Ascertained and obvious – Full Court declots Australia’s law on routine steps

In this regard, the Full Court has confirmed that inherent risks in conventional drug development work are not sufficient to provide an inventive step, rejecting the approach of the primary judge who found two Bayer patents inventive because (she said) the person skilled in the art would not have the relevant expectation of success at the pre-clinical phase of the drug development process, particularly in view of evidence that at least 90% of new chemical entity development never progresses the entire way along the drug development path.   

The Full Court found that her Honour erred in finding that the inventions claimed in both Bayer patents involved an inventive step, in addition to erring in finding that the skilled person could not be reasonably expected to have ascertained the key prior art document. 

Key takeaways

• An expectation of success is inherent in a person skilled in the art choosing to go down the conventional development route.
• Even if inherently risky, such risk will not always be sufficient to render something inventive.
• The decision provides greater scope for inventive step challenges to the validity of similar granted patents. 

Background

In 2021, Sandoz brought proceedings seeking to clear the way for its generic rivaroxaban product following the expiry of the compound patent.  

Sandoz contended that both Australian Patent No. 2004305226 (226 Patent) and Australian Patent No. 2006208613 (613 Patent) were invalid for lack of inventive step on the basis of the common general knowledge (as it existed at the relevant time) together with either International Patent Publication No. WO 01/47919 (WO 919), or the journal Blood.

The 226 Patent asserts a “special treatment” of rivaroxaban to improve its bioavailability – namely, the preparation of solid oral compositions comprising rivaroxaban in hydrophilized form. 
The 613 Patent asserts an inventive step in the administration of rivaroxaban orally once daily for at least five consecutive days, where the rivaroxaban has a plasma concentration half-life of 10 hours or less.  The administration of the tablet once a day is described as inventive because the half-life of rivaroxaban suggests more frequent dosing. 

Obviousness and WO 919

At first instance

In Australia, the test for determining whether an invention involves an inventive step requires a consideration of “whether the person skilled in the art at the relevant date with the relevant knowledge would directly be led, as a matter of course, to try the claimed invention in the expectation that it might well produce a useful alternative to, or a better drug than, the existing compound”. 

At first instance, Rofe J made extensive findings about the drug development process, and the likelihood of success in the drug development process both generally, and by reference to what was taught by WO 919. 

The findings of her Honour at first instance included that:

(a) it was not uncommon for the drug development process to fail; 

(b) the majority of lead drug candidates that make it to pre-clinical studies never advance to clinical trials, and most drugs that enter clinical trials do not get regulatory approval – with only a 10% chance of this occurring;

(c) the risk of failure for New Chemical Entities (NCE) is particularly acute because the development team is starting with a “blank slate”, so there is no way of anticipating what will be encountered in the development process;

(d) the substantial risks and uncertainties associated with drug development are particularly problematic in the high risk field of thrombosis involving a novel, first in class drug. 

Against this background, she found that WO 919 would be of interest to the skilled person, and that reading WO 919 that they would likely select rivaroxaban as a lead candidate to take into development work, including the full suite of pre-clinical tests.  

However, her Honour’s view was that the identification of rivaroxaban as a lead, or preferred candidate was a very early step along the drug development pathway, and that each further step presents an opportunity for “failure or change in direction” – such risk being compounded “when the compound is a first in class NCE, the side effects are entirely unknown, [and] other unrelated compounds … are known to have failed in early phase studies”. 

“The steps foreshadowed by [the experts] form part of a new, arduous, comprehensive, risky and unpredictable research project for a first class NCE”, she said, and so “the pre-clinical tests are not undertaken with the requisite expectation of developing a safe and efficacious drug”. 

Rather, such steps, she said, were a mere information gathering exercise along the path to development, and were “more akin to the voyage of discovery”.  

Accordingly, she found that the inventions claimed were not obvious. 

Full Court

On appeal, the Full Court…