The Federal Court dismissed Apotex’s action to invalidate the claims of Canadian Patent No. 2,527,646 (the 646 Patent), which was consolidated with Shire’s application to prohibit the Minister of Health from issuing a Notice of Compliance for Apotex’s generic version of VYVANSE® (lisdexamfetamine). Shire’s counterclaim for infringement in the action was dismissed but the Court granted the prohibition order against the Minister.
Patent found to be valid
Amphetamines are used to treat attention deficit and hyperactivity disorder (ADHD), but are controlled substances because they can be abused for their euphoric effect. Abuse typically occurs when tablets are crushed into a powder that is snorted or dissolved and injected. Sustained-release formulations improve convenience for patients but are more susceptible to abuse because they contained greater amounts of amphetamines.
Invention of the 646 Patent
The 646 Patent claimed prodrugs of amphetamines and derivatives or analogs formed by covalent attachments of chemical moieties to the amphetamine. These prodrugs are converted in the body to the active amphetamine over time, providing sustained release of amphetamine while reducing abuse potential. The asserted claims of the 646 Patent covered lisdexamfetamine (LDX), consisting of d-amphetamine conjugated to the amino acid L-lysine. The claims at issue also cover certain salts of LDX, pharmaceutical compositions containing LDX, and use of LDX to treat ADHD.
Not a selection patent
Shire argued that LDX is selected from the class of amphetamine amino acid conjugates encompassed by Australian Patent No. 54168/65 (the AU 168 Patent). Apotex disagreed. Justice Fothergill doubted that the 646 Patent may be properly characterized as a selection patent. However, he found that nothing turned on this point because the outcome of his anticipation and obviousness analyses were not affected by it. In coming to his conclusion, he distinguished and rejected Apotex’s reliance on Hoffmann-La Roche Ltd. v Apotex Inc., 2013 FC 718, noting that there may be reason to approach this decision with caution.
The Court held that the 646 Patent was not anticipated. Justice Fothergill found that the expert evidence raised many unanswered questions regarding the prior art, which did not clearly relate to prodrugs, did not disclose the process of making LDX, and did not teach that the compounds it disclosed provide a sustained release treatment for ADHD with, or even without, a reduced potential for abuse.
The Court held that the inventive concept for all the claims of the 646 Patent was a sustained-release formulation of a therapeutically useful dose of amphetamine that is resistant to abuse. Justice Fothergill found that the difference between the state of the art and the inventive concept was the compound LDX and its advantageous properties. He also found that the prior art did not indicate or suggest that LDX would provide sustained release of amphetamine with reduced abuse potential, and that the prior art did not suggest prodrugs would render a drug less susceptible to abuse.
The Court held that LDX was not obvious to try. There was no way to know the properties of LDX without testing, even if the testing was routine, and it was not more or less self-evident that the contemplated tests would overcome the differences between the starting point and the ending point
Justice Fothergill found that the claims were not overbroad, as he construed the term “L-lysine-d-amphetamine” as only LDX and a group of compounds.
Specification is not insufficient
Justice Fothergill held that the specification of the 646 Patent is not insufficient because LDX’s advantageous properties exist regardless of whether it is in a particular salt form, or as a free base. He also held that the invention of the 646 Patent does not relate to scale-up synthesis or to a particular crystal form, and that the skilled person was capable of making the claimed compounds by following the 646 Patent.
No reliance on foreign decisions
In reaching the foregoing conclusions, Fothergill J. rejected Shire’s position that the Court should regard foreign judgments involving comparable patents, which consistently affirmed the validity of the patents, as being instructive.
No infringement because of experimental or regulatory use exception
The Court found that Apotex obtained LDX for experimental or regulatory use, and that it was a sufficient defence for Apotex to have an internal policy that the approximately 900,000 capsules containing LDX dimesylate in its inventory would be used entirely for future research or making demonstration batches. As a result, the Court dismissed Shire’s infringement action.
Minister prohibited from granting Notice of Compliance
Having decided that the patent was valid, Justice Fothergill also granted a prohibition order against Apotex’s Apo-lisdexafetamine product as the proceeding under the Regulations was confined to the validity issues in the case.