5.6.5.6 Issues specific to Chemical Compositions

Date Published

Key Legislation:

Patents Act:

  • s7(1) Novelty
  • s9 Secret use  
  • s18(1)(b)(i) Patentable inventions
  • s24 Validity not affected by making information available in certain circumstance
  • s27 Notice of matters affecting validity of standard patents 
  • s102 What amendments are not allowable?
  • s104 Amendments by applicants and patentees  
  • Schedule 1 Dictionary

Patent Regulations:

  • reg 2.2 Information made publicly available--recognised exhibitions
  • reg 2.2A Information made publicly available--learned societies
  • reg 2.2B Information made publicly available--reasonable trial of invention
  • reg 2.2C Information made publicly available--other circumstances
  • reg 2.2D Information made publicly available without consent--period

Essential Features of Compound Inventions

When a claim is directed to a compound having a specific structural formula, the structure is an essential feature. Whilst it is possible that there are inessential parts of the structure (for example, the derivatised portion of a derivative), this would not normally be the case. During examination it should be presumed that all features of a structure are essential unless there are sound arguments to the contrary.

In order to establish that a particular group in a structure is not essential to the activity of a compound, it will usually be necessary to demonstrate that the activity is present when that group is absent (that is, replaced by hydrogen) and when the group is replaced by different groups, for example groups that are neither isosteric nor isoelectronic.

Relevant case law

See American Home Products Corporation Application [1994] APO 58 for a discussion on compound structures and when the structure is an essential feature.

See Rohm and Haas Co. v Nippon Kayaku Kabushiki Kaisha and Sankyo Co. Ltd (1997) APO 40 at page 8 regarding the requirements to establish a particular group is not essential.

The Hetacillin case (Beecham Group Ltd v Bristol Laboratories Ltd (1978) RPC 153) provides an example of a derivative of a known compound in which the derivatised portion of the compound was effectively found to be a non-essential feature.

Enabling Disclosure

An enabling disclosure of a chemical compound is a disclosure of sufficient detail to enable those skilled in the art to make the compound. The compounds do not need to have been prepared.

The disclosure of the mere existence of a compound, without an enabling disclosure, is not sufficient to establish lack of novelty.

Thus, to use a citation in a novelty objection, the citation must clearly and unmistakably disclose the chemical compound and enable the production of the compound. The assessment of these criteria is not always straight forward when a citation discloses generic chemical structures. The following sections provide guidance on determining whether a citation disclosing generic chemical structures provides an enabling disclosure of chemical compound.

What Compounds are Clearly and Unmistakably Disclosed by a Generic Disclosure?

A generic disclosure of a chemical structure in a prior art document will not disclose an individual compound merely because that individual compound falls within the scope of the generic chemical structure. Hence the Reverse Infringement Test may not always be appropriate when deciding if a prior disclosure of a generic chemical structure constitutes an anticipation for novelty purposes.

Rather, the prior art document must be read as a whole to determine what the skilled addressee would understand the generic chemical structure is disclosing. For example, what compounds are disclosed in the worked examples? What is the technical information the prior art document is teaching? Which compounds are discussed in the specification? Would the skilled addressee perceive or understand a specific compound to be disclosed by the broad, generic disclosure?

Does the Disclosure Enable the Production of the Compounds Whose Structures Have Been Disclosed?

An enabling disclosure is provided if a method to prepare the compound is given in the citation (including a generic method) or is self-evident, and the person skilled in the art would consider this method to be technically credible at the date of publication of the citation.

Where there is prima facie an enabling disclosure, the objection should be taken, and the onus placed on the applicant to show that the disclosure is not enabling.

Relevant case law

What Compounds are Clearly and Unmistakeably Disclosed by a Generic Disclosure?

Lundbeck v Alphapharm (2009) FCAFC 70 discusses what is required for a generic chemical structure to disclose a particular compound at paragraph 173:

"Where the prior disclosure is to a broad chemical claim encompassing many compounds, there may not be anticipation in the absence of the skilled addressee understanding or perceiving a specific compound in the disclosure (Imperial Chemicals Industries Pty Ltd v Commissioner of Patents (2004) FCA 1658; (2005) 213 ALR 399 at paragraphs 64 - 65). That is, there is no actual description of the particular compound to the skilled addressee; there is no relevant disclosure. There may be a distinction, albeit fine, between a "fleeting" or "paper’ disclosure or the "intellectual content" of a disclosure on the one hand and a "disclosure for novelty purposes" or "enabling disclosure" on the other (Imperial Chemicals at paragraph 68; University of Georgia Research Foundation v Biochem Pharma Inc. (2000) 51 IPR 222, a decision of Dr Barker of the Patent Office described by Crennan J in Imperial Chemicals as a ‘sound account of the relevant distinctions between a "paper disclosure" and an "enabling disclosure" in the field of chemistry’ (at 412)). It depends on what the skilled reader would understand."

University of Georgia Research Foundation v Biochem Pharma Inc. (2000) 51 IPR 222 , which was referred to above, also discusses what is required for a generic chemical structure to disclose a particular compound at paragraph 233:

"When a citation has a disclosure in generic form (as is common in chemical patents), the question arises as to which compounds within the scope of the generic disclosure are taught to the reader. I have considered this question in a number of earlier decisions: for instance, see Re Application by American Home Products Corp [1994] APO 58 (APO, Dr S D Barker, No 16397/92, 28 September 1994, unreported); Pharmacia Aktiebolag v Ueno Fine Chemicals Industry Ltd (1995) 34 IPR 445. It is not enough to find that a specific compound is within the scope of the broadest disclosure of the citation (which can be considered as the intellectual content of the disclosure). It is necessary to find that a reader would have understood that the specific compound was part of the technical information of the specification, and there must be an enabling disclosure of that compound (for instance, see my analysis of the doctrine of enabling disclosure in Biochem Pharma Inc v Emory University [1999] APO 50 (APO, Dr S D Barker, No 658136, 5 August 1999, unreported)."

Eli Lilly and Company Limited v Apotex Pty Ltd [2013] FCA 214 also discusses what is needed for a generic chemical structure to disclose a particular compound, starting at paragraph 276.

American Home Products Corporation [1994] APO 58, at page 12:

"A generic structural formula represents all the specific structural formulae encompassed by the generic formula. This can be described as the intellectual content of the generic formula. The question of what compounds are clearly and unmistakably disclosed goes beyond the intellectual content and is equivalent to asking what technical information the citation would make public to the instructed reader (though not necessarily revealed in every detail)."

Pharmacia Aktiebolag v Ueno Fine Chemicals Industry Ltd (1995) 34 IPR 445 further explains that a compound that is named in the worked examples part of a specification as a further example of the invention is disclosed in a technical sense.

Bristol-Myers Co. v L'Oreal (1989) 16 IPR 652, also contemplates what a generic chemical structure discloses, especially pages 657-658:

"A generic formula should always be considered in conjunction with the compounds specifically described in the citation to determine which combination of substituents and which substitution patterns are actually disclosed in the citation."

PPG Industries Inc v Stauffer Chemical Co. (1985) 5 IPR 496, discusses the disclosure of particular combinations of substituents at pages 509-511.

"The preferred, specifically identified compounds disclose the particular combinations of R, R1 and R2 in each individual compound. They do not disclose all the structural formulae that could be produced using different combinations of the R, R1 and R2 variables disclosed in those identified compounds."

Does the Disclosure Enable the Production of the Compounds Whose Structures Have Been Disclosed?

American Home Products Corporation [1994] APO 58 defines an enabling disclosure of a chemical compound at pages 13-14.

"The practice of placing the onus on the applicant to show that a prior disclosure is not enabling received judicial approval in Toyama Chemical Co. Ltd's Application [1990] RPC 555 at 564."

Pall Corp v Commercial Hydraulics (Bedford) Ltd (1990) FSR 329 gives the definition of an enabling disclosure for a chemical compound at paragraph 347.

Asahi Kasei Kogyo KK's Application [1991] RPC 485 discusses enabling disclosures and anticipation.

Enabling disclosures of specific chemical compound examples

Stereoisomers

The following information relates specifically to the situation where there is only one chiral centre and thus only two isomers (enantiomers) of the compound under examination. However, the principles can be extended to situations involving more chiral centres (for example, diastereomers).

  • If the other isomer, and the racemate, have not been previously disclosed, then the isomer in question is novel.
  • If the racemate is previously known, it can be argued that the single isomer has been generically disclosed since a person skilled in the art would appreciate that a compound having a chiral centre exists in two optically active forms. However, without anything further, it is doubtful whether the single isomer has been disclosed in a technical sense, or whether there is an enabling disclosure (see Imperial Chemical Industries Ltd (Howe's) Application [1977] RPC 121). Examiners may also have to consider whether there is a valid selection.
  • If the other isomer (that is, opposite to the claimed isomer) is previously known, but the racemate is not known, the problem appears somewhat different. This situation can arise in cases of naturally occurring compounds, such as steroids. It is unlikely there has been even a generic disclosure of the claimed isomer and consequently novelty is not an issue.

Constitutional and Geometric Isomers

Where a different constitutional or geometric isomer is described in the prior art, it would be unusual for this to be considered a disclosure, even in a generic sense, of other isomers. For example, an ortho substituted isomer does not generically disclose the para substituted isomer and the cis isomer does not disclose the trans isomer. Consequently, there would not be a clear and unmistakable disclosure of other isomers.

Tautomers

Tautomers are isomers that are in equilibrium (for example, keto-enol tautomerism). Where a single tautomeric form is claimed (explicitly or implicitly free of the other tautomer), disclosure of a different tautomer would not provide an enabling disclosure of the claimed tautomer. In the context of processes utilising a tautomer, an objection of lack of novelty must establish that the compound is in fact in equilibrium with the known compound, and that it was common general knowledge in the particular art that the forms would be in equilibrium.

See Canadian Industries Ltd v Australian Paper Manufacturers Ltd (1983) APO 21, where it was not established that tautomerism would occur.

See Australian Paper Manufacturers Ltd v CIL Inc. (1985) 4 IPR 612, where it was not established that the tautomerism was common general knowledge.

Purposive Construction of Compound Claims

It would be uncommon for examiners to have sufficient evidence to take a purposive construction of compound claims.

If sufficient evidence was available, the questions to ask to purposively construe the claimed compound are:

  • Does the variant (derivative) have a material effect on the way that the invention works? If yes, the derivative does not fall within the scope of the claim. If no, then:
  • Would it have been obvious that the variant would not have a material effect on the way the invention works? If no, the derivative does not fall within the scope of the claim. If yes, then:
  • Would a reader have understood from the claim that strict compliance with the primary meaning was an essential requirement of the invention? If yes, the derivative does not fall within the scope of the claim. If no, the derivative does fall within the scope of the claim.​​​​​​​

Relevant case law

See American Home Products Corp v Novartis Pharmaceuticals UK Ltd (2001) RPC 8.

Construction - Implicit Degree of Purity

Where a claim is directed to a compound without an explicit degree of purity, the degree of purity is implied by considering the context of the specification. If the whole context of the specification, and the nature of the problem with the prior art, is directed to the degree of purity, then that is implicitly a feature of the claim. If there is no such context in the specification, then the degree of purity is not a feature of the claim.

Relevant case law

See Biochem Pharma v Emory University (1999) APO 50.

Reach-Through Claims​​​​​​​

Where "reach-through" claims recite compounds that interact with, or modulate the activity of, a specific peptide or nucleic acid, it is important to understand the types of compounds that may fall within the scope of the claims. Often the compounds include known compounds. For example, known drugs or peptides where the drug or peptide is a member of a standard chemical library whose members have been tested for their ability to interact with the peptide or nucleic acid. In this situation, the claims will necessarily lack novelty.

Often the candidate compounds will be claimed as compounds identified, or selected, by screening. Although, as a matter of literal construction, such claims are directed to the compounds after, not prior to, screening, the compounds are the same regardless of whether or not they were identified in a screening process. Thus, examiners should construe such claims as directed to compounds per se. ​​​​​​​