Biotech Values

[genisi]

From Nature Patent watch on the Protonix patent case:

http://www.nature.com/nrd/journal/v8/n7/full/nrd2928.html#US-Court-reverses-policy-on-obviousness-of-gene-patents

Obviousness on the basis of chemical similarity

Medicinal chemistry often involves making modifications to previously identified lead compounds to improve biological activity or physicochemical properties. However, to be patentable, a compound must be non-obvious in the context of prior art. So, how can it be shown whether or not it was obvious to get from one structure to another? The US Court Of Appeals for the Federal Circuit (CAFC) has recently ruled in two cases that consider this issue.

The first case was between Wyeth and Altana Pharma, and the generics company Teva. Wyeth is exclusive licensee of a patent (US4,758,579) that protects the proton pump inhibitor Protonix (pantoprazole). Teva asserted that Protonix was obvious in light of an earlierAltana patent and literature articles. The structure of Protonix is very similar to that of a compound (known as compound 12) that is described in the earlier Altana patent, but with a different substitution on the pyridine ring.

To establish obviousness in situations that involve new chemical compounds, a reason or motivation can be identified that would have led a chemist to select and modify a known compound in a particular manner to achieve the claimed compound. So, working in this framework, would it have been obvious to choose compound 12 as a lead compound, and then obvious to make the substitution?

Altana and Wyeth argued that one would not have selected compound 12 over the other approx90 compounds in the prior art, and suggested that a new compound would only be obvious if the prior art pointed to a single compound for further development efforts. But the Court disagreed, considering that compound 12 was a "natural choice", and that it was one of the more potent compounds described in the earlier patent. Moreover, the Court rejected Altana and Wyeth's 'single-compound' argument, as it would have imposed a "rigid test" in determining obviousness.

In addition, it was felt that, on the basis of literature references, one would have known what the pKa (the acid dissociation constant) should be to achieve optimal stability of the compound in the body, and it was known that this pKa value could be achieved by the substitution of a methoxy group (as contained in compound 12) for a methyl group on the carbon atom at the 3 position of the pyridine ring to arrive at Protonix. On the basis of this and other findings, the Court therefore denied Altana and Wyeth's injunction to prevent Teva selling its generic drug before the expiration of the '579 patent.