Conor Medsystems Inc v Angiotech Pharmaceuticals Inc & Ors

Factual and Procedural Background

Company A, a Canadian corporation, and The University jointly own European Patent No. 0 706 376, which claims (inter alia) a stent coated with taxol for the purpose of treating or preventing recurrent stenosis. Company B, a United States competitor, sought revocation of the patent for obviousness in both the United Kingdom and the Netherlands. In first-instance proceedings before Judge [Pumfrey] and, on appeal, before Judges [Mummery], [Tuckey] and [Jacob] in the Court of Appeal, Company B succeeded. The District Court of The City in the Netherlands reached the opposite conclusion and upheld the patent.

After the litigation began, Company A and Company B settled. Because patent validity is a question in rem, the House of Lords invited Official A (the Comptroller-General of Patents) to present the case for invalidity. The appeal before the House therefore proceeded with Company A as Appellant and Official A opposing in place of Company B.

Legal Issues Presented

1. Whether Claim 12 of European Patent No. 0 706 376—“a stent coated with taxol for treating or preventing recurrent stenosis”—involves an inventive step or is obvious under Article 56 EPC and section 1(1)(b) of the Patents Act 1977.
2. Whether the lower courts erred by conflating the statutory requirements of inventive step with those of sufficiency and support when assessing obviousness.
3. How the “obvious to try” test should be applied where the patent discloses that the claimed product possesses a therapeutic property but supplies limited experimental data.

Arguments of the Parties

Appellant’s Arguments (Company A)

• The claimed invention is the taxol-coated stent itself; obviousness must be assessed against that concrete product, not against a “mere idea” to test taxol.
• The specification makes a plausible disclosure that taxol-coated stents prevent or treat restenosis, supported by CAM assay data; further experimental proof is unnecessary for inventive-step analysis.
• The prior art (Wolff, Kopia, Katsuda and the “Holy Grail” review) did not make it obvious to select taxol from the many anti-proliferative candidates or to expect it to succeed in vivo.
• The lower courts wrongly mixed sufficiency requirements (Articles 83/84 EPC) into the obviousness enquiry, thereby applying an “obvious to try without expectation of success” test unknown to patent law.

Opponent’s Arguments (Official A, adopting Company B’s earlier position)

• The patent offers no in vivo data or dosing guidance; it therefore discloses only that taxol is “worth trying,” which adds nothing inventive to the common general knowledge.
• At the priority date taxol was highly publicised as an anti-proliferative cancer drug; any skilled cardiovascular specialist, consulting an oncologist, would have considered it an obvious candidate for testing on a drug-eluting stent.
• Because the specification fails to demonstrate that taxol-coated stents actually work, the contribution to the art is merely speculative; such speculation does not satisfy the requirement for an inventive step.

Table of Precedents Cited

Court’s Reasoning and Analysis

The House identified the central error below as conflating inventive-step analysis with sufficiency/support requirements. Claim 12 defined a specific product—a taxol-coated stent—for a specific therapeutic purpose. Because the product was new, the only inventive-step question was whether, at the priority date, it was obvious to a skilled cardiovascular team to use that product to prevent or treat restenosis.

Reviewing the evidence, the House concluded:

• The patent made a plausible disclosure that taxol-coated stents would combat restenosis, supported by favourable CAM assay results identifying taxol as the best anti-angiogenic tested.
• No item of prior art (Wolff, Kopia, or Katsuda) singled out taxol or provided a fair expectation that it would succeed in vivo; the field contained numerous candidate drugs, and taxol’s toxicity would have discouraged selection.
• An “obvious to try” standard without an accompanying expectation of success is insufficient at law; such an “oxymoronic concept” would reduce inventive-step analysis to mere speculation.
• Article 84 EPC concerns had already been addressed in EPO opposition proceedings; they could not be repackaged as an obviousness attack.
• Uniform interpretation of the EPC favoured alignment with the Netherlands judgment and EPO practice rather than the divergent approach of the English courts below.

Holding and Implications

APPEAL ALLOWED; the challenge based on obviousness fails and Claim 12 of European Patent No. 0 706 376 remains valid in the United Kingdom.

Implications: The decision clarifies UK law on inventive step by confirming that:

• Obviousness must be assessed against the claimed invention itself, not against a paraphrased “idea” extracted from alleged deficiencies in the specification.
• The “obvious to try” doctrine applies only where there is a reasonable expectation of success; mere worthiness of experimentation is insufficient.
• Sufficiency and support requirements under Articles 83/84 EPC are conceptually and analytically distinct from the inventive-step enquiry under Article 56.
• The judgment promotes consistency with EPO jurisprudence, thereby fostering greater uniformity across EPC contracting states.