Conor Medsystems Inc v Angiotech Pharmaceuticals Inc & Anor

In assessing obviousness, the court must identify the contribution actually disclosed by the specification and the result which the skilled person would be seeking to achieve. Where a patent claims a physical device but gives no evidence that it will be safe or effective, an invention may be obvious if it was obvious to test the claimed device, even without an expectation that it would succeed in treatment. Commercial success, historical delay and other secondary evidence are aids to assessing the primary expert evidence. They must not replace the statutory, objective inquiry or become a mechanical checklist. The skilled person is assessed by reference to the relevant technical team and common general knowledge at the priority date.

Conor sought revocation of European Patent (UK) 706376, owned by Angiotech Pharmaceuticals Inc and the University of British Columbia. The patent concerned stents coated with a polymer containing taxol or a taxol derivative, including vascular stents for treating or preventing restenosis after angioplasty.

The alleged prior art comprised the Wolff and Kopia publications and the Katsuda abstract. The central issue was whether the claimed taxol-eluting stent involved an inventive step, particularly whether the skilled person would have regarded taxol as worth testing in a drug-eluting stent despite its toxicity and uncertain clinical efficacy.

1. Obviousness. The court applied the approach in Windsurfing International v Tabur Marine [1985] RPC 59. The correct question depended on the contribution disclosed by the specification. The specification disclosed incorporating taxol in a drug-eluting stent, but gave no data or indication that the stent was safe or effective in preventing restenosis.
2. Accordingly, the relevant objective was testing the stent to discover whether it had potential in treating or preventing restenosis. An expectation of therapeutic success was not required. The claims were obvious if the skilled person would regard taxol as worth testing. The approach was consistent with the guidance in Hickman v Andrews [1983] RPC 147 and Lilly Icos LLC v Pfizer Ltd [2002] EWCA Civ 1.
3. The skilled addressee comprised an interventional cardiologist and a person knowledgeable about relevant pharmaceutical agents. By the priority date, drug-eluting stents, local delivery of anti-proliferative drugs and taxol’s anti-proliferative properties were sufficiently known. Toxicity and possible side-effects justified testing and monitoring, but did not make testing taxol irrational.
4. Commercial success and contemporary history could assist in testing the expert evidence. However, the statutory inquiry remained objective. Such evidence was secondary and was not to be converted into a checklist. The court considered the factors discussed in Haberman v Jackel [1999] FSR 683 in that limited way.
5. Wolff made the use of drug-eluting stents with anti-replicate drugs an obvious avenue for testing taxol. Kopia directly taught local delivery of taxol to an angioplasty site, and Katsuda provided further evidence that taxol inhibited smooth-muscle-cell proliferation. The claims were therefore obvious in the light of the pleaded citations.
6. The patent was invalid for obviousness and was revoked.