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First posted on spicyip.com on May 31, 2010
Claim 1 of patent 207232 provides: The compound 2-(2-amino-l,6-dihydro-6-oxo-purin-9-yl) methoxy-3-hydroxy-l-propanyl-L-valinate or a pharmaceutically acceptable salt thereof, in the form of its (R)- or (S)-diastereomers, or in the form of mixtures of the two diastereomers.

The reasoning for §3(d) is based upon an obviousness analysis (§§ 2(1)(j), 2(1)(ja) inventive step). But the decision cannot substitute an obviousness analysis for the analysis required under § 3(d), because § 3(d) sets a higher bar than the inventive step analysis.

In this case, the mono ester was demonstrated to have more bio-availability compared to that of bis ester of ganciclovir. But the patent office did not consider it to be efficacy. The decision stressed that efficacy and bio-availability are two different concepts and are not the same. The decision discussed the definition of efficacy as therapeutic effect being independent of property (i.e. bio-availability) but did not provide any further detail. The decision then concluded that Claim 4 ( A compound according to Claim 1 in crystalline form) is not particularly described and in the absence of any improved effect the crystalline form considered as another form of known substance u/s 3(d) of the Act.

The decision refers to §3(d) under heading 6, ‘Not an invention’ and states that an “[e]ster of the known substance prima facie will get a patent only if it shows significant enhancement of efficacy.” The Chennai High Court in the case of Novartis A.G. v Union of Indiahad stated that “efficacy means therapeutic efficacy.”

In the judgment, the High Court had observed that the patent applicant is expected to be aware of the difference between the therapeutic effect of the patented drug and the drug in respect of which patent is asked for.

The High Court also made a requirement for providing comparative details showing that the discovery of a new form of a known substance had resulted in the enhancement of the known efficacy of the original substance and the derivatives so derived will not be the same substance, since the properties of the derivatives differ significantly with regard to efficacy. (Novartis AG v. Union of India W.P. 24760/2006).

The High Court decision does not contain a quantification/minimis requirement for efficacy. All it states is that there should a comparison between the new substance and the original substance. The draft Manual of Patent Practice and Procedure, 2008 (MPPP) does provide a specific statement regarding quantification of efficacy. The MPPP states that the efficacy need not be quantified in terms of numerical value to determine whether the product is efficacious because it is not possible to have a standard numerical value for efficacy for all products including pharmaceutical products.

There are two problems with this statement. First the law regarding the ‘quantification of efficacy’ is vague because it is not reasonably possible to comply with the requirements. Second it leaves great scope for discretion of the Patent Office while considering applicability of §3(d).

There is a heavy burden imposed upon the applicant to disclose a comparison between the new form of a substance and an existing form. Once the Applicant has provided the necessary details in the form of a comparison, the Patent Office cannot post-facto object to the comparison and substitute its own judgment of what kind of comparison is required (as has been done in this case). Hence the term ‘therapeutic efficacy’ requires that it be quantified in terms of a numerical value as there is unfettered discretion with the Patent Office.

The application and the declarations discussed in the decision clearly state the beneficial effects of the claimed invention are because of increased bio-availability, side-effect profile, and drug-interactions.

Paragraph 57 of the order states that improved bio-availability may increase the clinical efficacy in turn it may influence the therapeutic efficacy for which there is no support provided in the specification. It concludes that the claimed compound does not fulfill the requirement under the provision of the Act because it is obvious that the pro-drug of compound exhibit improved solubility, low resistance, no mutations, system exposure and avoidance of the drawbacks of the intravenous treatment which are inherent and expected properties of the prodrug.

The patentee tried to show a causal connection between increased bio-availability, and therapeutic efficacy but the Order took an extremely narrow view of the term therapeutic efficacy by concluding that increased bio-availability cannot be equated with therapeutic efficacy.

This decision of the Controller highlights the reason why the Courts need to provide more clarity in interpreting §3d as regards the term efficacy and provide a numerical quantifier to it.