintiffs had already enjoyed a twenty-year monopoly under IN 227719. Additionally, the defendants' Linagliptin-based products were significantly cheaper than the plaintiffs' imported versions, making affordability and public interest key considerations. The court also noted that monetary damages would be an adequate remedy if the plaintiffs ultimately succeeded at trial.
Consequently, the Delhi High Court denied the plaintiffs’ application for an interim injunction, allowing the defendants to continue manufacturing and selling Linagliptin products.
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