Inevitable Result and Clinical Trial Protocols

Grunenthal GmbH [2026] APO 9 (16 March 2026)

Introduction

On 9 February 2024, AU Pharma Pty Ltd filed a request for re-examination of the granted claims of Grunenthal’s AU2008241013 patent relating to titration methods of tapentadol.  Tapentadol is a centrally acting analgesic known to be effective for the treatment of moderate to severe acute or chronic pain.

In Australia, re-examination is an ex-parte procedure, and as such, once AU Pharma submitted its request and supporting documents, it played no further role in the matter.  The initial re-examination request resulted in a first adverse re-examination report issuing on 26 March 2024, with a further 4 adverse re-examination reports issuing before the Commissioner advised that he intended to revoke the patent and Grunenthal requested to be heard on the matter on 20 June 2025.

Following the hearing, the Commissioner’s Delegate has determined that the majority of the claims (including claim 1) lacked novelty and inventive step in light of prior art clinical trial information.  The Delegate did, however, find claims 7 and 39 to be novel and inventive, and provided Grunenthal with a two-month deadline within which to file claim amendments based on the allowable subject matter.

Interestingly, on 17 April 2026, AU Pharma withdrew its re-examination request on the newly introduced claims, stating that AU Pharma no longer requested the Commissioner to re-examine or revoke any of the newly introduced claims of Grunenthal’s patent.

Background

The object of Grunenthal’s invention in the AU2008241013 patent was stated to be “…to improve the tolerability of tapentadol in the treatment of pain, preferably chronic pain, particularly to reduce the frequency of somnolence; one of the most frequent reported adverse events, as well as other adverse events, without diminishing the efficacy of the compound and the patient compliance”.

The invention involved initiating a treatment at low doses and successively increasing the dose according to a titration regimen.  The tolerability of tapentadol was said to be surprisingly improved by administering tapentadol according to the recited titration regimen.

Claim 1 defined the invention as follows:

Use of tapentadol for the manufacture of a medicament comprising

– a first dose of tapentadol of 50 mg ± 5% or 100 mg ± 5% to be taken twice daily (bid),

– a second dose of tapentadol to be taken twice daily (bid), wherein the second dose is calculated by increasing said first dose by 50 mg to 100 mg ± 5% or 150 mg ± 5%, respectively, and

– a third dose of tapentadol to be taken twice daily (bid), wherein the third dose is calculated by increasing said second dose by 50 mg to 150 mg ± 5% or 200 mg ± 5%, respectively

for the treatment of pain with a lower incidence of somnolence in a subject,

wherein the first dose is administered during a first administration interval of at least 1 to 3 days, the second dose is administered during a second administration interval of at least 3 to 11 days following said first administration interval, and the third dose is administered during a third administration interval of at least 3 to 14 days following said second administration interval.

Key Issues and Consideration

The key issues in consideration were novelty and inventive step.

The only prior art document under consideration was the clinical trial record, D2,  Johnson & Johnson Pharmaceutical Research & Development, L.L.C.: “A Study to Evaluate Long-Term Safety of Multiple Doses of Tapentadol (CG5503) Prolonged-Release (PR) and Oxycodone Controlled-Release (CR) in Patients With Chronic Pain”, ClinicalTrials.gov [online], NCT00361504, version 1 April 2007.  Grunenthal argued that D2 did not anticipate the claimed invention or render the claimed invention obvious on the basis that there was no teaching or suggestion in D2 of lowering the incidence of somnolence in a subject.

The Delegate, however, concluded that D2 anticipated the majority of the claims (including claim 1) on the basis that the dosage regimen of tapentadol described in D2 was generally intended to reduce the incidence of side effects.  The primary and secondary outcomes of D2 included incidence of adverse events in general, changes in laboratory measures, results of physical examinations, pain intensity and patient global impression of change over one year.  While somnolence was not explicitly listed as a specific side effect to be monitored, it would nevertheless inevitably have been captured in “incidence of adverse events”.

At [57] the Delegate stated:

“there is no requirement that D2 explicitly hypothesise or test for a lower level of somnolence to provide clear and unmistakable directions to the method of claim 1. ……….the steps set out in D2 can only be carried out in a way that would fall within the scope of claim 1, including with respect to generating a lower level of somnolence.  Therefore, I must conclude that the result of treating pain with a lower level of somnolence is an inevitable result of D2.  As such it is not required to be explicitly stated that achieving a lower level of the specific side effect of somnolence is the goal for there to be anticipation of the Swiss style claims or method claims.”

In reaching this conclusion, the Delegate relied on the Full Federal Court decision in Mylan Health Pty Ltd v Sun Pharma ANZ Pty Ltd [2020] FCAFC 116 in which the Full Court stated at [104]:

“We do not accept that a documentary disclosure containing a hypothesis cannot be an anticipatory disclosure that deprives an invention of novelty.  In such a case the question, simply put, remains: what does the prior document disclose? The occasion on which, or the context in which, a particular documentary disclosure is made may well inform the interpretation of the document’s content.  But if, as a matter of interpretation, the document nonetheless discloses that which is later claimed as an invention, that disclosure will anticipate the invention and deprive it of novelty.”

The Delegate then went on to find that the claims which lacked novelty also lacked an inventive step on the basis that there was nothing inventive about carrying out methods and treatments that had already been disclosed.

Outcome and Implications

Accordingly, the majority of the claims (including claim 1) were found to lack novelty and inventive step.  The Delegate, however, did find certain claims to be allowable and provided Grunenthal with an opportunity to file claim amendments based on the allowable subject matter.

The Delegate’s decision illustrates the power of a re-examination request when there is strong prior art which can be cited against the patent.  This decision is also yet another example of prior art clinical trial information being found to anticipate the claimed invention, despite the clinical trial information not providing any scientific proof or substantiation of the results.

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