Case review by Fiona Galbraith
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The Full Federal Court has affirmed the trial judge’s decision in the Ranbaxy case (Ranbaxy Australia Pty Ltd v Warner-Lambert Company LLC (No 2) [2006] FCA 1787). This case involved the Australian challenge by Indian-based generic pharmaceutical company Ranbaxy to two patents for the world’s biggest selling drug, Pfizer’s cholesterol lowering drug Lipitor.
Our report on the first instance of decision of Justice Young is in this newsletter. His Honour found that the first Lipitor patent would be infringed by Ranbaxy’s generic version of Lipitor, but a second patent also covering Lipitor was invalid on the grounds of false suggestion and lack of utility.
The Full Court agree with Justice Young’s finding that the first Lipitor patent would be infringed and that the second patent was invalid on the ground of false suggestion. Given that finding, it was not necessary for the Full Court to decide whether the second patent was also invalid on the grounds of lack of manner of manufacture and lack of utility, which were also pressed by Ranbaxy.
The Lipitor patents have been the subject of global litigation between Ranbaxy and Pfizer. On 19 June 2008 the parties agreed to settle the litigation worldwide. As part of the settlement, Ranbaxy will be granted a licence to sell a generic version of Lipitor in Australia. It will be interesting to see whether this settlement prompts more pharmaceutical patent owners to consider entering licensing arrangements with generic manufacturers in relation to their patented drugs.
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The first patent: claim construction and stereochemistry
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The active ingredient of Lipitor is atorvastatin (“AT”). AT lowers cholesterol levels by inhibiting cholesterol biosynthesis. Our first report provides details about the chemistry associated with AT. In summary, it is important to know that AT is a single enantiomer compound. An enantiomer is one of a pair of compounds whose chemical structures are non-superimposable mirror images of each other. In general, one enantiomer will be substantially more active than its other enantiomer at a specific biological target. A mixture of equal amounts of each enantiomer is called a racemic mixture. Unless certain steps are taken, synthesis of an enantiomeric compound will normally produce a racemic mixture.
Ranbaxy argued that the first patent claimed only racemic mixtures including AT and did not claim AT alone. If this construction were accepted, Ranbaxy’s generic version of Lipitor (with the one enantiomer, AT) would not infringe that patent.
The Full Court held that the first patent did cover AT alone, in addition to its racemic mixture. The Court found that it would make no sense to confine the first patent to just racemic mixtures and therefore exclude patent protection for the more active enantiomer (ie AT) which would be known to be the key to the useful activity of the compounds disclosed in that patent.
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The second patent: false suggestion of potency
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If a representation that was false or materially misleading contributes to the Commissioner of Patents’ decision to grant a patent, even if other circumstances or causes also play a part in the making of that decision, it may be said that the patent was obtained by a false suggestion or representation. If this is so, the patent can be revoked under section 138 of the Patents Act 1990. The second patent was revoked by the Full Court on this ground.
The second patent was for AT (and salts) individually. The second patent specification contained biological data which, on its face, showed that AT was 10 times more potent than its racemic mixture. The data was surprising because ordinarily the active enantiomer is expected to be only twice as effective compared to its racemic mixture. The data was also reproduced in a letter to the Australian Patent Office filed during the prosecution of the patent application. The letter explained that AT was 10 times more active than its racemic mixture.
The first question was whether the data and statement to the Office was false in light of all the experimental data produced by the patentee in the course of its drug discovery program.
The Full Court rejected the possibility that the data simply represented that the activity of AT was more than twice that of the racemic mixture, or was a prediction or robust assertion of the merits or characteristics of AT. The Full Court found that the data, together with the letter, was a statement of a quantitative conclusion about the inhibition of AT compared to the racemic mixture. The Full Court did not disturb the trial judge’s finding that this statement was false, because in light of the totality of the patentee’s experimental data, AT was only in the order of twice as active as its racemic mixture.
The second question was whether this false statement materially contributed to the decision to grant the patent.
When the application for the second patent was examined, the examiner objected to its grant on the basis that AT (and salts) were already disclosed in the first patent (that is, the second patent was not novel). As already found by the Court, the first patent did cover AT alone, in addition to its racemic mixture. The first patent also covered many, many other compounds.
The Full Court said that in the ordinary course, a claim to an enantiomer would not be novel or inventive given:
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- the first patent was prior art;
- it was common general knowledge that the active enantiomer of the racemic mixture could be obtained; and
- the active enantiomer was likely to have an activity twice that of the racemic mixture.
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However, the universal application this statement should be carefully considered bearing in mind that a prior patent may cover a compound, yet not disclose that compound for novelty purposes. Further Ranbaxy did not pursue revocation of the second patent on the grounds of lack of novelty and inventive step.
In this case, the Full Court recognised the objections raised by the examiner could be overcome by the patentee, at the time of examination of the second patent, on the basis of the selection patent principles set out in the 1930 English case IG Farbenindustrie AG’s Patents:- in brief, certain previously known and now “selected” compounds may be the subject of a “selection patent” if those compounds have special advantages over a broader class of prior art compounds.
The Full Court found that the data and statement to the examiner sought to overcome the objection that the second patent lacked novelty. After the letter to the office explaining the data was received by the examiner, the second patent was granted. Given these circumstances, the Full Court held that:
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- the inference was clearly open, and should be drawn, that the grant of the second patent was made because the examiner accepted the truth of the patentee’s (and its attorneys’) representation; and
- it follows that the second patent was obtained by false suggestion or misrepresentation.
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Avoiding revocation for false suggestion
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Despite reaching this decision, the Full Court noted that it was relevant that the Commissioner had made no complaint about being misled or deceived. The Court also noted that Ranbaxy had not adduced evidence as to the way in which the false suggestion operated on the decision making process of the Commissioner. In future cases, these matters may warrant close attention from patentees seeking to avoid revocation on the basis that a false suggestion was not material to the grant of the patent.
Nevertheless, patentees and their attorneys must take care that, if data is included in a specification or correspondence with the Office, that data is representative of the entire of the patentee’s research relating to the invention.
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| The Court's decision is available here |
