An invention will be considered to be inherently disclosed, and thus unpatentable, where following an earlier known process would result in the same invention.  This can form an important defence against a claim of patent infringement, or alternatively can put your patent’s claims at risk of invalidation. However, a prior art disclosure will only anticipate the claims of a later patent if it can be shown that following the directions in the prior art will inevitably and inexorably lead to something falling within the scope of the claims.  If the prior art could also lead to something outside the scope of the claims, then there is no inherent disclosure of the invention by the prior art.  The law regarding this area has recently been confirmed in a case in the full Federal Court of Australia.

Background  

The Full Court of the Federal Court of Australia (Bristol Myers Squibb Co. v Apotex Pty Ltd [2015] FCAFC 2) has dismissed an appeal against a decision handed down by the Federal Court in an earlier patent infringement and validity case (Bristol Myers Squibb Co., Ltd v Apotex Pty Ltd [2013] FCA 1114) concerning Apotex’s generic version of Bristol Myers Squibb’s ABILIFY product, containing the antipsychotic agent Aripiprazole.

At trial, Otsuka Pharmaceutical Co. Limited (Otsuka), the patentee of Australian Patent No. 2002334413 (the Patent) and the exclusive licensee of the Patent, Bristol-Myers Squibb Co. (BMS), together argued that the sale of Apotex’s generic versions of the aripiprazole-containing drug used in the treatment of cognitive impairment associated with schizophrenia, would infringe or lead to infringement of several claims of the Patent.

Apotex denied infringement and counter-claimed that some of the claims of the Patent were invalid on a number of grounds, including lack of novelty, inventive step, clarity and fair basis, not a manner of manufacture, and false suggestion (misrepresentation).

Both at trial and during the subsequent appeal, it was evident that a large proportion of the arguments relating to invalidity revolved around the novelty of the claims in question, and in particular, whether such claims would be found to lack novelty in light of an inherent disclosure in a prior publication.

The Patent is directed to an improved form of anhydrous aripiprazole crystals (Crystals B) having a reduced hygroscopicityof 0.4% or less which makes them more amenable to pharmaceutical processing and formulation operations required for improved shelf-life as well as a suitable dissolubility and bioavailability.

Claim 12 of the Patent was deemed at trial to be of “central significance to the case” as a number of other claims are dependent, directly or indirectly on this claim and are relied on by BMS and Otsuka for their case of infringement.

At trial, Apotex sought to rely on European Patent Application No. 367141 (the ‘141 application), to support its arguments of lack of novelty of the Patent. The ‘141 application discloses processes for the preparation of aripiprazole and pharmaceutical compositions containing aripiprazole. Both Apotex and BMS/Otsuka accepted that Example 1 was of relevance.

The law

In determining whether there is an inherent disclosure in a prior publication, according to Australia case law, it is necessary to consider:

“…if carrying out the directions contained in the prior inventor’s publication will inevitably result in something being made or done which, if the patentee’s patent were valid, would constitute an infringement of the patentee’s claim, this circumstance demonstrates that the patentee’s claim has in fact been anticipated.…To anticipate the patentee’s claim the prior publication must contain clear and unmistakeable directions to do what the patentee claims to have invented…. “(Emphasis added).

Apotex argued that Example 1 of the ‘141 application contained clear and unmistakeable directions to produce anhydrous aripiprazole crystals having the same characteristics as Crystals B, and so would infringe the claims of the Patent, if carried out after the grant of the patent, thereby satisfying the ‘reverse infringement test’ as a novelty destroying piece of prior art.

To prove this contention, Apotex and Otsuka/BMS each looked to one of their respective expert witnesses to devise a protocol and to carry out an experiment based on that protocol to reproduce the method of Example 1 of the ‘141 application.

Based on the outcomes of the experts’ experiments, the primary judge was satisfied that when carrying out the directions in Example 1 of the ‘141 application, the person skilled in the art would have sought to dry the product of a second recrystallization step in an endeavour to obtain the colourless flake crystals. However, he noted that while both protocols led to the formation of aripiprazole crystals as a hemiethanolate, the expert for Otsuka/BMS stopped at that point, whereas the expert for Apotex carried out a further step of drying the obtained crystals to remove the ethanol so as to arrive at the free base form of aripiprazole.

The primary judge confirmed that the ‘141 application did indeed teach the skilled person to make aripiprazole and could, in at least some circumstances, result in Crystals B.  What was in dispute, however, was whether it was inherent in the ‘141 application to carry out a further drying step that would inevitably result in Crystals B.

After considering the expert evidence and the ‘141 application as a whole, the primary judge was not persuaded that by following the directions of Example 1 of the ‘141 application, the person skilled in the art would inevitably have obtained Crystals B when seeking to obtain anhydrous aripiprazole crystals in their free base form. Rather, in the course of following those directions, the person skilled in the art might have obtained Crystals B serendipitously, but it is equally possible that he or she would have obtained conventional anhydrous aripiprazole crystals with unacceptably high hygroscopicity. In this respect, the primary judge found that neither Example 1, nor more generally the ‘141 application, contains clear and unmistakeable directions to do what Otsuka claims to have invented.

In reaching this decision, the primary judge argued that the hygroscopicity of a crystalline compound is not just a function of its crystalline form, but may be influenced by other factors including particle size and, in subtle ways, by the surface properties of the polymorph in question.

Apotex sought on appeal to question the primary judge’s decision at trial, asserting that his analysis of the ‘141 application was wrong as the issue of whether the invention as claimed was novel was to be proved on the balance of probabilities. In particular, Apotex submitted that the results and mere speculation by experts about other drying methods to remove ethanol “should not have been allowed to displace, on the balance of probabilities, the successful experimental proof adduced by them.” Apotex further argued that, prior art may disclose more than one thing. If one of these things has as its inevitable result the production of something within the claims of the patent in suit, that is enough.

The Full Court found that Apotex’s submissions tended to assume that the only relevant evidence was the experiments conducted by the expert witnesses for both parties, and so, when rejecting the evidence provided by Otsuka/BMS’s expert as not going far enough, the primary judge was bound to accept their expert’s evidence as sufficient proof on the balance of probabilities.  The Full Court stated that this is not so. As the primary judge’s reasoning discloses, there was evidence of a broad range of drying options to remove ethanol. The Full Court argued that this expert evidence was based on opinion about matters of routine (and commonly held opinion at that), rather than mere speculation, and surmised that the weight of the evidence about a range of drying options was overwhelming.

The Full Court agreed with the findings of the first Federal court decision that while the evidence showed that one of a large number of different ways of carrying out the directions in Example 1 of the ‘141 application will result in Crystals B (and thus could have rendered the claims of the Patent not novel), it did not establish that this method was more likely than not to be carried out in preference to the other available methods.

In Summary

The law in Australia, in relation to inherency, remains settled in that a prior art disclosure will only anticipate the claims of a later patent if it can be shown that following the directions in the prior art will inevitably and inexorably lead to something falling within the scope of the claims. If the instructions of the prior art can reasonably be carried out in at least one way that will not result in infringement of the claims of the patent, then the prior art should not destroy the novelty of those claims.