The DAPA Saga in the Indian Courts
By Dr Mohaan Dewan 

A decision handed down in July 2021, in the DAPA saga, by the Divisional Bench of the Delhi High Court, had some thought-provoking observations.

The saga started in September 2020, when AstraZeneca filed a suite of two sets of litigations against several pharma companies in India. In the first set of litigation, AstraZeneca relied on the Indian patent no. IN205147 (IN ‘147) that covered a host of chemical compounds having a general structure of C-aryl glucosides. This patent was set to expire in India on 2^nd October 2020. In the second set of litigation, AstraZeneca relied on the Indian patent no. IN235625 (IN ‘625) specifically related to Dapagliflozin (‘DAPA’). IN ‘625 patent is still in force and set to expire on 15^th May 2023. Under the Indian Patent Law, there is no provision for the extension of the term of the patent.

A short discussion of the two patents is now in order. Both patents related to the field of C-aryl glucosides. C-aryl glucosides are compounds that act as inhibitors of sodium-dependent glucose transporters found in the intestine and kidney (SGLT2) and therefore are useful for the treatment of Type-II diabetes mellitus.

History:

IN ‘147 claimed a number of structures of C-aryl glucosides (the patent was therefore referred universally as a genus patent) whereas IN ‘625 claimed a specific C-aryl glucoside structure which is popularly known as Dapagliflozin (DAPA) (the patent was therefore referred universally as a species patent).

Both patents in India, IN ‘147 and IN ‘625, claimed priority from a first US patent no. 6414126 and its ‘continuation-in-part’ i.e., US patent no.6515117, respectively. In the Indian Patent system, there is no provision of the ‘continuation-in-part’ process. A crucial fact that was not disclosed in India by AstraZeneca (then BMS) was the ‘continuation-in-part’. During the US prosecution, the claims of ‘continuation-in-part’ application were rejected by the Examiner on the grounds of “double patenting”. To overcome the objection, AstraZeneca was invited to file a terminal disclaimer making the ‘continuation-in-part’ patent co-terminus with the parent patent. By filing the terminal disclaimer AstraZeneca agreed to the expiry date of the “continuation in part-application” to be equivalent to the parent patent i.e. 2^nd October 2020. A crucial fact that was discovered during the trial in India was that opting for the terminal disclaimer was not brought to the attention of the Indian Patent Office. Had this fact been brought to the attention of the Indian Examiner/Controller, the Controller would have considered the second patent (IN ‘625) as a “patent of addition” and applied the terminal disclaimer rule, with the result that, patent no. IN ‘625 would have also expired on 2^nd October 2020.

Analysis:

The IN ‘147 patent covers the structure of C-aryl glucosides with several possible compounds. Out of a very large number of compounds disclosed in IN ‘147, only 80 were identified and synthesized. Each of the 80 compounds had the common property of inhibiting reabsorption of sugar in kidneys, resulting in excess sugar discharge through the body and each of these compounds varied considerably in efficacy, and thermodynamic stability. The genus patent IN ‘147 covered the general structure of Dapagliflozin (DAPA) but its precise structure was not disclosed. AstraZeneca asserted that DAPA was invented only after further research and later in point of time after the filing of the genus patent. Therefore IN ‘625 (the DAPA patent) fell in the category of the species patent. The word ‘species’ has the same connotation here as in Biology. 

The Delhi Trial Court, initially, and the Delhi Appellate Court, subsequently, both refused to grant an interim injunction to AstraZeneca. Notably, the Appellate Court went one step further and ordered AstraZeneca to pay costs of Rs 5,00,000/- (approximately $6,718) to each of the defendants.  

The following factors were considered by the Court:

• The two sets of infringement suits filed by AstraZeneca were redundant as they were filed for the same subject matter.
• Theview of the Court was that if AstraZeneca’s position was that DAPA was not disclosed and/or not known at the time of seeking patent IN ‘147 and was invented only subsequently and covered by IN ‘625, there could be no infringement by the defendant(s) of IN ‘147 by manufacturing and/or selling DAPA. It was discovered that in a suit filed by AstraZeneca in the District Court of Delaware, USA, against one of the defendants, AstraZeneca had in fact asserted that DAPA was disclosed in the US equivalent of IN ’147. The general structure in example 12 of IN ‘147 (the closest structure to DAPA of IN ‘625) differed from the structure of DAPA only by the substitution of methyl with ethyl group. Such a substitution is prima facie obvious for a person skilled in the art. Therefore, it could not be said that IN ‘625 was a technical advancement. The attempt to file IN ‘625 could be considered as an intention of “ever greening” of IN ‘147. The provisions of Section 8 of the Indian Patents Act are mandatory, and there was a duty of disclosure on BMS who assigned the Patent to AstraZeneca to fully disclose the facts that transpired at the USPTO. Had these facts been brought to the attention of the Controller who examined IN ‘625, the Controller may have come to a different conclusion.

The Court agreed that a credible challenge was raised by the defendants against IN ‘625 and the fact of anticipation in view of the disclosure in IN 147. The only difference between the structures disclosed in IN 147 and claimed in IN 625 is a replacement of a methoxy group by an ethoxy group. A person skilled in the art understands that a methoxy and an ethoxy group are homologous and one could easily replace the other without any experimentation. There is, thus, a possibility that IN 625 shall appear to be anticipated in view of disclosure in IN 147. The plaintiff also failed in its duty to apprise the Indian patent office as mandated under section 8. The court has also directed the defendants to place on record all the financial transactions regarding the sale of DAPA. The law states that a new patentable product must show technical advancement and the difference in efficacy with respect to the closest prior art. In case the defendants can prove technical advancement or efficacy of IN 625 with respect to IN 147, the subject matter of the former is patentable. However, the dice are loaded against the plaintiff. It will be interesting to see how the saga will play out during the trial.