Eli Lilly and Company v Pfizer Research and Development Company NV/SA

REASONS FOR JUDGMENT 1 Pfizer Ireland Pharmaceuticals (Pfizer) is the assignee of the patentee of Australian Patent No 676571 entitled "Pyrazolopyrimidinones for the treatment of impotence" (the Patent). Under the Patent Pfizer and associated companies market the product Viagra, a treatment for male erectile dysfunction (MED). 2 Eli Lilly and Company (Lilly) and Bayer Aktiengesellschaft (Bayer) have each brought proceedings, respectively No V604 of 2002 and No V111 of 2003, seeking revocation of the Patent. 3 Pfizer seeks an order for amendment of the Patent pursuant to s 105 of the Patents Act 1990 (Cth) (the Act). The Patent presently includes claims 9 and 10 as follows: "9. A method of orally treating man to cure or prevent erectile dysfunction in man in need of such treatment, which comprises treatment with an orally effective amount of a cGMP PDE inhibitor, or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition containing either entity. 10. The method according to claim 9 wherein the inhibitor is cGMP PDEV inhibitor." The proposed amendment would delete claim 9 and amend claim 10 to read as follows: "10. A method of orally treating man to cure or prevent erectile dysfunction in man in need of such treatment, which comprises treatment with an orally effective amount of a cGMP PDEV inhibitor, or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition containing either entity." (emphasis added) In substance therefore the proposed amendment deletes the wider claim of claim 9 and retains the narrower claim of claim 10, with consequential amendments to the latter so that it makes sense when read on its own. 4 Section 102 of the Act prohibits amendments which would claim matters not in substance disclosed in the specification as filed or where, as a result of the amendment, a claim would not fall within the scope of the claims of the specification before amendment or the specification would not comply with s 40 (2) or (3). It is accepted that s 102 does not bar the proposed amendment. The Commissioner of Patents is aware of the proposed amendment and does not oppose it. Lilly and Bayer however oppose the amendment on discretionary grounds. 5 The genesis of the present amendment application is litigation in England where the corresponding Pfizer patent (the UK patent) was revoked by Laddie J in the Patents Court: Pfizer Ltd's Patent [2001] FSR 16, a decision handed down on 10 November 2000. 6 In the present application the parties have not put on any technical evidence. The following background is based on parts of the judgment of Laddie J where his Lordship was relying on an agreed primer. I believe therefore that these matters are not controversial. 7 Within the penis there are two symmetrical compartments, or corpora, each of which is called a corpus cavernosum. Each contains a network of very small blood vessels or passages. It is changes in the blood flow inside these compartments which lead to tumescence or detumescence. 8 When the penis is in flaccid state, the flow of blood into the corpora cavernosa is restricted by constriction of the smooth muscle which surrounds the vessels in the incoming arterial network. An erection occurs when the smooth muscles relax. The arteries open up, blood flows in and each corpus cavernosa swells. 9 The chemical messenger which causes the cells in the smooth muscle to relax is nitric oxide, which is generated by sexual stimuli. Nitric oxide enters the cell and causes a chemical reaction which produces cyclic guanosine monophosphate (cGMP). This in turn activates certain other enzymes which cause or promote chemical reactions which relax the smooth muscle. 10 But cGMP can itself be inactivated. A group of enzymes called phosphodiesterases (PDEs) cause cGMP to be turned into a chemical which is ineffective to relax muscles. 11 However penile smooth muscle is also relaxed by other agents, as well as cGMP, and in particular by a chemical called cyclic adenosine monophosphate (cAMP). It is produced from a different starting material to cGMP and in response to different messages. But again, there are PDEs which can make cAMP ineffective. 12 Before the relevant priority date it was found that PDEs could be classified into five enzymes or enzyme groups. These were distinguished by Roman numeral subscripts I to V. These do not affect cGMP and cAMP uniformly. As the table in Pfizer Ltd's Patent at [18] shows,PDEs I II and III affect both cGMP and cAMP, PDEIV affects cAMP only and PDEV affects cGMP only. A PDE which affects only, say, cAMP is said to be cAMP specific. A PDE which affects both cGMP and cAMP is not specific, but if it is more effective, or potent, in affecting one than another it is said to be selective to the former. PDEIII for example, it is more effective in destroying cAMP than cGMP, so it is said to be cAMP selective. 13 Some chemicals inhibit (ie wholly or significantly block) the operation of PDEs. But different inhibitors have different effects on different PDEs. For PDEI and ll there are no known inhibitors. For the remaining PDEs, each is affected by a different inhibitor (see the table). 14 In that setting, one of the issues before Laddie J was the construction of claims 10 and 11 of the UK patent. Although not identical in terms, for present purposes those claims correspond to claims 9 and 10 of the Patent. 15 Laddie J (at [44]-[57]) rejected the argument of Pfizer that "cGMP PDE inhibitor" in claim 10 of the UK patent meant an inhibitor of cGMP selective PDEs. His Lordship held (relevantly for present purposes) that claim 10 covered the use of any compound which inhibited cGMP PDEs, whether they were cGMP selective or not, that is to say whether or not they inhibited cAMP PDEs as well. 16 Part of the reasoning of Laddie J (at [47]) was that Pfizer's argument meant that since claim 11 only covered cGMP selective PDEV inhibitors it would be identical with the Pfizer construction of claim 10. 17 The main argument of Lilly and Bayer against the present application to amend was that the removal of claim 9 of the Patent would remove the context in which Laddie J construed the equivalent claim 10 in the UK patent. In other words, Lilly and Bayer at trial would not be able to argue that Pfizer's construction of claim 10 involved giving it the same meaning as claim 9. 18 The short answer to this argument is s 116 of the Act, which provides that, in interpreting a complete specification as amended, the Court may refer to the specification without amendment. Even without s 116, the construction of the Patent as at the date of its grant would necessarily involve construing a claim, amongst other things, in the light of the document as a whole, including, where relevant, other claims: see Terrell on the Law of Patents (15th ed) at 145. If on that approach a claim bore a certain construction as at the date of grant, it is difficult to see how the meaning could alter as a result of subsequent deletion of other claims. 19 But even if, contrary to my opinion, Pfizer were to gain some forensic advantage as a result of the proposed amendment, with corresponding disadvantage to Lilly and Bayer, the proposed amendment should still be granted. (I should make it clear that I do not accept the suggestion, somewhat faintly put on behalf of Lilly and Bayer, that there has been some lack of candour on Pfizer's part in somehow concealing a tactical advantage to be obtained by the amendment.) 20 Where the amendment sought is the deletion of a claim, the amendment will only be refused in exceptional circumstances: Chiron Corporation v Organon Technika Ltd (No 7) [1994] FSR 458 at 460-463, Mabuchi Motor KK's Patents [1996] RPC 387 at 397, Nutrinova Nutrition Specialties & Food Ingredients Gmbh v Scanchem UK Ltd (No 2) [2001] FSR 831 at 837, Hoeschst Marion Roussel Ltd & Ors v Kirin-Amgen Inc & Ors [2002] EWHC 471 at [68]. One obvious reason for this approach is that there is a public interest in the validity of a patent, extending beyond the patentee and those currently seeking revocation. The existence of patent claims which are in truth invalid, and which the patentee does not seek to propound, may inhibit persons from engaging in lawful and productive economic activity, with resultant disadvantage to the public by loss of competition and innovation. 21 Delay is relied on. Lilly and Bayer point to delay from the delivery of Laddie J's judgment in November 2000 until the first steps were taken by Pfizer towards amendment in January 2003. This delay is understandable because until Lilly commenced the first of these Australian revocation proceedings on 17 September 2002 the attention of Pfizer, or its relevant associated company, was not directed to possible invalidity of any claim of the Patent. In its defence filed on 24 January 2003 Pfizer's predecessor in title to the Patent foreshadowed the proposed amendments. No point is taken of any delay since then, which was partly due to the assignment. 22 It is not suggested by Lilly or Bayer that any other person has been inhibited in any way or suffered any loss or disadvantage by the existence of claim 9 up until now. 23 In any case, if there is, for the reasons mentioned, a public interest in allowing the amendment, it might be said to be a case of better late than never. Put another way, Pfizer cannot be forced to maintain the validity of claim 9. Ultimately at the trial of these proceedings it is inevitable that, whatever the result, claim 9 will fall. There have already been rather inconclusive discussions at directions hearings about a trial date. At the moment it seems likely that the trial will not take place until some time in 2005. I cannot see the sense in punishing Pfizer for any delay by leaving claim 9 in place for all this time, to the consequential detriment of the public. 24 There will be an order that the Patent be amended accordingly. 25 As to costs, it is said that, according to Terrell (14th ed) at 245, the normal practice is that the applicant for an amendment pays the respondent's costs: see also Wimmera Industrial Minerals Pty Ltd v RGC Mineral Sands Ltd & Ors [1997] FCA 1337. However there must remain a general discretion. Patent litigation, especially over pharmaceutical patents, is quite expensive enough, with the costs being passed on to consumers in the form of higher prices. I do not think it desirable that parties be encouraged to pursue unmeritorious objections like those in the present case by a belief that they will get their costs paid in any event. Because of the public interest element, applications to amend, at least where the amendment is by deletion, are not truly comparable to the "indulgence" said to be involved in the amendment of pleadings or the grant of adjournments. Indeed, there is some ground for thinking that Lilly and Bayer ought to pay Pfizer's costs, but since the latter moderately sought an order only for costs in the cause I will make an order accordingly. I certify that the preceding twenty-five (25) numbered paragraphs are a true copy of the Reasons for Judgment herein of the Honourable Justice Heerey.