It's one of the most consequential pharmaceutical patent disputes in years, one that is being closely watched by practitioners around the world. The patent litigation concerning Amgen's PCSK9 antibody patents has highlighted the divergent approach taken by major jurisdictions in assessing the validity of functionally and structurally defined antibody claims.
In the US, Amgen's patent claims were held to be invalid by the Supreme Circuit for lack of enablement.1 In corresponding European opposition proceedings, the claims of Amgen's patent were found to be enabled, but were subsequently invalidated by the Board of Appeal for lacking an inventive step.2 And in July this year, the Munich Central Division of the Unified Patent Court revoked a key Amgen patent – the first revocation decision from the newly created pan-European tribunal.3
In Australia, the outcome was different. In 2022, a Delegate of the Commissioner of Patents ruled in Amgen's favour, finding that five of its patent applications are valid and should proceed to grant.4 Sanofi appealed the decision to the Federal Court.
This article summarises our previous article on the Delegate's 2022 decision and provides an update on the Federal Court appeal.
Patent Office Opposition
The applicable law
The opposed applications cover Amgen's cholesterol-lowering antibody, evolocumab (REPATHA), and potentially cover Sanofi's competitor antibody, alirocumab (PRAULENT). The applications are all subject to Patents Act 1990 as it existed before the Intellectual Property Laws Amendment (Raising the Bar) Act 2012.
Under the current Patents Act, the requirements of support and sufficiency apply, meaning that, as in Europe, the claims must be commensurate with the technical contribution to the art, and the specification must enable a skilled person to perform the invention across the full scope of the claims without undue burden or further invention.
Under the "old" Patents Act, however, the more patentee-friendly requirements of "full description" and "fair basis" apply. Challenging a patent on these grounds has been notoriously difficult (and more often than not, unsuccessful).
The claims
The Delegate grouped the disputed claims into three classes:
- Epitope claims: define an isolated monoclonal antibody by its ability to bind an epitope of PCSK9, the epitope comprising nominated residues;
- Residue claims: define an isolated monoclonal antibody by its ability to bind one or more specific residues of PCSK9;
- Competition claim: Define an isolated monoclonal antibody by its ability to compete for binding with a structurally-defined antibody.5
The claims also include functional language referring to the ability of the antibody to block or reduce binding of PCSK9 to the LDL receptor (LDLR).
Clarity
Sanofi opposed the claims for lack of clarity, citing inexact language such as binds, blocks, reduces, neutralizing, and competes. The Delegate rejected these submissions, finding that each term could be given meaning and that the claims provide a workable standard.6
Fair basis
Sanofi argued that the claims were not fairly based on the specification, asserting that only two antibodies were made, tested, and shown to block PCSK9 binding to LDLR. The Delegate rejected this argument, pointing to broader statements in the specification indicating that the invention extends beyond the specific antibodies isolated. Although generic and not tied to specific examples, those paragraphs indicated to the Delegate that the invention extends beyond the specific antibodies isolated and characterised in the applications.7 The Delegate was satisfied that the specification provides a real and reasonably clear disclosure of the antibodies encompassed by the epitope, residue and competition claims.
Full description (sufficiency)
The test for sufficiency is whether the patent specification enables the addressee to produce something within each claim without new inventions or prolonged study. Sanofi argued that the applications do not disclose an antibody within the scope of any of the claims and that a skilled person could not reproduce the antibodies described in the applications. The Delegate reframed the test for sufficiency, asking if the disclosure would enable the addressee to produce an antibody that binds:
- an epitope that comprises the stated amino acid residues; or
- to the specific amino acid residues specified;
without new inventions or additions or prolonged study of matters presenting initial difficulty.
The Delegate was satisfied that the specification described the binding site or interaction interface between PCSK9 and LDLR, and that the specification showed how two exemplary antibodies interact with this region to block binding between PCSK9 and LDLR. The Delegate also accepted that the residues identified form non-covalent interactions between PCSK9 and the antibodies, and that the skilled addressee could generate antibodies within the scope of the claims using routine techniques.
The Delegate was not satisfied that the work required to produce one antibody embodying each claim using the information provided in the specification requires anything more than what is routine in the art, even if such work may be complex, time consuming and expensive.8 Consequently, this ground of opposition also failed.
Federal Court Appeal
Sanofi appealed the Delegate's decision to the Federal Court. In the run up to the Federal Court hearing, which commenced in November 2023, Sanofi filed two interlocutory applications.
Sanofi v Amgen Inc. [2023] FCA 264 concerned Sanofi's interlocutory application seeking orders for discovery and leave to rely on experimental evidence. In relation to the experimental evidence, Sanofi sought to rely on experiments conducted for the purpose of proceedings in other jurisdictions. The Court refused Sanofi's application for discovery and permitted reliance on some but not all of the experimental evidence.
In refusing leave to rely on certain experiments, Nicholas J considered that the experiments were of little relevance to Sanofi's alleged grounds of invalidity. His Honour also observed that there was significant debate in corresponding European proceedings about the conclusions that could be drawn from the experiments, and that introducing those experiments to the Australian proceedings would likely give rise to a substantial and undue waste of time and costs.
Experimental evidence for which leave was granted was considered to be directly relevant to Sanofi's alleged grounds of invalidity.
In Sanofi v Amgen Inc. (No 2) [2023] FCA 1156, Sanofi filed a further interlocutory application seeking orders to limit the evidence which Amgen could adduce at the hearing. Amgen had proposed to rely on declarations made by three experts in the Patent Office opposition, as well as supplementary affidavits from those same experts. Sanofi sought to exclude some of that evidence on the grounds that it was substantially duplicative. Justice Yates rejected Sanofi's application in its entirety noting that Sanofi could have raised its concerns at the first case management hearing but did not do so.
The appeal continues.
Footnotes
1 No. 20-1074, Fed. Cir. 2021.
2 T 0845/19.
3 Sanofi v Amgen, UPC-CFI_1/2023.
4 Sanofi v Amgen Inc. [2022] APO 67
('Sanofi v Amgen').
5 Sanofi v Amgen at [51].
6 Sanofi v Amgen at [109].
7 Sanofi v Amgen at [134] and [137].
8 Sanofi v Amgen at [174].
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