A recent decision of the United States Court of Appeals for the Federal Circuit has highlighted the risks of claiming broad pharmaceutical dosage regimens without providing enough practical guidance in the patent specification.
In Wyeth LLC v AstraZeneca Pharmaceuticals LP, the Federal Circuit held that claims directed to the daily administration of irreversible EGFR inhibitors were invalid for lack of enablement. Although the decision applies US law, its reasoning is highly relevant in Australia, where patent specifications must also enable the invention across substantially the full scope claimed.
What did the US court decide?
The Wyeth patents concerned methods of treating resistant non-small-cell lung cancer using a daily “unit dosage” of a broadly defined class of irreversible EGFR inhibitors.
The specification disclosed a wide dosage range but did not provide human dosing examples or a practical method for translating laboratory activity into an effective and tolerable daily dose.
The Federal Circuit held that it was not enough to show that the compounds inhibited EGFR or killed cancer cells in laboratory testing. The patent had to enable the skilled person to administer a repeatable daily dose capable of producing the claimed therapeutic effect.
The Court did not require the level of evidence needed for regulatory approval. However, it found that the skilled person would have needed to undertake substantial pharmacological, toxicological and dose-finding work before the claimed treatment could be performed. The specification therefore provided a starting point for further research, rather than an enabling disclosure of the invention.
How does this compare with Australian law?
The Australian position is broadly similar.
Section 40(2)(a) of the Patents Act 1990 requires a complete specification to disclose the invention clearly and completely enough for it to be performed by a person skilled in the relevant art.
Following the Raising the Bar reforms, it is generally not sufficient to enable only one embodiment falling within the claims. The invention must be enabled across substantially the whole scope claimed.
Australian law permits routine experimentation and ordinary optimisation. However, the specification must not leave the skilled person with a substantial research programme, an undue burden or the need to make further inventions.
The broader the claimed class of compounds, dosage regimens, patient groups or therapeutic outcomes, the broader and more informative the disclosure must be.
Would the Wyeth claims survive in Australia?
On equivalent facts, the claims would face a significant risk of invalidity in Australia.
A broad dosage range may be insufficient where effective and tolerable doses vary materially between compounds and the specification provides no reliable method for identifying a workable dose.
The absence of human clinical examples would not necessarily be fatal. A dosage regimen may be enabled through animal studies, pharmacokinetic or pharmacodynamic data, dose-response information, accepted scaling methods or information concerning closely related compounds.
The key issue is whether the specification, together with the common general knowledge, gives the skilled team a sufficiently reliable path to performing the claimed treatment.
An additional Australian risk: lack of support
Australian dosage patents may also be vulnerable under section 40(3), which requires the breadth of the claims to be supported by the technical contribution disclosed in the specification.
A patent showing only that a small number of compounds have activity in an in vitro assay may not justify claims covering a broad compound class, any therapeutically effective dose and successful treatment of a disease.
A challenger may therefore argue both that the invention is not enabled across the full scope claimed and that the claims extend beyond the disclosed technical contribution.
Key takeaway
The Wyeth decision does not require a pharmaceutical patent to prove safety and efficacy to the standard required for marketing approval.
It does, however, confirm that broad dosage claims must be matched by a sufficiently detailed technical disclosure. In Australia, such claims must satisfy both the full-scope enablement requirement and the separate support requirement.
The practical lesson is simple: broad dosage protection remains possible, but only where the specification provides enough substance to justify it.
