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An Update on Canadian Selection Patents – The Olanzapine Saga

December 15, 2011

Eli Lilly’s Canadian patent no. 2,041,113 (‘113 patent), covering its successful drug Olanzapine, has been the subject of several court proceedings, including an infringement action which was appealed and subsequently remanded back to the trial division.  The ‘113 patent was recently held to be invalid by the trial division for lack of a sound prediction with respect to its utility.1  The Olanzapine saga is instructive for inventors of selection patents in the pharmaceutical context, especially for drugs which are intended to treat chronic medical conditions.  Selection patents claim an advantage for a compound within a previously disclosed class of compounds which has not been disclosed in the prior patent.

Olanzapine is a thienobenzodiazepine anti-psychotic for the treatment of schizophrenia, and was generically disclosed in Eli Lilly’s Canadian patent no. 1,075,687 [‘687 patent].  With additional research, Eli Lilly discovered that Olanzapine possessed improved properties as an anti-psychotic, and subsequently applied for, and was granted, the ‘113 patent specifically directed to the drug. 

In the first trial decision2, the judge found that the ‘113 patent was invalid for not meeting the conditions for a valid selection, reasoning that the patent did not set out the special advantages of Olanzapine.  The Federal Court of Appeal overturned the trial judge’s decision.3 Significantly, the Appeal Court ruled that a determination that the conditions for a selection patent are not met does not constitute an independent basis for which to attack the validity of a patent.  The validity of a selection patent is only vulnerable to attack on the grounds set out in the Canadian Patent Act (i.e., anticipation, obviousness, inutility, etc.).  The Appeals Court also found that the chemical structure of Olanzapine was inventive over the chemical structure of the closest analogue in the ‘687 patent (flumezapine), which differed only in the substitution of a fluorine atom for a hydrogen atom. The finding of inventiveness of Olanzapine was based on the statements in the ‘113 patent declaring the superiority of Olanzapine over the compounds in the ‘687 patent with respect to side effects, efficacy, etc.    

On remand to the trial division, the judge held that the ‘113 patent was invalid for lacking utility on the basis that the support for Olanzapine as a superior anti-psychotic did not constitute a sound prediction compared to the compounds disclosed in the ‘687 patent.  While the ‘113 patent extolled the benefits of Olanzapine as a superior treatment for schizophrenia, based on certain special advantages (lower incidence of side effects, higher efficacy), the Court ruled that the evidence in the ‘113 patent did not meet the threshold for the utility, or sound prediction, of a selection patent.  It was clear that the trial court was employing a higher threshold of utility than the “mere scintilla” required for non-selection patents, as the judge ruled that the alleged advantages disclosed in the ‘113 patent were not “substantial.”  Importantly, the judge also appeared to require an even higher threshold for utility with respect to the treatment of chronic conditions as they “must be supported by a factual basis and line of reasoning consistent with the use of the compound over a long term.”  Eli Lilly does not appear to have filed an appeal to this decision.  As the ‘113 patent recently expired, it is unlikely that they would appeal.    

The Court of Appeal has explicitly stated that a determination that the requirements for a selection patent have not been met will not serve to independently invalidate a patent.  However, it is clear that a properly disclosed special advantage is still required for a valid selection patent. Accordingly, those involved in pharmaceutical research with respect to selecting compounds from a known genus should ensure they possess and provide in the patent application their evidence that a selected compound is superior over the genus.  Even more so, if the compound is for the treatment of a chronic condition, longer term pharmacological data would be beneficial.   

1 Eli Lilly Canada Inc. v. Novopharm Limited, 2011 FC 1288
2 Eli Lilly Canada Inc. v. Novopharm Limited, 2009 FC 1018
3 Eli Lilly Canada Inc. v. Novopharm Limited, 2010 FCA 197

Michael Fenwick, B.Sc., M.Sc. (Org. Chem.), LL.B., is an associate lawyer with Bereskin & Parr LLP's Biotechnology & Pharmaceutical practice group. Michael can be reached in Toronto at 416.957.1665 or mfenwick@bereskinparr.com.

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Author(s):

Michael Fenwick Michael Fenwick
B.Sc., M.Sc. (Org. Chem.), LL.B.
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416.957.1665  email Michael Fenwick