Angiotech Pharmaceuticals Inc. v Conor Medsystems Inc.

Angiotech Pharmaceuticals Inc, a Canadian company, and the University of British Columbia are joint proprietors of European patent 0 706 376 which claims, among other things, a stent coated with taxol for "treating or preventing recurrent stenosis". For convenience I shall call the patentees Angiotech. Conor Medsystems Inc (Conor), an American competitor, applied in both the United Kingdom and the Netherlands for revocation of the patent on the ground that the claimed invention was obvious. In the United Kingdom, before Pumfrey J and the Court of Appeal (Mummery, Tuckey and Jacob LJJ), it succeeded. In the Netherlands, before the District Court of The Hague (Robert van Peursem, Edgar Brinkman and Walter van Straalen) it failed. Angiotech appeals to your Lordships' House and says that the Dutch court was right and that the patent should be declared valid.

Since the decision of the Court of Appeal, Angiotech and Conor have reached a settlement. Conor does not oppose Angiotech's appeal. But a patent confers proprietary rights in rem and the validity of a patent cannot be established simply by a judgment in default of opposition. Your Lordships therefore invited the Comptroller General of Patents to assist the court in presenting what appeared to him to be the arguments against the validity of the patent. The House followed the procedure adopted by the Court of Appeal in a similar situation in Halliburton Energy Services Inc v Smith International (North Sea) Ltd [2006] EWCA Civ 1715. Angiotech agreed to pay the Comptroller's costs and the Comptroller instructed Mr Tappin to appear before the House. I have, as I am sure your Lordships will agree, found his written and oral submissions of great assistance.

There is still no European Patent Court. A European patent takes effect as a bundle of national patents over which the national courts have jurisdiction. It is therefore inevitable that they will occasionally give inconsistent decisions about the same patent. Sometimes this is because the evidence is different. In most continental jurisdictions, including the European Patent Office ("EPO"), cross-examination is limited or unknown. Sometimes one is dealing with questions of degree over which judges may legitimately differ. Obviousness is often in this category. But when the question is one of principle, it is desirable that so far as possible there should be uniformity in the way the national courts and the EPO interpret the European Patent Convention ("EPC"). In this case, as Pumfrey J made clear in his judgment, there is a question of principle at stake. It is about how you identify the concept embodied in the invention which may constitute the "inventive step" for the purposes of article 56 of the EPC and section 1(1)(b) of the Patents Act 1977.

The subject matter of the patent is a stent, a tubular metal scaffold inserted into an artery to keep it open. It is used in connection with angioplasty, one of the great modern advances in the treatment of sclerosis of the coronary arteries. A catheter carrying a balloon is inserted into the arterial system from outside ("percutaneously"), usually at the groin, and manoeuvred through the arteries to the point at which the coronary artery has become constricted or "stenosed". There the balloon is expanded to push back the artery walls and enlarge the channel. The insertion of a stent will prevent the walls from collapsing when the catheter and balloon are withdrawn.

A serious problem with this form of intervention was that the injury caused to the inner layer of the artery by the insertion of the stent often produced an exaggerated healing response, characterised by the proliferation of smooth muscle cells forming new tissue which once again constricted the arterial channel. This is called restenosis. It affected between a third and a half of patients in whom stents had been inserted and no one knew what to do about it.

There was however no shortage of suggestions and in 1993, more or less at the same time as the priority date of the patent in suit, a group of Dutch scientists of high repute in the field published a two-part article entitled Pharmacological Approaches to the Prevention of Restenosis Following Angioplasty: The Search for the Holy Grail? (Drugs 46(1) 18-52; 46(2) 249-262). Many people thought that the proliferation of smooth muscle cells in restenosis was analogous to the proliferation of cells in cancer tumours and might be treated by anti-proliferative drugs. Others favoured antithrombotic agents such as heparin, antiplatelet agents like aspirin, anti-inflammatories, calcium antagonists and lipid-lowering drugs. The article described two theories about how the process of restenosis took place. Both involved several stages at which different forms of pharmacological intervention might be appropriate.

The summary at the start of the second part of the article, which dealt with future possibilities, said:

"[D]espite 15 years of clinical experience and research in the field of restenosis prevention, this has not yet resulted in the revelation of unequivocal beneficial effects of any particular drug. Other newer approaches likely to receive more attention in the future include anti-bodies to growth factors, gene transfer therapy and antisense oligonucleotides. Whether there is a feasible monotherapy, whether we have to focus on a drug combination, or whether we are only searching for the 'Holy Grail' remain to be answered."

Meanwhile in Vancouver, a young medical student named William Hunter was studying angiogenesis, the process by which capillary blood vessels grow, under a Dr Arsenault, who had made it his particular area of research. It occurred to Dr Hunter that one approach to unwanted cell proliferation might be the inhibition of angiogenesis, because most cell tissue cannot grow more than 200 or so microns without blood. (Tumour cells are different; they are notoriously able to grow without a supply of oxygen from the blood but they are not the normal cause of restenosis). In 1991, during his third year at medical school, Dr Hunter met Dr Machan, who had experience in cardio-vascular intervention and the use of stents. As a result of their discussions, they decided to try to find an anti-angiogenic agent which could be used to inhibit or prevent tissue growth in restenosis. To fund the research, Drs Hunter, Arsenault and Machan formed Angiotech and obtained a grant from the Science Council of British Columbia.

They tested various drugs for anti-angiogenic properties by an assay using chick embryos (the chorioallantoic membrane or "CAM" assay). This was an established test, although perhaps not very sophisticated or discriminating. One of the drugs tested, in February 1993, was paclitaxel, a recently-discovered anti-proliferative derived from the Pacific yew tree, which was much in the news as a possible cancer treatment. Dissolved in cremophor for pharmacological use, it was marketed under the trade name of taxol. On the CAM assay, it appeared to have remarkable anti-angiogenic properties. Dr Hunter said it was effective to inhibit angiogenesis even in minute concentrations.

On 19 July 1993 Angiotech applied for a US patent which is the priority document for the patent in suit. The title of the patent is "Anti-angiogenic compositions and methods of use" and the patent, at least as originally applied for, is by no means confined to their use on stents. The primary emphasis is on the use of anti-angiogenics for the treatment of cancer. This was a bold claim because most anti-angiogenics such as taxol were anti-proliferatives and their use for treating cancer was well known. But their use on stents comes next, as is made clear by the introductory paragraph of the description:

"The present invention relates generally to compositions and methods for treating cancer and other angiogenic-dependent diseases, and more specifically, to compositions comprising anti-angiogenic factors and polymeric carriers, stents which have been coated with such compositions, as well as methods for utilizing these stents and compositions."

In the European Patent Office, the patent was opposed after grant on the ground, among others, that use for cancer treatment was either not new or obvious. As a result of a decision of the Opposition Division, the claims for treating cancer and other diseases were abandoned and the patent confined to the use of taxol on stents. Claim 1 as amended was for a stent coated with taxol, claim 11 to a stent according to claim 1 for treating a "narrowing of a body passageway" and claim 12 for a stent according to claim 11 "for treating or preventing recurrent stenosis". It is this last claim which is in issue in these proceedings.

The Angiotech stent has been a great commercial success. It has the largest share of the market in drug eluting stents, which have very considerably reduced the incidence of restenosis.

The action for revocation was commenced by Conor on 18 February 2005. In its amended grounds of invalidity it was said that the alleged invention was obvious having regard to three items of prior art: PCT Patent Application WO 91/ 12779 (Wolff) PCT Patent Application WO 93/ 11120 (Kopia) and an...