Pemetrexed (BGH, X ZR 29/15, 2016)

Dhenne Avocats · 11 October 2026

Our analysis

Summary

The Federal Court of Justice (BGH) set aside the judgment of the Düsseldorf Higher Regional Court, which had rejected any infringement of a claim to the use of pemetrexed disodium by a generic based on pemetrexed dipotassium, and remitted the case (operative part). It endorsed the literal reading confining the claim to the disodium salt, but held that equivalence was not excluded: the rule that equivalence is generally denied where the description discloses several options and only one is claimed does not apply where, as here, the patent discloses a single embodiment and does not name the substituted salt (Rn. 52, 55 and 59). Neither a narrowing of the claim for formal reasons nor the precision of a chemical name excludes equivalence in itself (Rn. 68, 72 and 76 to 81).

Facts and procedure

The parties are not named in the published text. The claimant is a co-proprietor of European patent EP 1 313 508, claim 1 of which covers the use of pemetrexed disodium in the manufacture of a medicament for combination therapy with vitamin B12 or a pharmaceutical derivative (Rn. 1). Protection for pemetrexed and its salts under EP 432 677 and a supplementary protection certificate ended on 10 December 2015 (Rn. 2). The defendants intended to market a generic containing pemetrexed dipotassium (Rn. 3). The Düsseldorf Regional Court found infringement by equivalent means on the auxiliary claim; the Düsseldorf Higher Regional Court dismissed the action entirely (Rn. 4), taking the view that the claim was limited to a single compound (Rn. 22 and 23).

The applicable law

The scope of protection is determined under Article 69 EPC and its Protocol. Equivalence requires a means having the same effect which the skilled person could find through considerations oriented on the meaning of the claim (Rn. 49); the BGH likened this test to the English Improver questions (Rn. 51). Under Okklusionsvorrichtung and Diglycidverbindung, equivalence is generally excluded where the description discloses several options and only one is claimed (Rn. 52). A claim to the use of a substance for a medical purpose is a form of purpose limited substance protection (Rn. 83).

Question

Where the claim is limited to one particular salt of an active ingredient, is equivalence excluded for another salt of the same active ingredient not mentioned in the patent?

Decision

The BGH upheld the literal reading: the term used covers only the disodium salt, even though the antitumour effect derives solely from the pemetrexed ion (Rn. 34). It overturned, however, the rejection of equivalence. Unlike in Okklusionsvorrichtung and Diglycidverbindung, the patent discloses only one embodiment (Rn. 55). Disclosing a general formula does not disclose the individual compounds it covers (Rn. 58), and the fact that pemetrexed dipotassium belongs to the same class of antifolates does not make it disclosed (Rn. 59). Nor does the obviousness of the substitution suffice to establish a choice excluding equivalence (Rn. 60). Such a choice may follow from a particular property of the selected compound, a question for each case (Rn. 62 and 63), or from a narrowing during grant made to distinguish the prior art, but not from a narrowing made to meet formal requirements or to avoid an inadmissible extension (Rn. 64 to 68). Here, a comparison of the claim versions pointed to formal considerations (Rn. 72). Legal certainty does not require pemetrexed dipotassium to be excluded (Rn. 73 to 75), and a precise chemical name does not bar equivalence (Rn. 76 to 81). As to indirect infringement, the court below could not reject it on the wording of the use claim alone (Rn. 87 and 88). On remittal, the court below must determine equal effect and findability for the skilled person and, if still relevant, the open questions on indirect infringement (Rn. 89 to 91).

Key points for practice

• Excluding equivalence on the basis of a choice between several options requires that the alternative actually be disclosed in the patent; membership of the same class of compounds is not enough (Rn. 55 and 59).
• A narrowing of the claim during grant reflects a choice excluding equivalence only if it was made to distinguish the prior art (Rn. 66 to 68).
• A precise chemical name in the claim does not, on its own, exclude equivalence (Rn. 76 to 81).
• Practical point: a generic company substituting another salt for the claimed salt cannot rely on the claim wording alone; the dispute turns on equal effect and on what the skilled person could find (Rn. 90).

Provisions applied

European Patent Convention

Art. 69; Art. 54(5)

Protocol on the Interpretation of Article 69 EPC

Arts 1 and 2

National law

Section 3(4) and Section 14 PatG

Case law cited

BGH, Okklusionsvorrichtung (X ZR 16/09); BGH, Diglycidverbindung (X ZR 69/10); BGH, Olanzapin (X ZR 89/07); BGH, Escitalopram (Xa ZR 130/07); BGH, Arzneimittelgebrauchsmuster (X ZB 7/03); BGH, Kollagenase I (X ZB 5/13); Catnic Components v Hill & Smith [1982] RPC 183; Improver v Remington [1990] FSR 181; Actavis v Eli Lilly [2014] EWHC 1511 (Pat) and [2015] EWCA Civ 555

Prepared by Dhenne Avocats from the text of the decision (WIPO Lex, German text), consulted on 11 October 2026. Only the official text is authoritative.