Patentee hides the "key": patents invalid for lack of best method

Zoetis Services LLC v Boehringer Ingelheim Animal Health USA Inc [2024] FCAFC 145

What you need to know

• The Full Court of the Federal Court of Australia has upheld Boehringer Ingelheim's opposition to three vaccine patents filed by Zoetis, on the grounds of (i) failure to disclose the best method of performing the invention, and (ii) lack of inventive step.
• A failure to disclose the best method can be established by proving that the specification omits information known to the patentee that is material to achieving the advantages of the invention.
• The Full Court has reaffirmed that routine pharmaceutical development work to ascertain an appropriate dosage (in this case, in the veterinary context) does not confer an inventive step.

What you need to do

• Failure to disclose the best method remains a powerful ground of invalidity that patentees and their opponents should keep front of mind.
• Patentees should ensure that patent specifications do not omit information known to the patentee that is material to achieving the advantages of the invention.

Background to the appeal

In April 2013, Zoetis filed three patents claiming compositions for immunising pigs against diseases caused by Mycoplasma hyopneumoniae (M. hyo), porcine circovirus type 2 (PCV-2) and porcine reproductive and respiratory syndrome virus (PRRSV).

Zoetis' patents were:

1. 2013243535 (a "platform" composition for immunising against M. hyo infection);
2. 2013243537 (a bivalent composition for immunising against M. hyo and PCV-2 infection); and
3. 2013243540 (a trivalent composition for immunising against M. hyo, PCV-2 and PRRSV infection).

Boehringer Ingelheim (Boehringer) opposed Zoetis' patents in January 2018. The Patent Office upheld Boehringer's opposition against the '535 patent in part. Boehringer appealed the decision to the Federal Court. Zoetis cross-appealed.

At first instance, the primary judge held that all three patents were invalid. The successful grounds (each of which applied to different groups of claims) were:

• failure to disclose the best method of performing the invention;
• lack of inventive step;
• lack of manner of manufacture; and
• lack of support and disclosure.

Zoetis appealed the primary judge's findings in relation to best method. Zoetis also appealed the findings of lack of inventive step, but only for certain dependent claims to the compositions providing protective efficacy for the lifetime of the pig when administered in a single dose.

On 15 November 2024, the Full Court dismissed Zoetis' appeal. Ashurst acted for Boehringer. The decision is Zoetis Services LLC v Boehringer Ingelheim Animal Health USA Inc [2024] FCAFC 145.

Best method

Australia's Patents Act 1990 (Cth) requires a patent specification to disclose the best method of performing the invention that was known to the patentee at the time of filing.

The Full Court confirmed that the best method enquiry is directed to the invention disclosed in the whole of the specification, including the claims. The Full Court indicated that, to the extent previous cases (such as Firebelt ¹) suggest that the form of the claims is determinative, that approach is incorrect.

The Full Court affirmed its previous observation in Servier ² that the patentee must include in the specification all aspects of its manufacturing process that are material to the advantages said to be achieved by the invention. Whether something is material will depend on the facts of the particular case.

In this case the primary judge found, and the Full Court agreed, that the precise concentrations of the M. hyo and PCV-2 antigens in the compositions of the invention were material to the advantages of the invention. In particular, antigen concentrations were relevant to the efficacy of administering the compositions in a single dose, and to the "balance" between the antigens when administered in combination.

The primary judge found, and the Full Court agreed, that Zoetis knew and failed to disclose the antigen concentrations of the compositions exemplified in the specification (known as Investigational Vaccine Products or IVPs). Zoetis disclosed the concentrations of the IVPs only in relative terms and withheld information about the comparator vaccine, which was the "key" to understanding what the relative concentrations meant in absolute terms.

The Full Court did not accept Zoetis' argument that it was enough for the specification to disclose a range of absolute antigen concentrations in micrograms per millilitre. The Full Court held that the disclosure of such a range was not a fair disclosure of the best method. The specification indicated that IVPs with different antigen concentrations demonstrated fluctuating levels of efficacy. Zoetis' disclosure of a range left the skilled addressee in the position of having to discover for themselves the best concentration within the range.

The decision is an important reminder of the distinction between the grounds of best method and clear and complete disclosure. The Full Court considered that there was no conceptual difficulty in concluding that the skilled person could make compositions with antigen concentrations across the range disclosed, while also concluding that Zoetis had not disclosed the best method of performing the invention known to Zoetis (being an IVP with a particular antigen concentration within the range).

The Full Court also considered that Boehringer was not required to plead or prove which particular IVP was considered by Zoetis to be the "best". Because Zoetis knew and did not disclose the absolute antigen concentration of any IVP, Boehringer had established that Zoetis knew of a better method than what was disclosed in the specification.

Inventive step

The Full Court upheld the primary judge's findings that the dependent claims to single dose administration were not inventive.

The Full Court considered that routine tests would have been performed during the vaccine development process to determine the dosage and duration of protection of the compositions. This routine and non-inventive work would have revealed that the compositions could provide protective efficacy when administered in a single dose. In this respect, the Full Court followed its recent decision in Sandoz ³ (discussed in our publication here).

Authors: Stuart D'Aloisio, Partner; Melanie Kitchin, Senior Associate and Daele Tyler, Lawyer.