Novel treatments for facioscapulohumeral muscular dystrophy (FSHD)

Abstract

The present invention provides anti-myostatin antibodies for use in treating, preventing, slowing progression and / or ameliorating facioscapulohumeral muscular dystrophy (FSHD).

Description

[Technical field]

[0001] The present invention relates to the use of anti-myostatin antibodies to treat FSHD. [Background technology]

[0002] Facioscapulohumeral muscular dystrophy (FSHD) is a muscular dystrophy that affects approximately 1 in 8000 individuals and is one of the most common types of muscular dystrophy (Deenan et al., 2014). FSHD is a genetic disorder that can be caused by two distinct mechanisms with a common downstream pathophysiological pathway: derepression of the expression of the DUX4 transcription factor and the resulting DUX4-mediated toxicity. FSHD type 1 (FSHD1, 95% of cases) is an autosomal dominant disorder resulting from contraction of D4Z4 repeats at the distal end of the subtelomeric region of chromosome 4q35. FSHD type 2 (FSHD2, 5% of cases) is a digestive disorder resulting from epigenetic modifications induced by mutations in genes such as SMCHD1 and DNMT3B, but is clinically similar to FSHD1 (Preston et al., 2020).

[0003] Symptom onset varies from childhood to adulthood, but typically manifests in the teens or twenties. The disease is primarily characterized by skeletal muscle weakness and atrophy, which asymmetrically affect muscles (Wagner 2019). Patients may present with difficulties with facial muscle weakness, such as inability to smile / whistle or close the eyes, axial muscle weakness, winging scapula, and limb muscle weakness. The progressive nature of the disease results in motor dysfunction, with some patients losing the ability to walk. There is considerable variability in the age of onset, severity, and rate of progression. Patients may present with a rapidly progressive infantile-onset form or a slowly progressive young adult-onset form. Respiratory involvement occurs in a subset of patients, particularly those with the most advanced disease (e.g., wheelchair-dependent patients). Extramuscular findings, such as retinal vascular disease and hearing loss, may occasionally be present and are primarily limited to those with the infantile-onset form (Statland et al., 2016).

[0004] Myostatin, called growth differentiation factor-8 (GDF8), is a secreted protein and a member of the transforming growth factor-beta (TGF-beta) superfamily of proteins. Members of this superfamily have growth regulatory and morphogenetic properties (see, e.g., NPL1, NPL2, and PTL1). Myostatin is expressed primarily in developing and adult skeletal muscle and functions as a negative regulator of muscle growth. Systemic overexpression of myostatin in adult mice results in muscle wasting (see, e.g., NPL3), whereas, conversely, myostatin knockout mice are characterized by skeletal muscle hypertrophy and hyperplasia, resulting in 2-3 times more muscle mass than their wild-type littermates (see, e.g., NPL4).

[0005] Like other members of the TGF-beta family, myostatin is synthesized as a large precursor protein that contains an N-terminal propeptide domain and a C-terminal domain that is considered to be the active molecule (see e.g., NPL5, PTL2). Two molecules of the myostatin precursor are covalently linked via a single disulfide bond present in the C-terminal growth factor domain. Active mature myostatin (a disulfide-linked homodimer consisting of the C-terminal growth factor domain) is released from the myostatin precursor through multiple steps of proteolytic processing. In the first step of the myostatin activation pathway, the peptide bond between the N-terminal propeptide domain and the C-terminal growth factor domain Arg266-Asp267 is cleaved by a furin-type proprotein convertase in both chains of the homodimeric precursor. However, the three resulting peptides (two propeptides and one mature myostatin (i.e., a disulfide-linked homodimer consisting of the growth factor domain)) remain associated and form a non-covalently inactive complex called "latent myostatin". Mature myostatin can then be liberated from latent myostatin by degradation of the propeptide. Members of the bone morphogenetic protein 1 (BMP1) family of metalloproteinases cleave a single peptide bond within the propeptide Arg98-Asp99, with concomitant release of mature, active myostatin, which is a homodimer (see, e.g., NPL6). Furthermore, latent myostatin can be activated in vitro by dissociating the complex with either acid or heat treatment (see, e.g., NPL7).

[0006] Myostatin exerts its effects through a family of transmembrane serine / threonine kinase heterotetrameric receptors, the activation of which enhances receptor transphosphorylation, leading to stimulation of serine / threonine kinase activity. The myostatin pathway has been shown to involve active myostatin dimers that bind to activin receptor type IIB (ActRIIB) with high affinity, then recruit and activate the transphosphorylation of lower affinity receptors, activin-like kinase 4 (ALK4) or activin-like kinase 5 (ALK5). It has also been shown that the proteins Smad2 and Smad3 are subsequently activated, form a complex with Smad4, and then translocate to the nucleus for transcriptional activation of target genes. It has been demonstrated that ActRIIB can mediate the effects of myostatin in vivo, as expression of a dominant-negative form of ActRIIB in mice mimics myostatin gene knockout (see, for example, NPL8).

[0007] Many disorders or conditions, such as muscular dystrophies (MD; including Duchenne muscular dystrophy), amyotrophic lateral sclerosis (ALS), muscular atrophy, spinal muscular atrophy (SMA); spinal muscular atrophy with respiratory distress type 1; stiff-body syndrome; Troyer syndrome; Guillain-Barré syndrome, organ atrophy, frailty, congestive obstructive pulmonary disease (COPD), sarcopenia, and cachexia due to cancer or other disorders, as well as renal disease, heart failure or heart disease, and liver disease, are associated with muscle wasting (i.e., loss of muscle tissue or dysfunction). Patients would benefit from increased muscle mass and / or strength. However, treatments available for these disorders are currently limited. Thus, because of its role as a negative regulator of skeletal muscle growth, myostatin represents a desirable target for therapeutic or preventive intervention of such disorders or conditions, or for monitoring the progression of such disorders or conditions. In particular, agents that inhibit the activity of myostatin may be therapeutically beneficial.

[0008] Inhibition of myostatin expression leads to both muscle hypertrophy and hyperplasia (NPL9). Myostatin negatively regulates muscle regeneration after injury, and the lack of myostatin in myostatin null mice promotes muscle regeneration (see, e.g., NPL10). For example, anti-myostatin (GDF8) antibodies described in PTL3, PTL4, PTL5, PTL6 and PTL7, as well as PTL8, PTL9 and PTL10, have been shown to bind to myostatin and inhibit myostatin activity in vitro and in vivo, including myostatin activity related to the negative regulation of skeletal muscle mass. Myostatin neutralizing antibodies increase body weight, skeletal muscle mass, and skeletal muscle size and strength in wild-type mice (see, e.g., NPL11) and mdx mice, a model of muscular dystrophy (see, e.g., NPL12; NPL13). However, all of these prior art antibodies are specific for mature but not latent myostatin, and the strategies described to inhibit myostatin activity utilize antibodies that can bind to and neutralize mature myostatin. AAV-mediated gene therapy of follistatin, a natural myostatin antagonist, in a tamoxifen-induced FSHD mouse model (a disease model that recapitulates the DUX4-dependent myopathy phenotype), resulted in increased muscle mass and strength (Giesige et al., 2018).

[0009] There is no approved treatment for FSHD and therefore there is a high unmet medical need as the disease can cause significant morbidity and impair quality of life for affected patients. Summary of the Invention

[0010] The present invention provides anti-myostatin antibodies for use in treating, preventing, slowing progression and / or ameliorating facioscapulohumeral muscular dystrophy (FSHD).

[0011] In one embodiment, the anti-myostatin antibody binds to latent myostatin and does not bind to mature myostatin, and the antibody blocks the non-proteolytic spontaneous release of mature myostatin from latent myostatin and inhibits activation of myostatin.

[0012] In one embodiment, the anti-myostatin antibody comprises six complementarity determining regions (CDRs), namely, CDRH1, CDRH2, CDRH3, CDRL1, CDRL2 and CDRL3, wherein CDRH1 comprises the sequence set forth in SEQ ID NO: 1, CDRH2 comprises the sequence set forth in SEQ ID NO: 2, CDRH3 comprises the sequence set forth in SEQ ID NO: 3, CDRL1 comprises the sequence set forth in SEQ ID NO: 4, CDRL2 comprises the sequence set forth in SEQ ID NO: 5, and CDRL3 comprises the sequence set forth in SEQ ID NO: 6.

[0013] In one embodiment, the anti-myostatin antibody comprises a VH domain comprising the amino acid sequence of SEQ ID NO:7 and a VL domain comprising the amino acid sequence of SEQ ID NO:8.

[0014] In one embodiment, the anti-myostatin antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO:9 and a light chain comprising the amino acid sequence of SEQ ID NO:10.

[0015] In one embodiment, the anti-myostatin antibody is administered to an individual at a dose of 90 mg every four weeks.

[0016] In a specific embodiment, the anti-myostatin antibody is GYM329. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Detailed Description All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety.

[0018] The nomenclature used in this application is based on the IPUAC Systematic Nomenclature unless otherwise indicated.

[0019] Unless otherwise defined, technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention belongs. Singleton et al., Dictionary of Microbiology and Molecular Biology 2nd ed., J. Wiley & Sons (New York, NY 1994), and March, Advanced Organic Chemistry Reactions, Mechanisms and Structure 4th ed., John Wiley & Sons (New York, NY 1992) provide those skilled in the art with general guidance for many of the terms used in this application. All references cited herein, including patent applications and publications, are incorporated by reference in their entirety.

[0020] For purposes of interpreting this specification, the following definitions shall apply, and whenever appropriate, terms used in the singular shall include the plural and vice versa. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. Unless otherwise stated, the following terms used in the specification and claims shall have the meanings indicated below.

[0021] An "individual" or "subject", used interchangeably, is a mammal. Mammals include, but are not limited to, livestock animals (e.g., cows, sheep, cats, dogs and horses), primates (e.g., humans and non-human primates such as monkeys), rabbits and rodents (e.g., mice and rats). In certain embodiments, an individual or subject is a human. In certain embodiments of the present invention, the subject is a human with FSHD.

[0022] The term "patient" refers to a human (such as a male or female human) who has been diagnosed with FSHD.

[0023] The term "active ingredient" (or "API") refers to a compound or molecule in a pharmaceutical composition that has a specific biological activity.

[0024] The terms "pharmaceutically acceptable excipient", "pharmaceutically acceptable carrier" and "therapeutically inactive excipient" can be used interchangeably and refer to any pharmaceutically acceptable ingredient in a pharmaceutical composition used in the formulation of a pharmaceutical product, such as a disintegrant, binder, filler, solvent, buffer, tonicity agent, stabilizer, antioxidant, surfactant, carrier, diluent, or lubricant, that has no therapeutic activity and is non-toxic to a subject to which it is administered.

[0025] The term "pharmaceutical composition" refers to a preparation in a form that effectively utilizes the biological activity of the active ingredient contained therein, and that does not contain additional ingredients that are unacceptably toxic to the subject to which the composition is administered. The term "pharmaceutical acceptable" refers to the attributes of materials that are useful in preparing pharmaceutical compositions that are generally safe, non-toxic, and not biologically or otherwise undesirable.

[0026] The term "Cmax" (expressed in ng / mL) means the maximum observed plasma concentration.

[0027] The term "Tmax" (expressed in hours or as the median time for Tmax in the study population) means the observed time to reach Cmax after drug administration; if it occurs at more than one time point, Tmax is defined as the first time point having this value.

[0028] The term "AUCT0-24h" (expressed in units of ng·h / mL) refers to the area under the plasma concentration-time curve (AUC).

[0029] The term "buffer" or "buffer system" refers to a pharma- ceutically acceptable excipient or mixture of excipients that stabilizes the pH of a pharmaceutical preparation. Suitable buffers are well known in the art and can be found in the literature. Particular pharma-ceutically acceptable buffers include citrate, malate, maleate or tartrate buffers, most particularly tartrate buffers. Particular buffer systems of the invention include a combination of an organic acid and a selected salt thereof, such as tribasic sodium citrate and citric acid, malic acid and sodium malate, sodium potassium tartrate and tartaric acid, or disodium tartrate and tartaric acid, particularly sodium potassium tartrate and tartaric acid. Alternatively, an organic acid (particularly tartaric acid) may be used alone as an "acidifier", instead of a combination of an acid and a corresponding salt. Regardless of the buffer used, the pH may be adjusted with acids or bases known in the art, such as hydrochloric acid, acetic acid, phosphoric acid, sulfuric acid and citric acid, sodium hydroxide and potassium hydroxide. A particular acidifier is tartaric acid.

[0030] The term "antioxidant" refers to a pharma- ceutically acceptable excipient that prevents oxidation of an active ingredient. Antioxidants include ascorbic acid, glutathione, cysteine, methionine, vitamin E TPGS, EDTA.

[0031] As used herein, the term "therapeutically effective amount" refers to an amount of a compound sufficient to treat, ameliorate, or prevent a specified disease or condition, or to exhibit a detectable therapeutic, preventive, or inhibitory effect. The effect may be detected, for example, by an improvement in clinical symptoms, or a reduction in symptoms. The exact effective amount for a subject will depend on the subject's weight, size, and health, the nature and extent of the condition, and the therapeutic agent or combination of therapeutic agents selected for administration. If the drug is approved by the U.S. Food and Drug Administration (FDA), "therapeutically effective amount" refers to the dosage approved by the FDA or an equivalent foreign agency for the treatment of the specified disease or condition.

[0032] As used herein, a patient "in need of GYM329 treatment" (or "in need of anti-myostatin antibody treatment") is a patient who would benefit from the administration of GYM329.

[0033] "GYM329", also known as RO7204239 according to the present invention, refers to an "anti-myostatin antibody", the antibody comprises six complementarity determining regions (CDRs), namely CDRH1, CDRH2, CDRH3, CDRL1, CDRL2 and CDRL3, where CDRH1 comprises the sequence shown in SEQ ID NO: 1, CDRH2 comprises the sequence shown in SEQ ID NO: 2, CDRH3 comprises the sequence shown in SEQ ID NO: 3, CDRL1 comprises the sequence shown in SEQ ID NO: 4, CDRL2 comprises the sequence shown in SEQ ID NO: 5 and CDRL3 comprises the sequence shown in SEQ ID NO: 6. GYM329 may also be defined by a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 7 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 8. Methods of making and using GYM329 are described and may be produced according to WO2016098357 and WO2017 / 104783. GYM329 is known to be an engineered Fc that allows for antigen removal from plasma.

[0034] The terms "host cell," "host cell line," and "host cell culture" are used interchangeably and refer to cells into which exogenous nucleic acid has been introduced, including the progeny of such cells. Host cells include "transformants" and "transformed cells," which include the primary transformed cell and its progeny, regardless of the number of passages. The progeny may not be completely identical in nucleic acid content to the parent cell and may contain mutations. Mutant progeny that have the same function or biological activity as screened or selected for in the originally transformed cell are included herein.

[0035] The terms "anti-myostatin antibody" and "antibody that binds to myostatin" refer to an antibody that can bind to myostatin with sufficient affinity such that it is useful as a diagnostic and / or therapeutic agent in targeting myostatin. In one embodiment, the extent of binding of an anti-myostatin antibody to an unrelated non-myostatin protein is less than about 10% of the binding of the antibody to myostatin, as measured, for example, by radioimmunoassay (RIA). In certain embodiments, an antibody that binds to myostatin has a dissociation constant (Kd) of 1 microM or less, 100 nM or less, 10 nM or less, 1 nM or less, 0.1 nM or less, 0.01 nM or less, or 0.001 nM or less (e.g., 10-8 M or less, e.g., 10-8 M to 10-13 M, e.g., 10-9 M to 10-13 M). In certain embodiments, the anti-myostatin antibody binds to an epitope of myostatin that is conserved among myostatin from different species.

[0036] The term "antibody" herein is used in the broadest sense and encompasses a variety of antibody structures, including, but not limited to, monoclonal antibodies, polyclonal antibodies, multispecific antibodies (e.g., bispecific antibodies), and antibody fragments, so long as they exhibit the desired antigen-binding activity.

[0037] "Antibody fragment" refers to a molecule other than an intact antibody that contains a portion of the intact antibody that binds to the antigen to which the intact antibody binds. Examples of antibody fragments include, but are not limited to, Fv, Fab, Fab', Fab'-SH, F(ab')2; bispecific antibodies; linear antibodies; single-chain antibody molecules (e.g., scFv); and multispecific antibodies formed from antibody fragments.

[0038] An "antibody that binds to the same epitope" as a reference antibody refers to an antibody that blocks the binding of the reference antibody to its antigen in a competitive assay and / or conversely, a reference antibody that blocks the binding of an antibody to its antigen in a competitive assay. Exemplary competitive assays are provided herein.

[0039] A "human antibody" is an antibody having an amino acid sequence that corresponds to the amino acid sequence of an antibody produced by a human or a human cell, or to the amino acid sequence of an antibody derived from a human antibody repertoire or other non-human source that utilizes human antibody coding sequences. This definition of a human antibody specifically excludes humanized antibodies, which contain non-human antigen-binding residues.

[0040] A "humanized" antibody refers to a chimeric antibody that comprises amino acid residues from non-human HVRs and amino acid residues from human FRs. In certain embodiments, a humanized antibody comprises substantially all of at least one, and typically two, variable domains, in which all or substantially all of the HVRs (e.g., CDRs) correspond to those of a non-human antibody, and all or substantially all of the FRs correspond to those of a human antibody. A humanized antibody may optionally comprise at least a portion of an antibody constant region derived from a human antibody. A "humanized form" of an antibody, e.g., a non-human antibody, refers to an antibody that has undergone humanization.

[0041] As used herein, the term "monoclonal antibody" refers to an antibody obtained from a population of substantially homogeneous antibodies, i.e., the individual antibodies constituting the population are identical and / or bind the same epitope, except for possible mutant antibodies, e.g., containing naturally occurring mutations or arising during the production of a monoclonal antibody preparation, and such mutants are generally present in small amounts. In contrast to polyclonal antibody preparations, which typically contain different antibodies against different determinants (epitopes), each monoclonal antibody of a monoclonal antibody preparation is directed against a single determinant on an antigen. Thus, the modifier "monoclonal" indicates the character of the antibody as being obtained from a substantially homogeneous population of antibodies and should not be construed as requiring production of the antibody by any particular method. For example, the monoclonal antibodies used in accordance with the present invention may be produced by a variety of techniques, including, but not limited to, hybridoma methods, recombinant DNA methods, phage display methods, and methods utilizing transgenic animals containing all or part of the human immunoglobulin loci, and such methods and other exemplary methods for producing monoclonal antibodies are described herein.

[0042] The term "chimeric" antibody refers to an antibody in which a portion of the heavy and / or light chain is derived from a particular source or species, while the remainder of the heavy and / or light chain is derived from a different source or species.

[0043] The "class" of an antibody refers to the type of constant domain or region carried by its heavy chain. There are five major classes of antibodies: IgA, IgD, IgE, IgG, and IgM, and some of these can be further divided into subclasses (isotypes), e.g., IgG1, IgG2, IgG3, IgG4, IgA1, and IgA2. The heavy chain constant domains corresponding to the different classes of immunoglobulins are called alpha, delta, epsilon, gamma, and mu, respectively.

[0044] The term "epitope" includes any determinant that can be bound by an antibody. An epitope is a region of an antigen that is bound by an antibody that targets that antigen and includes specific amino acids that make direct contact with the antibody. Epitopes may include chemically active surface groups of molecules such as amino acids, sugar side chains, phosphoryl or sulfonyl groups, and may have specific three-dimensional structural characteristics and / or specific charge characteristics. In general, an antibody specific for a particular target antigen will preferentially recognize an epitope on the target antigen in a complex mixture of proteins and / or macromolecules.

[0045] The term "Fc region" is used herein to define a C-terminal region of an immunoglobulin heavy chain that contains at least a portion of the constant region. This term includes native sequence Fc regions and variant Fc regions. In one embodiment, a human IgG heavy chain Fc region extends from Cys226 or Pro230 to the carboxyl terminus of the heavy chain. However, the C-terminal lysine (Lys447) of the Fc region may or may not be present. Unless otherwise specified herein, the numbering of amino acid residues in the Fc region or constant region is according to the EU numbering system, also called the EU index, as described in Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, MD, 1991.

[0046] The term "Fc region-containing antibody" refers to an antibody that comprises an Fc region. The C-terminal lysine (residue 447 according to the EU numbering system) of the Fc region may be removed, for example, during purification of the antibody or by recombinant engineering of the nucleic acid encoding the antibody. Thus, a composition comprising an antibody with an Fc region according to the present invention may include an antibody with K447, an antibody with all K447s removed, or a mixture of antibodies with and without the K447 residue.

[0047] "Framework" or "FR" refers to variable domain residues other than hypervariable region (HVR) residues. The FR of a variable domain generally consists of four FR domains: FR1, FR2, FR3 and FR4. Thus, the HVR and FR sequences generally appear in the VH (or VL) in the following sequence: FR1-H1(L1)-FR2-H2(L2)-FR3-H3(L3)-FR4.

[0048] The terms "full length antibody," "intact antibody," and "whole antibody" are used interchangeably herein and refer to an antibody having a structure substantially similar to a native antibody structure or an antibody having a heavy chain that includes an Fc region as defined herein.

[0049] A "functional Fc region" has an "effector function" of a native sequence Fc region. Exemplary "effector functions" include C1q binding; CDC; Fc receptor binding; ADCC; phagocytosis; downregulation of a cell surface receptor (e.g., B cell receptor; BCR), and the like. Such effector functions generally require that the Fc region be associated with a binding domain (e.g., an antibody variable domain) and may be assessed using a variety of assays, e.g., as disclosed in the definitions herein.

[0050] As used herein, the term "myostatin" may refer to any native myostatin from any vertebrate source, including mammals such as primates (e.g., humans) and rodents (e.g., mice and rats). Unless otherwise indicated, the term "myostatin" refers to a human myostatin protein having the amino acid sequence set forth in SEQ ID NO: 11 and containing the terminal propeptide domain of human myostatin as set forth in SEQ ID NO: 12 or 13. The term encompasses "full-length," unprocessed myostatin, as well as any form of myostatin resulting from processing in cells. The term also encompasses naturally occurring variants of myostatin, such as splice variants or allelic variants. An exemplary amino acid sequence of human myostatin (promyostatin) is set forth in SEQ ID NO: 11. An exemplary amino acid sequence of the N-terminal propeptide domain of human myostatin is set forth in SEQ ID NO: 12 or 13. Active mature myostatin is a disulfide-linked homodimer consisting of two C-terminal growth factor domains. Inactive latent myostatin is a non-covalently associated complex of two propeptides and mature myostatin. As disclosed herein, the antibodies of the present invention bind to inactive latent myostatin but do not bind to mature active myostatin homodimers. In some embodiments, the antibodies of the present invention bind to an epitope within a fragment consisting of amino acids 21-100 of the myostatin propeptide (SEQ ID NO: 13) but do not bind to mature active myostatin homodimers.

[0051] The term "variable region" or "variable domain" refers to the domain of an antibody heavy or light chain that is involved in binding the antibody to an antigen. The variable domains of the heavy and light chains of natural antibodies (VH and VL, respectively) generally have a similar structure, with each domain containing four conserved framework regions (FR) and three hypervariable regions (HVR). (See, for example, Kindt et al., Kuby Immunology, 6th ed., WH Freeman and Co., page 91 (2007)). A single VH or VL domain may be sufficient to confer antigen-binding specificity. Furthermore, antibodies that bind to a particular antigen may be isolated from an antibody that binds the antigen using a VH or VL domain, and a library of complementary VL or VH domains, respectively, may be screened. See, e.g., Portolano et al., J. Immunol. 150:880-887 (1993); Clarkson et al., Nature 352:624-628 (1991).

[0052] A "variant Fc region" comprises an amino acid sequence that differs from the amino acid sequence of a native sequence Fc region by at least one amino acid modification (alteration), preferably one or more amino acid substitutions. Preferably, the variant Fc region has at least one amino acid substitution compared to a native sequence Fc region or the Fc region of a parent polypeptide, e.g., from about 1 to about 10 amino acid substitutions, preferably from about 1 to about 5 amino acid substitutions in the native sequence Fc region or the Fc region of a parent polypeptide. The variant Fc region herein will preferably have at least about 80% homology with the native sequence Fc region and / or the Fc region of the parent polypeptide, most preferably at least about 90% homology, and more preferably at least about 95% homology thereto.

[0053] As used herein, the term "vector" refers to a nucleic acid molecule capable of propagating another nucleic acid to which it is linked. The term includes vectors as self-replicating nucleic acid structures and vectors integrated into the genome of a host cell into which it is introduced. Certain vectors are capable of directing the expression of a nucleic acid to which they are operably linked. Such vectors are referred to herein as "expression vectors."

[0054] As used herein, the term "hypervariable region" or "HVR" refers to each region of an antibody variable domain that is hypervariable in sequence ("complementarity determining region" or "CDR") and / or forms structurally defined loops ("hypervariable loops") and / or contains residues that contact the antigen ("antigen contacts"). Generally, antibodies contain six HVRs, three in the VH (H1, H2, H3) and three in the VL (L1, L2, L3). Exemplary HVRs herein include: (a) hypervariable loops occurring at amino acid residues 26-32 (L1), 50-52 (L2), 91-96 (L3), 26-32 (H1), 53-55 (H2), and 96-101 (H3) (Chothia and Lesk, J. Mol. Biol. 196:901-917 (1987)); (b) CDRs occurring at amino acid residues 24-34 (L1), 50-56 (L2), 89-97 (L3), 31-35b (H1), 50-65 (H2), and 95-102 (H3) (Kabat et al., Sequences of Proteins of Immunological Interest, 5th ed. Public Health (c) antigenic contacts occurring at amino acid residues 27c-36 (L1), 46-55 (L2), 89-96 (L3), 30-35b (H1), 47-58 (H2), and 93-101 (H3) (MacCallum et al., J. Mol. Biol. 262:732-745 (1996)); and (d) combinations of (a), (b) and / or (c), including HVR amino acid residues 46-56 (L2), 47-56 (L2), 48-56 (L2), 49-56 (L2), 26-35 (H1), 26-35b (H1), 49-65 (H2), 93-102 (H3), and 94-102 (H3). Unless otherwise indicated, HVR residues and other residues in the variable domain (eg, FR residues) are numbered herein according to Kabat et al., supra.

[0055] In some embodiments, the isolated anti-myostatin antibody of the invention is a monoclonal antibody. In some embodiments, the isolated anti-myostatin antibody of the invention is a human antibody, a humanized antibody, or a chimeric antibody. In some embodiments, the isolated anti-myostatin antibody of the invention is an antibody fragment that binds to myostatin. In some embodiments, the isolated anti-myostatin antibody of the invention is an antibody fragment that binds to latent myostatin. In some embodiments, the isolated anti-myostatin antibody of the invention is a full-length IgG antibody.

[0056] The antibody or polypeptide (and optionally additional therapeutic agent) comprising the mutated Fc region of the present invention can be administered by any suitable means, including parenteral, intrapulmonary and intranasal, and, if desired for localized treatment, intralesional administration. Parenteral infusions include intramuscular, intravenous, intraarterial, intraperitoneal, or subcutaneous administration. Dosing can be by any suitable route, for example, injection, such as intravenous or subcutaneous injection, depending in part on whether the administration is brief or chronic. Various dosing schedules are contemplated herein, including, but not limited to, single or multiple doses over various time periods, bolus administration, and pulse infusion.

[0057] The antibodies or polypeptides comprising the variant Fc region of the present invention can be formulated, dosed and administered in a manner consistent with good medical practice. Factors to consider in this context include the particular disorder being treated, the particular mammal being treated, the clinical condition of the individual patient, the cause of the disorder, the site of delivery of the agent, the method of administration, the administration schedule, and other factors known to the medical profession. The antibody is optionally, but not necessarily, formulated with one or more agents currently used to prevent or treat the disorder in question. The effective amount of such other agents depends on the amount of antibody present in the formulation, the type of disorder or treatment, and other factors mentioned above. These are generally used in the same dosages and routes of administration as described herein, or at about 1% to 99% of the dosages described herein, or at any dosage, by any route empirically / clinically determined to be appropriate.

[0058] For the prevention or treatment of disease, the appropriate dosage of the antibody of the present invention depends on the course of the disease and whether the antibody is administered for prophylactic or therapeutic purposes, previous treatment. The antibody or polypeptide comprising the mutant Fc region of the present invention is suitably administered to the patient at one time or over a series of treatments. Depending on the type and severity of the disease, about 1 microg / kg to 15 mg / kg (e.g., 0.1 mg / kg to 10 mg / kg) of the antibody may be an initial candidate dosage for administration to the patient, whether by one or more separate administrations or by continuous infusion. In particular, the anti-myostatin may be administered intermittently, weekly, every three weeks, or specifically every four weeks, more specifically every four weeks. A higher initial loading dose may be administered, followed by one or more lower doses. The progress of this treatment is easily monitored by conventional techniques and assays.

[0059] In accordance with the present invention, the anti-myostatin can be formulated into a pharmaceutical formulation comprising the antibody and a pharma- ceutically acceptable carrier.

[0060] Exemplary lyophilized antibody formulations are described in U.S. Patent No. 6,267,958. Aqueous antibody formulations include those described in U.S. Patent No. 6,171,586 and WO 2006 / 044908, the latter formulations including a histidine-acetate buffer.

[0061] In a further aspect, the invention provides pharmaceutical formulations comprising the anti-myostatin antibodies provided herein, e.g., for use in FSHD. In one embodiment, the pharmaceutical formulation comprises the anti-myostatin antibodies provided herein and a pharma- ceutical acceptable carrier.

[0062] The antibody or polypeptide comprising the mutated Fc region of the present invention can be administered by any suitable means, including parenteral, intrapulmonary and intranasal, and, if desired for localized treatment, intralesional administration. Parenteral infusions include intramuscular, intravenous, intraarterial, intraperitoneal, or subcutaneous administration. Dosing can be by any suitable route, such as injection, for example, intravenous or subcutaneous injection, depending in part on whether administration is brief or chronic. Various dosing schedules are contemplated herein, including, but not limited to, single or multiple doses over various time periods, bolus administration, and pulse infusion. More specifically, the administration of anti-myostatin antibodies according to the present invention will be administered every 4 weeks, more specifically by subcutaneous injection.

[0063] In a further aspect, the present invention provides a method for preparing a medicament or pharmaceutical formulation, the method comprising mixing an anti-myostatin antibody provided herein with a pharma- ceutical acceptable carrier, e.g., for use in treating FSHD.

[0064] According to the present invention, the effective amount of myostatin inhibitor for treating FSHD is the amount that achieves both clinical efficacy and safety. In some embodiments, the effective amount is the amount that enhances muscle function, such as force generation and motor function. In some embodiments, the effective amount is the amount that enhances motor function that requires fast muscle fibers (e.g., type II fibers). In some embodiments, the motor function includes eccentric contraction of muscle. In some embodiments, an effective amount of myostatin treatment is an amount sufficient to slow or ameliorate the progression of a disease (e.g., muscle atrophy); maintain a disease state (e.g., as measured / monitored by appropriate motor function tests, plasma protein markers, metabolic markers, etc.); slow the loss of motor neurons; prevent or delay the expression of immature muscle markers; prevent, ameliorate, or delay intramuscular fat deposition (e.g., fatty replacement of muscle tissue); prevent metabolic dysregulation; prevent or reduce the frequency of bone loss or fractures; increase the Expanded Hammersmith Motor Scale score by more than 1 point compared to a control not administered a myostatin inhibitor; slow the rate of deterioration; slow the regression (e.g., progressive decrease) of the Expanded Hammersmith Motor Scale over a 12-month, 24-month, or 36-month period; and / or increase the CHOP INTEND score by more than 1 point compared to a control not receiving a myostatin inhibitor; and / or increase the MFM-32 score by more than 1 point compared to a control not receiving a myostatin inhibitor.

[0065] In accordance with the invention described herein, more detailed embodiments of the invention are described below.

[0066] Embodiment 1: A method for treating, preventing, slowing the progression and / or ameliorating FSHD in a subject in need thereof, wherein an anti-myostatin antibody is administered to the subject in need thereof.

[0067] Embodiment 2: The method described in embodiment 1, wherein the anti-myostatin antibody binds to latent myostatin and does not bind to mature myostatin, and the antibody blocks the non-proteolytic spontaneous release of mature myostatin from latent myostatin and inhibits activation of myostatin.

[0068] Embodiment 3: The method described in embodiment 1 or 2, wherein the anti-myostatin antibody comprises six complementarity determining regions (CDRs), namely, CDRH1, CDRH2, CDRH3, CDRL1, CDRL2 and CDRL3, wherein CDRH1 comprises the sequence set forth in SEQ ID NO: 1, CDRH2 comprises the sequence set forth in SEQ ID NO: 2, CDRH3 comprises the sequence set forth in SEQ ID NO: 3, CDRL1 comprises the sequence set forth in SEQ ID NO: 4, CDRL2 comprises the sequence set forth in SEQ ID NO: 5, and CDRL3 comprises the sequence set forth in SEQ ID NO: 6.

[0069] Embodiment 4: The method described in embodiments 1 to 3, wherein the anti-myostatin antibody comprises a VH chain having the amino acid sequence of SEQ ID NO: 7 and a VL chain having the amino acid sequence of SEQ ID NO: 8.

[0070] Embodiment 5: The method described in embodiments 1 to 4, wherein the anti-myostatin antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 9 and a light chain comprising the amino acid sequence of SEQ ID NO: 10.

[0071] Embodiment 6. The method of embodiments 1-5, wherein the anti-myostatin antibody is administered to the subject, preferably a human subject, at a dose of 90 mg every 4 weeks.

[0072] Embodiment 7: The method of embodiments 1 to 6, wherein the anti-myostatin antibody is administered subcutaneously.

[0073] Embodiment 8: Use of an anti-myostatin antibody for the manufacture of a medicament for treating, preventing, slowing the progression and / or ameliorating FSHD in a subject in need thereof.

[0074] Embodiment 9: The use described in embodiment 8, wherein the anti-myostatin antibody binds to latent myostatin and does not bind to mature myostatin, and the antibody blocks the non-proteolytic spontaneous release of mature myostatin from latent myostatin and inhibits activation of myostatin.

[0075] Embodiment 10: The use described in embodiment 8 or 9, wherein the anti-myostatin antibody comprises six complementarity determining regions (CDRs), namely CDRH1, CDRH2, CDRH3, CDRL1, CDRL2 and CDRL3, wherein CDRH1 comprises the sequence set forth in SEQ ID NO: 1, CDRH2 comprises the sequence set forth in SEQ ID NO: 2, CDRH3 comprises the sequence set forth in SEQ ID NO: 3, CDRL1 comprises the sequence set forth in SEQ ID NO: 4, CDRL2 comprises the sequence set forth in SEQ ID NO: 5, and CDRL3 comprises the sequence set forth in SEQ ID NO: 6.

[0076] Embodiment 11: The use described in embodiments 8 to 10, wherein the anti-myostatin antibody comprises a VH chain having the amino acid sequence of SEQ ID NO: 7 and a VL chain having the amino acid sequence of SEQ ID NO: 8.

[0077] Embodiment 12: The use described in embodiments 8 to 11, wherein the anti-myostatin antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 9 and a light chain comprising the amino acid sequence of SEQ ID NO: 10.

[0078] Embodiment 13. The use of embodiments 8 to 12, wherein the anti-myostatin antibody is administered to a subject, preferably a human subject, at a dose of 90 mg every 4 weeks.

[0079] Embodiment 14: The use described in embodiments 8 to 13, wherein the anti-myostatin antibody is administered subcutaneously.

[0080] Embodiment 15: A pharmaceutical formulation for use in treating FSHD comprising an anti-myostatin antibody.

[0081] Embodiment 16: A pharmaceutical formulation described in embodiment 15, wherein the anti-myostatin antibody binds to latent myostatin and does not bind to mature myostatin, and the antibody blocks the non-proteolytic spontaneous release of mature myostatin from latent myostatin and inhibits activation of myostatin. Embodiment 17: An anti-myostatin antibody is provided comprising six complementarity determining regions (CDRs):

[0082] The pharmaceutical formulation of embodiment 15 or 16, comprising CDRH1, CDRH2, CDRH3, CDRL1, CDRL2 and CDRL3, wherein CDRH1 comprises the sequence set forth in SEQ ID NO: 1, CDRH2 comprises the sequence set forth in SEQ ID NO: 2, CDRH3 comprises the sequence set forth in SEQ ID NO: 3, CDRL1 comprises the sequence set forth in SEQ ID NO: 4, CDRL2 comprises the sequence set forth in SEQ ID NO: 5, and CDRL3 comprises the sequence set forth in SEQ ID NO: 6.

[0083] Embodiment 18: A pharmaceutical formulation described in embodiments 15 to 17, wherein the anti-myostatin antibody comprises a VH chain having the amino acid sequence of SEQ ID NO: 7 and a VL chain having the amino acid sequence of SEQ ID NO: 8.

[0084] Embodiment 19: A pharmaceutical formulation described in embodiments 15 to 18, wherein the anti-myostatin antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 9 and a light chain comprising the amino acid sequence of SEQ ID NO: 10.

[0085] Embodiment 20: A pharmaceutical formulation described in embodiments 15 to 19, wherein the anti-myostatin antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 9 and a light chain comprising the amino acid sequence of SEQ ID NO: 10.

[0086] Embodiment 21: The pharmaceutical formulation according to embodiments 15 to 20, wherein the pharmaceutical formulation is administered to a subject, preferably a human subject, at a dose of 90 mg every 4 weeks.

[0087] Embodiment 22: The pharmaceutical formulation according to embodiments 15 to 21, wherein the pharmaceutical formulation is administered subcutaneously.

[0088] Embodiment 23: A pharmaceutical for treating FSHD comprising an anti-myostatin antibody.

[0089] Embodiment 24: The pharmaceutical described in embodiment 23, wherein the anti-myostatin antibody binds to latent myostatin and does not bind to mature myostatin, and the antibody blocks the non-proteolytic spontaneous release of mature myostatin from latent myostatin and inhibits activation of myostatin.

[0090] Embodiment 25: The pharmaceutical of embodiment 23 or 24, wherein the anti-myostatin antibody comprises six complementarity determining regions (CDRs), namely CDRH1, CDRH2, CDRH3, CDRL1, CDRL2 and CDRL3, wherein CDRH1 comprises the sequence set forth in SEQ ID NO: 1, CDRH2 comprises the sequence set forth in SEQ ID NO: 2, CDRH3 comprises the sequence set forth in SEQ ID NO: 3, CDRL1 comprises the sequence set forth in SEQ ID NO: 4, CDRL2 comprises the sequence set forth in SEQ ID NO: 5, and CDRL3 comprises the sequence set forth in SEQ ID NO: 6.

[0091] Embodiment 26: A pharmaceutical described in embodiments 23 to 25, wherein the anti-myostatin antibody comprises a VH chain having the amino acid sequence of SEQ ID NO: 7 and a VL chain having the amino acid sequence of SEQ ID NO: 8.

[0092] Embodiment 27: A pharmaceutical described in embodiments 23 to 26, wherein the anti-myostatin antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 9 and a light chain comprising the amino acid sequence of SEQ ID NO: 10.

[0093] Embodiment 28: A pharmaceutical described in embodiments 23 to 27, wherein the anti-myostatin antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 9 and a light chain comprising the amino acid sequence of SEQ ID NO: 10.

[0094] Embodiment 29: The medicament according to embodiments 23 to 28, which is administered to a subject, preferably a human subject, at a dose of 90 mg every 4 weeks.

[0095] Embodiment 30: The pharmaceutical of embodiments 23 to 29, which is administered subcutaneously.

[0096] [Table 1] [Table 2]

[0097] The following examples are intended only to illustrate the practice of the present invention and are not offered as limitations. EXAMPLES

[0098] Example 1: A Phase II, multicenter, randomized, double-blind, placebo-controlled study to evaluate the pharmacodynamics, safety, tolerability, pharmacokinetics and efficacy of GYM329 (RO7204239) in ambulatory adult FSHD participants.

[0099] The study will enroll approximately 48 participants. If all requirements are met, there will be a screening period (up to 28 days) to determine the participant's eligibility, followed by enrollment into the study. Participants will then complete a 3-week pre-treatment period to collect baseline exercise data via wrist and ankle wearable devices prior to randomization (1:1, RO7204239:placebo) for a 52-week double-blind treatment period.

[0100] RO7204239 or placebo will be administered by SC injection into the abdomen every 4 weeks.

[0101] Once participants complete the 52-week double-blind treatment period, they will have the option to transition to the OLE period, in which all participants will receive RO7204239 for an additional 52 weeks, unless development of RO7204239 in FSHD is halted.

[0102] The primary analysis will occur after 52 weeks of treatment, as measured by magnetic resonance imaging (MRI) and exploratory endpoints of muscle strength and motor function.

[0103] The nature, frequency, severity, and timing of adverse events, serious adverse events, local and systemic infusion reactions, vital signs, laboratory values, ECGs, and echocardiograms will be assessed regularly by an open-label iDMC.

[0104] Blood samples for evaluation of PK, PD and ADA profiles will be obtained from all participants.

[0105] An independent review agency collects, stores, and reviews image data.

[0106] Individuals who do not meet the criteria for inclusion in the study (screen-failed) may be eligible for one re-screening opportunity (for a total of two screens per individual) at the discretion of the investigator. Individuals are not required to re-sign the consent form if they are re-screened within 29 days after previously signing the consent form. The investigator will record the reason for screen-failed in the screening log.

[0107] The trial period for each participant will be divided as follows: Screening: Days -52 to -24 · Registration: -23rd day Pretreatment period: Day -22 to Day -2 Randomization: Day -1 Baseline: Day -1 to Day 1 Baseline evaluations are completed prior to administration of study treatment. Treatment Starts: Day 1 Double-blind treatment period: 52 weeks Open-label extension period: 52 weeks Safety follow-up: 3 months after the last dose of RO7204239

[0108] Study design rationale Rationale for study population This trial will enroll individuals genetically diagnosed with FSHD1 or FSHD2, as both FSHD types have the same phenotype (Hamel and Tawil, 2018). RO7204239 has the potential to be effective in both FSHD1 and FSHD2 patients, given that its mechanism of action is independent of underlying FSHD genetics.

[0109] Only ambulatory participants will be included in the study. Data from patients with neuromuscular diseases indicate that blood levels of myostatin decline with disease progression (Burch et al., 2017). Given that myostatin is the target of RO7204239, ambulatory FSHD patients are likely to have the greatest potential to demonstrate benefit from anti-myostatin treatment in this study due to greater functional muscle preservation as a result of less advanced disease.

[0110] Rationale for a control group The control group in this study will receive a placebo.

[0111] FSHD is generally a slowly progressive disease, but is highly variable in symptoms and rate of progression. There is limited natural history data for FSHD regarding expected changes in skeletal muscle MRI parameters and clinical outcomes within one year. It is therefore important to distinguish these changes from any effects of RO7204239 treatment.

[0112] Since there are no approved treatments for FSHD, the use of a placebo control is considered ethical and justified. Furthermore, the study allows for concomitant symptomatic medications (e.g., in the case of pain) that may be part of the standard of care treatment for FSHD patients.

[0113] All participants enrolled in this study will ultimately receive RO7204239 treatment. Participants receiving placebo will have the option to receive RO7204239 during the 52-week OLE period.

[0114] Considering all of the above, the use of a placebo control is justified and necessary for a robust evaluation of the pharmacodynamics, safety, tolerability, and efficacy of RO7204239.

[0115] Rationale for Selection of Primary Endpoint The primary endpoint is based on MRI assessment of changes in skeletal muscle mass. Quantitative muscle MRI has been shown to have a strong correlation with clinical outcome measures in FSHD and can detect early muscle changes (Mul et al., 2017). Increases in contractile muscle mass are considered evidence of bioactivity of RO7204239 based on its mechanism of action.

[0116] Considering that fatty infiltration may be heterogeneous along the muscle length ( Janssen et al., 2014 ), we chose MRI volumetric measurements for assessment of the primary endpoint compared with measurements of cross-sectional area, which are considered a surrogate for changes in muscle mass and are assessed as secondary endpoints.

[0117] The quadriceps is chosen for the assessment of the primary endpoint because it is the muscle affected in FSHD (Tasca et al., 2016), with variable complications and degree of fatty infiltration at which effects can be observed (Mul et al., 2017), and it is a functionally important muscle for walking and stair climbing, and its contractile cross-sectional area significantly correlates with muscle strength in FSHD (Lassche et al., 2020).

[0118] Appropriateness of dose and schedule RO7204239 is a humanized mAb administered SC in the abdomen every 4 weeks.

[0119] In Study BP40484, a SAD study investigating the pharmacodynamics, safety, tolerability, pharmacokinetics, and immunogenicity of RO7204239 in healthy adult participants, single doses up to 90 mg were well tolerated and demonstrated target engagement (i.e., sustained total potential, free potential, and mature myostatin inhibition).

[0120] Therefore, a dose of 90 mg every 4 weeks was selected as the dosing regimen for this study, which is predicted to provide ≧95% inhibition of total latent myostatin, with complete myostatin inhibition predicted to lead to the maximal efficacy possible in this study.

[0121] Study population Approximately 48 participants with FSHD will be enrolled in the study.

[0122] Inclusion criteria Participants were eligible for inclusion in the study only if all of the following criteria were met: Age ≥ 18 and ≤ 65 years at the time of signing the informed consent form Genetic confirmation of FSHD1 or FSHD2, including one of the following: -FSHD1: Heterozygous pathogenic contraction of the D4Z4 repeat in the subtelomeric region of chromosome 4q35 on a permissive chromosome 4 haplotype -FSHD2: hypomethylation of the D4Z4 repeat in the subtelomeric region of chromosome 4q35 on a permissive chromosome 4 haplotype and a heterozygous SMCHD1 pathogenic variant or a heterozygous DNMT3B pathogenic variant Clinical findings consistent with FSHD according to the investigator's clinical judgment Ambulatory, where ambulatory is defined as being able to walk / run 10 meters in >4 seconds and ≤12 seconds unassisted (i.e., without the use of assistive devices such as canes, crutches, or walkers, or without human / handheld assistance) at the time of screening Ricci Clinical Severity Score ≥ 2.5 and ≤ 4 Agreement to maintain the same frequency and intensity of physical therapy, occupational therapy and other forms of exercise therapy during the clinical trial. ·Are able and willing to comply with the study protocol and complete all study procedures, measurements, and visits. For female participants of childbearing potential: Agreement to maintain abstinence (abstain from heterosexual intercourse) or use contraception, as defined below: Female participants must remain abstinent or use a contraceptive method with an annual failure rate of <1% during treatment and for 17 months after the last dose of RO7204239. Female participants are considered of childbearing potential if they have passed menarche, have not reached postmenopausal status (≥12 consecutive months of amenorrhea with no identified cause other than menopause), and are not permanently infertile due to surgery (i.e., removal of the ovaries, fallopian tubes, and / or uterus) or another cause as determined by the investigator (e.g., Müllerian agenesis). By this definition, female participants who have undergone tubal ligation are considered of childbearing potential. The definition of childbearing potential may be adjusted to local guidelines or regulations. Examples of contraceptive methods with annual failure rates of <1% include bilateral tubal ligation, male sterilization, hormonal contraceptives that block ovulation, hormone-releasing intrauterine devices, and copper intrauterine devices. The reliability of sexual abstinence should be evaluated with respect to the duration of the clinical trial and the individual's preferred usual lifestyle. Periodic abstinence (e.g., calendar, ovulation, symptom-temperature, or postovulation methods) and withdrawal are not adequate contraceptive methods. If required according to local guidelines or regulations, information on locally accepted appropriate contraceptive methods and reliability of abstinence will be included in the local informed consent document. For male participants: agree to maintain abstinence (refrain from heterosexual intercourse) or use a contraceptive method, and agree to refrain from sperm donation, as defined below: For non-pregnant female partners of fertile potential, male participants must remain abstinent or use condoms and an additional method of contraception with a combined annual failure rate of 1% during treatment and for <120 days after the last dose of RO7204239. Male participants must refrain from sperm donation during this same period. In the case of pregnant female partners, male participants must maintain abstinence or use condoms to avoid exposing the embryo to pregnancy during the treatment period and for 120 days after the final dose of RO7204239. The reliability of sexual abstinence should be evaluated with respect to the duration of the clinical trial and the individual's preferred usual lifestyle. Periodic abstinence (e.g., calendar, ovulation, symptom-temperature, or postovulation methods) and withdrawal are not adequate contraceptive methods. If required according to local guidelines or regulations, information on locally accepted appropriate contraceptive methods and reliability of abstinence will be included in the local informed consent document.

[0123] Exclusion criteria Participants will be excluded from the study if any of the following criteria apply to them: - Pregnant or breastfeeding, or intending to become pregnant during the study or within 17 months after the last dose of RO7204239. Female participants of childbearing potential must have a negative serum pregnancy test result within 14 days prior to the start of study treatment. Current or previous administration of anti-myostatin therapy Treatment with any investigational therapy within 90 days or 5 half-lives of the drug prior to screening, whichever is longer Contraindications to MRI scanning (including but not limited to claustrophobia, presence of metallic foreign bodies in the heart or body such as pacemakers, artificial heart valves, cochlear implants, spinal rods, intracranial vascular clips, insulin pumps, etc.), difficulty maintaining a supine position for extended periods of time, or any other clinical history or examination findings that pose a potential risk in combination with MRI The presence of clinically significant ECG abnormalities from the average of three measurements at screening or cardiovascular disease (e.g., heart failure, coronary artery disease, cardiomyopathy, congestive heart failure, family history of congenital long QT syndrome, family history of sudden death) indicating a safety risk for the participant The presence of a clinically significant abnormality on echocardiography at screening, with the exception of mitral valve prolapse, which would not exclude the participant from the study -Major illness within one month prior to screening -Recognized or suspected hypersensitivity to RO7204239 or any component of its formulations (e.g. anaphylactic reactions) Any comorbidity or medical condition or abnormality in clinical laboratory tests that may interfere with the conduct of the study or whose treatment may impair the conduct of the study or may pose an unacceptable risk to participants in the study. In case of uncertain or doubtful results, tests performed during screening may be repeated before randomization to confirm eligibility. History of malignancy (excluding basal cell carcinoma in situ of the skin and intraepithelial carcinoma of the cervix that has been excised, isolated, and pathologically proven with clean margins) History of clinically relevant anaphylactic reactions requiring inotropic support Abnormal skin symptoms, pigmentation or lesions in the area intended for SC injection (abdomen) that would prevent visualization of a potential injection site reaction to RO7204239. Immobilization, surgical procedure, fracture, or trauma to the upper or lower limbs within 90 days or more prior to screening, if determined by the investigator to be likely to affect motor function assessment Participants who had surgery for scapular fixation in the 12 months prior to screening or planned to undergo any surgery that may affect motor function assessments during the study, including participants planned to undergo surgery until the end of the study. Substance abuse within 12 months prior to screening, or at risk for substance abuse as determined by the investigator Use of the following drugs within 90 days prior to enrollment: -Salbutamol or another orally administered beta2-adrenergic agonist -Creatine -Growth hormone -IGF-1 -Testosterone, Oxandrolone or other anabolic steroids - Chronic oral or parenteral use of corticosteroids unless needed to manage infusion reactions (use of inhaled corticosteroids is acceptable) -Medications that are expected to increase or decrease muscle mass or strength

[0124] Study treatments and combination therapies A study treatment is defined as any investigational treatment, marketed product, placebo, or medical device intended to be administered to study participants according to a study protocol.

[0125] The investigational medicinal products (IMPs) for this study are RO7204239 and placebo.

[0126] Study treatment administered Table 1 provides a description of the study treatments assigned to this study. [Table 3]

[0127] RO7204239(GYM329) RO7204239 is supplied in a 3 mL glass vial containing 80 mg / mL and must be prepared for administration under appropriate sterile conditions. The solution must be diluted if necessary and filtered prior to injection using a needle filter. The ready-to-inject solution should preferably be used immediately. Detailed instructions are provided in the Pharmacy Manual.

[0128] RO7204239 will be administered by SC injection into the abdomen every 4 weeks. Dosage is as described in the Pharmacy Manual. Each injection should be administered in a separate location within the rotational quadrant of the abdomen at each study visit where this treatment is administered. RO7204239 will be administered at the clinical site by site staff. Participants will be monitored at the site for a minimum of 6 hours after the first 2 doses of the double-blind treatment period and the first 2 doses of the OLE. For all other doses, participants will be monitored for 2 hours (or longer if deemed necessary by the investigator / site staff).

[0129] Only participants enrolled in the study will receive RO7204239, only authorised staff will supply RO7204239, and only authorised staff or trained study personnel may administer the study medication.

[0130] placebo A placebo of identical appearance, composition (except for RO7204239) and identical volume as RO7204239 will be administered by SC injection to all participants randomized to placebo and at the same dose regimen (every 4 weeks).

[0131] Efficacy evaluation FSHD Composite Functional Performance Scale The FSHD Composite Functional Outcome Scale (FSHD-COM) is an assessment of disease-related domains of functional burden. It is a performance-based functional composite outcome scale that combines multiple functional domains and individual rater-administered items into a single scale, capturing important components of patient-identified disease burden. Lower scores correlate with better function (Eichinger et al., 2018).

[0132] The FSHD-COM contains 18 items grouped into five body domains (leg function, arm and shoulder function, trunk function, hand function, and balance). Each item is scored on a 5-point ordinal scale, with 0 representing "unaffected / normal performance" and 4 representing "severely affected." A total score is calculated based on the sum of the item scores and ranges from 0 to 72, with higher scores representing higher functional burden. Subscale scores are also calculated for each of the five body domains.

[0133] The scale will be administered by a trained clinical assessor (physiotherapist or other appropriately qualified professional trained in administering the FSHD-COM). If possible, the same assessor should observe the participant throughout the study. Scores will be recorded on the score sheet and eCRF.

[0134] The FSHD-COM takes approximately 35 minutes to complete, including a 10-minute rest period before the 6-minute walking distance.

[0135] Muscle strength by myometry Assess muscle strength using handheld dynamometry. All assessments should be performed on the right and left sides.

[0136] The following are tested: Elbow flexion ·Elbow extension Shoulder abduction Knee flexion ·Knee extension Ankle dorsiflexion

[0137] For each test, three values ​​of maximum muscle strength (peak force) are collected on the right and left sides at the time points specified in the schedule of assessment. All values ​​are transferred to the appropriate eCRF. For data analysis purposes, only the highest value per test per side per visit is analyzed.

[0138] Training of clinical assessors and quality assurance of site myometry assessment administration are described in the Motor Function and Strength Assessment Test Manual and Site Manual. Video recording of site myometry assessments may be performed to allow central quality review by an expert physiotherapist. All collected videos are masked (anonymized) using blurring technology before being centrally screened.

[0139] Primary Endpoint The primary efficacy endpoint is percent change from baseline in quadriceps CMV at week 52 of treatment, as defined in Section 3 (Table 3). Percent change from baseline in quadriceps CMV as assessed by MRI will be derived at each time point.

[0140] The primary estimation targets are defined as the following attributes: Population: FSHD1 or FSHD2 participants who were ambulatory at randomization as defined by the study inclusion and exclusion criteria, aged 18-65 years at the time of signing the informed consent form, Variables: Quadriceps CMV assessed by MRI treatment: - RO7204239 90mg every 4 weeks by SC injection or Placebo by SC injection every 4 weeks Intermediate events: - Early discontinuation from study treatment (RO7204239 or placebo) -death Treatment of intercurrent events: - Early discontinuation from study treatment for reasons related to study drug (e.g., treatment-related adverse events, lack of efficacy, etc.). All available data will be included in the analysis of treatment-policy strategies. - Early discontinuation from study treatment for reasons unrelated to study drug (e.g., death). A hypothetical treatment strategy will be applied, assuming participants continue on randomized treatment until the primary analysis time point. Population-level summary: Difference between the RO7204239 and placebo arms in mean percent change from baseline in quadriceps CMV assessed by MRI after 52 weeks of treatment.

[0141] Percentage change from baseline in CMV at week 52 is defined as

number

[0142] The hypothesis to be tested is the difference in mean percent change (δ) from baseline in quadriceps CMV assessed by MRI at week 52 between the RO7204239 and placebo groups. H0: δ = 0 (null) vs. H1: δ ≠ 0 (alternative)

[0143] The tests are performed at a two-sided 5% significance level:

[0144] Estimates of treatment effects are calculated using mixed model repeated measures (MMRM) analysis. The model includes the percent change from baseline in quadriceps CMV assessed by MRI as the dependent variable. Independent variables in the model include baseline CMV, treatment group, time, and treatment-time interactions. An unstructured variance-covariance matrix structure is applied. Estimated treatment differences in mean percent change from baseline in quadriceps CMV assessed by MRI at week 52 for RO7204239 versus placebo are presented with 95% confidence intervals. Percent change from baseline in CMV, actual CMV, and actual change from baseline in CMV are also summarized at each time point by treatment group and study period.

[0145] Efficacy results for patients from the enrollment population rather than the efficacy analysis population will be listed separately, if applicable.

[0146] The primary safety endpoints, as defined in Section 3, Table 2, were as follows: Incidence, severity, and causality of adverse events will be determined according to NCI CTCAE v5.0. Changes from baseline in vital signs, physical examination, ECG, echocardiogram, and laboratory findings Incidence of local and systemic injection reactions Incidence of abnormal test findings Incidence of abnormal ECG parameters Incidence of abnormal echocardiographic parameters Incidence of abnormal vital signs

[0147] All safety analyses are based primarily on the safety population.

[0148] Safety will be assessed by a summary of exposure to study treatment, adverse events, abnormal results of vital signs, ECG, echocardiogram, and laboratory evaluations, and may also be assessed by a summary of results regarding physical examination findings, echocardiograms, laboratory tests, vital signs, and changes in ECG test results.

[0149] Study treatment exposure (duration of treatment, total dose received, and dose modifications) will be summarized with descriptive statistics by treatment group and study period.

[0150] All verbatim adverse event terms will be mapped to thesaurus terms from the Medical Dictionary for Regulatory Activities, and the severity of the adverse events will be graded according to NCI CTCAE v5.0. All adverse events occurring at or after the first dose of study treatment, serious adverse events, adverse events leading to death, adverse events of special interest, and adverse events leading to discontinuation of study treatment (i.e., treatment-emergent adverse events) will be summarized by mapped term, appropriate thesaurus level, and severity. For events of differing severity, the highest grade will be used in the summary. Adverse event outcomes will be summarized by treatment group and study period. Deaths and causes of death will be listed. Serious adverse events observed during the pretreatment period will also be summarized and listed for the enrollment population.

[0151] Abnormal results of laboratory, vital, echocardiographic, and ECG test evaluations will be summarized at each time point by treatment group and study period. Relevant changes from baseline results in laboratory, vital signs (pulse rate, respiratory rate, blood pressure, pulse oximetry, and temperature), echocardiographic, and ECG data may be displayed by time with identified grades as appropriate. Additionally, shift tables for selected laboratory tests may be used to summarize baseline and post-baseline maximum severity grades as appropriate.

[0152] Secondary endpoints The secondary efficacy endpoints defined in Section 3 (Table 3) are as follows: Change from baseline in serum concentrations of total latent myostatin, free latent myostatin, and mature myostatin Percent change from baseline in quadriceps CMV assessed by MRI at 28 weeks of treatment Percent change from baseline in CMV of the tibialis anterior muscle assessed by MRI at 28 and 52 weeks of treatment Percent change from baseline in biceps CMV assessed by MRI at 28 and 52 weeks of treatment Percent change from baseline in skeletal muscle contraction area of ​​proximal lower limb muscles assessed by MRI at 28 and 52 weeks of treatment Percent change from baseline in skeletal muscle contraction area of ​​distal lower limb muscles assessed by MRI at 28 and 52 weeks of treatment Percent change from baseline in skeletal muscle contraction area of ​​the proximal upper limbs assessed by MRI at 28 and 52 weeks of treatment Change from baseline in fat compartment of proximal leg muscles assessed by MRI at 28 and 52 weeks of treatment Change from baseline in fat compartment of distal leg muscles assessed by MRI at 28 and 52 weeks of treatment Change from baseline in fat compartment of proximal upper limb muscles assessed by MRI at 28 and 52 weeks of treatment

[0153] All analyses of secondary efficacy endpoints will be performed for each individual in the efficacy analysis population on data through Week 52. Efficacy results from patients in the enrolled population but not in the efficacy analysis population will be listed separately, if applicable.

[0154] Each of the secondary endpoints will be tested at a two-sided 5% significance level without adjustment for multiplicity.

[0155] Continuous secondary efficacy endpoints will be analyzed using MMRM in a similar manner as described for the primary efficacy endpoint. Estimated treatment differences and corresponding 95% confidence intervals are reported.

[0156] Results of all secondary efficacy endpoints will also be summarized by treatment group and study period for each time point. [Table 4] TIFF2025511167000006.tif249170 TIFF2025511167000007.tif30170

[0157] References Brooks R. EuroQol: the current state of play. Health Policy 1996;37:53 - 72. Burch PM, Pogoryelova O, Palandra J, et al. Reduced serum myostatin concentrations associated with genetic muscle disease progression. J Neurol 2017;264(3):541 - 53. Deenan JCW, Arnts H, van der Maarel SM, et al. Population - based incidence and prevalence of facioscapulohumeral dystrophy. Neurology 2014;83(12):1056 - 9. Eichinger K, Heatwole C, Iyadurai S, et al. Facioscapular muscular dystrophy functional composite outcome measure. Muscle Nerve 2018;58:72 - 8. EuroQol Group. EuroQol: a new facility for the measurement of health - related quality of life. Health Policy 1990;16:199 - 208. Giesige CR,Wallace LM,Heller KN,et al.AAV-mediated follistatin gene therapy improves functional outcomes in the TIC-DUX4 mouse model of FSHD.JCI Insight 2018;3(22):e123538. Hamel J,Tawil R.Facioscapulohumeral muscular dystrophy:Update on pathogenesis and future treatments.Neurotherapeutics 2018;15(4):863-71. Han JJ,Kurillo G,Abresch RT,et al.Reachable workspace in facioscapulohumeral muscular dystrophy(FSHD)by Kinect.Muscle Nerve 2015;51(2):168-75. Herdman M,Gudex C,Lloyd A,et al.Development and preliminary testing of the new five-level version of EQ-5D(EQ5D-5L).Qual-Life Res 2011;20:1727-36. Janssen BH,Voet NB,Nabuurs CI,et al.Distinct disease phases in muscles of facioscapulohumeral dystrophy patients identified by MR detected fat infiltration.PLoS One 2014;9(1):e85416. Janssen MF,Pickard AS,Golicki D,et al.Measurement properties of the EQ-5D-5L compared to the EQ-5D3L across eight patient groups:a multi-country study.Qual-Life Res 2013;22:1717-27. Lassche S,Voermans NC,Schreuder T,et al.Reduced specific force in patients with mild and severe facioscapulohumeral muscular dystrophy.Muscle Nerve 2021;63:60-7. LoRusso S,Johnson N,McDermott MP,et al.Clinical trial readiness to solve barriers to drug development in FSHD(ReSolve):Protocol of a large,international,multi-center prospective study.BMC Neurol 2019;19:224. Mul K,Vincenten SCC,Voermans NC,et al.Adding quantitative muscle MRI to the FSHD clinical trial toolbox.Neurology 2017;89(20):2057-65. Muramatsu,H.,Kuramochi,T.,Katada,H.et al.Novel myostatin-specific antibody enhances muscle strength in muscle disease models.Sci Rep 2021;11:2160. Personius KE, Pandya S, King WM, et al. Facioscapulohumeral dystrophy natural history study: standardization of testing procedures and reliability of measurements. The FSH DY Group. Phys Ther 1994;74:253-63. Preston MK, Tawil R, Wang LH. Facioscapulohumeral muscular dystrophy. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle(WA): University of Washington, Seattle, 1999 [Updated 2020 Feb 6]:1993-2021. Statland JM, Tawil R. Facioscapulohumeral muscular dystrophy. Continuum(Minneap Minn)2016;22(6):1916-31. Tasca G, Monforte M, Ottaviani P, et al. Magnetic resonance imaging in a large cohort of facioscapulohumeral muscular dystrophy patients: Pattern refinement and implications for clinical trials. Ann Neurol 2016;79:854-64. Tawil R,Kissel JT,Heatwole C,et al.Evidence-based guideline summary:Evaluation,diagnosis,and management of facioscapulohumeral muscular dystrophy:Report of the Guideline Development,Dissemination,and Implementation Subcommittee of the American Academy of Neurology and the Practice Issues Review Panel of the American Association of Neuromuscular&Electrodiagnostic Medicine.Neurology 2015;85(4):357-64. Wagner KR.Facioscapulohumeral Muscular Dystrophies.Continuum(Minneap Minn)2019;25(6):1662-81.

Claims

1. A pharmaceutical composition comprising an anti-myostatin antibody for use in the treatment, prevention, delay of progression, and / or improvement of facioscapulohumeral muscular dystrophy (FSHD).

2. The pharmaceutical composition according to claim 1, wherein the anti-myostatin antibody binds to latent myostatin but does not bind to mature myostatin, blocks the non-proteolytic spontaneous release of mature myostatin from latent myostatin, and inhibits myostatin activation.

3. The pharmaceutical composition according to claim 1, wherein the anti-myostatin antibody comprises six complementarity-determining regions (CDRs): CDRH1, CDRH2, CDRH3, CDRL1, CDRL2, and CDRL3, wherein CDRH1 comprises the sequence of SEQ ID NO: 1, CDRH2 comprises the sequence of SEQ ID NO: 2, CDRH3 comprises the sequence of SEQ ID NO: 3, CDRL1 comprises the sequence of SEQ ID NO: 4, CDRL2 comprises the sequence of SEQ ID NO: 5, and CDRL3 comprises the sequence of SEQ ID NO:

6.

4. The pharmaceutical composition according to claim 1, wherein the anti-myostatin antibody comprises a VH chain containing the amino acid sequence of SEQ ID NO: 7 and a VL chain containing the amino acid sequence of SEQ ID NO:

8.

5. The pharmaceutical composition according to claim 1, wherein the anti-myostatin antibody comprises a heavy chain containing the amino acid sequence of SEQ ID NO: 9 and a light chain containing the amino acid sequence of SEQ ID NO:

10.

6. A pharmaceutical composition according to claim 1, for administration to a patient.

7. The pharmaceutical composition according to claim 1, wherein the anti-myostatin antibody is administered to the subject at a dose of 90 mg every four weeks.

8. The pharmaceutical composition according to any one of claims 1 to 7, wherein the anti-myostatin antibody is administered subcutaneously.