Drug Patents and their Evergreening Conundrum

Hyderabad-based Natco Pharma Ltd (appellant) has recently been granted interim relief by the Division Bench of the Delhi High Court in a patent dispute with Novartis AG (respondent) over an active pharmaceutical ingredient/ pharmaceutical product/ formulation containing Eltrombopag olamine (ELT-O), a salt of Eltrombopag (ELT). The Court overturned a decree of permanent injunction dated December 13, 2021, issued by the learned Single Judge in response to Novartis's application to protect its patent IN 233161 (IN’ 161) for “Eltrombopag Olamine." Eltrombopag olamine, a salt of Eltrombopag, claimed to enhance platelet production in patients with thrombocytopenia.

Natco had launched its generic version “TROMBOPAG^TM” in the year 2021. However, Novartis objected to it, arguing that the same is infringing its patent IN’ 161, granted on March 27, 2009 (species patent) claiming that it had the core active pharmaceutical ingredient “Eltrombopag Olamine”, marketed by Novartis as “REVOLADE^TM” and “PROMACTA^TM”. The patent IN’161 was filed as a national phase PCT application PCT/US2003/16255 dated May 21, 2003.

The application for interim relief was allowed by the learned Single Judge restraining Natco from manufacturing, using, selling, distributing, advertising, marketing, exporting, offering for sale, importing or dealing in any manner in API, pharmaceutical products, or formulation containing ELT-O either separately or in combination with any other compound, infringing the suit patent, either under the brand “TROMBOPAG^TM” or any other brand.

In response to the same, Natco has filed this appeal seeking an interim relief under order XXXIX Rules 1 and 2 of the Code of Civil Procedure, 1908 (CPC).

The controversy in this appeal primarily revolves around whether Natco has presented a credible challenge to the validity of the patented suit and whether Novartis was entitled to an interim injunction preventing Natco from distributing ELT-O, marketed under the trade name TROMBOPAG^TM. At the heart of the dispute lies the question of whether Novartis has the right to patent ELT-O, even though it was previously covered under Patent IN 213176 (IN’ 176) (genus patent), which expired before Natco launched its product. Natco claims that this is an attempt to evergreen the patent in respect of ELT. The Patent IN’176 expired on May 24, 2021. Thus, ELT-O was not entitled to any patent protection after May 24, 2021.

Natco's primary challenge stemmed from ELT-O not meeting the requirements set out in Section 3(d) of the Act. This challenge was coupled with claims of the patent being invalid due to prior claiming, prior publication, lack of novelty, lack of inventive step, misrepresentation, and failure to disclose information under Section 8 of the Act.

Novartis contended that despite ELT-O being a salt of ELT, it qualifies for an exception under Section 3(d) of the Act due to its significantly greater therapeutic efficacy, attributed to its higher bioavailability.

1. On Natco’s principal challenge to the validity of the IN’161: The Division Bench noted that the present dispute centers around the tension between a 'genus patent' and a 'species patent', terms not explicitly defined in statutes. 'Genus patent' typically refers to broad patents covering multiple compounds with a shared core and inventive concept, commonly seen in pharmaceuticals where it includes molecules with therapeutic value used in formulations. On the other hand, 'species patent' refers to specific compounds falling within the broad claims of a 'genus patent.'

Referring to the ruling in Novartis AG ν. Union of India & Ors., Merck Sharpe & Dohme ν. Glenmark Pharmaceuticals and Astrazeneca AB & Anr. v. Intas Pharmaceuticals Ltd. , the Division Bench noted that when both a genus patent and a species patent are claimed by the patentee, the question arises whether the monopoly granted for the substance can be extended because it's covered by a patent that expires later.

2. Section 3(d) of the Act: The Division Bench observed that Novartis did not assert any increased therapeutic effectiveness in its patent application. The only additional advantage claimed for ELT-O was "improved solubility and bioavailability." The Bench reconsidered the interpretation of Section 3(d) based on the Supreme Court's ruling in Novartis AG ν. Union of India & Ors. It concluded that improved bioavailability doesn't equate to greater therapeutic efficacy. The Division Bench observed that:

“The assumption that enhanced bioavailability necessarily leads to higher therapeutic efficacy is too broad an assumption. It is desirable to have optimal pharmacokinetic parameters. In cases where a formulation has side effects, a lower bioavailability may be more beneficial.” 

Additionally, the Division Bench, citing the decision in Merck Sharpe & Dohme ν. Glenmark Pharmaceuticals, stated that the determination that “Natco didn't present a credible challenge to the validity of IN’ 176” is incorrect. According to the Division Bench, the question of whether ELT-O was disclosed in IN’ 176 is a disputed issue. Nonetheless, considering that ELT-O wasn't disclosed in IN’ 176 would be essential to assess its enhanced efficacy compared to compounds disclosed in IN’ 176.

3. Coverage νs. Disclosure: The Division Bench relying on Merck Sharpe & Dohme ν. Glenmark Pharmaceuticals, and Astrazeneca AB & Anr. v. Intas Pharmaceuticals Ltd.,  stated that it's important to clarify that a broad claim, known as a Markush claim, covering numerous compounds with a common inventive concept, is acceptable as long as it's not excessively broad or vague. The disclosure must be interpreted in the context of the invention being patented. Therefore, when an active therapeutic ingredient with therapeutic value is claimed and disclosed, it may be patentable. Protection for such a claim would extend to disclosed substances, as well as those not specifically disclosed but obvious to and/ or anticipated by a person skilled in the art. The gap between coverage and disclosure should only include substances anticipated or obvious to a person skilled in the art, not extending to substances or products neither disclosed nor obvious or anticipated by a person skilled in the art.

Additionally, the Division Bench concurred with Natco's assertions that the rulings in Merck Sharpe & Dohme ν. Glenmark Pharmaceuticals, and Astrazeneca AB & Anr. v. Intas Pharmaceuticals Ltd. are two sides of the same coin. Natco specifically contended that ELT-O, which was being sold under the brand name “PROMACTA^TM”, was covered under Claim 1 of US patent 7160870 (US’870). Undisputedly, Claim No.1 of US’870 is Claim No.6 of IN’176. It was contended on behalf of Natco – and not controverted by Novartis – that the predecessor-in-interest of Novartis had applied for a Patent Term Extension (PTE) for US’870 to compensate for the time spent in obtaining regulatory approvals.

In alignment with Natco's stance, the US Food and Drug Administration (USFDA) had also sent a communication dated February 22, 2011 to the US Patent Office confirming that US’870 (which is the counterpart of IN’176) claims PROMACTA^TM (Eltromopobag Olamine). Additionally, Novartis provided a “statement regarding the working of patented invention on commercial scale in India” in Form 27 regarding IN’176 and IN’161, indicating that Novartis had implemented the patented inventions commercially in India based on ELT-O.

The Division Bench emphasized that if the complete specifications adhere to Section 10 of the Act and the claim is valid, any compound covered within the claim would be included in the complete specifications. Consequently, a second patent for such a fully covered compound would be susceptible to challenge on grounds of prior claiming [under Section 64(1)(a) of the Act] and lack of novelty [Section 64(1)(e) of the Act] and lack of inventive steps [Section 64(1)(f) of the Act].

In view of the above, the Division Bench held that Natco had indeed met the threshold for presenting a credible challenge to the validity of IN’161. The Court overturned the permanent injunction order issued by the learned Single Judge. Furthermore, the Division bench concluded that delving into other issues was unnecessary, given that the term of IN’161 has expired on May 21, 2023, and there was no need for further judicial orders.

The Division Bench's ruling effectively prohibits the practice of evergreening a patented product, a strategy commonly adopted by pharmaceutical companies to extend the duration of their patents. Typically, this involves making minor alterations to the drug, such as introducing new formulations, dosage forms, or modifying the active ingredients, and subsequently securing new patents for these adjustments. This enables the pharmaceutical company to retain exclusive rights to sell the drug for an extended period, effectively delaying the introduction of generic versions into the market. While this can be financially advantageous for the company, allowing them to maintain market dominance and maximize profits from the drug, it can also be controversial. It has the potential to stifle competition and keep drug prices high, which may limit access to affordable medication for patients. For developing countries like India, access to affordable medication is of paramount importance.

About the authors: Mahua Roy Chowdhury is the Managing Partner of Royzz & Co. Anupriya S is a Senior Associate at the Firm.

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