After judge Arnold J declared that Actavis was not infringing Eli Lilly's European patent in France, Italy, Spain or the UK [see note 1 below] the Court of Appeal have now taken a broader approach to the construction of the claims and found that Actavis are contributory infringers [see note 2 below]. Additionally, the Court of Appeal have warned against relying on the prosecution history of the patent to construe the claims.

Background

Eli Lilly's Patent (EP 1 313 508 B1) granted on 18 April 2007 with both Swiss-type claims and purpose-limited product claims directed to the use of pemetrexed disodium. The Swiss-type claim read (emphasis added):

"Use of pemetrexed disodium in the manufacture of a medicament for use in combination therapy for inhibiting tumor growth in mammals, wherein said medicament is to be administered in combination with vitamin B12 or a pharmaceutical derivative thereof, said pharmaceutical derivative of vitamin B12 being hydroxocobalamin, cyano-10-chlorocobalamin, aquocobalamin perchlorate, aquo-10-chlorocobalamin, perchlorate, azidocobalamin, chlorocobalamin or cobalamin."

At first instance in the Patents Court, Arnold J granted Actavis declarations of non-infringement (DNI) in France, Italy, Spain and the UK for generic products containing pemetrexed diacid, pemetrexed dipotassium or pemetrexed ditromethamine. Arnold J concluded that there was no direct or contributory infringement and that applying the infringement laws of France, Italy and Spain would lead to the same result as the application of English law.

In coming to this conclusion Arnold J relied on the prosecution history of the patent. He stated that "consideration of the prosecution file may assist in ensuring that patentees do not abuse the system by accepting narrow claims during prosecution and then arguing for a broad construction of those claims for the purpose of infringement". During prosecution of this case, Eli Lilly had narrowed the claims to pemetrexed disodium in order to overcome clarity, sufficiency and added matter objections.

Eli Lilly appealed and in the Court of Appeal, Lord Justice Floyd gave the only reasoned judgement.

Claim construction: prosecution history

Unlike Arnold J, however, Floyd LJ did not rely on the prosecution history to construe the claims. He explained that he had "difficulty" endorsing Arnold J's reasoning because:

  • it assumes that the skilled reader will always read the prosecution history; and
  • it suggests that the story told by the prosecution history will assist the court in preventing abuse of the system.

Floyd LJ also noted that patent offices are usually concerned with patentability not scope of protection.

Claim construction: improver questions

Floyd LJ instead made reference to the established case law on claim construction and to the teachings of the patent specification.

Pemetrexed disodium is an antifolate and LJ Floyd noted that there were several passages in the patent where the use of "the antifolate" rather than "anantifolate" was indicative that the invention was not concerned with the use of antifolates as a class, but with the use of a specific antifolate. He thus concluded that it was clear that the claims were limited by the term "pemetrexed disodium".

LJ Floyd acknowledged that English courts do not apply a general doctrine of equivalence to the construction of patent claims, but that this "does not mean that the existence of equivalents which have no material effect on the way the invention works has no bearing on the proper, purposive interpretation of a patent claim". This is borne out by the 'improver' or 'protocol' questions which ask:

  1. Does the variant have a material effect upon the way the invention works? If yes, the variant is outside the claim. If no?
  2. Would this have been obvious at the date of publication of the patent to a skilled reader? If no, the variant is outside the claim. If yes?
  3. Would the skilled reader nevertheless have understood from the language of the claim that the patentee intended that strict compliance with the primary meaning was an essential requirement of the invention? If yes, the variant is outside the claim.

As will become clear from the discussion below, one of the key issues in the present case was question (2). LJ Floyd stressed that this question asked what would be obvious "in the sense of immediately apparent" to a skilled reader reading the patent in light of his common general knowledge.

Direct infringement

Floyd LJ agreed with Arnold J that Actavis did not directly infringe Eli Lilly's patent. He decided that the claim did not extend to cover the use of other pemetrexed salts because, like Arnold J, he was not convinced that the second or third improver question had been answered positively.

Whilst Actavis' active ingredients would not have had a material effect on the way the invention worked, Floyd LJ agreed that this would not have been obvious to the skilled reader. The skilled reader would not have been able to predict whether a particular salt form could be made and/or what its properties would be once it was made, eg, whether the salt would be sufficiently soluble to effectively treat the disease.

Floyd LJ explained that the latter is important for a Swiss-type/purpose-limited product claim because these claims include the step of manufacturing a medicament for treating a disease. The claim therefore requires that the manufactured medicament is to some extent effective for treating the disease.

Contributory infringement

Floyd LJ, however, came to the opposite conclusion for contributory infringement.

Contributory infringement is assessed under section 60(2) of the Patents Act 1977 which states that a person infringes if they supply or offer to supply in the UK, the means relating to an essential element of the invention, for putting the invention into effect when the person knows that those means are suitable for and intended to put the invention into effect in the UK.

In the present case, contributory infringement was alleged because each of Actavis' active ingredients would be dissolved and/or diluted in saline before administration to the patient. The result is thus a solution containing pemetrexed ions and sodium ions.

Arnold J held that this did not give rise to contributory infringement because pemetrexed disodium per se was not used in the manufacture of the medicament. Floyd LJ, however, disagreed.

Floyd LJ noted that the patent was not limited to solid pemetrexed disodium, but included solutions containing pemetrexed ions and sodium ions.

He also highlighted that section 60(2) refers to a means relating to an essential element of the invention, and that in the present case this clearly included a means for releasing pemetrexed ions into solution. The invention is thus put into effect when a pharmacist makes up the solution using Actavis' active ingredients because there comes a stage when pemetrexed disodium is present and is used.

In coming to this conclusion, Floyd LJ referred to the earlier Court of Appeal case: Grimme Maschinenfabril v Scott [see note 3 below], where the court recognised that the "essential means" of section 60(2) did not have to be something which could be used without alteration. Pemetrexed dipotassium was therefore a means relating to an essential element of the invention.

Consequently, Actavis were refused their DNIs under English law. DNIs were also refused for France, Italy and Spain since there are no detectable differences in their approach to contributory infringement.

It is interesting to note that the Court of Appeal's conclusion on contributory infringement contradicted that of the Düsseldorf Court of Appeal (Oberlandesgericht Düsseldorf) for the German designation of the patent. Floyd LJ reasoned, however, that the German court appeared in the judgment to understand "pemetrexed disodium" as describing only that substance in solid form.

Comments

Although no decision was made by the Court of Appeal as to the admissibility of the prosecution history, Floyd LJ's comments give some guidance as to the Court of Appeal's position on this issue. Reassuringly this is the status quo in that the prosecution history has little weight when construing the claims of a patent in the UK. This is good news for applicants, patent proprietors and practitioners. Care should, however, still clearly be taken when making amendments and arguments during prosecution.

This case also contributes to the ongoing development of the law on contributory infringement of second medical use claims. See the article on page 10 of this newsletter for further discussion of the dispute between Warner-Lambert and Actavis on the scope of section 60(2) for Swiss-type claims.