T 1403/24 (Sost antagonist/OSSIFI-MAB) 08-09-2025

1. Admissibility of the opposition by opponent 2

In decision T 9/00, the filing of a second opposition by the same legal entity who had already filed an opposition was considered inadmissible for lack of an interest in judicial relief (see T 9/00, reasons 2c: "mangels Rechtsschutzbedürfnisses").

In contrast to the situation in T 9/00, opponent 2 is a distinct legal person from opponent 1 and opponent 3. The considerations in T 9/00 are therefore not applicable to the admissibility of the opposition filed by opponent 2.

According to decisions G 3/97 and G 4/97 an opposition filed on behalf of a third party is inadmissible, if the involvement of the opponent is to be regarded as circumventing the law by abuse of process, in particular if the opponent is acting on behalf of the patent proprietor or on behalf of a client without possessing the relevant qualifications required by Article 134 EPC. The decisions G 3/97 and G 4/97 explicitly concluded that a circumvention of the law by abuse of process does not arise purely because a professional representative is acting in its own name on behalf of a client and that the burden of proof regarding the circumvention of the law by abuse of process is to be borne by the party alleging that the opposition is inadmissible.

Given the shared interest among opponents in revoking the patent, it is not uncommon for them to exchange documents and coordinate their submissions during opposition proceedings. The citation of document D24 by opponent 2, and the presence of similar or identical passages in the notices of opposition filed by Opponents 2 and 3, do therefore not establish that opponent 2 acted on behalf of opponent 1 or opponent 3. The patent proprietor has thus not provided convincing evidence that the opposition filed in the name of opponent 2 was filed on behalf of opponent 1 or opponent 3 to circumvent the law by abuse of process.

Accordingly, the Board has confirmed the admissibility of the opposition filed by opponent 2.

2. Main request - Articles 76(1), 123(2), 100(c) EPC

2.1 It was common ground that the technical content of the divisional application as originally filed from which the patent derives corresponds to the content of the earlier application as published in WO 2009/131553 A2.

The Board therefore refers to this content as published in WO 2009/131553 A2 for the assessment of the requirement that amendments may not result in subject-matter extending beyond the content of the original application, as formulated in Articles 76(1) and 123(2) EPC, and as reflected in the ground of opposition under Article 100(c) EPC.

2.2 The original application describes in paragraphs [0014]-[0026] under the heading "Summary of the invention" various objects of the claimed invention.

Disclosed are inter alia the object of providing a method of promoting local bone growth by local administration of a sclerostin (Sost) antagonist (see paragraph [0014]), the object of providing a method of increasing bone density involving the administration of a Sost antagonist together with an antiresorptive drug (see paragraph [0020]), the object of providing a method of reducing bone involving the administration of a Sost agonist (see paragraph [0022]), and the object of providing a method of protecting a mammalian kidney from chemical injury involving the administration of a Sost antagonist (see paragraph [0024]). It is explained that the Sost antagonists or agonists are administered locally with or without an osteoconductive matrix or in conjunction with an antiresorptive agent, or alternatively systemically in conjunction with an antiresorptive (see paragraph [0025]).

In this context paragraph [0020] specifically describes:

"It is a still further object of the present invention to provide a method of increasing bone density both systemically (whole body) and locally, comprising the steps of administering, to a mammalian patient in need thereof, a therapeutic amount of a Sost antagonist together with an antiresorptive drug."

The original application describes under the heading "Detailed description of the invention" in paragraphs [0043]-[0044] that the claimed invention is directed to methods of promoting local bone deposition in mammals using materials that antagonize Sost proteins, in particular Sost-recognizing antibodies, and that the antagonist may be coadministered or serially administered with an antiresorptive drug to increase or hasten bone formation:

"The present invention is directed to methods for promoting local bone deposition in mammals using materials that antagonize Sost proteins. Suitable

antagonists may be provided by blocking antibodies. (...) The antagonist may be coadministered or serially administered with an antiresorptive drug if desired to increase or hasten bone formation. (...) These blocking Sost-recognizing antibodies may be made readily by those of ordinary skill in this art by conventional techniques."

The original application continues to describe the utility of Sost agonists in methods for reducing bone (see paragraph [0045]) and the further utility of Sost antagonists in methods of protecting kidneys from chemical injury (see paragraph [0046]).

In the subsection "Therapeutic applications" the original application explains in paragraph [0080]:

"Individuals to be treated using methods of the present invention may be any mammal, for example local increase in bone may be used for fracture healing, fusion (arthrodesis), orthopedic reconstruction, and periodontal repair. Systemic increase in bone would be for treatment of low bone mass, i.e. osteoporosis. Bone reduction would be used to treat unwanted heterotopic bone formation, ossification of longitudinal ligament, ossification during cervical stenosis, or osteosarcoma."

The original application further explains in paragraph [0085]:

"The methods of the present invention include application of SOST antagonists in cocktails including other medicaments, for example, antibiotics, fungicides, and anti-inflammatory agents. Alternatively, the methods may comprise sequential dosing of an afflicted individual with a SOST antagonist and one or more additional medicaments to optimize a treatment regime. In such optimized regimes, the medicaments, including the granulation inhibitor may be applied in any sequence and in any combination."

This disclosure of subject-matter is reflected in the independent claims of the application as filed, which define:

- "A method of promoting local bone growth, comprising the steps of administering a therapeutic amount of a Sost, Wise, or LRP antagonist locally to a mammalian patient in need thereof" (claim 1)

- "A method of promoting bone growth, comprising the steps of administering locally, to a mammalian patient in need thereof, a therapeutic amount of a Sost, Wise, or LRP antagonist together with a BMP recombinant protein" (claim 4)

- "An orthopedic or periodontal medical device, comprising a structural support, wherein an implantable portion of said structural support is adapted to be permanently implanted within a mammalian body, said implanted structural support being retained in said body by local bone growth, said structural support bearing at least a partial external coating of a Sost antagonist" (claim 13)

- "A method of increasing bone density, comprising the steps of administering, to a mammalian patient in need thereof, a therapeutic comprising an effective amount of a Sost, Wise, or LRP antagonist together with an antiresorptive drug" (claim 23)

- "A method of reducing bone, comprising the steps of administering either a systemic or local therapeutic amount of a Sost or Wise agonist to a mammalian patient in need thereof" (claim 35)

- A method of protecting a mammalian kidney from chemical injury resulting in renal damage (or glomerulonephritis), comprising administering, to a patient in need thereof, a therapeutic amount of a Sost or Wise antagonist (claim 40).

Notably, claim 23 is followed by dependent claims which further define that the bone density is increased systemically (claim 24) or increased by local application of the therapeutic (claim 25).

2.3 Claim 1 as granted combines the feature of the utility of the Sost antagonist antibody for increasing bone density in a patient with low bone mass with the feature that the Sost antagonist is serially administered with an antiresorptive drug.

2.3.1 As demonstrated in section 2.2 above, the administration of a Sost antagonist together with an antiresorptive drug for increasing bone density in a patient in need thereof as disclosed in paragraph [0020] and claim 23 of the original application only represents one of several therapeutic methods disclosed in the original application.

Moreover, paragraph [0020] and claims 23-25 of the original application explicitly refer to patients in need of an increase in bone density either locally or systemically (whole body). The skilled person understands that these patients may thus suffer from a local or systemic low bone density. However, claim 1 as granted additionally defines the patient to be treated as a patient with low bone mass. It is not evident that this definition of a patient with low bone mass encompasses, in the context of the patent and the application as originally filed, in addition to patients with systemic low bone density also patients with only a local low bone density. On the contrary, the only passage in the patent (see paragraph [0086]) and the original application (see paragraph [0080]) which mentions the term "low bone mass" relates this term to patients in need of a systemic increase in bone by stating: "Systemic increase in bone would be for low bone mass, i.e. osteoporosis".

The Board therefore agrees with the opponents that the administration of a Sost antagonist together with an antiresorptive drug for increasing bone density in a patient with low bone mass represents a first selection from a list of therapeutic indications for Sost antagonists described in the original application.

2.3.2 As indicated in section 2.2 above, the original application describes in paragraph [0043] that the antagonist may be co-administered or serially administered with an antiresorptive drug if desired to increase or hasten bone formation, and in paragraph [0085] that the methods of the claimed invention include the application of Sost antagonists in cocktails including other medicaments, for example, antibiotics, fungicides, and anti-inflammatory agents or, alternatively, the sequential dosing of an afflicted individual with a Sost antagonist and one or more additional medicaments to optimize a treatment regimen.

Insofar as the option of serial or sequential administration described in paragraphs [0043] and [0085] may be considered as encompassed by the administration of the Sost antagonist together with the antiresorptive drug for increasing bone density as described in paragraph [0020] and claim 23 of the original application, the Board observes that the definition of serial or sequential administration in any case represents a further selection with respect to the modes of administration mentioned in paragraphs [0043] and [0085], which also included co-administration or co-formulation in a cocktail.

2.3.3 The Board agrees with the opponents that the original application does not convey any preference or otherwise provide any pointer to the combination of the selected feature of the utility of the Sost antagonist antibody for increasing bone density in a patient with low bone mass with the selected feature that the Sost antagonist is serially or sequentially administered with an antiresorptive drug.

The patent proprietor's argument that paragraph [0085] of the original application expresses a preference for sequential dosing by indicating that the sequential dosing of a Sost antagonist with one or more further additional medicaments allows for the optimization of treatment is not considered persuasive. Paragraph [0085] discloses that the methods of the claimed invention include the application of Sost antagonists in combination with other medicaments, including antibiotics, fungicides and anti-inflammatory agents, either in a cocktail or by sequential dosing to optimize a treatment regimen. This passage does not not specifically address any optimization from the combination of a Sost antagonist with an antiresorptive drug, let alone the optimization from serial or sequential administration of this combination of drugs as opposed to its administration in a cocktail.

Notably, the original application does not present any example which could otherwise serve as a pointer towards the defined combination of features in claim 1 as granted.

2.4 It is established jurisprudence that, when an amendment involves the combination of features selected from more than a single list, there generally needs to be a pointer in the original disclosure towards this combination of selected features for the amendment to be directly and unambiguously derivable from the content of the original application and thus to comply with Articles 76(1) or 123(2) EPC (see Case Law of the Boards of Appeal of the EPO, 11th edition, 2025, II.E.1.6).

As explained above in section 2.3.2, claim 1 as granted defines the combination of selected features from different lists, namely the selected therapeutic indication for the Sost antagonist directed at increasing bone density in a patient with low bone mass and the selected feature of the serial or sequential administration of the Sost antagonist with an antiresorptive drug. Moreover, as explained in section 2.3.3 above, the original application provides no pointer towards this combination.

Claim 1 as granted therefore comprises subject-matter extending beyond the content of the application as originally filed. The main request can therefore not be allowed.

3. Auxiliary requests 1-30 - Articles 76(1), 123(2) EPC

Following the announcement during the oral proceedings that claim 1 as granted is considered not to comply with the requirements of Articles 76(1) and 123(2) EPC, the Board indicated, as already suggested in the communication pursuant to Article 15(1) RPBA, that its considerations regarding claim 1 as granted also appeared to apply to the independent claims of auxiliary requests 1-30. The Board explained that the independent claims as amended in all auxiliary requests still seemed to involve the unallowable combination of the selection of the therapeutic indication for the Sost antagonist antibody with the selection of serial or sequential administration of the Sost antagonist with an antiresorptive drug.

In response, the patent proprietor maintained auxiliary requests 1-30, but did not present any additional arguments regarding the basis of the independent claims as amended in these requests in the original application.

The Board therefore confirms its conclusion that the auxiliary requests 1-30 do not comply with the requirements of Articles 76(1) and 123(2) EPC for the same reasons as set out for the main request.

Accordingly, a decision on the admittance of auxiliary requests 12-14 and 30 is not required.