Claim construction checkpoints: Application as filed versus granted patent (T 0715/24)

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Aug 9, 2026, 9:54:15 AM (7 days ago) Aug 9

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Claim construction checkpoints: Application as filed versus granted patent (T 0715/24)

Dr Rose Hughes Friday, August 07, 2026 - epo, G1/24, G1/26, patents, PatKat, Rose Hughes

G 1/24 requires that the description must always be “consulted” to interpret a claim. The question remains whether a definition in the description can override an otherwise clear meaning in the claims. In T 0715/24, Bristol-Myers Squibb (BMS) sought to persuade the Board of Appeal that a negative feature, read together with a paragraph of the description, gave the word “monotherapy” for a cancer treatment an unusual meaning that found basis in the application as filed. The Board of Appeal was not persuaded that the description of the granted patent could be used to alter the definition of monotherapy as it is normally understood in the art. On that ordinary reading, the claim was found to add matter over the application as filed.

This decision comes as we await the Enlarged Board of Appeal (EBA) response to G 1/26 on claim interpretation and added matter. The Board of Appeal in this case appeared to have no issues with how G 1/24 should be applied, and that a claim can add matter in view of the application as filed when read in the context of the description of the granted patent.

Monotherapy

Legal background on claim construction, added matter and G 1/24

Article 123(2) EPC prohibits amendments that introduce subject-matter extending beyond the content of the application as filed. The test is the “gold standard” confirmed by the EBA in G 2/10. An amendment is allowable only within the limits of what a skilled person would derive “directly and unambiguously, using common general knowledge, and seen objectively and relative to the date of filing, from the whole of the application as filed” (r. 9). It is, infamously, an unforgiving standard (IPKat). Before it can be applied, however, the claim must first be construed. The question of added matter, as the Board of Appeal put it in the present case, “can only be answered on the basis of a proper construction of the claim” (r. 1).

In G 1/24, the EBA held that the description and drawings shall always be consulted to interpret the claims, and not only where a claim is unclear (IPKat). What the EBA arguably did not settle in G 1/24 was what “consulting” the description actually entails, and in particular whether a definition in the description can be used to give a claim term a meaning it would not otherwise bear (IPKat). That purportedly unresolved question has now generated its own referral. In G 1/26, the EBA has been asked how far description definitions can influence an assessment of added matter (IPKat).

Case background: Checkpoint inhibitors

Nivolumab (BMS’s OPDIVO) is one of the anti-PD-1 checkpoint inhibitors that has reshaped the treatment of melanoma and other solid tumours. The commercial stakes are large. The global net sales for OPDIVO were $10 billion in 2025. OPDIVO is now also marketed in combination with the anti-LAG-3 antibody relatlimab (OPDUALAG), approved in 2022, which reached $1.2 billion in global net sales in 2025. The 480 mg dose of nivolumab is indicated in the approved labels for both OPDIVO and OPDUALAG.

The case in T 0715/24 concerned EP 3288980, owned by BMS, relating to the treatment of PD-L1-positive melanoma using an anti-PD-1 antibody. Opposed by five Opponents, inter alia for added matter, the patent was revoked by the Opposition Division. Three Opponents (respondents III, IV and V) took part in the appeal.

Claim 1 of the main request was directed to “a composition comprising nivolumab for use in treating a melanoma” in a PD-L1-positive patient, “to be administered a flat dose of 480 mg of nivolumab as monotherapy once every four weeks”, with a negative feature stating that the patient is not administered a combination of nivolumab and an anti-CTLA-4 antibody (such as ipilimumab).

The negative limitation introduced into the claim makes commercial sense. “Monotherapy” might be considered to exclude the newer OPDUALAG relatlimab + nivolumab combination. However, a look at the approved label for OPDIVO reveals how the monotherapy language found its way into the claim. The label makes a clear distinction between nivolumab “monotherapy” and nivolumab combined with the CTLA-4 inhibitor ipilimumab. A combination with relatlimab is not contemplated in the patent or the OPDIVO label. With this patent, BMS may have wished to cover both of their marketed nivolumab products, each of which uses the 480 mg nivolumab dose, either alone (OPDIVO) or in combination with relatlimab (OPDUALAG).

Interpretation of the claim in view of the granted patent

Both sides accepted the ordinary meaning of monotherapy as treatment with a single drug (r. 4). The Patentee argued that the term in the claim should be understood as excluding only the combination with an anti-CTLA-4 antibody, whilst permitting other drugs (e.g. relatlimab). This was how the claim was originally drafted:

“1. A method for treating a melanoma comprising:

(i) identifying a patient having a PD-L1 positive melanoma tumor; and

(ii) administering to the patient an anti-PD-1 antibody or an antigen-binding portion thereof that binds specifically to a human PD-1 ("anti-PDl antibody monotherapy"), wherein the patient is not administered a combination of an anti-PD-1 antibody or an antigen-binding portion thereof and an anti-CTLA-4 antibody or an antigen-binding portion thereof that binds specifically to a human CTLA-4 ("combination therapy").”

This limitation and interpretation seem to be an attempt by BMS to align the meaning of “monotherapy” in the claim with how it is used in the OPDIVO label, i.e. to distinguish it from the combination with ipilimumab, but to still cover combination with other drugs such as the on-market combination with relatlimab.

The granted claim narrowed the disclaimer. Where the claim as filed excluded a combination of any anti-PD-1 antibody with an anti-CTLA-4 antibody, the granted claim excluded only a combination of “nivolumab and an anti-CTLA-4 antibody”.

On claim construction, the Patentee argued that, read as a whole, the patent pointed to a special definition of “monotherapy” in paragraph [0040]. Paragraph [0040] stated: “The term ‘anti-PD-1 antibody monotherapy’ as used herein includes a therapy of an anti-PD-1 antibody without an anti-CTLA-4 antibody therapy.” The Patentee also argued that the negative feature in the claim also modified the definition of monotherapy.

The Board of Appeal was, however, not persuaded. Interpreting the claim “with a mind willing to understand” (r. 5), the Board of Appeal found the negative feature did no defining work. In the words of the Board of Appeal, “The negative feature is not drafted as a definition ... against the well-recognised meaning of ‘monotherapy’ it merely introduces a fundamental ambiguity” (r. 7).

Nor did paragraph [0040] define the term, thought the Board of Appeal. This paragraph merely listed embodiments and did so for “anti-PD-1 antibody monotherapy” in general, not “nivolumab as a monotherapy”. The term “monotherapy” was not mentioned specifically in the paragraph.

For the Board of Appeal, “monotherapy” therefore kept its usual meaning, and the skilled person would understand it in the context of the claim as meaning nivolumab used as a single drug. The original claim as filed was, critically, not used to interpret the claim of the granted patent.

Added matter in view of the application as filed

Given the construction of monotherapy according to its ordinary meaning, the question became whether that interpretation added matter. The Opponents first attacked the wording of the negative feature itself as added matter. However, the Board of Appeal expressly declined to decide that point. The objection that succeeded was aimed instead at the combination of features produced by the construction of monotherapy, i.e. monotherapy plus the specified dose and selected anti-PD-1 antibody. The question instead was whether the application as filed disclosed, directly and unambiguously, nivolumab for treating PD-L1-positive melanoma as an ordinary-sense monotherapy at the claimed flat dose.

Notably, the Board of Appeal considered how claim 1 as originally filed had defined “anti-PD-1 antibody monotherapy” in contradistinction to “combination therapy”, in quotation marks: “The use of quotation marks and parenthesis indicates that monotherapy is being assigned a specific definition in claim 1 as filed” (r. 13). Importantly for the Board of Appeal, this special meaning was not the usual one now in the granted claim, a reading reinforced by claim 49 as filed, which contemplated administering a further anti-cancer agent (r. 14). In contrast to the granted claim, the original claim was therefore considered to have an altered definition of monotherapy.

“[Claim 49] is thus consistent with the special definition of monotherapy set out in claim 1 as filed, according to which the administration of additional therapeutic agents is not excluded, provided that the patient is not administered the combination of nivolumab and an anti-CTLA-4 antibody.” (r. 14)

Crucially, this was not considered to change how the granted claim should be interpreted. Instead, it was found to support the argument that the granted claims added matter.

The key issue for the Patentee was therefore that monotherapy according to its ordinary meaning had not been unambiguously disclosed, in the view of the Board of Appeal, in combination with the selection of nivolumab and the specifically claimed dose. The Board of Appeal accepted that the claims as originally filed used an altered definition of monotherapy. However, the claim was considered to have been so amended that a skilled person, reading it in view of the granted patent, would consider monotherapy to have its ordinary meaning. Auxiliary request 1, which redefined monotherapy positively as nivolumab “without another anti-cancer agent”, fell for the same missing link (r. 21). The appeal was dismissed and the patent revoked.

Final thoughts

The problem for the Patentee in this case was that they used an unusual definition of a term in the original claims that they were unable to persuade the Board of Appeal could be combined with specific limitations later added to the claim. Another warning against using “unusual definitions”, and the particularly unforgiving nature of the EPO’s added matter test. The present case thus drew a key distinction, namely interpretation in view of the description as granted versus the application as filed. The claim was construed in the light of the description of the granted patent. Basis was tested against the application as filed, including the original claims.

G 1/26 asks the EBA whether the order that the description must always be consulted also applies when a claim is tested for added matter (IPKat). In effect, the question is whether a patentee may invoke a description definition to construe a claim into a shape that has basis as filed and so escape an objection the prima facie wording would attract. T 0715/24 is tangentially relevant. The Board of Appeal consulted the description, as G 1/24 requires, and held that consultation neither defined the term nor cured the ambiguity. T 0715/24 nonetheless leaves plenty else that may be considered in G 1/26. In particular, the Board of Appeal never had to decide whether a description definition can rescue a claim because it found that there was no definition to apply. G 1/26 concerns the harder case in which the description is found to explicitly define the disputed term.

It is a welcome change to have a G 1/24 related case that can be mapped onto the commercial consequences (does anyone in the real world care if the tobacco in cigarettes is gathered or spiralled…?). The shifting definitions at play in this case make perfect sense when the on-market products are considered. Had the patent survived, it would have been interesting to see how courts might have chosen to interpret “monotherapy” in infringement proceedings.