Enhanced Therapeutic Efficacy

1The enhancement of known efficacy has to be determined by the Controller. The standard of efficacy applied for determining the patentability of an invention has to be developed by the Patent Office and the courts, and applied on a case to case basis. The spirit of the provisions in the Patents Act does indicate that the threshold of efficacy is likely to be high. The bar against selection patents and Swiss form of claims under s 3(d) of the Patents Act would further strengthen the requirement of a higher standard of efficacy.

2The first part of s 3(d) will be relevant in determining novelty of a known substance, i.e., if it amounts to a new form of a known substance. (See Novartis Application 1602/MAS/98 (Unreported); Wockhardt's Application (2006) 32 PTC 261 (PO) (Mumbai), where the patent applications were rejected applying s 3(d).) It has an in-built guideline as it refers to two comparative concepts, ie, 'known efficacy' and 'enhanced efficacy' for determining patentability of new forms of known substance. The first part states that the 'enhanced efficacy' has to be determined vis-à-vis the 'known efficacy'. As the first part of s 3(d) pertains to known substances, it is quite reasonable to assume that the efficacy or effectiveness of the substance will also be known. Thus, with the 'known efficacy' as the benchmark, the Controller has to look at the 'enhanced efficacy', and decide whether there has been a significant difference in the efficacy of the new form compared to the existing form. This would reiterate the proposition that the first part of 3(d) provides for patents for improvements. The law with regard to improvements is well-settled and the Patents Act statutorily provides for the same. (Patents Act 1970, ss 54-56.)

3The first part of s 3(d) encompasses the tests of novelty recognised by the courts. Revocation of patents for known substances on the ground of lack of novelty is a well-established ground as illustrated in a recent decision of the House of Lords where an application for revocation of a patent related to the crystalline methanesulfonate salt of the known therapeutic agent paroxetine was upheld, and the patent was revoked on the ground of lack of novelty. (SmithKline Beecham Plc's (Paroxetine Methanesulfonate) Patent [2006] 1 All ER 685, (2006) RPC 10, para 55. Also reported as Synthon BV v Smithkline Beecham plc [2005] UKHL 59.)

Proof of Enhanced Efficacy

4The courts have demanded proof for demonstration of enhanced efficacy. In F Hoffmann-La Roche v Cipla (2009) (para 33) the Division Bench held that even if the plaintiffs take the view that stability of the product is not the same as efficacy, it would still have to be demonstrated. The court opined that demonstrating therapeutic efficacy may involve testing on a sample population.