Jon Gowshall and Ross Walker, patent attorneys with the UK law firm Forresters, announced that they have successfully defended European patent (UK) number 0706376 (to Angiotech Pharmaceuticals Inc and the University of British Columbia), claiming a stent which eluted paclitaxel to prevent restenosis

In the case, the House of Lords overturned the first and second instances finding of obviousness. The result is moving the principles for assessing inventive step in the UK closer to those applied by the European Patent Office.

The patent teaches that restenosis can be prevented by preventing the growth of local blood vessels (angiogenesis). The inventors had discovered, in experiments, that paclitaxel, a recently discovered cancer drug, had remarkable anti-angiogenic properties. They concluded from this that it could prevent restenosis when delivered from a stent. The claimed stent is sold as the Taxus stent. It is a great commercial success.

The European patent was challenged in the UK Patents Court by Conor Medsystems Inc. The only ground of alleged invalidity was that the claimed stent was obvious.

Conor argued that the patent did not teach that the stent actually worked in preventing restenosis. They argued that, because of this, the test for obviousness was not whether the worker in the field would find it obvious that taxol on a stent would treat restenosis, but whether that worker would find it obvious to test the combination, without any expectation of success.

The Patents Court accepted Conor’s argument. The Judge agreed that, because the application did not actually show that paclitaxel would prevent restenosis, there was no need to decide if one might expect it to succeed.

The Court of Appeal agreed with the judge in the Patents Court and upheld his decision and Angiotech appealed to the House of Lords. The House of Lords is the highest court in the UK, and so the supreme court of appeal. It decides on points of law rather than the facts of an individual case and its decisions are binding on all courts below it.

The House of Lords upheld Angiotech’s appeal, and found that the claimed stent was inventive, using the proper test for obviousness. A number of important findings on the law of obviousness come from the decision. The overall tenor of the decision moves the UK law closer to the practice of the European Patent Office in assessing obviousness.

The Lords confirmed that inventive step must be decided on the claimed invention and the disclosure in the application has nothing to do with this assessment. In other words, the court must decide whether the subject matter of the claims is obvious, and the content, or otherwise, should not affect this decision.

However, the Lords also followed recent practice of the European Patent Office, as exemplified by T 1329/04. They confirmed that, before considering inventive step, the patent must pass a “threshold test” of plausibility. In that test, the court reviews the whole specification and decides whether, on the basis of the specification alone, it is plausible that the invention will work. The Lords found it plausible that the claimed invention would work to treat restenosis, based on the data and teaching in the specification.

Finally, the Lords confirmed that the court must assess the obviousness of the claimed invention in the light of the purpose for which is intended. The court should also take into account the expectation of success that the skilled person would have of achieving that purpose with the invention. Both of these principles are followed by the European Patent Office. The Netherlands court also applied them in parallel proceedings, which was noted with approval by the Lords.

Lord Hoffman described the idea of assessing whether something is obvious to try without an expectation of success (the test applied in the Patents Court) as an “oxymoronic concept”, with no precedent in patent law.

The Lords held that the claimed stent was inventive, in that a skilled person would not have tried it with any reasonable expectation that it would be effective to treat restenosis. In doing so, they have moved the UK approach to obviousness significantly closer to that taken by the European Patent Office.

You can read the text of the full decision here.

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