Supreme Court upholds rosiglitazone maleate (Avendia) patent despite earlier claim

Rosiglitazone maleate is a patented drug manufactured by SmithKline Beecham (SKB) under the trade name 'Avendia' , and used to treat Type II diabetes.

When Israeli drug manufacturers Unipharm and Trima began manufacturing generic versions of the drug, SKB filed for an injunction and damages. Unipharm and Trima's defence was that the patent in question, IL106904, which claims priority from an earlier UK application (UK9218830/9) was invalid, since it lacked novelty and inventive step in light of an earlier European patent (EP0306228) that was published before the priority date.

The Court of First Instance found that Rosi, the generic product produced by Unipharm and Trima, infringed the IL106904 patent, which was upheld over the prior patent. Lack of sales rendered moot the issues of unfair trade and compensation. The decision was appealed to the Supreme Court.

On appeal, Unipharm and Trima claimed that the Court of First Instance was wrong to determine that since there was novelty and inventive step, the issue of whether the patent in question was a selection patent did not need to be addressed. They argued that although a preferred salt had been isolated, it could not be used fairly to extend the term of protection beyond the expiry date of the earlier patent. They also argued a lack of enablement. Finally, they pointed out that although advantages were claimed, this was in a qualitative and not a quantitive manner.

The court reminded the parties that it reviews not factual determinations of the Court of First Instance, but only matters of law. It went on to rule that even if the wide Claim 1 were to be invalidated, nevertheless Claim 4 for the specific rosiglitazone maleate could survive on its own merits if shown to be novel and inventive as it was widely supported by the specification. It also defended the principle of at risk manufacture, pointing out that the Section 182 of the Patent Law allows invalidity as a defence for patent infringement.

The Court of First Instance was impressed by the patentee's witnesses and by the fact that a defence witness admitted that rosiglitazone maleate was novel. The court also found that the selected sale was not obvious because: 

  • The patentee could show trial and error in the research programme.
  • It considered other salts like the hydrochloride more likely to be appropriate.
  • It almost gave up the project for lack of progress.

The court saw no reason to overturn the lower court's ruling. Pointing out that the Patent Law requires enabling disclosure to establish novelty, the court stated that rosiglitazone maleate was not mentioned in the earlier patent, and so was novel. By virtue of the earlier patent teaching basic salts and the present invention being an acidic salt, in view of improved efficacy, higher solubility and stability, rosiglitazone naleate was considered to be novel and inventive. In regard to enablement, the court pointed out that the ease of copying the patented salt by a person skilled in the art, on the basis of the disclosure in the patent, was evidence that the description was enabling.

The Supreme Court awarded costs of NIS60,000 to the patentee (Appeal 8802/06 Unipharm v Smith Kline Beecham, 18th May 2011, judgment given by Retired Judge Fructzia and endorsed by Judges Heyot and Fogelman. 

The appellants claimed that rosiglitazone maleate was claimed in a dependent claim (Claim 4) and that if the main claim failed, this dependent claim should fail with it. Such argument is found in several decisions of the outgoing arbitrator of intellectual property at the Patent Office, Noach Shalev Shlomovich. In Giraffa v Melnicke Shlomovitch ruled that where a main claim was invalid, all dependent claims also failed (although he did once admit to the author that this was a mistake). Nevertheless, in other oppositions, where main claims are shown to be invalid, he punished the applicant for greed and cancelled the dependent claims. In this case, the Supreme Court ruled that where there was adequate support for the dependent claim and it was fairly based on the specification, it survived even if the independent claim on which it was based was invalidated. It is hoped that this Supreme Court ruling is considered as binding precedent and this controversial issue is laid to rest.

The claims of the prior art do relate to rosiglitazone salts, which does include rosiglitazone maleate. Since the specification relates to basic salts, the court has effectively construed the term "rosiglitazone and its pharmaceutical acceptable salts" to mean basic salts only. However, this appears unnecessary. If some specific molecule is found to have advantages over the prior art, this could fairly be patentable. When the main patent expires, other salts outside the scope of the second patent will move into the public domain.

As is often the case, it is the obiter that is most interesting. In this case the court essentially rejected selection patents as a separate class, arguing that previous Supreme Court rulings related to the mandatory regime before the Patent Law was passed and that by not relating to selection patents, the law has essentially rejected them as a class. Another interesting point is that secondary uses of known pharmaceuticals are patentable inventions. In the past, the title of an Israeli patent has been considered unimportant, and it is generally considered as used for classification purposes only. In this ruling it is clear that the courts do consider the title as indicative of the scope of the invention. Reiterating Section 49, the court ruled that it considered that the scope of the patent included its nucleus and the exact wording of the claims was not all-important. It appears that unnecessary limitations in the claim language will not be considered to limit the scope of the monopoly.

This is an Insight article, written by a selected partner as part of IAM's co-published content. Read more on Insight

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