Lilly ICOS Ltd v Pfizer

This Court held that a patent claiming the use of known cGMP PDE V inhibitors for treatment of male erectile dysfunction was obvious.

The court applied the established four-step Windsurfing approach to obviousness and concluded that prior publications disclosed the operative mechanism and expressly suggested impotence as a therapeutic target.

Where prior art both taught the biochemical pathway and recommended testing of cGMP PDE V inhibitors for impotence, routine screening and development did not involve inventive skill.

Oral administration was an obvious and routine route to pursue where oral bioavailability testing was standard practice.

This is an appeal from the Chancery Division (Laddie J) against a judge's finding revoking European Patent No. 0702555, which claimed the use of certain known compounds (including sildenafil/Viagra) as medicaments to treat erectile dysfunction.

The primary ground at first instance was obviousness. The judge held the patent obvious in the light of published scientific articles (notably Rajfer (New England Journal) and a review by Murray) and earlier Pfizer Bell patents. Pfizer appealed that conclusion. Lilly cross-appealed on other grounds but the Court of Appeal heard and decided the appeal on obviousness.

The central issue was whether the prior art made it obvious to a person skilled in the art to use selective cGMP PDE V inhibitors, and to pursue oral administration, to treat male erectile dysfunction.

1. Disposition: The appeal is dismissed. The Court of Appeal (Aldous LJ, Buxton LJ and Longmore LJ) upheld Laddie J's conclusion that the patent was invalid for obviousness.
2. Legal test applied: The court applied the four-step Windsurfing/Windsurfing-Obviousness structure: identify inventive concept; identify common general knowledge; identify differences between prior art and inventive concept; ask whether those differences would have been obvious to try without knowledge of the invention. The court treated this as a jury-type, fact-sensitive inquiry to be approached with caution but reviewed de novo where appropriate (see discussion of [1985] RPC 59).
3. Prior art and its effect:
   • The Murray review explicitly described the therapeutic potential of PDE V inhibitors and listed impotence as a possible utility. That disclosure would prompt a skilled worker to test such inhibitors for erectile dysfunction (applied to outcome) (see judgment paras 71–75, 138).
   • The Rajfer article experimentally demonstrated that a selective cGMP PDE inhibitor (zaprinast) potentiated NO-mediated relaxation of human corpus cavernosum. That made clear the mechanism by which PDE V inhibition could promote erection (applied to outcome) (see judgment paras 71–73, 90–91).
4. Obviousness findings:
   1. The court held that reading Murray and Rajfer together would have led the skilled addressee to regard PDE V inhibitors as promising candidates for MED treatment and that trying them was routine rather than inventive (see judgment paras 138, 99–109).
   2. Screening to identify orally active PDE V inhibitors was conceded by Pfizer not to require inventive effort; routine bioavailability studies would have been carried out and would have been expected to discover suitable orally active candidates (see judgment paras 112–113).
   3. Selection claims directed to particular "especially preferred" compounds (claims 5–7) added nothing inventive where those compounds were already disclosed in the earlier Bell patents and no basis for a selection patent was shown (see judgment paras on Claim 5–7).
   4. Claims directed to oral administration (claim 9 and claims 10–11) were obvious because oral delivery was the obvious and commercially preferred route and prior art and common practice pointed to routine testing by oral bioavailability studies (see judgment paras 99–109, 112–113).
5. Applications and guidance:
   • When prior literature both elucidates a mechanism and expressly suggests a therapeutic use, testing known compounds that act on that mechanism will often be routine and non-inventive.
   • Concessions by a patentee that routine screening involves no inventive step may be decisive where the specification provides no further enabling guidance for selection beyond routine methods.
6. Orders: The appeal is dismissed and the patent remains revoked for obviousness. No further orders on other grounds were necessary.

• Court of Appeal (Civil Division): Appeal from Chancery Division; judgment given 23 January 2002; [2002] EWCA Civ 1. Appeal dismissed.
• Chancery Division (Laddie J): First-instance judgment 10 November 2000 holding the patent obvious and revoked (decision reported in the transcript and referred to in the Court of Appeal judgment).