Validity of maintenance dose patent maintained
The Federal Court of Appeal provided insight into what constitutes an unpatentable method of medical treatment in Janssen v Pharmascience, the latest chapter in the paliperidone palmitate saga.
Janssen markets an injectable paliperidone palmitate product in Canada under the brand name INVEGA SUSTENNA. Canadian Patent 2,655,335 is listed on the Patent Register and relates to dosing regimens that includes two loading doses and ongoing maintenance doses. The doses are fixed but can be administered at different times in dosing windows and at different injection sites. The 335 Patent contains four sets of claims:
- prefilled syringes adapted for administration according to the dosing regimen
- the use of a dosage form according to the dosing regimen
- the use of paliperidone palmitate to manufacture a medicament adapted for administration according to the dosing regimen
- a dosage form adapted for administration according to the dosing regimen
Trial Decision
At trial, Pharmascience challenged the 335 Patent on the basis that it claimed methods of medical treatment, which are unpatentable subject matter. The trial judge held that this challenge was only relevant to the claims directed to the use of a dosage form according to the dosing regimen; the other claims were all directed to a vendible product, which cannot be a method of medical treatment.
The Trial Judge noted that claims to methods of medical treatment are those where professional skill and judgment is required to practice the claimed invention. Because the 335 Patent claimed dosing regimens with fixed dosing and the only variability provided (the dosing windows and injection site) had no clinical implications, the Trial Judge concluded that the 335 Patent discloses patentable subject matter.
Appeal Decision
On Appeal, Pharmascience argued that the Trial Judge erred by not subjecting all claims of the 335 Patent to the method of medical treatment analysis even though all claims included a dosing regimen as an essential element. Pharmascience argued that these claims were not directed to a vendible product, as held by the Trial Judge. The Court of Appeal disagreed, noting that “a claim may concern a vendible product even if it includes a dosing regimen as an essential element.”
Pharmascience also argued that the Trial Judge erred in his analysis of whether the claims that were subject to the method of medical treatment analysis were directed to unpatentable subject matter. The Court of Appeal reviewed the jurisprudence and summarized the applicable test:
The question of patentable subject matter does not necessarily turn simply on whether the claim in question is limited to a fixed dosage and schedule. Rather, the proper question is whether professional skill and judgment would be required in using the patented invention. Though a fixed dosage and schedule may be a good indication that no such skill and judgment would be required, evidence may indicate otherwise.
The Court of Appeal concluded that the Trial Judge had not erred and confirmed that the variability in the 335 Patent provided flexibility in the administration of the drug; the variability had no clinical implications and did not interfere with a physician’s exercise of skill and judgment. Pharmascience noted that the 335 Patent referred to the titration of the maintenance dose and that titration had been cited in earlier jurisprudence as supporting a finding of unpatentable subject matter. The Court of Appeal disagreed, concluding that this reference was not determinative.
A copy of the decision may be found here. The Trial Judge’s decision may be found here.