Use of myostatin inhibitors for treatment of spinal muscular atrophy

Abstract

Administration of apitegumab improves motor function and / or quality of life in subjects suffering from spinal muscular atrophy.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Patent Application Nos. 63 / 364,188, filed May 4, 2022; 63 / 366,447, filed June 15, 2022; 63 / 366,662, filed June 20, 2022; and 63 / 378,987, filed October 10, 2022; each entitled “USE OF ANTI-PRO / LATENT MYOSTATINANTIBODY FOR TREATING SPINAL MUSCULAR ATROPHY,” the contents of which are expressly incorporated herein by reference in their entirety. Technical Field

[0002] The present disclosure relates to methods of treatment, uses, and compositions comprising anti-pro / latent myostatin antibodies for treating spinal muscular atrophy (SMA) in human patients. Background Art

[0003] Myostatin (also known as growth differentiation factor 8, abbreviated as GDF-8 or GDF8) is a regulator of muscle homeostasis. Mutations that result in loss of myostatin, as well as pharmacological inhibition of myostatin activity, have been shown to increase muscle growth in many species, including humans. Over the past 15 years, at least 15 different myostatin inhibitor drug candidates (including small molecules and biologics) have been evaluated in human patients with the aim of treating various muscle disorders, but none has been successful in the clinic to date (Hanna et al. (2019) Lancet Neurol. 18(9):834-844; Rooks et al. (2020) JAMA Network Open. 3(10):e2020836). In addition, most of these inhibitors lack selectivity and therefore antagonize other related growth factors (such as activin A), causing toxicity issues. Most of these programs have now been discontinued. Therefore, in many cases, promising preclinical results have not been successfully translated into safe and effective drugs.

[0004] In most cases of SMA, deletion mutations on chromosome 5q13.2 are the cause of SMA, however, in a minority of cases, SMA is not associated with 5q13.2 mutations (Peeters et al. (2014) Brain 137:2879-2896). Non-5q13.2 mutations can lead to early-onset or late-onset forms of SMA with a range of clinical phenotypes. Sequencing methods can detect multiple genes associated with spinal muscular atrophy, which may manifest as conditions such as, but not limited to, early-onset scapulohumeral muscular atrophy and Farber disease (Teoh et al. (2017) Neural Plasticity 2017; 2017:6509493. doi:10.1155 / 2017 / 6509493. Epub 2017 May 28; Axente et al. (2021) J. Medicine and Life 14(3):424-427).

[0005] The SMN1 gene, which is deleted or mutated in SMA, is responsible for the production of most of the SMN protein. A second gene (SMN2), located near SMN1, is responsible for the production of a smaller amount of SMN protein. Because SMN protein is essential for the function and survival of motor neurons that control muscle function, the SMN protein deficiency caused by the deletion or mutation of the SMN1 gene in SMA leads to a significant but incomplete loss of motor neurons in the anterior horn of the spinal cord, thereby ensuring at least some intact innervation. This partial denervation causes a massive atrophy of fast-twitch muscle fibers, which in turn leads to motor dysfunction, followed by debilitating muscle atrophy and weakness. A patient's muscles can become so weak that moving, breathing, and eating become difficult.

[0006] In some countries, (nusinersen) is approved for the treatment of pediatric and adult patients with SMA, and EVRYSDI (onasemnogene abeparvovec-xioi) is approved for the treatment of SMA in pediatric patients up to two years of age who have biallelic mutations in the SMN1 gene. TM Risdiplam (a small molecule SMN therapy) has also been approved in the United States and Europe. Risdiplam is an SMN2-directed antisense oligonucleotide (ASO) designed to treat SMA caused by mutations that result in SMN protein deficiency. Risdiplam works in a similar manner and is a pyridazine derivative that modifies the splicing of SMN2 messenger RNA. Sovaldi is a recombinant adeno-associated virus vector-9-based gene therapy designed to deliver a copy of the gene encoding the human SMN protein.

[0007] SMN therapies (e.g., SMN-directed or SMN-targeted therapies), such as nusindrone, lisapram, sovaprevir, and other products under development, act primarily on motor neurons to prevent further loss. Consistent with this view, clinical data reported from an expanded group of SMN-targeted therapies suggest that after the first 15 months of improvement with nusindrone, the effect appears to plateau, approaching steady-state, as measured by the mean change from baseline in HFMSE scores. Limited further enhancement of motor function is observed over the next three years or more (Darras et al. (2019) Neurology 92(21):e2492-e2506). Similarly, long-term evaluation of risdiplam showed only stabilization or slight / variable improvement in primary and secondary endpoints after 12 months (Oskoui et al., “SUNFISH Part 2: 24-month efficacy and safety of risdiplam in patients with type 2 or non-ambulant type 3 spinal muscular atrophy (SMA).” presented at the MDA Clinical and Scientific Conference 2021; March 15–18. Panel 80). Therefore, SMN therapy may help maintain motor function in the long term but may provide limited long-term enhancement of motor function. Although SMN therapy, approved for the treatment of SMA, has been shown to significantly improve clinical outcomes by providing progressive improvements in motor function and developmental milestones and preventing worsening of SMA symptoms, patients may continue to have severe motor impairments because SMN therapy focuses on motor neurons within motor units rather than on muscle atrophy that has already occurred. Regardless of when SMN therapy is started, patients who receive these disease-stabilizing therapies after symptom onset continue to have significant unmet medical needs and may not see sustained progress in benefit, for example, after years of treatment. Such patients may benefit from various therapies (such as the myostatin inhibition methods disclosed herein) that surprisingly provide lasting improvement over a longer period of time.

[0008] There are currently no approved muscle-targeted therapies (i.e., muscle-directed or muscle-enhancing therapies) for the treatment of SMA. Therefore, there remains an unmet need for effective and durable muscle-targeted therapies that can address muscle atrophy and motor dysfunction in SMA patients (Day et al. (2022) BMC Pediatrics 22:632). Overview

[0009] The present disclosure particularly includes methods, uses, and compositions for treating SMA patients using muscle-enhancing agents (i.e., muscle-directed or muscle-targeted agents) such as apitegrumab (also known as SRK-015). In various embodiments, apitegrumab or a composition comprising apitegrumab is used to treat late-onset SMA in human subjects as a monotherapy or as an adjunct to motor neuron-directed therapy (e.g., SMN upregulator / corrector therapy (i.e., SMN therapy)). The data provided herein demonstrate that a 24-month administration of a muscle-enhancing agent to patients with type 2 and type 3 SMA has a lasting effect. Provided herein is apitegrumab therapy for treating subjects with SMA.

[0010] In addition, disclosed herein are the selection of certain SMA patient subpopulations that may particularly benefit from muscle-enhancing agents, such as myostatin inhibitors. In some embodiments, the myostatin inhibitor is a myostatin-selective inhibitor, wherein optionally the myostatin-selective inhibitor is an antibody that binds to latent myostatin, thereby inhibiting its activation, such as apitegromab. In some embodiments, the myostatin inhibitor binds myostatin and GDF11, but does not bind activin A.

[0011] According to the present disclosure, certain subpopulations of SMA patients who may benefit from muscle strengthening agents include: patients with muscle weakness and / or tightness. In some embodiments, patients suffer from fatigue; patients with difficulty or impairment of bulbar function (e.g., coughing, swallowing, and / or eating difficulties); and / or patients with difficulty or disturbance of emptying (e.g., urinary urgency, frequency, bowel changes, etc.).

[0012] In some embodiments, the patient has Type 2 or Type 2-like SMA, wherein, optionally, the patient is 2 years of age or older. In some embodiments, the patient has Type 3 or Type 3-like SMA, wherein, optionally, the patient is 2 years of age or older. In some embodiments, the patient has ambulatory SMA. In some embodiments, the patient has nonambulatory SMA. In some embodiments, the patient is less than 2 years of age. In some embodiments, the patient is 13-21 years of age, wherein, optionally, the patient has nonambulatory Type 2 or Type 3 SMA.

[0013] According to the present disclosure and the data presented herein, in some embodiments, when administered every 4 weeks (i.e., Q4W) or monthly, the therapeutic dose is greater than 2 mg / kg and up to 20 mg / kg of Apitalumab. In some embodiments, a therapeutic dose of less than 20 mg / kg can be used, such as 2 mg / kg, 5 mg / kg, 7.5 mg / kg, 10 mg / kg, 12 mg / kg, and 15 mg / kg. In some embodiments, the therapeutic dose is 10 mg / kg. In some embodiments, the therapeutic dose is 20 mg / kg. In some embodiments, the therapeutic dose is 10 mg / kg when administered once every four weeks (i.e., Q4W) or once a month. In some embodiments, the therapeutic dose is 20 mg / kg when administered once every four weeks (i.e., Q4W) or once a month. In various embodiments, Apitalumab therapy can improve motor function in patients with late-onset SMA.

[0014] Pharmacokinetic (PK) analysis provides a relationship between the dose (e.g., therapeutic dose) and bioavailability (serum exposure) of a therapeutic agent. In some embodiments, the therapeutic dose is the dose that is present at the trough (C 波谷 ) to achieve or produce a serum apivolumab exposure of between about 25 and 250 μg / mL when measuring the serum concentration of apivolumab. Doses that achieve this result can be administered by any suitable route (e.g., intravenously or subcutaneously). In some embodiments, the doses described herein are achieved by intravenous administration.

[0015] In some embodiments, the therapeutic dose is within about two hours of administration (dosing), when the peak (C max ) when measuring serum concentrations of apilectumab at a dose that achieves or produces a serum exposure of up to about 1100 μg / mL (e.g., between about 25 and 1100 μg / mL). Doses that achieve this result can be administered by any suitable route (e.g., intravenously or subcutaneously).

[0016] In some embodiments, pharmacodynamic (PD) analysis allows for the assessment of target engagement, i.e., the assessment of binding of a therapeutic antibody to promyostatin / latent myostatin, as measured by serum concentrations of latent myostatin (LM). In some embodiments, a therapeutic dose is a dose that achieves or produces a serum concentration of latent myostatin in a subject, preferably at steady state (e.g., 14 days or later after administration of apivolumab), of at least about 100, or preferably at least about 250 ng / mL. A dose that achieves this result can be administered by any suitable route (e.g., intravenously or subcutaneously). For example, the serum concentration of latent myostatin can be about 250 ng / mL or more, 400 ng / mL or more, 550 ng / ml or more, 700 ng / ml or more, 950 ng / ml or more, or 1100 ng / ml or more, etc.

[0017] In some embodiments, the PD analysis that allows assessment of target engagement includes measuring the serum concentration of creatinine. In some embodiments, the therapeutic dose of a treatment comprising apivolumab is a dose that achieves or produces an increase in serum concentration of creatinine of at least 10% (e.g., at least 20%, at least 25%, at least 30%, or more) in the subject compared to the concentration before the start of treatment. In some embodiments, the serum concentration of creatinine is measured at steady state, for example, at least two weeks (e.g., at least three weeks, at least four weeks, or at least one month) after the start of treatment. In some embodiments, treatment with apivolumab includes administering an amount and / or dosing regimen that is sufficient to obtain an increase in serum creatinine of 10% or greater (e.g., at least 20%, at least 25%, at least 30%, or more) when measured before and after treatment (e.g., at steady state before treatment and after the start of treatment).

[0018] Apilitubine or another selective myostatin inhibitor can be used to treat SMA alone (e.g., monotherapy) or in combination with another therapy such as an SMN therapy or an SMN-targeted therapy (including an SMN upregulator or corrector therapy) to treat SMA (e.g., add-on therapy / adjuvant therapy or combination therapy). In some embodiments, the use of an SMN upregulator therapy (e.g., nusindroxin) is effective in treating SMA. or risperidone In some embodiments, the subject is treated with an SMN corrector therapy (such as an SMN gene therapy, e.g., sovaroprevir). ) Treating a subject. In some embodiments, the subject begins SMN therapy at or after age five. In some embodiments, neuron-directed therapy increases progranulin to maintain neuronal viability.

[0019] In some embodiments, SMN therapy (e.g., SMN targeted therapy, such as SMN upregulator / corrector therapy) and apilectomycin therapy (e.g., muscle targeted therapy) are used as a combination therapy, or add-on therapy, or adjuvant therapy. Thus, SMN therapy and apilectomycin can be used to treat SMA in a patient, wherein the treatment comprises administering SMN therapy and apilectomycin in an amount sufficient to treat SMA, wherein apilectomycin therapy is administered intravenously to the patient in an amount greater than 2 mg / kg and up to 20 mg / kg every four weeks or monthly. In some embodiments, the SMN therapy is an SMN1-directed gene therapy. In some embodiments, the SMN therapy is an SMN upregulator therapy, such as an SMN2-directed therapy, wherein optionally the SMN2-directed therapy is a splicing modifier. In some embodiments, the SMN corrector can be administered orally, intrathecally, or intravenously. In some embodiments, the patient suffers from late-onset SMA.

[0020] In some embodiments, the present disclosure provides a therapy comprising apilectomycin and an SMN therapy (e.g., an SMN upregulator or corrector therapy, such as nusinersen, risdiplam, and / or sovaprevir) for treating SMA in a patient two years of age or older with type 2 or type 3 SMA, wherein the treatment comprises administering an amount of the SMN therapy and apilectomycin sufficient to treat SMA, wherein the apilectomycin therapy is administered intravenously to the patient at a dose of greater than 2 mg / kg and up to 20 mg / kg every four weeks or monthly.

[0021] In some embodiments, the present disclosure provides a therapy comprising apilectomycin and an SMN therapy (e.g., an SMN upregulator or corrector therapy, such as nusinersen, risdiplam, and / or sovaprevir) for treating SMA in a patient with ambulatory SMA, wherein the treatment comprises administering an amount of the SMN therapy and apilectomycin sufficient to treat SMA, wherein the apilectomycin therapy is administered intravenously to the patient at a dose greater than 2 mg / kg and up to 20 mg / kg every four weeks or monthly.

[0022] In some embodiments, the present disclosure provides a therapy comprising apilectomycin and an SMN therapy (e.g., an SMN upregulator or corrector therapy, such as nusinersen, risdiplam, and / or sovaprevir) for treating SMA in a patient aged 13-21 years with non-ambulatory SMA type 2 or type 3, wherein the treatment comprises administering an amount of the SMN therapy and apilectomycin sufficient to treat SMA, wherein the apilectomycin therapy is administered intravenously to the patient at a dose of greater than 2 mg / kg and up to 20 mg / kg every four weeks or monthly.

[0023] In some embodiments, the present disclosure provides a therapy comprising apilectomycin and an SMN therapy (e.g., an SMN upregulator or corrector therapy, such as nusinersen, risdiplam, and / or sovaprevir) for treating SMA in a patient under 2 years of age, wherein the treatment comprises administering an amount of the SMN therapy and apilectomycin sufficient to treat SMA, wherein the apilectomycin therapy is administered intravenously to the patient at a dose of greater than 2 mg / kg and up to 20 mg / kg every four weeks or monthly.

[0024] In some embodiments, the patient has two copies of the SMN2 gene. In some embodiments, the patient has three copies of the SMN2 gene. In some embodiments, the patient has four copies of the SMN2 gene. In some embodiments, the patient has five copies of the SMN2 gene. In some embodiments, the patient has six copies of the SMN2 gene.

[0025] In some embodiments, the patient begins combination therapy at age five or older. In some embodiments, the patient begins combination therapy before age five. In some embodiments, the patient begins combination therapy before age two. In some embodiments, the patient begins combination therapy before age six weeks. In some embodiments, the patient is diagnosed with SMA (e.g., identified as a carrier of an SMN1 mutation) by genetic screening, wherein optionally, for example, the genetic screening is neonatal screening or in utero screening for one or more SMN1 mutations. In some embodiments, the patient is presymptomatic.

[0026] In some embodiments, apilectomycin therapy is used as an additional or adjuvant therapy for the treatment of SMA. Thus, a composition comprising apilectomycin can be used to treat late-onset SMA in a patient, wherein the treatment comprises intravenous administration of a composition comprising apilectomycin at a therapeutic dose, wherein the therapeutic dose is greater than 2 mg / kg and up to 20 mg / kg every four weeks or monthly, and wherein the patient is treated with an SMN therapy. In some embodiments, the SMN therapy is an SMN1-directed therapy, wherein optionally the SMN1-directed therapy is a gene therapy. In some embodiments, the SMN therapy is an SMN2-directed therapy, wherein optionally the SMN2-directed therapy is an SMN upregulator therapy, such as a splicing modifier. In some embodiments, any of the SMN therapies can be administered orally, intrathecally, or intravenously. In some embodiments, the patient has type 2 or type 2-like SMA. In some embodiments, the patient has nonambulatory type 3 or type 3-like SMA. In some embodiments, the patient has ambulatory type 3 or type 3-like SMA. In some embodiments, the patient has two copies of the SMN2 gene. In some embodiments, the patient has three copies of the SMN2 gene. In some embodiments, the patient has four copies of the SMN2 gene. In some embodiments, the patient has five copies of the SMN2 gene. In some embodiments, the patient has six copies of the SMN2 gene. In some embodiments, the patient begins SMN corrector therapy before the age of five. In some embodiments, the patient begins SMN corrector therapy at the age of five or older. In some embodiments, the patient is diagnosed with SMA (e.g., identified as a carrier of an SMN1 mutation) by genetic screening, wherein optionally, the genetic screening is newborn screening or in utero screening. In some embodiments, the patient is a fetus diagnosed with SMA. In some embodiments, the patient is a fetus treated with apilectomycin in utero. In some embodiments, the patient is presymptomatic. In some embodiments, the patient is treated with an SMN corrector prior to apilectomycin therapy. In some embodiments, the patient is treated with apilectomycin prior to receiving SMN corrector therapy.

[0027] Patients with SMA who may benefit from apilectomycin therapy include those who meet one or more of the following criteria: a documented diagnosis of 5qSMA and late-onset (and / or type 2, type 2-like, type 3, or type 3-like) SMA prior to receiving SMA-directed therapy; SMA not caused by a 5q mutation; nonambulatory subjects who can sit independently according to the WHO motor milestone definition; ambulatory subjects who can walk more than 10 meters independently in 30 seconds or less without assistance; and subjects with a Revised Hammersmith Scale (RHS) score of less than or equal to 63 and / or a Hammersmith Functional Motor Scale score of less than or equal to 63. Subjects with a HFSME score of 10 or higher; subjects who have not used positive pressure tracheotomy or chronic daytime non-invasive ventilation support for more than 16 hours per day within two weeks prior to treatment; subjects who have not suffered from any acute or coexisting conditions that interfere with the subject's health within two weeks prior to treatment; subjects who do not have severe scoliosis or contractures; and / or subjects who have not used systemic corticosteroids, valproic acid, or therapies with potential muscle or neuromuscular effects within 60 days, except for approved SMN targeted therapies (e.g., SMN upregulators (also known as SMN correctors) therapy). Therapies with potential muscle or neuromuscular effects include androgens, insulin-like growth factor, growth hormone, systemic beta-agonists, botulinum toxin, muscle relaxants, muscle strengthening supplements, or acetylcholinesterase inhibitors. In some embodiments, the patient has a documented diagnosis of 5q SMA and late-onset (and / or type 2, type 2-like, type 3, or type 3-like) SMA before receiving therapy for SMA, and meets one or more of the additional criteria listed in the table above. In various embodiments, the methods disclosed herein comprise selecting such a patient or patient population for treatment with apilectumab, e.g., according to a dose or regimen disclosed herein.

[0028] SMA patients who may benefit from apilectomycin therapy include those who meet one or more of the following criteria: have 1, 2, 3, or 4 copies of the SMN2 gene and achieve one or more of the gross motor milestones according to the World Health Organization (WHO) Developmental Motor Scales: 1) sitting upright without support (e.g., head upright for at least 10 seconds; not using arms or hands for balance); 2) crawling on hands and knees (e.g., moving in the same direction at least three times without belly touching a support surface); 3) standing with assistance (e.g., standing on two feet without leaning on anything for at least 10 seconds); 4) walking with assistance (e.g., taking at least five steps while holding onto a stable object); 5) standing without support (e.g., standing without touching people or objects for at least 10 seconds); and, 6) walking without support (e.g., taking at least five steps independently).

[0029] Patients with SMA who may benefit from apivolumab therapy include those who meet one or more of the following criteria: have one, two, three, or four copies of the SMN2 gene and achieve one or more gross motor milestones according to the HFMSE: 1) neck support (e.g., able to lift or support head while lying prone); 2) roll over; 3) sit in a tripod position (e.g., support oneself on hands while sitting); 4) sit without support; 5) stand with support; 6) crawl / crawl; 7) pull to a standing position (e.g., pull to a standing position and walk slowly along furniture); 8) stand without support; 9) take a few steps independently and then fall; 10) walk independently (e.g., walk independently without support); 11) squat to pick up an object (e.g., a toy); 12) walk / crawl up and down stairs; 13) jump; 14) go up stairs on both feet; 15) hop on one foot; 16) go down stairs on both feet.

[0030] In some embodiments, patients treated with apilectomycin as disclosed herein have previously received or are currently being treated with an SMN-targeted therapy (also known as an SMN upregulator or corrector) such as nusindromic acid, risperidone, or sovaprevir. In some embodiments, the patient begins SMN upregulator (corrector) therapy before the age of five. In some embodiments, the patient begins SMN upregulator (corrector) therapy at or after the age of five. In some embodiments, the SMN corrector therapy is an SMN2 upregulator therapy. In some embodiments, the SMN corrector therapy is an SMN1 gene therapy.

[0031] In some embodiments, patients receive apilectomycin therapy for at least six months (e.g., 6 months, 12 months, 24 months, or longer) at a therapeutic dose sufficient to achieve a clinical benefit characterized by improved motor function, stable disease, and / or delayed disease progression.

[0032] In some embodiments, patients receiving apivolumab therapy may obtain an improvement in motor function. The improvement in motor function may correspond to an increase in HFMSE score or RHS score. For example, after 6 months, 12 months, or 24 months of treatment with apivolumab (i.e., apivolumab therapy), the patient may achieve an increase in HFMSE score by at least 1 point, 2 points, 3 points, 4 points, 5 points, or more compared to the baseline. In some embodiments, in patients who begin receiving background SMN targeted therapy at an early stage, 12 months of apivolumab therapy may increase the HFMSE score by 3 points or more (e.g., at least 3 points, at least 5 points, at least 10 points, up to about 20 points) compared to the baseline. In some embodiments, the improvement in HFMSE score is additive and may be synergistic with background therapy (e.g., background SMN upregulator / corrector therapy). In some embodiments, 24 months of apilectomycin therapy may increase HFMSE scores by 3 points or more (e.g., at least 3 points, at least 5 points, at least 10 points, up to about 20 points) compared to baseline in patients who started background SMN therapy at an early age (e.g., less than 2 years of age). In some embodiments, the improvement in HFMSE scores is additive and may be synergistic with background therapy (e.g., background SMN upregulator / corrector therapy).

[0033] In some embodiments, patients receiving apilectomycin therapy may have stable disease. Stable disease can correspond to, for example, a net zero (e.g., at least no change or increase) or near-zero change in HFMSE score or RHS score relative to baseline over at least 24 months. In some embodiments, this is a clinically meaningful result compared to an untreated patient population (e.g., natural history) or a patient population treated with prior art methods (e.g., background therapy) where a gradual decline in motor function is expected.

[0034] In some embodiments, patients receiving apilectomycin therapy may experience a delay in disease progression. A delay in disease progression may include, for example, a slower rate of decline in HFMSE score over time, for example, after at least 12 or 24 months of treatment, compared to a suitable control (e.g., an untreated patient who exhibits the natural history of the disease in a particular patient population). In some embodiments, a delay may include a later transition from ambulatory SMA to nonambulatory SMA.

[0035] In some embodiments, apilectomycin is capable of increasing the therapeutic response rate in a patient population relative to a control that did not receive apilectomycin.

[0036] In any embodiment, the therapeutically effective amount of apilectumab does not cause serious adverse events in the patient after 12 months of treatment or after 24 months of treatment.

[0037] The present disclosure is based, at least in part, on the discovery that anti-promyostatin / latent myostatin antibodies that selectively inhibit the activation of latent myostatin can improve muscle function in human patients with SMA (including SMA patients who may or may not be treated with background SMN upregulator therapy (e.g., nusindrone, risperidone, and / or sovaprevir)), and in some cases, to a surprising degree that would not normally be expected or observed in a particular patient population while avoiding adverse events (e.g., compared to Mercuri et al. (2018) New Engl J Med 378(7):625-635). Accordingly, the present disclosure provides various embodiments of methods, uses, and compositions comprising anti-promyostatin / latent myostatin antibodies for treating SMA in human subjects. Furthermore, based on the data provided herein demonstrating the clinical benefit of selective myostatin inhibition for treating neuromuscular diseases, the present disclosure also encompasses the concept that other selective myostatin inhibitors can also be used in a similar manner. These might include, for example, neutralizing antibodies that selectively inhibit myostatin (but not other associated growth factors such as activin A) and ligand traps engineered to preferentially bind myostatin.

[0038] In some embodiments, a therapeutically effective amount of greater than 2 and up to 20 mg / kg of apivolumab achieves one or more of the following in a subject: maintaining motor function compared to a decrease in a control, delaying disease progression, delaying or preventing ambulatory Type 3 SMA patients from becoming non-ambulatory, delaying or preventing the need for respiratory assistance or intervention, reducing the rate of decline in one or more motor function scores compared to a control, and / or maintaining at least a net zero change in one or more motor function scores compared to baseline. In some embodiments, the amount is a dose of greater than 2 and up to 20 mg / kg of apivolumab administered intravenously every four weeks or monthly. In some embodiments, a mean decrease relative to baseline can be observed in the patient population, but the majority of patients exhibit stable disease (no change or increase in RHS). In some embodiments, a subset of the patient population (e.g., 10% or more, e.g., 15% or more, 20% or more) achieves an increase in RHS of three or more after 12 months of treatment with apivolumab as a monotherapy. In some embodiments, a subset of the patient population (e.g., 10% or more, e.g., 15% or more, 20% or more) achieves an increase in RHS of three points or more after 24 months of treatment with apilectomycin as monotherapy.

[0039] In some embodiments, the present disclosure provides a method of treating SMA in a human subject, the method comprising administering to the subject a composition comprising apilectumab and a composition comprising an SMN-targeted therapy (e.g., an SMN upregulator), wherein apilectumab is administered to the subject by intravenous infusion in an amount greater than 2 and up to 20 mg / kg every four weeks or monthly for at least six or 12 months, in an amount sufficient to produce a mean increase in HFMSE score of at least one point relative to a pre-treatment baseline score (e.g., in a cohort of at least 14 subjects).

[0040] In some embodiments, the present disclosure provides a composition comprising apilectomycin for use in treating SMA in a human subject receiving an SMN upregulator, wherein apilectomycin is administered to the subject by intravenous infusion in an amount greater than 2 and up to 20 mg / kg every four weeks or monthly for at least six months, an amount sufficient to produce a mean increase in HFMSE score of at least one point relative to a pre-treatment baseline score (e.g., in a cohort of at least 14 subjects).

[0041] In some embodiments, the composition comprising apiltuzumab for use in treating SMA in a human subject receiving SMN treatment is administered intravenously in a healthcare facility. In some embodiments, the composition comprising apiltuzumab for treating SMA in a human subject receiving SMN treatment is administered intravenously outside a healthcare facility (e.g., at the subject's home). In some embodiments, the composition comprising apiltuzumab for treating SMA in a human subject receiving SMN treatment is administered intravenously at the subject's home by a healthcare worker (e.g., a healthcare professional). In some embodiments, the composition comprising apiltuzumab for treating SMA in a human subject receiving an SMN upregulator is administered subcutaneously at the subject's home, for example, by a healthcare worker (e.g., a healthcare professional). In some embodiments, the composition comprising apiltuzumab is administered subcutaneously by the patient.

[0042] In some embodiments, the present disclosure provides use of apilectomycin in the manufacture of a composition for treating SMA in a human subject receiving an SMN upregulator, wherein apilectomycin is administered to the subject by intravenous infusion in an amount greater than 2 mg / kg and up to 20 mg / kg (e.g., 10 mg / kg or 20 mg / kg) every four weeks or monthly for at least six months, in an amount sufficient to produce a mean increase in HFMSE score of at least one point relative to a pre-treatment baseline score (e.g., in a cohort of at least 14 subjects).

[0043] In some embodiments, the SMA is late-onset SMA. In some embodiments, the SMA is type 2 SMA or type 2-like SMA. In some embodiments, the SMA is nonambulatory type 3 SMA or type 3-like SMA. In some embodiments, the subject is 5 to 21 years of age. In some embodiments, the SMN upregulator therapy is nusinib, risopram, and / or sovaprevir. In some embodiments, the SMN upregulator therapy is nusinib. In some embodiments, the SMN upregulator therapy is risopram. In some embodiments, the sufficient amount is an intravenous dose of greater than 2 and up to 20 mg / kg, optionally about 5, 7.5, 10, 15, or 20 mg / kg. In some embodiments, the therapeutic dose of apilectomycin is sufficient to increase the HFMSE of a patient (e.g., a majority (e.g., greater than 50%, e.g., greater than 60%) of a patient population) by one or more points and / or to increase the HFMSE of a patient (e.g., at least 20% (e.g., at least 25%) of a patient population) by three or more points.

[0044] In some embodiments, SMA is late-onset SMA, wherein the late-onset SMA is type 2 SMA or type 2-like SMA, wherein the patient starts background SMN corrector therapy at an early age (e.g., before the age of five). Apital therapy can achieve significant motor function improvement in this patient population (e.g., an increase of five points or more in HFMSE score). In some embodiments, the patient's HFMSE increases by 3+ points, 5+ points, or 10+ points compared to baseline at 12 months of Apital therapy, wherein the baseline is measured before or at the time of the first administration of Apital. In some embodiments, the patient's HFMSE increases by 3+ points, 5+ points, or 10+ points compared to baseline at 24 months of Apital therapy, wherein the baseline is measured before or at the time of the first administration of Apital. In some embodiments, the patient obtains a greater increase in HFMSE relative to baseline at 24 months of Apital treatment than at 12 months of Apital treatment.

[0045] In some embodiments, based on the WHO Motor Development Milestones classification, the subject is a patient who has not achieved the ability to sit unassisted by 4-9 months of age. In some embodiments, the subject is a patient who has achieved the ability to sit unassisted by 4-9 months of age. In some embodiments, the subject is a patient who has achieved the ability to stand unassisted by 5-11 months of age. In some embodiments, the subject is a patient who has achieved the ability to stand unassisted by 5-11 months of age. In some embodiments, the subject is a patient who has achieved the ability to crawl on hands and knees by 5-13 months of age. In some embodiments, the subject is a patient who has achieved the ability to crawl on hands and knees by 5-13 months of age. In some embodiments, the subject is a patient who has not achieved the ability to walk unassisted by 6-14 months of age. In some embodiments, the subject is a patient who has achieved the ability to walk unassisted by 6-14 months of age. In some embodiments, the subject is a patient who has achieved the ability to stand unassisted by 7-14 months of age. In some embodiments, the subject is a patient who has achieved the ability to stand unassisted by 7-14 months of age. In some embodiments, the subject is a patient who has achieved the ability to walk unassisted by 8-18 months of age. In some embodiments, any of the above-mentioned patients who cannot walk may also be characterized as having Type 2, Type 2-like, Type 3, or Type 3-like SMA. In some embodiments, any of the above-mentioned patients who are able to walk (with or without assistance) can also be characterized as having type 3 or type 3-like SMA. In some embodiments, the subject starts SMN upregulator / corrector therapy before the age of five. In some embodiments, the subject starts SMN upregulator / corrector therapy after the age of five. In some embodiments, after 6-12 months of treatment with a myostatin inhibitor (e.g., apivolumab), any of the above-mentioned patients may obtain one or more new milestones according to the WHO motor development milestones. In some embodiments, after 6-24 months of treatment with a myostatin inhibitor (e.g., apivolumab), any of the above-mentioned patients may obtain one, two, or three new milestones, such as one or more of the ability to walk independently, the ability to stand independently, the ability to stand with assistance, the ability to crawl on hands and knees, and / or the ability to walk with assistance, according to the WHO motor development milestones.

[0046] In some embodiments, the present disclosure provides a method of treating SMA in a patient, comprising administering to the patient a therapeutically effective amount of a myostatin inhibitor, e.g., apilectumab, wherein the therapeutically effective amount is an amount sufficient to achieve one or more WHO motor developmental milestones after 12, 24, or 36 months of treatment, wherein the patient was unable to perform one or more WHO motor developmental milestones at baseline.

[0047] In some embodiments, the target patient population for treatment with apivolumab includes a population 12 years of age or younger at the time of initiation of myostatin inhibitor (e.g., apivolumab) therapy. In some embodiments, the target patient population includes a population 2 years of age or older. In some embodiments, the target patient population includes a population between 2 and 12 years of age. In some embodiments, the target patient population includes a population between 2 and 5 years of age.

[0048] In some embodiments, apilectomycin is administered as a monotherapy to SMA patients. In some embodiments, apilectomycin is administered as a monotherapy to SMA patients who are unable to receive intrathecal injections as required by SMN upregulator therapy (e.g., due to spinal fusion) or have opted out of SMN upregulator therapy.

[0049] In some embodiments, the present disclosure provides the use of apivolumab in the manufacture of a pharmaceutical composition (e.g., a drug) for treating late-onset SMA in a human subject. The drug is intended to be administered to a subject at a dose of more than 2 mg / kg and up to 20 mg / kg of apivolumab every four weeks or monthly, wherein optionally the subject begins motor neuron-directed therapy for SMA before the age of five, and wherein the motor neuron-directed therapy increases SMN1 or SMN2 expression. The manufacturing method may include providing a cell line comprising one or more vectors having nucleic acid sequences of heavy and light chains of apivolumab immunoglobulin polypeptides capable of producing recombinant antibodies corresponding to apivolumab or its antigen-binding fragment. This cell line can be used to produce apivolumab in cell culture (such as mammalian cell culture, e.g., CHO cells). In some embodiments, apivolumab can be produced using large-scale (e.g., 250L, 1000L, 2000L, 3000L, 4000L, etc.) bioreactors. The recombinant antibody molecule can then be purified from the cell culture and the purified antibody can be formulated into a pharmaceutical composition comprising apilectomycin and one or more excipients. This method typically includes a sterile filtration step. In some embodiments, the pharmaceutical composition is a liquid formulation containing about 50 mg / mL apilectomycin suitable for intravenous administration.

[0050] In some embodiments, apivolumab is contained in a multi-dose vial (e.g., a glass vial). In some embodiments, the container (e.g., a glass vial) containing apivolumab is part of a kit. In some embodiments, apivolumab is contained in a prefilled syringe. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 Shown are the HFMSE scores after 15 months of Nusinsan treatment.

[0052] Figure 2A Shown are the mean changes from baseline in HFSME over 24 months (95% CI).

[0053] Figure 2B Mean changes (95% CI) in RULM over 24 months are shown.

[0054] Figure 3A A correlation between HFSME and RULM was shown at 12 months of apilectomycin treatment. Figure 3B The correlation between HFSME and RULM at 24 months of apilectomycin treatment was shown.

[0055] FIG4 shows the mean changes in HFMSE scores (left panel) and RULM scores (right panel) over 24 months of apilectomycin treatment.

[0056] Figure 5 A relationship was shown between the change from baseline in HFMSE score and baseline age in patients with type 2 and nonambulatory type 3 SMA.

[0057] Figure 6A Correlation of the change from baseline in HFMSE with the ratio of latent myostatin concentration and age is shown.

[0058] Figure 6B Correlation of the change from baseline in HFMSE with the ratio of latent myostatin fold change and age is shown.

[0059] Figure 7 shows the PEDI-CAT scores of patients with type 2 and nonambulatory type 3 SMA.

[0060] Figure 8 PROMIS scores for patients with type 2 and nonambulatory type 3 SMA are shown.

[0061] Figure 9A Showing the severity of muscle function in patients with Type 2 and Type 3 SMA.

[0062] Figure 9B Shown are the severity of fatigue in patients with type 2 and type 3 SMA.

[0063] Figure 9C Showing the severity of bulbar function in patients with type 2 and type 3 SMA.

[0064] Figure 9D The severity of emptying in patients with SMA types 2 and 3 is shown.

[0065] Figure 9E Showing the severity of daily life in patients with Type 2 and Type 3 SMA.

[0066] Figure 9F Showing the severity of social impact in patients with SMA types 2 and 3.

[0067] Figure 10A The relationship between changes in muscle volume and changes in serum creatinine in nonhuman primates treated with apilectomycin is shown.

[0068] Figure 10B Shown are the percent changes in serum creatinine in healthy human volunteers treated with apilectomycin. DETAILED DESCRIPTION definition

[0069] In order to more easily understand this disclosure, certain terms are first defined. These definitions should be read in conjunction with the remainder of this disclosure and should be understood as those of ordinary skill in the art. Unless otherwise defined, all scientific and technical terms used herein have the same meaning as those of ordinary skill in the art. Additional definitions are set forth throughout the detailed description.

[0070] Administration: The terms "administer," "administering," and "administering" include any method of delivering a therapeutic agent (e.g., an anti-promyostatin / latent myostatin antibody, e.g., apitocatumumab) to a subject's system or to a specific area within or on a subject (systemic and local administration, respectively). In some embodiments, the therapeutic agent is apitocatumumab. In some embodiments, apitocatumumab is formulated for administration as a composition (e.g., a pharmaceutical composition). In some embodiments, apitocatumumab is formulated for intravenous administration. For example, in some embodiments, apitocatumumab is administered by intravenous injection / infusion (e.g., by intravenous infusion). In some embodiments, apitocatumumab is administered by intravenous infusion (e.g., over about one to two hours). In some embodiments, apitocatumumab is administered by intravenous infusion over about two hours. In some embodiments, the infusion duration is less than two hours but not less than one hour.

[0071] Antibody: As used herein, the term "antibody" encompasses any naturally occurring, recombinant, modified or engineered immunoglobulin or immunoglobulin-like structure or its antigen-binding fragment or portion or derivative thereof. Thus, the term refers to an immunoglobulin molecule that specifically binds to a target antigen and includes, for example, chimeric, humanized, fully human and multispecific antibodies (including bispecific antibodies). A complete antibody typically comprises at least two full-length heavy chains and two full-length light chains, but in some cases may include fewer chains, such as antibodies naturally occurring in camelids, which may only comprise heavy chains. An antibody may be derived from only a single source, or may be "chimeric", i.e., different parts of the antibody may be derived from two different antibodies. Antibodies or their antigen-binding portions may be produced in hybridomas by recombinant DNA technology or by enzymatic or chemical cleavage of complete antibodies. As used herein, the term antibody includes monoclonal antibodies, multispecific antibodies (such as bispecific antibodies), miniantibodies, domain antibodies, synthetic antibodies (sometimes referred to herein as "antibody mimics"), chimeric antibodies, humanized antibodies, human antibodies, and antibody fusions (sometimes referred to herein as "antibody conjugates"). The term "antigen-binding fragment" encompasses fibronectin. In various embodiments of the methods of treatment, uses, and compositions disclosed herein, the antibody is a pro / latent myostatin antibody (eg, apilectumab).

[0072] Apilitubine: Apilitubine (also known as "SRK-015") is an investigational fully human monoclonal antibody that specifically binds with high affinity to the proforms of myostatin (i.e., inactive precursor forms, i.e., promyostatin and latent myostatin), thereby inhibiting myostatin activation. See, e.g., CAS Registry Number 2278276-46-1; International Nonproprietary Names for Pharmaceutical Substances (INN) (2020) WHO Drug Information, Vol. 34, No. 2, pp. 272-273; see also GtoPdb Ligand ID: 11180; GtoPdb PubChem SID: 434122240; IMGT / mAb-DB Database ID: 829; NIH ChemIDplus Database: RN: 2278276-46-1; UNII: UZ54216N0Y. Apilituzumab is a human immunoglobulin G4 (IgG4) / λ isotype. Apitalomab binds to latent myostatin in a manner that inhibits tolloid-mediated cleavage of latent myostatin into its active form, thereby preventing the activation and release of mature myostatin growth factors that inhibit muscle growth. Apitalomab is a selective myostatin inhibitor (myostatin-selective activation inhibitor). See, for example, International Publication No. WO 2017 / 049011. The term "selective myostatin inhibitor" (or "myostatin selective inhibitor") refers to an agent that can block, inhibit, or otherwise antagonize the activation or activity of myostatin / GDF-8 without affecting structurally related growth factors such as activin A.Apilivumab comprises the CDR regions of SEQ ID NO: 1 (HCDR1), SEQ ID NO: 2 (HCDR2), SEQ ID NO: 3 (HCDR3), SEQ ID NO: 4 (LCDR1), SEQ ID NO: 5 (LCDR2), and SEQ ID NO: 6 (LCDR3), as defined by the Kabat numbering system; or SEQ ID NO: 7 (HCDR1), SEQ ID NO: 8 (HCDR2), SEQ ID NO: 9 (HCDR3); SEQ ID NO: 10 (LCDR1), SEQ ID NO: 11 (LCDR2), and SEQ ID NO: 12 (LCDR3), as defined by the IMGT numbering system; a heavy chain variable region of SEQ ID NO: 13 and a light chain variable region of SEQ ID NO: 14; and a heavy chain amino acid sequence of SEQ ID NO: 15 and a light chain amino acid sequence of SEQ ID NO: 16. Apilivumab is being developed for the treatment of SMA in pediatric and adult patients.

[0073] Baseline: As used herein, in the context of SMA-related parameters, the term "baseline" or "baseline score" refers to the value of the patient's SMA-related parameter at the start of treatment with the SMA therapy of the present disclosure or before treatment (e.g., within 6 months before starting treatment) (e.g., when apilectomycin is first administered alone or as an adjunct to background therapy comprising SMA therapy). Examples of SMA-related parameters include scores on motor function scales, such as the Revised Upper Limb Module (RULM) score, the Hammersmith Functional Motor Scale Expanded (HFMSE) score, and / or the Revised Hammersmith Scale (RHS) score.

[0074] In other embodiments, a baseline RULM, RHS, or HFMSE score is measured in a patient (e.g., a patient with late-onset SMA, such as a patient with nonambulatory SMA (e.g., type 2 or nonambulatory type 3 SMA)) who is being treated with apivolumab (e.g., apivolumab as an adjunct to background therapy for SMN therapy). In some embodiments, the baseline score is measured at or before the start of treatment with apivolumab (i.e., apivolumab therapy). In some embodiments, the patient is receiving SMN therapy at the time of the baseline measurement. In some embodiments, the patient has been receiving SMN therapy for at least six months prior to the baseline measurement. In some embodiments, the patient has been receiving SMN therapy for at least two years at the time of initiation of apivolumab therapy, at which time the baseline measurement is performed. In some embodiments, therefore, the baseline score used to assess the therapeutic effect of apivolumab therapy is higher than the therapeutic effect of background therapy (if any). In some embodiments, the patient responds to background therapy alone based on an increase in motor function score, e.g., 1-7 points, measured relative to pre-treatment, demonstrating the therapeutic ability of apivolumab to improve the effect of background therapy alone.

[0075] The RHS (Ramsey et al. (2022) PLOS ONE https: / / doi.org / 10.1371 / journal.pone.0278996) and HFMSE (Main et al. (2003). Eur J Paediatr Neurol. 7(4):155-9) have been validated for assessing physical performance in patients with SMA types 2 and 3. The RULM has also been used to study upper limb function in ambulatory and nonambulatory patients with SMA (Mazzone et al. (2017) Muscle Nerve. 55(6):869-874).

[0076] In some embodiments, the HFMSE is used to assess physical fitness in patients with type 2 and type 3 SMA (O'Hagen et al. (2007) Neuromuscul Disord. 17(9-10):693-697; Glanzman et al. (2011) J Child Neurol. 26(12):1499-1507). In some embodiments, the HFMSE is used to assess patients with non-ambulatory SMA. The HFMSE consists of 33 items that assess an individual's ability to perform various activities. The quality and execution of each action for the parameters listed above are graded on a scale of 0, 1, and 2, where 0 indicates inability to perform, 1 indicates modification or adaptation, and 2 indicates no modification or adaptation. The maximum achievable score is 66.

[0077] In other embodiments, a baseline Hammersmith Infant Neurological Exam (HINE) score is measured in patients to be treated with apivolumab (e.g., apivolumab as an adjunct to background therapy for SMN therapy). The HINE assesses seven different areas of motor milestone development, such as kicking, head control, rolling, sitting, crawling, standing, or walking, with a maximum score of 2-4 points for each motor development milestone (Day et al. (2022) BMC Pediatrics [BMC Pediatrics] 22:632). The HINE can be used as a whole or the HINE-2 (developmental module) can be used independently to assess motor milestones during development. In other embodiments, a Hammersmith Neonatal Neurological Examination (HNNE) is measured in infant patients to be treated with apivolumab (e.g., apivolumab as an adjunct to background therapy for SMN therapy). The HNNE assesses 34 items divided into categories such as posture and tone, tone pattern, reflexes, movements, abnormal signs / patterns, and direction / behavior (Pane et al. (2022) Eur. J Pediatr 181:2821-29).

[0078] The RULM is based on 19 scorable items reflecting different areas of function and is graded on a 3-point system—0 (cannot), 1 (can, with revision), and a maximum of 2 (can, without difficulty), with one additional item scored as can / cannot (1 being the highest score). The maximum total RULM score is 37 (Mazzone et al. (2017) Muscle Nerve. 55(6):869-874).

[0079] The RHS is a clinician-rated SMA-specific outcome measure that contains 36 items that assess physical motor performance. The motor functions assessed include the ability to sit, lie on one's back, roll over, lie prone, move and rise from the floor, balance, stand, run / walk, climb stairs, ascend and descend steps, and jump. Thirty-three items are rated on an ordinal 0, 1, 2 scale, where 0 represents the lowest physical ability or function achieved and 2 represents the highest physical ability or function achieved. Three items are rated 0 and 1, where 0 represents the inability to complete the item and 1 represents the achievement of the item. The scale includes two timed tests, and the WHO motor milestones can also be completed in parallel. Ramsey et al. (2022) PLOS ONE [Public Library of Science: One] https: / / doi.org / 10.1371 / journal.pone.0278996).

[0080] Cohort: As used herein, the term "cohort" or "cohort population" refers to a group or population of human subjects that share common factors or influences, such as age, SMA disease severity (e.g., Type 2 and / or Type 3 SMA), concurrent treatment (e.g., SMN therapy), etc. In some embodiments, as used herein, a "cohort" refers to a group of human subjects that have the same age, SMA disease severity, and / or concurrent treatment.

[0081] Control: As used herein, the term "control" or "control sample" refers to any clinically or scientifically relevant comparison sample, population, or counterpart, including, for example, a sample from a healthy subject, a sample from a subject with a defect that may cause or predispose the subject to a disease or condition, a subject with a disease or condition of interest, a sample from a subject treated with a placebo, a sample from a subject before treatment, a sham-treated or buffer-treated subject or sample, an untreated subject or sample, etc.

[0082] Inhibit: As used herein, the term "inhibit" or "inhibition of" means a reduction by a measurable amount, and may include but does not require complete prevention or inhibition.

[0083] Effective amount: The terms "effective amount" and "therapeutically effective amount" refer to the ability or amount to achieve one or more of its intended purposes, i.e., to achieve a desired biological or drug response in a subject, and / or to achieve a statistically significant clinical benefit (e.g., efficacy) in a patient population. An "effective amount" may refer to a therapeutically effective amount or therapeutic dose, which is a dose or dosing regimen that is sufficient to produce a detectable change in a parameter of a disease, e.g., to slow, halt, reverse, attenuate, or alleviate a parameter, symptom, or downstream effect of a disease. The term encompasses, but does not require, an amount that completely cures the disease. As described herein, the dose of the anti-promyostatin / latent myostatin antibody referred to herein (e.g., a dose of apivolumab) may be a therapeutically effective dose. In some embodiments, efficacy may be measured by well-known motor function assessments and / or by one or more surrogate biomarkers (e.g., serum concentrations of latent TGFβ and / or serum concentrations of creatinine). For example, in certain embodiments of the present disclosure, the intended purpose may be to inhibit the activation of myostatin in vivo to achieve clinically meaningful results associated with myostatin inhibition.

[0084] The relevant intended measurement of interest can be objective (i.e., measurable by some assay or marker) or subjective (i.e., the subject gives an indication of an effect or feels an effect). In some embodiments, a therapeutically effective amount is an amount that, when administered to a patient population meeting specific clinical criteria for SMA (e.g., as determined by symptom presentation, disease progression / stage, genetic characteristics, etc.), achieves a statistically significant therapeutic response in the population.

[0085] An effective amount may also refer to an amount that, when administered according to a particular regimen, produces a positive clinical outcome with a reasonably acceptable level of adverse effects (e.g., toxicity), such that the adverse effects, if any, are sufficiently tolerated by the patient to continue the treatment regimen and the benefits of the therapy outweigh the risks of toxicity. One of ordinary skill in the art will appreciate that in some embodiments of the present disclosure, a dose may be considered to contain an effective amount if it contains an amount suitable for administration in the context of a dosage regimen associated with a positive outcome.

[0086] Latent myostatin: As used herein, the term "latent myostatin" refers to an inactive precursor of mature myostatin, the precursor comprising a disulfide-linked homodimer, each molecule of which comprises an amino-terminal prodomain non-covalently bound to a carboxyl-terminal mature myostatin domain. In some embodiments, "latent myostatin" is produced by promyostatin that has been cleaved by a proprotein convertase but not by a protease from the BMP / tolloid family. In some embodiments, "latent myostatin" can be produced by combining the prodomain and the carboxyl-terminal mature myostatin domain in vitro and allowing them to fold correctly. See, e.g., Sengle et al. (2011) J. Biol. Chem., 286(7): 5087-5099.

[0087] Late-onset SMA: As used herein, unless otherwise specifically defined, the term "late-onset SMA" refers to patients who do not show the onset of SMA symptoms until after six months of age, regardless of genotype, whether or when SMN therapy is administered (e.g., no symptoms were detected at a 6-month medical screening). Late-onset SMA patients may also be patients characterized as having type 2, type 3, or type 4 SMA based on traditional disease classifications known in the art. Patients with late-onset SMA typically have at least two copies of the SMN2 gene (e.g., 2 copies, 3 copies, 4 copies, or more, e.g., 2-4 copies). In some embodiments, patients with late-onset SMA receive or have received motor neuron-directed therapy (e.g., such therapy has been received before the age of five), such as SMN-targeted therapy (e.g., SMN upregulators). In contrast to late-onset SMA, "early-onset SMA" or "infantile-onset SMA" refers to SMA that develops symptoms at or before the age of six months (including patients who may also be classified as type 1 SMA using traditional classifications known in the art). In contrast, patients with early or infantile-onset SMA typically have one or two copies of the SMN2 gene. In some embodiments, the patient has late-onset SMA due to having received early intervention (e.g., one or more SMN therapies), where the patient would be considered early-onset if he or she had not received such early intervention.

[0088] In some embodiments, a patient with late-onset SMA has 2-4 copies of the SMN2 gene. In some embodiments, a patient with late-onset SMA has 1-2 copies of the SMN2 gene. In some embodiments, patients with late-onset SMA who develop late-onset SMA as a result of early therapeutic intervention (i.e., patients who would otherwise develop symptoms before the age of six months) may also be referred to as "newly emerging" or "treatment-emerging" late-onset SMA patients or patient populations. In some embodiments, a patient with late-onset SMA who emerges during treatment may have a different genotype (e.g., 1-2 copies of the SMN2 gene), phenotype (e.g., gait), and / or disease course and response to myostatin treatment than a patient with SMA who does not emerge during treatment. In some embodiments, a patient with late-onset SMA would not be able to walk and / or sit independently without treatment (e.g., an SMN-targeted therapy) (e.g., may already have Type 1 and / or non-ambulatory Type 2 SMA), but is able to do so as a result of treatment. In some embodiments, patients with late-onset SMA who are already unable to walk Type 3 SMA who appear during the treatment period would have lost the ability to walk at 18 months of age if they had not been treated (e.g., SMN targeted therapy), but due to treatment, they retained the ability to walk at 18 months of age. When considering the treatment of patients with ambulatory Type 3 SMA, in some embodiments, any ambulatory patient is treated. In some embodiments, Type 3 patients are patients who can retain the ability to walk at 18 months of age without intervention. In some embodiments, Type 3 patients are patients who may lose the ability to walk without intervention. In some embodiments, patients are identified by neonatal screening or in utero and treatment (e.g., SMN directed therapy) is started before the onset of the disease. In some embodiments, due to early treatment initiation after neonatal screening, no onset of SMA symptoms is observed. In some embodiments, the patient receiving treatment suffers from Type 4 SMA (e.g., patients with 4 or more copies of the SMN2 gene and later onset of symptoms (e.g., at 18 years of age or later)).

[0089] Mature myostatin: As used herein, the term "mature myostatin" refers to the mature, biologically active form of myostatin. In some embodiments, mature myostatin is capable of binding to and / or activating a myostatin receptor. The activation and release of mature myostatin from its promyostatin form in vivo is accomplished through several discrete protease cleavage events. First, "promyostatin" is cleaved by a proprotein convertase, generating a "latent myostatin," in which the mature myostatin is shielded from binding to its receptor by a portion of the prodomain. Activation and release of mature myostatin is accomplished after the latent myostatin is cleaved by another protease from the BMP / tolloid family, such as mTLL-2. As used herein, the term "mature myostatin" can refer to both full-length mature myostatin and fragments of full-length mature myostatin that retain biological activity. So-called neutralizing antibodies bind to mature myostatin, thereby interfering with its ability to bind to and activate its cellular receptor.

[0090] Motor neuron therapy. "Motor neuron therapy" refers to any therapy that can partially or fully restore motor neuron function. Examples include, but are not limited to, agents that affect neurotransmitter signaling, agents that reduce oxidative stress in neurons, and neuroprotective stem cell therapy. Motor neuron therapy includes SMN therapy.

[0091] Motor skills: As used herein, "motor skills," "motor skills," or "motor function" refers to a subject's ability to perform one or more tasks designed to measure muscle function. Motor skills can be measured by tests designed to assess certain physical activities, which produce a score that indicates the patient's level of muscle function. For example, a subject's motor skills can be assessed using the Hammersmith Functional Motor Scale Extended (HFMSE) test; the Revised Upper Limb Module (RULM) test; the Revised Hammersmith Scale (RHS) test; the Motor Function Measure (MFM) test (e.g., MFM-D1, MFM-D2, MFM-32); the WHO Motor Development Milestones; or any other known muscle function test.

[0092] Muscle-directed therapy: As used herein, the term "muscle-directed therapy" or "muscle-targeted therapy" refers to any therapy that restores muscle function. Examples of muscle-targeted therapies include myostatin inhibitors.

[0093] Pro / latent myostatin: As used herein, the term "pro / latent myostatin" refers to promyostatin, latent myostatin, or both. In some embodiments, an anti-promyostatin / latent myostatin antibody specifically binds to promyostatin. In some embodiments, an anti-promyostatin / latent myostatin antibody specifically binds to latent myostatin. In some embodiments, an anti-promyostatin / latent myostatin antibody specifically binds to both latent myostatin and promyostatin. In some embodiments, the anti-promyostatin / latent myostatin antibody is apilectomycin and specifically binds to both latent myostatin and promyostatin. The term "promyostatin" (or "promyostatin") refers to an inactive precursor of mature myostatin, which comprises a disulfide-linked homodimer, each molecule of which comprises an amino-terminal prodomain covalently bound to a carboxyl-terminal mature myostatin domain. In some embodiments, "promyostatin" is not cleaved by proprotein convertases or proteases from the BMP / tolloid family. Promyostatin and latent myostatin (see below) are proforms of myostatin / GDF-8. As used herein, the term "promyostatin" refers to an inactive (e.g., precursor or latent) form of the myostatin growth factor associated with the N-terminal latency-associated peptide (LAP) domain. The proform of myostatin consists of a dimer. The term encompasses both "promyostatin" and "latent myostatin." The term excludes mature growth factors (GDF8) that are not associated with the LAP domain.

[0094] Natural history: The natural history of SMA refers to how SMA progresses over time in a person without treatment.

[0095] Progression: The progression of a disease (e.g., SMA) is the process of worsening symptoms or worsening of a condition over a period of time. In the absence of pharmacological intervention (e.g., therapy), progression reflects or corresponds to the natural history of the disease observed in a particular patient population. Disease progression can be assessed by the rate at which the condition worsens and / or the extent to which the condition worsens. Thus, efficacy can include the ability of a drug or therapy to delay or slow the progression of a disease. For example, a patient's motor function scores may decline over time, but at a slower rate than expected based on the natural history of the disease. Efficacy can include the ability of a drug or therapy to reduce the extent of the decline. Efficacy can include stabilization of the disease, i.e., at least a net zero change in one or more functional parameters over time.

[0096] Quality of Life (QoL): As used herein, QoL is defined by outcomes that are meaningful from the patient's perspective and that measure the impact of therapy on dimensions of life, rather than assessing significant changes in survival or motor milestones, such as activities of daily living, work productivity, and fatigue.

[0097] SMN therapy / SMN targeted therapy: In the context of this disclosure, the terms "SMN therapy" or "SMN targeted therapy" or "SMN-directed therapy" (used interchangeably herein) refer to pharmacological agents (drugs, biologics) intended to increase the amount or availability of functional SMN protein in a patient to treat SMA.

[0098] As used herein, other synonymous terms include "SMN upregulator" or "SMN upregulator therapy" or "SMN directed therapy" or "SMN corrector" or "SMN corrector therapy" or "SMN enhancing therapy" or "SMN enhancer". These agents encompass any therapy or compound that can be used to increase or improve SMN gene expression (e.g., SMN1 gene expression and / or SMN2 gene expression), SMN protein production, and / or functional SMN activity. For example, SMN1 directed therapy can include gene therapy aimed at supplementing or replacing a deleted or mutated SMN1 gene. SMN2 directed therapy can include splicing modifiers that target one or more exons of the SMN2 backup gene to increase the availability of at least partially functional SMN protein in the body. Non-limiting examples of SMN therapies include nusindrone, sovaprevir, and risperidone. SMN upregulators can be central correctors or systemic correctors. Central upregulators can be administered directly to the central nervous system (CNS) via an intrathecal route. In contrast, systemic upregulators can be administered via any route, such as oral administration, and affect not only the CNS, but also other tissues throughout the body. Systemically delivered SMN splicing modifiers may also affect SMN splicing in other (i.e., non-neuronal) tissues expressing SMN. In some embodiments, a "functional SMN protein" is capable of promoting motor neuron function and / or survival, or partially or completely restoring motor neuron function in a cell (e.g., a cell within a subject). In some embodiments, a functional SMN protein is capable of restoring at least 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99%, or more motor neuron function in a cell (e.g., a cell within a subject). In some embodiments, a full-length SMN protein is the result of protein translation (e.g., in a cell) of a correctly spliced ​​SMN mRNA. In some embodiments, a functional SMN protein is encoded by an SMN2 mRNA containing exon 7.

[0099] Specific binding: As used herein, the term "specific binding" or "specifically binds" means that an antibody or antigen-binding portion thereof exhibits a specific affinity (e.g., by binding to a specific structure (e.g., antigenic determinant or epitope) in an antigen. In some embodiments, if the antibody has a KD of at least about 10 -8 M, 10 -9 M, 10 -10 M, 10 -11 M, 10 -12 M, or a target KD of less than 1.0x10 M, then the antibody or its antigen-binding portion specifically binds to the target (e.g., pro / latent myostatin). In the context of this disclosure, an "antibody that specifically binds to an antigen with high affinity" generally refers to an antibody with a KD of 1.0x10 -8 In some embodiments, an antibody, or antigen-binding portion thereof, may also "selectively" (i.e., "preferentially") bind to a target antigen if it binds to that target relatively more strongly than to other antigens, for example, with a 10-fold, 100-fold, 1000-fold, or greater affinity for the target antigen (e.g., pro / latent myostatin) as compared to a non-target antigen (e.g., mature myostatin (GDF-8), GDF-11, and / or other members of the TGFβ superfamily of growth factors).

[0100] Steady state: As used herein, the term "steady state" refers to a state in which the overall uptake and elimination of a molecule (e.g., apivolumab) are in dynamic equilibrium. In some embodiments, the steady-state serum concentration of apivolumab is measured, for example, as the maximum serum concentration of apivolumab (i.e., C ) following administration to a human subject or cohort of human subjects. max ) or minimum (trough) serum concentration (i.e., C min or C 波谷 ). For example, the maximum serum concentration of apivolumab or the minimum serum concentration of apivolumab can be used in a pharmacokinetic (PK) analysis to determine the steady state of apivolumab. In some embodiments, the pharmacodynamic (PD) target is latent myostatin. In some embodiments, the PD profile of apivolumab is assessed by measuring the serum latent myostatin concentration. In some embodiments, the serum latent myostatin concentration is the steady state concentration. In some embodiments, the serum latent myostatin concentration is measured, for example, as a pre-dose concentration or trough concentration (i.e., C min or C 波谷 ).

[0101] Subject: In the context of clinical applications, the term "subject" refers to an individual receiving or requiring clinical care or intervention (e.g., treatment, diagnosis, etc.). Suitable subjects include vertebrates, including but not limited to mammals (e.g., humans and non-human mammals). Where the subject is a human subject, the term "patient" is used interchangeably. In a clinical setting, the terms "patient population" or "patient subpopulation" are used to refer to a group of individuals that meet a set of criteria (e.g., clinical criteria, medical history, health status, gender, age group, genetic criteria, and / or lifestyle factors). As used herein, unless the context indicates otherwise, a human subject, patient, or patient population refers to an SMA patient or patient population.

[0102] Target engagement: As used herein, the term "target engagement" refers to the ability of a molecule (e.g., apilectomycin) to bind to its intended target (e.g., latent myostatin) in vivo (e.g., in skeletal muscle). As used herein, saturation of target engagement indicates a dose sufficient to achieve some therapeutic effect (e.g., efficacy), although efficacy may be achieved without saturation.

[0103] Therapeutic dose: The term "therapeutic dose" refers to an amount (e.g., an amount of apivolumab) that, when administered to a patient in a specific manner (e.g., using a specific dosing regimen), is sufficient to achieve efficacy as determined by a clinical endpoint measuring therapeutic effect (e.g., as measured by one or more clinical endpoints discussed herein). For example, when administered intravenously every four weeks, the therapeutic dose of apivolumab can be greater than 2 mg / kg and up to 20 mg / kg. In certain embodiments, when administered intravenously every four weeks, the therapeutic dose of apivolumab is 10 mg / kg or 20 mg / kg.

[0104]

[00136] Treat: As used herein, the term "treating" or "treatment" of a disease or disorder (e.g., SMA) means, for example, slowing, delaying, or preventing the onset of such disease or disorder, or reversing, alleviating, ameliorating, inhibiting, slowing, stabilizing, or halting progression, exacerbating, or worsening the progression or severity of a condition associated with such disease or disorder (e.g., where treatment is observed to arrest disease progression in the absence of treatment), as compared to a baseline in the absence of treatment. The term includes, but does not necessarily require, complete treatment or prevention of a disease or disorder. As used herein, "treating" or "treatment" refers to administering one or more active agents (simultaneously or sequentially), or one or more compositions comprising one or more active agents, to a subject, e.g., with SMA, with the purpose of curing, rehabilitating, alleviating, alleviating, altering, remedying, improving, ameliorging, or affecting a disorder, a symptom of a disease, or a susceptibility to a disease, such as SMA.

[0105] Treatment-emerging patient populations: Traditional classifications of SMA patient populations or types (e.g., type 0, type 1, type 2, non-ambulatory type 3, ambulatory type 3, type 4, etc.) are largely based on the natural history of disease manifestations, which show a strong correlation with the number of SMN2 gene copies. Based on the traditional classification, type 0 is the most severe form, which develops in utero with reduced or absent movements and requires mechanical ventilation at birth. With the advent of approved SMN-targeted therapies (e.g., SMN2 upregulators, SMN1 gene therapy, etc.) and newborn screening in recent years, additional classifications may be needed to describe emerging patient populations (referred to herein as "emerging" or "treatment-emerging" patient populations). In these populations, the manifestations of SMA expected based on natural history and / or genetic analysis may change when patients start SMN-targeted therapy early. In other words, regardless of the disease genotype, early intervention can affect the course of disease progression expected from natural history. For example, infants with confirmed SMN1 deletion and one copy of the SMN2 gene may be able to sit independently at 12 months of age if they receive early SMN therapy, otherwise they will develop type 1 SMA. SMA patients with two copies of the SMN2 gene may develop severe (e.g., type 2) disease without SMN-targeted therapy, but if they receive SMN-targeted therapy, especially early intervention, the clinical manifestations of such patients may be similar to those of mild disease. As a result of such therapy, patients with non-ambulatory type 3 SMA (who have lost the ability to walk) may regain the ability to walk, or patients with type 2 SMA may walk for the first time. Similarly, due to early SMN-targeted therapy, patients who are expected to develop non-ambulatory type 3 SMA after 18 months of age may show the ability to maintain walking at a later age, but show a different phenotype (e.g., gait) and / or response to SMA treatment. (Mercuri et al. (2020) Nature Reviews Neurology, 16:706-715). The field continues to evolve to accommodate changes associated with medical advances in SMA therapies, including adjustments to certain nomenclature / terms intended to better describe the various diseases.

[0106] Type 1 SMA: Children with type 1 SMA typically decline rapidly during the natural history of the disease (Cances et al. (2022) Orphanet J Rare Dis 17:300). Early symptoms include hypotonia, small or weak muscles, difficulty breathing, difficulty swallowing, a weak cough or cry, and inability to sit. Infants with type 1 are very weak and unable to sit. By 5-6 months of age, patients often require respiratory and / or nutritional support. More than 90% of patients die before their second birthday. These patients typically have one or two copies of the SMN2 gene.

[0107] Type 2 SMA: Children with type 2 SMA are nonambulatory without therapeutic intervention and typically have three copies of the SMN2 gene. Symptoms develop between 6 and 18 months of age. Muscle weakness is common, affecting patients' ability to stand or walk without assistance, and they often require a wheelchair. Generally, they begin to lose abilities before the age of two. However, they can sit independently, maintain head control, and roll over.

[0108] Type 3 SMA: In patients with Type 3 SMA, symptoms may begin after 18 months of age, usually in early childhood, based on clinical classification and / or physical milestones (such as sitting or walking). These patients typically have three or four or more copies of the SMN2 gene and are nonambulatory. The more severe form of Type 3 SMA is often associated with three copies of the SMN2 gene (Type 3a), while the less severe form of Type 3 SMA is often associated with four copies (Type 3b). Typically, patients with Type 3 SMA can initially at least walk and climb with assistance, eat with utensils, and dress themselves, but they are usually unable to run, jump, or climb without assistance. As they age, they lose many motor functions, including the ability to walk and climb. Among Type 3 patients, those who are able to walk are called ambulatory Type 3 SMA, while those who lose the ability to walk are called nonambulatory Type 3 SMA. Type 3 patients typically lose the ability to walk between the ages of 4 and 16 years (e.g., around 10 years on average).

[0109] Type 4 SMA: Type 4 SMA is a rare, adult-onset form of SMA. These patients typically have four or more copies of the SMN2 gene and typically experience only mild muscle weakness, which may begin around age 18 but more often develops in older adults (for example, in their 20s or 30s).

[0110] As more patients receive treatment, such as SMA therapy, patients diagnosed with SMA type 1, 2, 3, or 4 may demonstrate clinical improvement, bringing their phenotype closer to another SMA type. For example, in the absence of treatment, a patient classified as a type 1 SMA patient may display characteristics of a type 2 patient and therefore be "type 2-like"; a type 2 patient may exhibit characteristics of a type 3 patient and therefore be "type 3-like"; and a type 3 patient may exhibit characteristics of a type 4 patient and therefore be "type 4-like." As used herein, the terms "type 1-like," "type 2-like," "type 3-like," and "type 4-like" with respect to SMA classification refer to clinical observations, measurements, or behaviors of a patient in the absence of intervention, regardless of genotype or natural history.

[0111] Wearable medical device: A wearable medical device is an autonomous, non-invasive device that performs a specific medical function (e.g., monitoring or support) and is attached to the body or clothing. Examples include, but are not limited to, wearable sensor devices, electromyography patches, etc. and AUTOMA, a wearable device that measures upper limb muscle activity.

[0112] Except in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein are to be understood as modified in all instances by the term “about.” When used in conjunction with percentages, the term “about” can mean ±1%.

[0113] Unless clearly indicated otherwise, the indefinite articles "a" and "an" as used herein should be understood to mean "at least one."

[0114] As used in the specification and in the claims, the phrase "and / or" as used herein should be understood to mean "any one or both" of the elements so conjoined, i.e., the elements are present conjointly in some cases and separately in other cases. In addition to the elements specifically identified by the "and / or" phrase, other elements may optionally be present, whether related or unrelated to those elements specifically identified, unless clearly indicated to the contrary. Thus, as a non-limiting example, when used in conjunction with open-ended language such as "comprising," a reference to "A and / or B" may, in some embodiments, refer to A without B (optionally including elements in addition to B); in other embodiments, to B without A (optionally including elements in addition to A); in other embodiments, to both A and B (optionally including other elements); etc.

[0115] As used herein, the phrase "at least one" in connection with a list of one or more elements should be understood to mean at least one element selected from any one or more elements in the list of elements, but not necessarily including at least one of each element specifically listed in the list of elements, and not excluding any combination of multiple elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified in the list of elements to which the phrase "at least one" refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or equivalently, “at least one of A or B,” or equivalently, “at least one of A and / or B”) may in some embodiments refer to at least one, optionally including more than one A, without B (and optionally including elements other than B); in other embodiments, may refer to at least one, optionally including more than one B, without A (and optionally including elements other than A); in other embodiments, may refer to at least one A, optionally including more than one A, and at least one B, optionally including more than one B (and optionally including other elements); etc.

[0116] The use of ordinal numbers such as "first", "second", "third", etc. in the claims to modify claim elements does not in itself imply any priority, precedence or order of one claim element over another, nor does it imply a temporal order in which method actions are performed. Instead, it serves only as a label to distinguish one claim element with a certain name from another element with the same name (but using an ordinal number) to distinguish these claim elements.

[0117] Ranges provided herein are understood to be shorthand for all values ​​within the range. For example, a range of 1 to 10 is understood to include any one number, combination of numbers, or sub-range of the following group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, e.g., 2-8, 1-5, etc.

[0118] All references cited herein are incorporated by reference for all purposes. In the event of a conflict between a reference and the specification, the specification shall prevail. It should be understood that certain features of the disclosed compositions and methods described herein in the context of individual embodiments for the purpose of clarity may also be provided in combination in a single embodiment. Conversely, different features of the disclosed compositions and methods described in the context of a single embodiment for the purpose of brevity may also be provided separately or in any sub-combination. Spinal muscular atrophy (SMA)

[0119] Spinal muscular atrophy (SMA) is a debilitating, often fatal neuromuscular disease and is the most common genetic cause of infantile death (Awano et al. (2014) Neurotherapeutics 11:786-795). SMA is an autosomal recessive genetic disorder that involves a mutation or deletion in the survival motor neuron 1 (SMN1) gene. Specifically, SMA is caused by a decrease in SMN protein levels, a sufficient amount of which is necessary to promote the survival of anterior horn cells in the spinal cord. The loss of motor neurons leads to severe muscle atrophy, often leading to death due to respiratory insufficiency (Monani (2005) Neuron 48:885-896). The muscle pathology in SMA is characterized by the presence of small atrophic fibers that are thought to represent denervated or partially denervated muscle fibers. The presence of atrophic fibers is a typical manifestation of motor neuron denervation caused by motor neuron loss or dysfunction. Unlike patients with Duchenne muscular dystrophy (DMD), SMA patients do not exhibit the characteristic necrotic and inflammatory changes even in the most severe stages of the disease (Le Verche V. et al. Spinal Muscular Atrophy; Disease Mechanisms and Therapy, 2011). y Disease Mechanisms and Treatment 2017; Chapter 21: 341-356).

[0120] While SMA patients typically lack a functional SMN1 gene, the paralogous gene SMN2 produces low levels of functional SMN protein due to alternative splicing of truncated transcripts. Advances in molecular medicine technologies have facilitated the diagnosis of SMA patients based on SMN1 and SMN2 copy number genotyping. SMA patients are also diagnosed based on clinical presentation and phenotypically classified based on maximum motor milestones achieved and age of symptom onset. Disease-modifying drugs have changed some of the traditional diagnoses and classifications. In some embodiments, classification can be based on one or more of the age at initiation of treatment, age at onset of symptoms, and / or number of SMN2 copies, for example, to refine the definition of the SMA phenotype alone or in the clinic, rather than the traditional classification defined solely by age of onset and severity ( M. et al. Degener Neurol Neuromuscul Dis. [Degenerative Nervous System Disorders] 2020;10:39-47).

[0121] In some embodiments, patients with late-onset SMA receive or have received motor neuron-directed therapy (e.g., received such therapy before the age of 5 years), such as SMN therapy. In some embodiments, patients with late-onset SMA have at least two copies of the SMN2 gene (e.g., at least three copies or at least four copies of SMN2). In some embodiments, patients with late-onset SMA develop diagnosable symptoms of SMA after six months of age. Subjects with SMA can be treated before symptoms of the disease appear or after diagnosable symptoms appear.

[0122] In some embodiments, patients with infantile-onset SMA are treated with or have received motor neuron-directed therapy (e.g., SMN therapy). In some embodiments, patients with infantile-onset SMA have one copy of SMN2. In some embodiments, patients with infantile-onset SMA develop diagnosable symptoms of SMA before six months of age. In some embodiments, patients with infantile-onset SMA would have developed diagnosable symptoms before six months of age but did not develop them due to treatment, such as SMN therapy. In some embodiments, these subjects are diagnosed with infantile-onset SMA based on, for example, SMN2 copy number, and are distinguished from patients with late-onset SMA based on factors other than age of disease onset (e.g., genotype (e.g., SMN2 copy number), phenotype (e.g., gait or other observed motor characteristics), and / or response to SMA therapy. Genotype-based SMA classification

[0124] The clinical heterogeneity of SMA is due in part to the complex genetics of the disease. Mutations in the SMN1 gene cause SMA (Lefebvre et al. (1995) Cell 80:155-165); however, in humans, a nearly identical gene, SMN2, is located very close to SMN1 (Monani et al. (1999) Hum Mol Genet 8:1177-1183). The major difference between these genes is a C-to-T transition that creates an exonic splicing silencer, resulting in the removal of exon 7 from the final mRNA transcript. Truncated SMN proteins are unstable and rapidly degraded. However, approximately 10% of the mRNA produced from SMN2 is correctly spliced ​​to produce full-length SMN protein, but this amount is insufficient to fully compensate for the loss of SMN1.

[0125] The number of SMN2 copies varies between individuals and is closely associated with SMA disease severity. More copies (e.g., three or four copies) are generally associated with milder forms of SMA. SMA patients with a single SMN2 copy are rare, but this copy number is highly predictive of the severe type 1 phenotype, which has a poor prognosis. Most patients with the type 1 form of SMA have one or two copies of SMN2; most patients with type 2 have three SMN2 copies; and most patients with type 3 have three or four SMN2 copies. To illustrate this, according to Calucho et al. ((2018) Neuromuscular Disorders. [Neuromuscular Disorders] 28:208-215 in Table 2), approximately 80% of type 1 SMA patients carry one or two SMN2 copies, approximately 94% of type 2 patients carry two or three copies, approximately 93% of type 3 patients carry three or four copies, and nearly 100% of type 4 patients carry four to six SMN2 copies.

[0126] Traditional SMA classifications include Type 1, Type 2, Type 3, and sometimes Type 4 SMA (in order of severity). Type 1 SMA is typically diagnosed between birth and six months of age, and without early intervention, patients never gain enough strength to sit independently. Without intervention, most Type 1 patients do not survive more than two years without respiratory support. People with Types 2 and 3 produce more SMN protein and have less severe, but still life-altering, forms of SMA. Type 2 patients are generally diagnosed between six and 18 months of age. While they are able to sit unassisted, they are unable to walk unassisted. With Type 3 SMA, patients are typically diagnosed after 18 months of age and are able to sit and walk unassisted, although they may become wheelchair-dependent later in life. Thus, Type 3 SMA includes both ambulatory and nonambulatory subgroups. As the disease progresses, many ambulatory Type 3 SMA patients will at some point become nonambulatory. Type 4 SMA is an adult-onset form with a milder phenotype and is very rare.

[0127] While stratifying SMA by type is a useful clinical paradigm, the disease phenotype exists more as a continuum than as discrete categories. For example, patients with SMA gene mutations may be presymptomatic (not showing overt disease phenotypes).

[0128] In some cases, patients with genetic mutations in SMN genes (such as SMN1) may be phenotypically presymptomatic and identified as requiring treatment based on genetic screening. In some embodiments, the delay in disease manifestation may be due, at least in part, to early intervention, such as SMN upregulator therapy (e.g., SMN2 upregulator therapy and SMN1 gene therapy). Early intervention typically refers to starting treatment before the age of five, for example, before the age of four, three, two, one, or shortly after birth. In recent years, newborn genetic screening has become increasingly common, making it possible to identify individuals born with genetic disorders such as SMA. For example, in the United States, many states have included SMA in routine newborn screening panels for other known genetic disorders, with screening typically performed in the first few days of life. As a result, infants with mutations in the SMN gene (SMN1) who may develop the disease can be identified early, often when they are asymptomatic (presymptomatic). Early detection and diagnosis can lead to early therapeutic intervention, for example, even before a child begins to show symptoms. This may help prevent certain clinical manifestations and / or potentially delay the onset or progression of SMA.

[0129] Genetic screening can be performed in newborn / infant subjects, as well as in utero (e.g., in a fetus). In some embodiments, the subject is or has been determined to be a carrier of an SMN mutation, e.g., by in utero or newborn / infant genetic screening. In some embodiments, genetic screening is performed in newborns / infants (e.g., within 24 hours of birth). In other embodiments, genetic screening is performed in utero. SMA classification based on onset

[0130] Severe forms of SMA often show symptoms early, such as before six months of age. This may be called infantile-onset, in contrast to late-onset SMA. When SMA symptoms appear at birth or by six months of age, the disease is also SMA type 1 (also called infantile-onset or Werdnig-Hoffmann disease). Infants typically have generalized muscle weakness, a weak cry, and difficulty breathing.

[0131] More recently, with the advent of approved SMN upregulator therapies (such as nusinsen, risperidone, and / or sovaprevir), early intervention has been shown to be particularly effective in delaying the onset and / or reducing the severity of more severe SMA phenotypes based on a specific patient's genotype. For example, some patients diagnosed with type 1 SMA (or at risk for type 1 SMA due to a low copy number of the SMN2 gene) may have their phenotype altered by early intervention with an SMN upregulator to be more consistent with later-onset SMA.

[0132] In some embodiments, definitions based on symptom onset can be used to categorize certain patient populations for early intervention that alters the normal course or timeline of disease progression. Targeting myostatin to improve muscle function - myostatin inhibition

[0133] In some embodiments, the present disclosure encompasses the use of agents that inhibit myostatin activation, regardless of their mechanism of action. In some embodiments, the inhibitor is a small molecule. In some embodiments, the inhibitor is an antibody or antigen-binding fragment (e.g., an adnectin such as taldefgrobep alfa). In some embodiments, the antibody is a myostatin-selective antibody, e.g., a pro / latent myostatin-selective antibody.

[0134] In some embodiments, disclosed herein are antibodies capable of binding to promyostatin and / or latent myostatin, thereby inhibiting myostatin activity, and their use in treating diseases and disorders associated with muscle atrophy, such as SMA.

[0135] In some embodiments, the present disclosure provides methods comprising the use of apilectumab or an antibody having a CDR sequence, variable domain sequence, or full-length antibody sequence provided in Tables 1-10 below. Table 1. Amino acid sequences of Kabat CDRs of anti-promyostatin / latent myostatin antibodies Table 2. Amino acid sequences of IMGT CDRs of anti-pro-myostatin / latent-myostatin antibodies Table 3. Amino acid sequences of the variable regions of anti-promyostatin / latent myostatin antibodies Table 4. Amino acid sequences of full-length Ig chains of anti-promyostatin / latent myostatin antibodies

[0136] Apitalomab's inhibition of myostatin activation may result in the accumulation of pro-myostatin and latent myostatin. Since pro-myostatin is primarily present in skeletal muscle, and latent myostatin is primarily present in serum, in some embodiments, serum latent myostatin levels can be used as a target engagement marker for Apitalomab, such as engagement of the target with Apitalomab in skeletal muscle. In some embodiments, serum latent myostatin levels and / or serum creatinine levels may be relatively low at baseline (i.e., before treatment) and may increase after treatment with Apitalomab. In some embodiments, an increase in serum latent myostatin and / or serum creatinine levels indicates engagement of the target with Apitalomab, for example, in skeletal muscle. In some embodiments, low baseline serum levels of latent myostatin and / or serum creatinine, compared to high levels after treatment, indicate that the major portion of the drug target is located within skeletal muscle, rather than in the systemic circulation. In a similar manner, in some embodiments, serum latent myostatin levels can serve as a target engagement marker for other promyostatin / latent myostatin antibodies (e.g., GYM329, or an antibody or antigen-binding fragment that competitively binds to apivolumab or GYM329 in a similar manner). In some embodiments, serum latent myostatin levels may be relatively low at baseline (i.e., before treatment) and increase after treatment with apivolumab. In some embodiments, an increase in serum latent myostatin levels indicates target engagement with apivolumab, for example, target engagement with apivolumab in skeletal muscle. In some embodiments, low baseline serum levels of latent myostatin compared to high levels after treatment indicate that a major portion of the drug target is located within skeletal muscle rather than in the systemic circulation.

[0137] In some embodiments, serum creatinine levels can be used as a target engagement marker for apivolumab. In some embodiments, serum creatinine levels may be relatively low at baseline (ie, before treatment) and increase after treatment with apivolumab.

[0138] In some embodiments, an increase in serum creatinine levels indicates target engagement with apivolumab, for example, target engagement with apivolumab in skeletal muscle. In some embodiments, serum creatinine levels can serve as a target engagement marker for another pro-myostatin / latent myostatin antibody (e.g., GYM329 (RO7204239), or an antibody or antigen-binding fragment that competitively binds to the antigen with apivolumab or GYM329). Circulating creatine (i.e., 2-[carbamimido(methyl)amino]acetic acid) is transported from the circulation into the muscle, where it is used as an energy storage buffer. Serum creatinine is derived from creatine stored in these muscles; creatine is converted to creatinine and released into the circulation at a constant rate of approximately 1.7% per day. It is well known that serum creatinine levels are correlated with muscle mass and negatively correlated with disease severity in spinal muscular atrophy (Alves et al. (2019) Neurology 94:e921).

[0139] In some embodiments, saturation of target engagement indicates a dose sufficient to achieve some therapeutic effect (eg, efficacy), although efficacy may be achieved without saturation.

[0140] In certain embodiments, the present disclosure encompasses the use of alternative anti-myostatin antibodies or antigen-binding fragments, for example, anti-promyostatin / latent myostatin antibodies or antigen-binding fragments, for example, selective anti-promyostatin / latent myostatin antibodies, such as any of the antibodies or antigen-binding fragments disclosed in PCT / JP2015 / 006323 (International Publication No. WO 2016098357) (the contents of which are hereby incorporated by reference in their entirety). As used herein, the myostatin selective inhibitor can be an alternative anti-promyostatin / latent myostatin antibody or antigen-binding fragment as described herein, such as GYM329. In certain embodiments, the present disclosure encompasses anti-promyostatin / latent myostatin antibodies or antigen-binding fragments that are humanized variants of MST1032-G1m disclosed in PCT / JP2015 / 006323. In certain embodiments, the present disclosure encompasses an anti-promyostatin / latent myostatin antibody or antigen-binding fragment comprising a heavy chain variable domain comprising three CDR sequences of HCDR1, HCDR2, and HCDR3, and a light chain variable domain comprising three CDR sequences of LCDR1, LCDR2, and LCDR3, wherein the heavy chain CDRs comprise the following amino acid sequences, respectively: X1X2DIS (HCDR1; SEQ ID NO: 17); IISYAGSTYYASWAKG (HCDR2; SEQ ID NO: 18); GVPAYSX3GGDL (HCDR3; SEQ ID NO: 19); and the light chain CDRs comprise the following amino acid sequences, respectively: X4X5SQSVYX6X7NWLS (LCDR1; SEQ ID NO: 20); WASTLAX8 (LCDR2; SEQ ID NO: 21); and AGGYGGGX9YA (LCDR3; SEQ ID NO: 22). ID NO: 22), wherein any one of X1-X9 is any amino acid residue. In certain embodiments, X1 is S or H; X2 is Y, T, or D; X3 is T or H; X4 is Q or T; X5 is S or T; X6 is D or H; X7 is N or E; X8 is S or Y; X9 is L or R. In certain embodiments, the antibody or antigen-binding fragment comprises six CDR sequences of the following sequences: SEQ ID NO: 23-28; 29-34; 35-40; or 41-46. In certain embodiments, the antibody or antigen-binding fragment comprises a heavy chain variable domain comprising the amino acid sequence of any one of SEQ ID NO: 47-50. In certain embodiments, the antibody or antigen-binding fragment comprises a light chain variable domain comprising the amino acid sequence of any one of SEQ ID NO: 51-54.In some embodiments, the antibody or antigen-binding fragment comprises a set of six CDRs (e.g., from the same MST1032 variant antibody) or paired VH / VL (e.g., from the same MST1032 variant antibody) from those listed in the table below. Table 5. Consensus amino acid sequences of VH CDRs of anti-promyostatin / latent myostatin antibodies or antigen-binding fragments Table 6. Consensus amino acid sequences of VL CDRs of anti-promyostatin / latent myostatin antibodies or antigen-binding fragments Table 7. Amino acid sequences of VH CDRs of MST1032-G1m and humanized variants Table 8. Amino acid sequences of VL CDRs of MST1032-G1m and humanized variants Table 9. Amino acid sequences of the heavy chain variable domains of MST1032-G1m and humanized variants Table 10. Amino acid sequences of the light chain variable domains of MST1032-G1m and humanized variants

[0141] In certain embodiments, the present disclosure encompasses the use of GYM329 or an antibody comprising any of the sequences in Tables 5-10 (e.g., a set of six CDRs or a pair of variable domains) as an alternative anti-pro-myostatin / latent-myostatin antibody for treating subjects with SMA. In certain embodiments, GYM329 or an antibody comprising any of the sequences in Tables 5-10 is used in combination with an SMN therapy (e.g., risperidone, nusin, and / or sovaprevir) for treating SMA. In certain embodiments, GYM329 or an antibody comprising any of the sequences in Tables 5-10 is used to treat a subject with SMA who is ambulatory or has the ability to walk independently. In certain embodiments, the subject has late-onset SMA. In certain embodiments, the subject has early-onset SMA. In certain embodiments, the patient has type 2 or type 3 SMA. In certain embodiments, the patient has ambulatory SMA. In certain embodiments, the patient has non-ambulatory SMA, such as non-ambulatory type 2 and type 3 SMA. In certain embodiments, the patient has non-ambulatory SMA. In certain embodiments, the subject is 2-10 years old. In certain embodiments, the subject is 13-21 years old. In certain embodiments, the subject is less than 2 years old. In certain embodiments, the subject has previously been treated with an SMN upregulator. In certain embodiments, the subject has previously been treated with an SMN therapy, such as risapram, nusin, and / or sovaprevir. In certain embodiments, the subject has not previously been treated with an SMN upregulator. In certain embodiments, GYM329 is used to treat SMA in ambulatory or independently ambulating subjects, preferably those 2-10 years old, wherein the use comprises administering GYM329 in combination with an SMN therapy to the subject, wherein the subject has previously received at least one dose of an SMN therapy, such as risapram, nusin, or sovaprevir. In some embodiments, the subject is able to walk or run 10 meters in less than or equal to 30 seconds and / or has a confirmed genetic diagnosis of 5q-autosomal recessive SMA and symptomatic disease. In certain embodiments, the use of GYM329 or an antibody comprising any sequence in Tables 5-10 above, alone or in combination with an SMN up-regulator, may result in better results than no treatment. Improvement may be measured by RHS and / or motor function measurement-32 (MFM32) scores. Improvement may be improvement in muscle mass as measured by MRI and / or dual-energy X-ray absorptiometry (DXA) scanning. Improvement may be improvement in muscle strength as measured by dynamometer. Improvement in muscle strength as measured by dynamometer may be improvement in upper limb strength as measured by MyoGrip or MyoPinch. Improvement may be assessed by the SMA Independence Scale (SMAIS). Improvement may be seen in more than one of the above indicators.

[0142] In some embodiments, a composition comprising an anti-myostatin antibody, e.g., an anti-promyostatin / latent myostatin antibody, such as GYM329 or apilectomycin, is used to treat SMA in patients two months of age or older, wherein optionally, the treatment further comprises lisapram. . In some embodiments, GYM329 or Apitalgumab and risperidone are administered to the patient as a combination therapy. In some embodiments, GYM329 or Apitalgumab is administered in combination with SMN therapy (e.g., nusinsen), for example, as a combination therapy to the patient. In some embodiments, GYM329 or Apitalgumab is administered in combination with sovaprevir, for example, as a combination therapy to the patient. In some embodiments, GYM329 or Apitalgumab is administered as an add-on therapy or adjuvant therapy to a patient who has been treated with SMN therapy (e.g., risperidone, nusinsen, or sovaprevir) (i.e., has already received the SMN therapy). In some embodiments, SMN therapy is administered as an additional or adjuvant therapy to a patient who has been treated with GYM329 or Apitalgumab (i.e., has already received). In some embodiments, the patient has been administered SMN therapy for at least eight weeks prior to receiving GYM329. In some embodiments, patients receiving SMN therapy receive GYM329 for at least 18 weeks, at least 24 weeks, at least 54 weeks, or at least 72 weeks. In some embodiments, GYM329 or apivolumab is administered intravenously. In some embodiments, GYM329 or apivolumab is administered subcutaneously. In some embodiments, the patient is two to seven months old, wherein optionally the patient has or is suspected of having type 1 SMA. In some embodiments, the patient is two to 25 years old, wherein optionally the patient has type 2 or type 3 SMA. In some embodiments, the patient is 5-10 years old. In some embodiments, the patient is 2-4 years old. In some embodiments, the patient is under 2 years old. In some embodiments, the patient is of any age (e.g., infant, child, or adult) and has type 1, type 2, or type 3 SMA. In some embodiments, the patient is of any age and has ambulatory SMA. In some embodiments, the patient is of any age and has non-ambulatory SMA. In some embodiments, the patient's motor activity is monitored by a wearable device. In an embodiment, the wearable device is one or more instrumented insoles. In some embodiments, motor function is measured as a change from baseline in RHS, MFM D1, MFM D2, MFM32, or SMA Independence Score (SMAIS) scores. In some embodiments, muscle strength is measured by dynamometers. In some embodiments, muscle wasting is monitored by MRI. In some embodiments, circulating myostatin levels are measured. In some embodiments, immune response is monitored.

[0143] In certain embodiments, the present disclosure encompasses the use of taldefgrobep alfa as an alternative to anti-pro-myostatin / latent myostatin antibodies to treat subjects with SMA. Taldefgrobep alfa, also known as BHV2000 or BMS-986089, has the sequence of CAS1580565-26-5 (INN 10661) and is an IgG (human Fc fragment) fusion protein with a peptide (synthetic 17-aa linker) protein and fibronectin (adnectin) (dimer derived from the tenth domain of anti-(human GDF-8) human clone BMS-986089 fibronectin type III). In certain embodiments, taldefgrobep alfa is combined with SMN upregulator therapy (e.g., risperidone, nusin and / or sovarprevir) for the treatment of SMA. In certain embodiments, taldefgrobep alfa is used to treat SMA subjects who are ambulatory or have the ability to walk independently. In certain embodiments, the subject suffers from late-onset SMA. In certain embodiments, the subject has early-onset SMA. In certain embodiments, the subject has SMA type 2 or type 3. In certain embodiments, the subject has ambulatory SMA. In certain embodiments, the subject has nonambulatory SMA, such as nonambulatory SMA type 2 and type 3. In certain embodiments, the subject is 2-10 years old. In certain embodiments, the subject is 13-21 years old. In certain embodiments, the subject is less than 2 years old. In certain embodiments, the subject has previously been treated with an SMN upregulator. In certain embodiments, the subject has previously been treated with risapram, nusindrone, and / or sovaprevir. In certain embodiments, the subject has not previously been treated with an SMN upregulator. In certain embodiments, taldefgrobep alfa is used to treat SMA in ambulatory or independently ambulatory subjects, preferably subjects 2-10 years old, wherein the use comprises administering taldefgrobep alfa in combination with risapram to the subject, wherein the subject has previously taken at least one dose of risapram, nusindrone, or sovaprevir. In some embodiments, the subject is able to walk or run 10 meters in less than or equal to 30 seconds, and / or has a confirmed genetic diagnosis of 5q-autosomal recessive SMA and symptomatic disease. In some embodiments, taldefgrobep alfa alone or in combination with an SMN upregulator may be improved relative to no treatment. Improvement can be measured by RHS and / or Motor Function Measure-32 (MFM32) scores. Improvement can be improvement in muscle mass as measured by MRI and / or dual energy X-ray absorptiometry (DXA) scans. Improvement can be improvement in muscle strength as measured by myodynamometer.Improvements in muscle strength measured by dynamometers can be improvements in upper limb strength measured by the MyoGrip or MyoPinch. Improvements can be assessed using the SMA Independence Scale (SMAIS). Improvements can be seen in more than one of the above indicators.

[0144] In some embodiments, a composition comprising an anti-myostatin antibody or antigen-binding fragment thereof (e.g., apivolumab or taldefgrobep alfa) is used to treat SMA in patients two months of age or older, wherein the treatment optionally also includes an SMN therapy, such as nusin, lisapram, or sovaprevir. In some embodiments, taldefgrobep alfa or apivolumab is administered to the patient as a combination therapy with an SMN therapy. In some embodiments, taldefgrobep alfa or apivolumab is administered as an additional or adjunctive therapy to a patient who has already been treated with (i.e., received) an SMN therapy. In some embodiments, the SMN therapy is administered as an additional or adjunctive therapy to a patient who has already been treated with (i.e., received) taldefgrobep alfa or apivolumab. In some embodiments, the patient has been receiving SMN therapy for at least eight weeks prior to receiving taldefgrobep alfa. In some embodiments, the patient receiving lisapram receives taldefgrobep alfa for at least 18 weeks, at least 24 weeks, at least 12 months, or at least 24 months. In some embodiments, taldefgrobep alfa or apivolumab is administered intravenously. In some embodiments, taldefgrobep alfa or apivolumab is administered subcutaneously. In some embodiments, the patient is two to seven months old, wherein optionally the patient has or is suspected of having type 1 SMA. In some embodiments, the patient is two to 25 years old, wherein optionally the patient has type 2 or type 3 SMA. In some embodiments, the patient is 5-10 years old. In some embodiments, the patient is 2-4 years old. In some embodiments, the patient is under 2 years old. In some embodiments, the patient is of any age (e.g., infant, child, or adult) and has type 1, type 2, or type 3 SMA. In some embodiments, the patient is of any age and has ambulatory SMA. In some embodiments, the patient is of any age and has non-ambulatory SMA. In some embodiments, the patient's motor activity is monitored by a wearable device. In some embodiments, the wearable device is one or more instrumented insoles. In some embodiments, motor function is measured as the change from baseline in RHS, MFM D1, MFM D2, MFM32, or SMA Independent Score (SMAIS) score. In some embodiments, muscle strength is measured by dynamometer. In some embodiments, muscle wasting is monitored by MRI. In some embodiments, circulating myostatin levels are measured. In some embodiments, immune response is monitored. Motor neuron-directed therapy

[0145] In some embodiments, motor neuron-directed therapies are contemplated for use in the combination therapies disclosed herein.

[0146] As used herein, the term "motor neuron directed therapy" refers to an agent intended to improve (e.g., enhance or restore) neuronal function. Such therapies can be used to treat disorders involving impaired signal conduction between motor neurons and their target muscles. In particular, motor neuron directed therapy may be particularly useful for treating disorders involving partial but incomplete loss of neurons that innervate muscles. In certain embodiments, motor neuron directed therapy is gene therapy, small molecules, or antisense oligonucleotides. In certain embodiments, motor neuron directed therapy is an "SMN up-regulator." In certain embodiments, motor neuron directed therapy is an agent that can fully restore the motor neuron function in a cell (e.g., a cell in a subject). In certain embodiments, motor neuron directed therapy is an agent that can partially restore the motor neuron function in a cell (e.g., a cell in a subject). In some embodiments, a motor neuron-directed therapy is an agent that is capable of restoring at least 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99%, or more motor neuron function in a cell (e.g., a cell in a subject). One of ordinary skill will understand that motor neuron function generally includes membrane excitability, axonal transport, vesicle transport, neurotransmitter release, mitochondrial function, and / or mitochondrial availability, and these functions are measured using assays known to those of ordinary skill in the art.

[0147] In some embodiments, motor neuron targeted therapy includes therapy that slows or stops neuronal degeneration. Such therapy is known in the context of Parkinson's disease and Huntington's disease. Such therapy can improve nerve cell mitochondrial function, prevent protein imbalance or reduce cell apoptosis. In an embodiment, the therapy that slows or stops neuronal degeneration can include providing progranulin (Chitramuthu et al. (2010) Molec Neurodegen [Molecular Neurodegeneration] 5:41) in combination with muscle-directed therapy, for example, by providing progranulin gene therapy (e.g., using ALPHA-0602).

[0148] In some embodiments, the motor neuron targeted therapy comprises transcutaneous spinal cord stimulation. In some embodiments, transcutaneous spinal cord stimulation is combined with another motor neuron targeted therapy, for example, as described in NCT05430113. In some embodiments, the motor neuron targeted therapy comprises a therapy that affects neurotransmitter signaling. In some embodiments, the motor neuron targeted therapy comprises a therapy that reduces oxidative stress in neurons. In some embodiments, the motor neuron targeted therapy comprises a neuroprotective stem cell therapy.

[0149] Exemplary motor neuron-directed therapies suitable for use in combination with apivolumab according to the present disclosure include, but are not limited to, SMN upregulator therapies (also referred to as SMN corrector therapies). Exemplary motor neuron-directed therapies include "SMN upregulators," such as splicing modifiers, SMN gene replacement or gene therapy, SMN transcription enhancers, SMN protein translation enhancers, and SMN protein stabilizers (discussed further below). As used herein, the terms "splicing corrector," "splicing regulator," and "splicing modifier" are interchangeable and refer to agents that correct abnormal splicing of RNA transcripts (such as transcripts encoded by the SMN2 gene) and / or regulate SMN protein expression. In some embodiments, the SMN2 splicing corrector increases the inclusion of exon 7 in the SMN2 pre-mRNA. In some embodiments, the increased inclusion of exon 7 in the SMN2 pre-mRNA results in increased expression of a functional SMN protein (e.g., from the SMN2 gene) in a cell or subject, such as an SMN protein that can promote neuronal function and / or survival.

[0150] In some embodiments, an SMN upregulator is an agent, such as a small molecule or oligonucleotide (e.g., an antisense oligonucleotide), that increases expression of a functional SMN protein, for example, by promoting the inclusion of exon 7 in SMN2 mRNA transcripts. In some embodiments, the cell is a cell in a subject, e.g., a subject to whom the SMN upregulator is administered. In some embodiments, the SMN upregulator increases the relative amount of SMN2 mRNA that includes exon 7 compared to SMN2 mRNA that does not include exon 7 in the cell (e.g., a cell in a subject). In some embodiments, an "effective amount" of an SMN upregulator increases the amount of correctly spliced ​​SMN2 mRNA in a cell (e.g., a cell in a subject) such that at least 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99%, or more of the SMN2 mRNA in the cell contains exon 7. In some embodiments, an "effective amount" of an SMN upregulator increases the level of SMN2 mRNA containing exon 7 in a subject by at least 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 150%, 200%, 400%, 500%, 600%, 700%, 800%, 900%, 1000%, or more. In some embodiments, an "effective amount" of an SMN upregulator increases the level of functional SMN protein in a subject by at least 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 150%, 200%, 400%, 500%, 600%, 700%, 800%, 900%, 1000%, or more.

[0151] Novartis and PTC Therapeutics / Roche have both developed small molecules that selectively enhance inclusion of SMN2 exon 7, thereby increasing full-length SMN protein levels and therapeutic efficacy in SMA mouse models (Calder et al. (2016) J Med Chem 59:10067-10083; Naryshkin et al. (2014) Science 345:688-693; Palacino et al. (2015) Nat Chem Biol 11:511-517; Ratni et al. (2016) J Med Chem 59:6086-6100). For example, Roche has developed a small molecule that selectively enhances inclusion of SMN2 exon 7, thereby increasing full-length SMN protein levels and therapeutic efficacy in SMA mouse models (Calder et al. (2016) J Med Chem 59:10067-10083; Naryshkin et al. (2014) Science 345:688-693; Palacino et al. (2015) Nat Chem Biol 11:511-517; Ratni et al. (2016) J Med Chem 59:6086-6100). Lisapram (formerly known as RO7034067, CAS#1825352-65-5), marketed under the brand name, is the first oral medication approved for the treatment of SMA. Branaplam (formerly known as LMI070 and NVS-SM1) is being studied in a Phase 1 / 2, multi-part, first-in-human, open-label clinical study in infants with type 1 SMA (see U.S. clinical trial NCT02268552, Novartis).

[0152] In preclinical models of mild and severe SMA, oral administration of SMN-C2 (a lisapram analogue, CAS#1446311-56-3) and SMN-C3 (CAS#1449597-34-5) showed that these compounds increased SMN protein levels in the brain and muscle tissue of treated mice compared to vehicle. These molecules also effectively crossed the blood-brain barrier (BBB). Both compounds showed initial promise in a mouse model of severe SMA, but clinical programs were paused.

[0153] Other small molecule-based SMN2 splicing correctors are described, for example, in U.S. Patent Publication No. US2009 / 0031435 and U.S. Patent No. 8,399,437; each of which is incorporated herein by reference in its entirety. However, it should be understood that other small molecule splicing correctors, including SMN2 splicing correctors known in the art, such as lisapram, and which will be apparent to a skilled artisan, are also within the scope of the present disclosure.

[0154] In some embodiments, the SMN upregulator is an oligonucleotide molecule. In some embodiments, the SMN upregulator is an antisense molecule. In some embodiments, the SMN upregulator is an antisense molecule that increases expression of the SMN2 gene. In some embodiments, the SMN upregulator is an antisense molecule that increases expression of SMN2 mRNA containing exon 7. In some embodiments, the SMN upregulator is an antisense molecule that increases expression of a functional SMN protein (e.g., an SMN protein encoded by an SMN2 mRNA containing exon 7). For example, an antisense oligonucleotide directed against an intronic splicing silencer site (ISS) in intron 7 of the SMN2 gene can modulate pre-mRNA processing, resulting in a greater likelihood that exon 7 will be included in the mature mRNA transcript of SMN2, leading to increased production of a functional SMN protein.

[0155] In some embodiments, antisense oligonucleotides (ASOs) that block the SMN2 intronic splicing silencer, thereby increasing exon 7 inclusion, also rescue disease in SMA mouse models (Hua et al. (2010) Genes Dev 24:1634-1644; Hua et al. (2011) Nature 478:123-126; Passini et al. (2011) Sci Transl Med 3:72ra18). Biogen / Ionis has developed Nusin, an ASO splicing modifier, which has shown clinical efficacy and is FDA-approved for the treatment of SMA in pediatric and adult patients and is marketed as Nusinersen is currently on the market (Chiriboga et al. (2016) Neurology 86:890-897; Finkel et al. (2016) Lancet 388:3017-3026; FDA, Nusinersen; Office of Drug Evaluation Decisional Memorandum (2016)). However, each administration of Nusinersen requires intrathecal delivery under general anesthesia. Furthermore, while the antisense corrector Nusinersen has shown promise, its clinical efficacy appears modest: 60% of patients with infantile-onset SMA (type I) were reportedly non-responders, and 43% of patients treated with Nusinersen did not achieve an increase of ≥3 points as measured by the HFMSE, while the mean increase in the treated group was less than six points compared to placebo. Thus, treatment with Nusinersen resulted in only partial improvement.

[0156] While these ASO therapies have demonstrated efficacy in preclinical, clinical, or clinical settings, none has completely cured the disease. In mouse models, while both small molecules and ASO splicing modifiers significantly reduced disease severity, treated animals exhibited deficits in lifespan, body weight, muscle mass, and muscle function compared to healthy animals (Hua et al. (2011) Nature 478:123-126; Feng et al. (2016) Hum Mol Genet 25:964-975). In a double-blind clinical trial for infantile-onset SMA, at an interim analysis, nusin produced clinically meaningful benefits (41% of treated patients and 0% of placebo patients improved in motor milestones using the Hammersmith Infant Neurological Examination). For patients with type I, the motor milestones achieved were impressive, with five of 81 treated patients able to sit independently (a milestone rarely achieved by these patients). However, these patients did not achieve all developmental milestones, and the milestones achieved would be considered disappointing in normal individuals. In a second placebo-controlled trial for type 2 SMA, nusindrone again demonstrated clinically meaningful improvements, with a 5.9-point improvement in HFMSE scores relative to placebo. Note that the maximum HFMSE score is 66, and most type 2 patients score below 20 (Glanzman et al. (2011) J Child Neurol 26:1499-1507; Kaufmann et al. (2011) Arch Neurol 68:779-786). However, in this trial, 43% of patients failed to achieve at least a 3-point improvement in motor function. These results suggest that while SMN2 splicing modulators have the potential to significantly impact the course of SMA, additional functional gains will be needed to further improve and reduce the burden of the disease.

[0157] In some embodiments, the SMN upregulator is a gene therapy. As used herein, the term "gene therapy" refers to any procedure that uses nucleic acids to rehabilitate, cure, or otherwise improve a subject's condition. In gene therapy, nucleic acids are delivered to specific cells. Delivery methods include viral and non-viral methods known in the art. See, for example, Patil et al. (2005) AAPS J. [AAPS Magazine] 7 (1): E61-E77; Gascon et al., Non-Viral Delivery Systems in Gene Therapy [Non-Viral Delivery Systems in Gene Therapy] (2013); Somiari et al. (2000) Molecular Therapy [Molecular Therapy], 2 (3): 178-187; Herweijer and Wolff (2003) Gene Therapy [Gene Therapy] 10 (6): 453-458; Nayerossadat et al. (2012) Advanced Biomedical Research [Advanced Biomedical Research] 1 (2): 1-11. Viral methods of delivering gene therapy involve the use of viral vectors. Viral vectors are genetically modified viruses that can carry therapeutic gene payloads and have been reprogrammed to allow infection and subsequent propagation of the payload into specific tissues without the side effects typically associated with wild-type viral infections. Many viruses can be used as viral vectors, including retroviruses, adenoviruses, herpes simplex viruses, slow viruses, pox viruses, and Epstein-Barr viruses. Although safer than wild-type viruses, viral vectors may induce an immune response and sometimes require the use of non-viral delivery methods. In certain embodiments, the viral vector is an AAV viral vector. Non-viral delivery methods include, but are not limited to, physical methods, such as injection of naked DNA, electroporation, gene gun bombardment, and ultrasound, as well as biochemical methods. Another delivery technology, magnetofection, combines physical and biochemical elements.

[0158] SMN1 gene replacement therapy using adeno-associated viral vectors (AAV) has shown benefit in treating SMA; Sovaprevir (formerly known as AVXS-101) is an AAV9-SMN1 vector from Novartis Gene Therapies (formerly AveXis) and has been approved by the FDA in the United States for the treatment of pediatric patients under two years of age with spinal muscular atrophy (SMA) and biallelic mutations in the survival motor neuron 1 (SMN1) gene. ANB-004 is an AAV9-SMN1 vector from Biocad (WO 2022 / 164351) currently in a Phase 1 / 2 clinical trial in infants under six months of age with symptomatic SMA.

[0159] In some embodiments, gene therapy involves introducing one or more transgenes into a patient. In some embodiments, gene transfer is achieved by using a suitable vector (such as a viral vector and a lipid-based vector). For viral vector-mediated gene delivery, gene therapy may involve initial treatment with a specific serotype, followed by subsequent treatment with a different serotype to minimize adverse immune responses in the subject. In some embodiments, gene therapy involves targeted genome editing, such as CRISPR / Cas9 technology or variants thereof. Non-limiting examples of SMN upregulators suitable for use in combination with apivolumab according to the present disclosure include, but are not limited to: nusinsen; risperidone; and sovaprevir. Nusinsen is an SMN2-directed antisense oligonucleotide (ASO) that is intended to treat SMA caused by mutations that result in SMN protein deficiency. See, for example, Darras et al. (2019) Neurology. 92(21)e2492-e2506; Mercuri et al. (2018) N Engl J Med. 378:625-635. Risdiplam works in a similar manner and is a pyridazine derivative that modifies the splicing of SMN2 messenger RNA. See, for example, Oskoui et al., "SUNFISH Part 2: 24-month efficacy and safety of risdiplamin patients with type 2 or non-ambulant type 3 spinal muscular atrophy (SMA).," presented at the MDA Clinical and Scientific Conference 2021; March 15-18. Panel 80. Sovaprevir is a gene therapy based on a recombinant adeno-associated virus vector 9 that is designed to deliver a copy of the gene encoding the human SMN protein. Clinical benefits of SMN therapy

[0160] Based on the natural history of patients with nonambulatory late-onset SMA aged five years or older (i.e., without treatment), mean HFMSE scores would be expected to decline over a 12-month period, with less than 5% of patients showing an increase of 3 points or more (Mercuri et al. (2016) Neuromuscul Disord. 26(2):126-131). Natural history data from longitudinal studies of ambulatory patients with type 3 SMA provide further insights. These patients typically experience motor decline, which in some cases is severe, e.g., loss of the ability to walk (Coratti et al. (2020) American Neurology Association, 88:1109-1117, e.g., Figure 1 In this study of 130 participants with a mean age of 10.05 years and a mean HFMSE score of 52.81 at baseline, the mean change from baseline in the HFMSE was -0.79 points at 12 months, and 11 patients lost the ability to walk (mean age at loss of ambulation was 10.21 years (SD ± 6.43)). Participants were relatively stable until age seven, showing modest functional improvements before the steep decline observed in subsequent years.

[0161] In patients with nonambulatory late-onset SMA who are five years of age or older, the mean HFMSE score is expected to decline over 12 months based on the natural history of this patient population, with few patients (e.g., less than 5%) showing an increase of 3 points or more in the HFMSE score (Mercuri et al. (2016) Neuromuscul Disord. 26(2):126-131). In patients with type 2 and type 3 SMA who have not received disease-modifying therapy, a natural history has shown a decline in upper limb strength and MFM32 scores over 24 months (Annoussamy et al. (2020) Annals of Clinical and Translational Neurology 8:359-373).

[0162] In this context, it has been reported that nusindrone provides limited clinical benefit in patients who started treatment at age five years or older. More specifically, in the CHERISH study, among patients who started nusindrone at age five years or older, the mean HFMSE decreased by >0.5 points after 15 months of nusindrone treatment, and <15% of patients showed an increase of 3 points or more in HFMSE scores during this time (Mercuri et al. (2018) N Engl J Med. 378:625-635, e.g., Figure 2A In the earlier study, these patients were followed up for 15 months. In the CHERISH trial, most patients in this age group did not improve on their HFMSE, and few achieved an increase of more than 3 points.

[0163] Treatment with nusinam has been shown to improve motor function and plateau within the first year of treatment. In the initial CHERISH and subsequent SHINE trials, subjects achieved a 3.9-point (mean ± SE) increase from baseline in the HFMSE score after the first 450 days of nusinam treatment and a 4.6-point (mean ± SE) increase from baseline after 1650 days of treatment. Thus, after approximately the first year of treatment, nusinam provides a less than one-point improvement in the HFSME in the long term (Mercuri et al., presented at the World Muscle Society Congress 2020, p. 257).

[0164] Figure 1 This indicates that the burden of disease persists after SMN treatment. The bottom gray bar represents the baseline HFMSE score observed in the Phase 3 CHERISH trial after 15 months of treatment with Nusin. The solid black bar above it represents the mean improvement in HFMSE scores for patients with type 2 and nonambulatory type 3 SMA. The diagonal striped bar represents the chance of achieving a total improvement of 66 points for these patients. Therefore, limitations in mobility still exist (Darras et al. (2019) Neurology 92(21):e2492-e2506). In addition, limitations in mobility and daily activities persist and are associated with a gradual deterioration of motor function (Yang et al. (2022) Adv Ther 39:1915; Wan et al. (2020) Orphanet J Rare Dis 15:70).

[0165] A study reporting the efficacy and safety of lisapram after 24 months of treatment in patients with type 2 and nonambulatory type 3 SMA (SUNFISH) showed no improvement in 32 motor function movement outcomes (MFM32) between 12 and 24 months (Oskoui et al. (2023) J. Neurol. https: / / doi.org / 10.1007 / s00415-023-11560-1). The mean change from baseline in MFM32 was 1.7 points (95% CI, 0.8-2.5) at 12 months and 1.8 points (95% CI, 0.7-2.9) at 24 months. Data from nusindrone and lisapram are consistent in showing that treatment with SMN therapy, unless initiated early in life, results in an initial period of improvement followed by disease stabilization with limited or no sustained improvement (Mercuri et al. (2018) N Engl J Med 378(7):625-635; Mercuri et al. (2020) 2 nd Int'l Sci Clin Cong SMA [Second International Conference on Spinal Muscular Atrophy Science and Clinic]). Thus, long-term treatment with SMN-targeted therapies appears to initially improve the disease and then stabilize it, for example, preventing further loss of motor function. Additional therapies are still needed to improve motor function in patients treated with SMN-targeted therapies (Mercuri et al., SUNFISH Part 2, presented at the American Academy of Neurology 2020). Additional / adjuvant therapy, combination therapy

[0166] The present disclosure includes add-on therapies (also called adjunctive therapies) and combination therapies that include a first agent (a motor neuron-directed therapy (e.g., SMN therapy)) and a second agent (a muscle-targeted therapy (e.g., a myostatin inhibitor, such as apivolumab)) intended to treat SMA in a patient. The two agents are used in conjunction with each other to enhance the therapeutic effect. Add-on or adjunctive therapy means treatment given to a patient who is already receiving background therapy. For example, a muscle-targeted therapy (such as apivolumab) can be administered to an SMA patient who is already receiving SMN therapy. In contrast, combination therapy refers to the administration of two therapies to a patient by a physician or team of physicians as part of a coordinated or predetermined treatment plan. The combination therapy and the add-on therapy can be administered separately or in the same setting, such as during the same clinic visit.

[0167] In various embodiments, the present disclosure provides for the use of an anti-myostatin / latent myostatin antibody (e.g., apivolumab) for treating SMA in patients who are also receiving therapy (e.g., motor neuron-directed therapy, e.g., SMN upregulators) to address motor neuron deficiency. The present disclosure encompasses methods of treating SMA in subjects treated with SMN upregulators comprising administering an anti-myostatin / latent myostatin antibody. In various embodiments, the anti-myostatin / latent myostatin antibody is apivolumab.

[0168] In various embodiments, the present disclosure provides for the use of an anti-latent myostatin antibody (e.g., GYM329) for treating SMA in patients who are also receiving therapy (e.g., motor neuron-directed therapy, e.g., SMN upregulators) to address motor neuron deficiency. The present disclosure encompasses methods of treating SMA in subjects treated with SMN upregulators comprising administering an anti-latent myostatin antibody. In various embodiments, the anti-promyostatin / latent myostatin antibody is GYM329.

[0169] In some embodiments, apilectomycin used in combination with SMN therapy provides additive clinical benefit. In some embodiments, apilectomycin used in combination with SMN therapy provides synergistic clinical benefit. "Synergistic" means that when two agents are used in combination with each other, whether as an add-on therapy or a combination therapy, the efficacy they achieve together is greater than the sum of the effects achieved by each agent alone.

[0170] Apilitubine can be administered to patients with SMA who are responders, poor responders, or non-responders to SMN upregulator therapy. For poor responders or non-responders, simultaneous inhibition of myostatin signaling may improve neuromuscular signaling, in part due to enhanced muscle function, thereby making the innervating motor neurons of non-responders more responsive to SMN upregulators. Without wishing to be bound by a particular theory, it is contemplated that due to the bidirectional nature of neuromuscular signaling, enhancement of the muscle component may influence the neuronal component through positive feedback, and vice versa.

[0171] Although poor responders and / or non-responders to SMN upregulators may still benefit from myostatin inhibition, an exemplary patient population includes SMN upregulator responders. It is expected that motor function in these individuals can be further improved by combining myostatin inhibition therapy (such as apilectomycin) with motor neuron-directed therapy (such as SMN upregulator therapy).

[0172] In the context of an SMA treatment regimen comprising two or more therapeutic agents (e.g., apivolumab used in combination with an SMN upregulator therapy), the phrase "in combination with" means that in a subject receiving two or more therapies, the therapeutic effect of the first therapy overlaps temporally and / or spatially with the therapeutic effect of the second and / or additional therapy. The two or more therapies do not have to be administered as a single formulation, nor do they have to be administered in parallel, nor do they have to be administered via the same route. The first, second, and / or additional compositions can be administered concurrently (e.g., simultaneously), separately, or sequentially. Thus, the two or more therapies can be formulated as a single formulation for simultaneous administration, or as separate formulations for sequential, co-administered, or simultaneous administration of treatment. When a subject who has been treated with a first therapy for SMA (e.g., apivolumab) receives a second and additional therapy for SMA (e.g., an SMN upregulator therapy), the second and additional therapy may be referred to as an "add-on" therapy or an "adjunct" therapy.

[0173] In some embodiments, the treatment regimens described herein comprising two or more therapeutic agents (e.g., apilectomycin used in combination with an SMN-targeted therapy (e.g., an upregulatory therapy)) achieve improved clinical benefit in patients compared to monotherapy with each agent used alone. In particular, targeting the affected muscles with myostatin inhibition therapy (e.g., apilectomycin) in combination with a motor neuron-directed therapy (e.g., an SMN upregulatory therapy) may produce beneficial clinical outcomes compared to the use of either myostatin inhibition therapy or motor neuron-directed therapy alone. This effect may be additive or synergistic compared to the respective monotherapies. In some embodiments, the effect of the two or more therapies combined is additive, i.e., the effect of the therapies taken together is equal to or approximately equal to the sum of the effects of the therapies when taken alone. In some embodiments, the effect of the two or more therapies combined is synergistic, i.e., superadditive, i.e., the effect of the therapies taken together is greater than the sum of the effects of the therapies when taken alone.

[0174] In some embodiments, one or more beneficial therapeutic effects (e.g., effect on at least one symptom or risk / rate of disease progression) of apivolumab in combination with SMN upregulator therapy are additive. In some embodiments, one or more beneficial therapeutic effects (e.g., effect on at least one symptom or risk / rate of disease progression) of apivolumab in combination with SMN upregulator therapy are synergistic. In some embodiments, apivolumab in combination with SMN upregulator therapy has a combined effect that is additive, synergistic, and / or provides one or more additional combined benefits. In some embodiments, apivolumab in combination with SMN upregulator therapy may have an additive or synergistic effect on at least one efficacy parameter of SMA (e.g., HFMSE score or RULM score). In some embodiments, apivolumab in combination with SMN upregulator therapy has an additive or synergistic effect on the HFMSE score of SMA patients and / or SMA patient populations. In some embodiments, apivolumab, when used in combination with an SMN upregulator therapy, further improves HFMSE scores compared to treatment with an SMN upregulator therapy alone (see, e.g., Example 1 and Darras et al. (2019) Neurology. 92(21)e2492-e2506). In some embodiments, the further improvement in HFMSE scores is additive. In some embodiments, the further improvement in HFMSE scores is synergistic. In some embodiments, apivolumab, when used in combination with an SMN therapy, has an additive or synergistic effect on RULM scores in SMA patients and / or populations of SMA patients. In some embodiments, apivolumab, when used in combination with an SMN therapy, further increases RULM scores compared to treatment with an SMN therapy alone. In some embodiments, the further improvement in RULM scores is additive. In some embodiments, the further improvement in RULM scores is synergistic. In some embodiments, apilectomycin used in combination with SMN therapy provides an additive or synergistic effect on RULM score in SMA patients for at least 24 months, wherein optionally, the combination therapy improves RULM score over 24 months, or the combination therapy maintains an increase in RULM score over 24 months. Patient selection

[0175] The present disclosure includes identifying or selecting suitable human subjects to be treated with a selective myostatin inhibitor, such as apivolumab. Suitable human subjects are patients who may benefit from apivolumab therapy, whether as a monotherapy or in conjunction (or combination) with another therapy.

[0176] In some embodiments, the patient or patient population is an early or infantile-onset SMA patient or patient population. In some embodiments, the patient or patient population is a late-onset SMA patient or patient population. In some embodiments, the patient or patient population is a Type 2 SMA patient or patient population. In some embodiments, the patient or patient population is a non-ambulatory Type 3 SMA patient or patient population. In some embodiments, the patient or patient population is an ambulatory Type 3 SMA patient or patient population. In some embodiments, the patient or patient population is an ambulatory late-onset SMA patient or patient population. In some embodiments, the patient or patient population is a non-ambulatory patient or patient population. In some embodiments, the patient or patient population is a presymptomatic or asymptomatic patient or patient population. In some embodiments, the patient or patient population is a symptomatic patient or patient population. In some embodiments, the patient or patient population has two or more copies of the SMN2 gene, e.g., 2-3 copies, 2-4 copies, 3-4 copies, etc. In some embodiments, the patient or patient population has late-onset SMA and has two or more copies of the SMN2 gene, e.g., 2-3 copies, 2-4 copies, 3-4 copies, etc.

[0177] SMA patients who may benefit from such therapies include those who meet one or more of the following criteria: a documented diagnosis of 5q SMA and late-onset (e.g., type 2 or type 3) SMA prior to receiving SMA-directed therapy; nonambulatory subjects who can sit independently according to the WHO motor milestone definition; ambulatory subjects who can walk independently for more than 10 meters in 30 seconds or less without assistance; subjects with an RHS score less than or equal to 63 and / or an HFMSE score of 10 or higher (e.g., an HFMSE score ≥10 and ≤45 at screening); subjects who have not used a positive pressure tracheostomy or chronic daytime noninvasive ventilatory support for more than 16 hours per day within the two weeks prior to treatment; subjects who have not had any acute or coexisting conditions that interfered with the subject's health within the two weeks prior to treatment; subjects who do not have severe scoliosis or contractures; and / or subjects who have not used systemic corticosteroids, valproic acid, or therapies with potential muscle or neuromuscular effects within 60 days, except for approved SMN upregulators (e.g., also known as SMN correctors). Therapies with potential muscle or neuromuscular effects include androgens, insulin-like growth factor, growth hormone, systemic beta-agonists, botulinum toxin, muscle relaxants, muscle strengthening supplements, or acetylcholinesterase inhibitors. In some embodiments, the patient has a documented diagnosis of 5q SMA and late-onset (e.g., type 2 or type 3) SMA prior to receiving therapy for SMA and meets one or more of the additional criteria listed in the table above. In some embodiments, for example, in patients with type 2 SMA, there is a positive correlation between the age-normalized change in motor function and the age-normalized fold change in latent myostatin levels. In various embodiments, the methods disclosed herein include selecting such a patient or patient population for treatment with a myostatin inhibitor (e.g., apivolumab), for example, according to a dose or regimen disclosed herein.

[0178] SMA patients who may be sensitive to apilectomycin therapy (whether as monotherapy or in combination with another therapy) include patients under two years of age with any type of SMA, as well as patients who present with an SMA type 1 phenotype or have up to three SMN2 copies. In some embodiments, apilectomycin may have enhanced therapeutic efficacy in younger patients (e.g., those under 21 years of age) because these patients have higher background anabolic activity. In some embodiments, younger patients (e.g., those under 21 years of age or those who are anabolic active) receive apilectomycin therapy. In some embodiments, the patient is two years of age or younger, e.g., newborn to 24 months of age. In some embodiments, the patient is six weeks of age or younger, e.g., newborn to six weeks of age. In some embodiments, the patient is 2-21 years of age. In some embodiments, the patient is 13-21 years of age. In some embodiments, the patient is 12 years of age or younger. In some embodiments, the patient is 2-12 years of age. In some embodiments, the patient is 5-12 years of age. In some embodiments, apilectomycin may be particularly effective in patients before the onset of puberty (e.g., before the age of 12). In some embodiments, treatment with apivolumab may be effective in preventing the rapid decline in motor function associated with the onset of puberty in younger patients (e.g., patients younger than 12 years of age). In some embodiments, the patient is about two years of age. In some embodiments, the patient is younger than two years of age. In some embodiments, the patient exhibits a phenotype of SMA type 1. In some embodiments, the patient has up to three copies of SMN2. In various embodiments, the methods disclosed herein include selecting such a patient or patient population for treatment with a myostatin inhibitor (e.g., apivolumab), for example, according to a dose or regimen disclosed herein.

[0179] Patients who may be susceptible to apivolumab therapy (whether as monotherapy or in combination with another therapy) include patients with type 2 SMA whose baseline (i.e., prior to initiating apivolumab therapy) serum latent myostatin (LM) concentration is at least 1 ng / mL (e.g., greater than 1.5 ng / ml, greater than 2 ng / ml, greater than 2.5 ng / ml, greater than 3 ng / ml, or greater). In some embodiments, apivolumab therapy (whether as monotherapy or in combination with another therapy) may be more effective in patients with higher baseline serum LM concentrations compared to patients with lower baseline serum LM concentrations. In some embodiments, such therapy may be particularly effective in patients younger than 12 years of age. In some embodiments, such therapy may be particularly effective in patients 2-5 years of age. In some embodiments, such therapy may be particularly effective in patients 12-21 years of age with type 2 SMA. In some embodiments, such therapy may be particularly effective in patients 12-21 years of age with type 3 SMA. In some embodiments, such therapy may be particularly effective in patients 2-21 years of age who are non-ambulatory. In some embodiments, this therapy may be particularly effective for non-ambulatory patients aged 2-12 years. In some embodiments, this therapy may be particularly effective for non-ambulatory patients aged 2-21 years of age, type 2 and type 3. In some embodiments, this therapy may be effective for patients under two years of age. In some embodiments, patients with type 2 SMA who are less than 12 years of age and have a baseline serum LM concentration of at least 1 ng / mL (e.g., greater than 1.5 ng / ml, greater than 2 ng / ml, greater than 2.5 ng / ml, greater than 3 ng / ml, or greater) may be responsive to apilectomycin therapy. In some embodiments, patients with type 2 SMA who are less than two years of age and have a baseline serum LM concentration of at least 1 ng / mL (e.g., greater than 1.5 ng / ml, greater than 2 ng / ml, greater than 2.5 ng / ml, greater than 3 ng / ml, or greater) may be responsive to apilectomycin therapy. In some embodiments, apilectomycin therapy comprises administering more than 2 mg / kg of apilectomycin, for example, 10 mg / kg or 20 mg / kg.

[0180] In some embodiments, the method of treating SMA comprises administering apilectomycin therapy (whether as monotherapy or in conjunction with another therapy (or combination)) to a patient having a baseline serum LM concentration of at least 1 ng / mL (e.g., greater than 1.5 ng / ml, greater than 2 ng / ml, greater than 2.5 ng / ml, greater than 3 ng / ml, or greater). In some embodiments, the method of treating SMA comprises administering apilectomycin therapy (whether as monotherapy or in conjunction with another therapy (or combination)) to a patient less than 12 years of age and having a baseline serum LM concentration of at least 1 ng / mL (e.g., greater than 1.5 ng / ml, greater than 2 ng / ml, greater than 2.5 ng / ml, greater than 3 ng / ml, or greater). In some embodiments, the method of treating SMA comprises administering apilectomycin therapy (whether as monotherapy or in conjunction with another therapy (or combination)) to a patient less than 2 years of age and having a baseline serum LM concentration of at least 1 ng / mL (e.g., greater than 1.5 ng / ml, greater than 2 ng / ml, greater than 2.5 ng / ml, greater than 3 ng / ml, or greater). In some embodiments, apilectomycin therapy comprises administering greater than 2 mg / kg of apilectomycin, such as 10 mg / kg or 20 mg / kg.

[0181] In some embodiments, apilectomycin is used to treat SMA in patients with a baseline serum LM concentration of at least 1 ng / mL (e.g., greater than 1.5 ng / ml, greater than 2 ng / ml, greater than 2.5 ng / ml, greater than 3 ng / ml, or greater), whether as a monotherapy or in conjunction with another therapy (or combination). In some embodiments, apilectomycin is used to treat SMA in patients less than 12 years of age with a baseline serum LM concentration of at least 1 ng / mL (e.g., greater than 1.5 ng / ml, greater than 2 ng / ml, greater than 2.5 ng / ml, greater than 3 ng / ml, or greater), whether as a monotherapy or in conjunction with another therapy (or combination). In some embodiments, apilectomycin is used to treat SMA in patients less than two years of age with a baseline serum LM concentration of at least 1 ng / mL (e.g., greater than 1.5 ng / ml, greater than 2 ng / ml, greater than 2.5 ng / ml, greater than 3 ng / ml, or greater), whether as a monotherapy or in conjunction with another therapy (or combination). In some embodiments, apilectomycin therapy is suitable for administration at greater than 2 mg / kg of apilectomycin (eg, 10 mg / kg or 20 mg / kg).

[0182] In various embodiments, the SMA patient (e.g., any of the exemplary SMA patients described above) is currently being treated with (is receiving) an SMN-targeted therapy or has been treated with it. In some embodiments, the SMN-targeted therapy comprises nusindrone, risapram, and / or sovaprevir. In some embodiments, the patient is currently being treated with (is receiving) nusindrone or has been treated with nusindrone. In some embodiments, the patient has previously been treated with nusindrone. In some embodiments, the patient is currently being treated with (is receiving) risapram or has been treated with risapram. In some embodiments, the patient has previously been treated with risapram. In some embodiments, the patient is currently being treated with (is receiving) or has previously been treated with sovaprevir.

[0183] In various embodiments, the present disclosure provides methods of treating a patient or one or more patient populations with a myostatin inhibitor (such as apivolumab), alone or in combination (or in combination) with an SMN-targeted therapy, wherein the patient or one or more patient populations meet one or more of the following criteria: having any type of SMA at or before the age of two years, exhibiting an SMA type 1 phenotype, and / or having up to three SMN2 copies. In some embodiments, the treatment comprises apivolumab therapy, for example, as a monotherapy, according to a dose or regimen disclosed herein. In some embodiments, the treatment comprises apivolumab therapy, for example, in combination (or in combination) with an SMN-targeted therapy (such as nusin, risopram, or sovaprevir), according to a dose or regimen disclosed herein. In some embodiments, the patient is currently receiving or has been treated with nusin. In some embodiments, the patient has previously been treated with nusin. In some embodiments, the patient is currently receiving or has been treated with risopram. In some embodiments, the patient has previously been treated with risopram. In some embodiments, the patient has previously been treated with sovaprevir.

[0184] In some embodiments, the patient is symptomatic or pre-symptomatic.

[0185] Presymptomatic patients include those who have been genetically identified as carriers of one or more mutations in the SMN1 gene, either alone or in combination with identification of one or more additional genetic modifications (e.g., determination of SMN2 copy number). Genetic identification of SMA patients can be performed as part of newborn or in utero screening. At the time of identification (e.g., diagnosis), the patient (e.g., newborn) may not exhibit obvious / overt symptoms (asymptomatic), but based on the genetic profile and possibly other factors, the patient may develop the disease.

[0186] In severe cases, newborns may already show signs of the disease (ie, have symptoms). Typically, based on the natural history of SMA, such patients are likely to have Type 1 SMA and are generally not expected to gain the ability to sit independently without intervention.

[0187] In some embodiments, the patient is a neonatal patient (aged zero to six months). In some embodiments, the patient is a fetus. In some embodiments, the patient is a pediatric patient, aged between six months and 17 years. In some embodiments, the patient is less than five years old. In some embodiments, the patient is five years old or younger, for example, 2-5 years old. In some embodiments, the patient is two years old or younger, for example, newborn to 24 months old. In some embodiments, the patient is six weeks old or younger, for example, newborn to six weeks old. In some embodiments, the patient is two years old or older. In some embodiments, the patient is 2-10 years old. In some embodiments, the patient is 2-12 years old. In some embodiments, the patient is 13-21 years old. In some embodiments, the patient is five years old or older, for example, 5-17 years old. In some embodiments, the patient is between 5-21 years old. In some embodiments, the patient is an adult.

[0188] In some embodiments, the patient has not received or been treated with an SMN corrector therapy (e.g., an SMN2 upregulator and / or SMN1 gene therapy). In some embodiments, the patient has received or been treated with an SMN corrector therapy (e.g., an SMN2 upregulator and / or SMN1 gene therapy). In some embodiments, the patient initiated or started SMN corrector therapy before the age of five. In some embodiments, the patient initiated or started SMN corrector therapy after the age of five.

[0189] In some embodiments, the patient has disease progression, i.e., a decline in motor function, as evidenced by a decrease of one or more points in motor function assessment test scores (e.g., HFMSE, RHS, and / or RULM scores) within 12 months or 24 months prior to treatment with a selective myostatin inhibitor (e.g., apivolumab).

[0190] In some embodiments, the patient treated herein is in a stable disease phase such that the rate of decline in motor function (e.g., as measured by HFMSE and RHS scores) has not changed significantly over at least six months prior to the start of treatment with a selective myostatin inhibitor (e.g., apivolumab). In some embodiments, the patient has stable disease such that the patient's motor function (e.g., as measured by HFMSE and RHS scores) has not changed significantly over at least six months prior to the start of treatment with a selective myostatin inhibitor (e.g., apivolumab). In some embodiments, the patient has nonambulatory SMA. In some embodiments, the patient has nonambulatory SMA type 2 or type 3. In some embodiments, the patient has ambulatory SMA. In some embodiments, the patient has ambulatory SMA type 3. In some embodiments, the patient begins SMN upregulator / corrector therapy before the age of five. In some embodiments, the patient begins SMN upregulator / corrector therapy after the age of five. In some embodiments, the patient is two years old or younger, e.g., newborn to 24 months old. In some embodiments, the patient is 2-12 years old. In some embodiments, the patient is six weeks old or younger, e.g., newborn to six weeks old. In some embodiments, the patient is 2-12 years of age and starts SMN upregulator / corrector therapy (e.g., nusinoxant, risopram, and / or sovarprevir) before age 5. In some embodiments, the patient is 2-12 years of age and starts SMN upregulator / corrector therapy (e.g., nusinoxant, risopram, and / or sovarprevir) after age five. In some embodiments, the patient is 5-12 years of age and starts SMN upregulator / corrector therapy (e.g., nusinoxant, risopram, and / or sovarprevir) after age five.

[0191] In some embodiments, the patient is a patient with 5q spinal muscular atrophy (SMA) with a biallelic mutation in the SMN1 gene and a clinical diagnosis of SMA type 1, or the patient is a patient with 5q SMA with a biallelic mutation in the SMN1 gene and up to three copies of the SMN2 gene. Such patients can be treated with a selective myostatin inhibitor in combination with gene therapy (e.g., SMN1 gene therapy). In some embodiments, the patient weighs between 2.6 kg and 21.0 kg at the time of receiving gene therapy. In some embodiments, the patient's motor milestones can be monitored, such as head control, rolling from back to side, sitting unsupported for 30 seconds, sitting unsupported for at least 10 seconds, etc.

[0192] In some embodiments, the patient who can sit but never walk is a Type 2 SMA patient, wherein the patient is between the ages of 2 and 18 years old. In some embodiments, SMN1 gene therapy is used to treat Type 2 SMA in a patient who is between the ages of 2 and 18 years old and can sit but has never acquired the ability to walk, and wherein the patient is treated with a myostatin inhibitor, wherein optionally the myostatin inhibitor is a myostatin selective inhibitor, such as apivolumab, GYM329, trevogrumab, or a variant of any of the foregoing. In some embodiments, the myostatin inhibitor is used to treat Type 2 SMA in a patient who is between the ages of 2 and 18 years old and can sit but has never acquired the ability to walk, and wherein the patient is treated with SMN1 gene therapy, wherein optionally the SMN1 gene therapy comprises sovaprevir. In preferred embodiments, the myostatin inhibitor is a myostatin selective inhibitor, such as apivolumab, GYM329, trevogrumab, or a variant of any of the foregoing. In some embodiments, SMN1 gene therapy and a myostatin inhibitor are used as a combination therapy to treat SMA in a patient aged 2-18 years who is able to sit but has never acquired the ability to walk, and wherein the patient is treated with a myostatin inhibitor, wherein optionally the myostatin inhibitor is a myostatin selective inhibitor such as apilectomycin, GYM329, trevogrumab, or a variant of any of the foregoing, and wherein further optionally, the SMN1 gene therapy comprises sovaprevir. In some embodiments, the antibody variant may have a nucleic acid and / or amino acid sequence with significant homology (e.g., >90% sequence identity) compared to a known antibody and retain one or more physical and / or functional properties.

[0193] In some embodiments, the patient has stable disease (as assessed by motor function) such that motor function assessment test scores (e.g., HFMSE and RHS scores) have not changed significantly in at least six months prior to treatment with a selective myostatin inhibitor (e.g., apivolumab). In some embodiments, the patient has received or is being treated with an SMN corrector therapy.

[0194] In some embodiments, the patient has undergone spinal fusion, eg, a primary posterior spinal fusion.

[0195] According to the present disclosure, patient selection or classification can be based on the highest motor milestone achieved relative to the number of copies of the SMN2 gene. Thus, the present disclosure includes the therapeutic use of a myostatin selective inhibitor (such as apivolumab, GYM329, or trogeluzumab) to treat SMA in patients, wherein the treatment comprises administering a composition comprising the myostatin selective inhibitor. In a preferred embodiment, the myostatin selective inhibitor is apivolumab, which can be administered intravenously at a therapeutic dose, wherein the therapeutic dose is greater than 2 mg / kg and up to 20 mg / kg (such as 10 mg / kg). In some embodiments, the patient has 1, 2, 3, or 4 copies of the SMN2 gene and achieves one or more of the following gross motor milestones: 1) lifting / supporting head (i.e., neck support, e.g., being able to lift or support head while lying prone); 2) rolling over; 3) sitting in a tripod position (e.g., supporting oneself with hands while sitting) or sitting with support; 4) sitting without support; 5) standing with support / assistance; 6) crawling / crawl; 7) pulling to a standing position; 8) walking with assistance (e.g., walking slowly along furniture); 9) standing without support; 10) taking a few steps independently followed by a fall; 11) walking independently (e.g., walking independently without support); 12) squatting to pick up an object (e.g., a toy); 13) walking / crawl up and down stairs; 14) running; 15) jumping; 16) going up stairs on both feet; 17) hopping on one foot; 18) going down stairs on both feet.

[0196] In some embodiments, the patient has one copy of the SMN2 gene, and the highest motor milestone reached is lifting or supporting the head while prone. In some embodiments, the patient has one copy of the SMN2 gene, and the highest motor milestone reached is rolling over. In some embodiments, the patient has one copy of the SMN2 gene, and the highest motor milestone reached is sitting with support. In some embodiments, the patient has one copy of the SMN2 gene, and the highest motor milestone reached is sitting without support. In some embodiments, the patient has one copy of the SMN2 gene, and the highest motor milestone reached is standing with support. In some embodiments, the patient has one copy of the SMN2 gene, and the highest motor milestone reached is crawling. In some embodiments, the patient has one copy of the SMN2 gene, and the highest motor milestone reached is pulling to a standing position. In some embodiments, the patient has one copy of the SMN2 gene, and the highest motor milestone reached is walking with assistance. In some embodiments, the patient has one copy of the SMN2 gene, and the highest motor milestone reached is standing without support. In some embodiments, the patient has one copy of the SMN2 gene, and the highest motor milestone reached is walking independently (without support). In some embodiments, the patient has one copy of the SMN2 gene, and the highest motor milestone reached is running. In some embodiments, the patient has one copy of the SMN2 gene and the highest motor milestone reached is hopping. In some embodiments, the patient has one copy of the SMN2 gene and the highest motor milestone reached is walking up stairs with alternating feet. In some embodiments, the patient has one copy of the SMN2 gene and the highest motor milestone reached is hopping on one foot. In some embodiments, the patient has one copy of the SMN2 gene and the highest motor milestone reached is walking down stairs with alternating feet.

[0197] In some embodiments, the patient has two copies of the SMN2 gene, and the highest motor milestone reached is lifting or supporting the head while prone. In some embodiments, the patient has two copies of the SMN2 gene, and the highest motor milestone reached is rolling over. In some embodiments, the patient has two copies of the SMN2 gene, and the highest motor milestone reached is sitting with support. In some embodiments, the patient has two copies of the SMN2 gene, and the highest motor milestone reached is sitting without support. In some embodiments, the patient has two copies of the SMN2 gene, and the highest motor milestone reached is standing with support. In some embodiments, the patient has two copies of the SMN2 gene, and the highest motor milestone reached is crawling. In some embodiments, the patient has two copies of the SMN2 gene, and the highest motor milestone reached is pulling to a standing position. In some embodiments, the patient has two copies of the SMN2 gene, and the highest motor milestone reached is walking with assistance. In some embodiments, the patient has two copies of the SMN2 gene, and the highest motor milestone reached is standing without support. In some embodiments, the patient has two copies of the SMN2 gene, and the highest motor milestone reached is walking independently (without support). In some embodiments, the patient has two copies of the SMN2 gene, and the highest motor milestone reached is running. In some embodiments, the patient has two copies of the SMN2 gene and the highest motor milestone reached is hopping. In some embodiments, the patient has two copies of the SMN2 gene and the highest motor milestone reached is walking up stairs with alternating legs. In some embodiments, the patient has two copies of the SMN2 gene and the highest motor milestone reached is hopping on one leg. In some embodiments, the patient has two copies of the SMN2 gene and the highest motor milestone reached is walking down stairs with alternating legs.

[0198] In some embodiments, the patient has three copies of the SMN2 gene, and the highest motor milestone reached is lifting or supporting the head while prone. In some embodiments, the patient has three copies of the SMN2 gene, and the highest motor milestone reached is rolling over. In some embodiments, the patient has three copies of the SMN2 gene, and the highest motor milestone reached is sitting with support. In some embodiments, the patient has three copies of the SMN2 gene, and the highest motor milestone reached is sitting without support. In some embodiments, the patient has three copies of the SMN2 gene, and the highest motor milestone reached is standing with support. In some embodiments, the patient has three copies of the SMN2 gene, and the highest motor milestone reached is crawling. In some embodiments, the patient has three copies of the SMN2 gene, and the highest motor milestone reached is pulling to a standing position. In some embodiments, the patient has three copies of the SMN2 gene, and the highest motor milestone reached is walking with assistance. In some embodiments, the patient has three copies of the SMN2 gene, and the highest motor milestone reached is standing without support. In some embodiments, the patient has three copies of the SMN2 gene, and the highest motor milestone reached is walking independently (without support). In some embodiments, the patient has three copies of the SMN2 gene and the highest motor milestone reached is running. In some embodiments, the patient has three copies of the SMN2 gene and the highest motor milestone reached is jumping. In some embodiments, the patient has three copies of the SMN2 gene and the highest motor milestone reached is walking up stairs with alternating legs. In some embodiments, the patient has three copies of the SMN2 gene and the highest motor milestone reached is hopping on one leg. In some embodiments, the patient has three copies of the SMN2 gene and the highest motor milestone reached is walking down stairs with alternating legs.

[0199] In some embodiments, the patient has four copies of the SMN2 gene and the highest motor milestone reached is sitting with support. In some embodiments, the patient has four copies of the SMN2 gene and the highest motor milestone reached is sitting without support. In some embodiments, the patient has four copies of the SMN2 gene and the highest motor milestone reached is standing with support. In some embodiments, the patient has four copies of the SMN2 gene and the highest motor milestone reached is crawling. In some embodiments, the patient has four copies of the SMN2 gene and the highest motor milestone reached is pulling to a standing position. In some embodiments, the patient has four copies of the SMN2 gene and the highest motor milestone reached is walking with assistance. In some embodiments, the patient has four copies of the SMN2 gene and the highest motor milestone reached is standing without support. In some embodiments, the patient has four copies of the SMN2 gene and the highest motor milestone reached is walking independently (without support). In some embodiments, the patient has four copies of the SMN2 gene and the highest motor milestone reached is running. In some embodiments, the patient has four copies of the SMN2 gene and the highest motor milestone reached is jumping. In some embodiments, the patient has four copies of the SMN2 gene and the highest motor milestone achieved is walking up stairs with alternating legs. In some embodiments, the patient has four copies of the SMN2 gene and the highest motor milestone achieved is hopping on one leg. In some embodiments, the patient has four copies of the SMN2 gene and the highest motor milestone achieved is walking down stairs with alternating legs.

[0200] In some embodiments, the patient has more than four copies of the SMN2 gene and the highest motor milestone reached is sitting with support. In some embodiments, the patient has more than four copies of the SMN2 gene and the highest motor milestone reached is sitting without support. In some embodiments, the patient has more than four copies of the SMN2 gene and the highest motor milestone reached is standing with support. In some embodiments, the patient has more than four copies of the SMN2 gene and the highest motor milestone reached is crawling. In some embodiments, the patient has more than four copies of the SMN2 gene and the highest motor milestone reached is pulling to a standing position. In some embodiments, the patient has more than four copies of the SMN2 gene and the highest motor milestone reached is walking with assistance. In some embodiments, the patient has more than four copies of the SMN2 gene and the highest motor milestone reached is standing without support. In some embodiments, the patient has more than four copies of the SMN2 gene and the highest motor milestone reached is walking independently (without support). In some embodiments, the patient has more than four copies of the SMN2 gene and the highest motor milestone reached is running. In some embodiments, the patient has more than four copies of the SMN2 gene and the highest motor milestone reached is jumping. In some embodiments, the patient has more than four copies of the SMN2 gene and the highest motor milestone reached is walking up stairs with alternating feet. In some embodiments, the patient has more than four copies of the SMN2 gene and the highest motor milestone reached is hopping on one foot. In some embodiments, the patient has more than four copies of the SMN2 gene and the highest motor milestone reached is walking down stairs with alternating feet.

[0201] In some embodiments, the patient has one copy of the SMN2 gene and has achieved the WHO motor milestone of walking independently. In some embodiments, the patient has one copy of the SMN2 gene and has achieved the WHO motor milestone of standing independently. In some embodiments, the patient has one copy of the SMN2 gene and has achieved the WHO motor milestone of standing with assistance. In some embodiments, the patient has one copy of the SMN2 gene and has achieved the WHO motor milestone of crawling on hands and knees. In some embodiments, the patient has one copy of the SMN2 gene and has achieved the WHO motor milestone of walking with assistance.

[0202] In some embodiments, the patient has two copies of the SMN2 gene and has achieved the WHO motor milestone of walking independently. In some embodiments, the patient has two copies of the SMN2 gene and has achieved the WHO motor milestone of standing independently. In some embodiments, the patient has two copies of the SMN2 gene and has achieved the WHO motor milestone of standing with assistance. In some embodiments, the patient has two copies of the SMN2 gene and has achieved the WHO motor milestone of crawling on hands and knees. In some embodiments, the patient has two copies of the SMN2 gene and has achieved the WHO motor milestone of walking with assistance.

[0203] In some embodiments, the patient has three copies of the SMN2 gene and has achieved the WHO motor milestone of walking independently. In some embodiments, the patient has three copies of the SMN2 gene and has achieved the WHO motor milestone of standing independently. In some embodiments, the patient has three copies of the SMN2 gene and has achieved the WHO motor milestone of standing with assistance. In some embodiments, the patient has three copies of the SMN2 gene and has achieved the WHO motor milestone of crawling on hands and knees. In some embodiments, the patient has three copies of the SMN2 gene and has achieved the WHO motor milestone of walking with assistance.

[0204] In some embodiments, the patient has four copies of the SMN2 gene and has achieved the WHO motor milestone of walking independently. In some embodiments, the patient has four copies of the SMN2 gene and has achieved the WHO motor milestone of standing independently. In some embodiments, the patient has four copies of the SMN2 gene and has achieved the WHO motor milestone of standing with assistance. In some embodiments, the patient has four copies of the SMN2 gene and has achieved the WHO motor milestone of crawling on hands and knees. In some embodiments, the patient has four copies of the SMN2 gene and has achieved the WHO motor milestone of walking with assistance.

[0205] In some embodiments, the patient has more than four copies of the SMN2 gene and has achieved the WHO motor milestone of walking independently. In some embodiments, the patient has more than four copies of the SMN2 gene and has achieved the WHO motor milestone of standing independently. In some embodiments, the patient has more than four copies of the SMN2 gene and has achieved the WHO motor milestone of standing with assistance. In some embodiments, the patient has more than four copies of the SMN2 gene and has achieved the WHO motor milestone of crawling on hands and knees. In some embodiments, the patient has more than four copies of the SMN2 gene and has achieved the WHO motor milestone of walking with assistance.

[0206] In some embodiments, the subject is able to lift or support the head before the age of three months, six months, nine months, or 12 months. In some embodiments, the subject is able to roll over before the age of six months, nine months, or 12 months. In some embodiments, the subject is able to sit with support or in a tripod position before the age of six months, nine months, or 12 months. In some embodiments, the subject is able to sit without support before the age of six months, nine months, or 12 months. In some embodiments, the subject is able to stand with support before the age of nine months or 12 months. In some embodiments, the subject is able to stand without support before the age of 12 months. In some embodiments, the subject is able to crawl or crawl before the age of six months, nine months, or 12 months. In some embodiments, the subject is able to pull into a standing position before the age of nine months or 12 months.

[0207] In some embodiments, the subject is able to walk with assistance before being 12 months or 15 months old. In some embodiments, the subject is able to walk without assistance before being 12 months or 15 months old. In some embodiments, the subject is able to run before being 15 months, 18 months or 24 months old. In some embodiments, the subject is able to jump before being 15 months, 18 months or 24 months old. In some embodiments, the subject is able to squat and pick up objects before being 15 months, 18 months or 24 months old. In some embodiments, the subject is able to walk / crawl up and down stairs before being 15 months, 18 months or 24 months old. In some embodiments, the subject is able to go upstairs with alternating feet before being 30 months or 36 months (3 years old). In some embodiments, the subject is able to go downstairs with alternating feet before being 36 months old (3 years old). In some embodiments, the subject is able to hop on one foot before being four or five years old.

[0208] The present disclosure provides for the therapeutic use of apilectomycin in treating SMA in a patient, wherein the treatment comprises intravenously administering a composition comprising apilectomycin at a therapeutic dose, wherein the therapeutic dose is greater than 2 mg / kg and up to 20 mg / kg (e.g., 10 mg / kg or 20 mg / kg), and wherein optionally the patient can be selected from any one or more of the following categories, or the patient is characterized by:

[0209] The patient is two years of age or younger, e.g., newborn to 24 months of age, wherein optionally, the patient has non-ambulatory SMA type 2 or type 3, wherein further optionally, the patient is receiving SMN therapy (e.g., nusinsen, risopram, and / or sovaroprevir).

[0210] The patient is two years of age or younger, eg, newborn to 24 months of age, wherein optionally, the patient has ambulatory SMA, wherein further optionally, the patient is receiving SMN therapy (eg, nusinsen, risopram, and / or sovaroprevir).

[0211] The patient is six weeks old or younger, e.g., newborn to six weeks old.

[0212] The patient is two years of age or older, wherein optionally, the patient has non-ambulatory SMA Type 2 or Type 3, wherein further optionally, the patient is receiving SMN therapy (eg, nusinsen, risopram, and / or sovaroprevir).

[0213] The patient is two years of age or older, wherein optionally, the patient has ambulatory SMA, wherein further optionally, the patient is receiving SMN therapy (eg, nusinsen, risopram, and / or sovaroprevir).

[0214] The patient is 2-21 years old, wherein optionally, the patient has non-ambulatory SMA type 2 or type 3, wherein further optionally, the patient is receiving SMN therapy (eg, nusinsen, risopram, and / or sovaroprevir).

[0215] The patient is 2-21 years old, wherein optionally, the patient has ambulatory SMA, wherein further optionally, the patient is receiving SMN therapy (eg, nusinsen, risopram, and / or sovaroprevir).

[0216] Patients were 2-12 years old, 2-10 years old, 2-5 years old, or 5-12 years old.

[0217] The patient is 13-21 years old, wherein optionally, the patient has non-ambulatory SMA type 2 or type 3, wherein further optionally, the patient is receiving SMN therapy (eg, nusinsen, risopram, and / or sovaroprevir).

[0218] The patient is 13-21 years old, wherein optionally, the patient has ambulatory SMA, wherein further optionally, the patient is receiving SMN therapy (eg, nusinsen, risopram, and / or sovaroprevir).

[0219] The patient has late-onset SMA, wherein optionally the patient is receiving SMN therapy (eg, nusinsen, risopram, and / or sovaroprevir).

[0220] The patient has ambulatory SMA, wherein optionally, the patient is receiving SMN therapy (eg, nusinsen, risopram, and / or sovaroprevir).

[0221] The patient has nonambulatory SMA, wherein optionally, the patient is receiving SMN therapy (eg, nusinsen, risopram, and / or sovaroprevir).

[0222] The patient has type 2 SMA.

[0223] The patient has Type 3 SMA, wherein optionally the patient has non-ambulatory Type 3 SMA.

[0224] The patient has Type 3 SMA, wherein optionally the patient has ambulatory Type 3 SMA.

[0225] The patient has at least two copies of the SMN2 gene, eg, two, three, four, five, or six copies of the SMN2 gene; or wherein optionally the patient has 2-4 copies of the SMN2 gene.

[0226] The patient has at least two copies of the SMN2 gene, such as two, three or four copies of the SMN2 gene, etc.; or wherein optionally the patient has 2-4 copies of the SMN2 gene, wherein optionally the patient has type 2 SMA or non-ambulatory type 3 SMA.

[0227] The patient has at least three copies of the SMN2 gene, such as three, four, five or six copies of the SMN2 gene; or wherein optionally the patient has 3-5 copies of the SMN2 gene, wherein optionally the patient has ambulatory SMA, wherein further optionally the ambulatory SMA is type 4 SMA.

[0228] The patient has SMA (e.g., any type of SMA) and is up to two years old, wherein optionally the patient has been treated with SMN therapy, wherein further optionally the SMN therapy includes an SMN2 upregulator (e.g., nusindrone, risperidone, and / or sovaroprevir) or SMN1 gene therapy.

[0229] The patient has type 1 SMA with up to three copies of the SMN2 gene, wherein optionally the patient has been treated with SMN therapy, wherein further optionally the SMN therapy comprises an SMN2 upregulator (e.g., nusinirvana, risopram, and / or sovaprevir) or SMN1 gene therapy.

[0230] The patient has symptoms of SMA.

[0231] The patient had presymptomatic SMA.

[0232] Patients are identified as carriers of one or more SMA mutations but are asymptomatic (presymptomatic).

[0233] The patient has not been treated with SMN-targeted therapy.

[0234] The patient is being treated with (is receiving) or has been treated with an SMN-targeted therapy, wherein optionally, the SMN-targeted therapy is a gene therapy, a splicing modifier, or a combination thereof, wherein further optionally, the splicing modifier is a nucleic acid-based agent or a low molecular weight compound that modifies SMN2 splicing.

[0235] The patient is being treated with (is receiving) or has been treated with an SMN-targeted therapy, wherein optionally, the SMN-targeted therapy is a gene therapy, a splicing modifier, or a combination thereof, wherein further optionally, the splicing modifier is a nucleic acid-based agent or a low molecular weight compound that modifies SMN2 splicing; and wherein the patient initiated the SMN-targeted therapy before the age of five years.

[0236] The patient is being treated with (is receiving) or has been treated with an SMN-targeted therapy, wherein optionally, the SMN-targeted therapy is a gene therapy, a splicing modifier, or a combination thereof, wherein further optionally, the splicing modifier is a nucleic acid-based agent or a low molecular weight compound that modifies SMN2 splicing, and wherein the patient initiated the SMN-targeted therapy at age five years or older.

[0237] Patients had been receiving SMN-targeted therapy for at least 12 months at the time of initiation of apilectomycin therapy (e.g., before receiving the first dose of apilectomycin).

[0238] Patients had been receiving SMN-targeted therapy for at least 15 months at the time of initiation of apilectomycin therapy (e.g., before receiving the first dose of apilectomycin).

[0239] Patients had been receiving SMN-targeted therapy for at least 24 months at the time of initiation of apilectomycin therapy (e.g., before receiving the first dose of apilectomycin).

[0240] Patients were five years of age or younger when apilectomycin therapy was initiated.

[0241] Patients were two years of age or younger when apilectomycin therapy was initiated.

[0242] Patients were six weeks of age or younger when apilectomycin therapy was initiated.

[0243] Patients received their first dose of apilectomycin before the age of five years.

[0244] The patient has a baseline HFMSE score of at least 10, eg, at least 13, eg, a score of 13-39 (eg, no greater than 39).

[0245] In some embodiments, the present disclosure provides for the therapeutic use of apilectomycin for treating SMA in a patient who is 2-12 years of age and has received at least six months of SMN upregulator / corrector therapy (e.g., nusindrone, risperidone, and / or sovaprevir) prior to starting apilectomycin treatment, wherein the apilectomycin treatment comprises intravenous administration of a composition comprising apilectomycin at 10 mg / kg or 20 mg / kg, for example, once every four weeks or once a month. In some embodiments, the patient starts SMN upregulator / corrector therapy before the age of five. In some embodiments, the patient starts SMN upregulator / corrector therapy after the age of five. In some embodiments, the present disclosure provides for the therapeutic use of apilectomycin for treating SMA in a patient who is 2-12 years of age and has received at least six months of risperidone prior to starting apilectomycin treatment, wherein the apilectomycin treatment comprises intravenous administration of a composition comprising apilectomycin at 10 mg / kg or 20 mg / kg, once every four weeks or once a month. In some embodiments, the present disclosure provides for the therapeutic use of apilectomycin for the treatment of SMA in patients aged 2-12 years who have received nusinirvana, risperidone, and / or sovaprevir for at least 10 months prior to initiating apilectomycin treatment, wherein the apilectomycin treatment comprises intravenous administration of a composition comprising 10 mg / kg or 20 mg / kg of apilectomycin once every four weeks or once monthly.

[0246] In some embodiments, the present disclosure provides for the therapeutic use of apilectomycin for treating SMA in a patient who is 5-12 years of age and has received at least six months of SMN upregulator / corrector therapy (e.g., nusindrone, risperidone, and / or sovaprevir) prior to starting apilectomycin treatment, wherein apilectomycin treatment comprises intravenous administration of a composition comprising apilectomycin at 10 mg / kg or 20 mg / kg, for example, once every four weeks or once a month. In some embodiments, the patient starts SMN upregulator / corrector therapy before the age of five. In some embodiments, the patient starts SMN upregulator / corrector therapy after the age of five. In some embodiments, the present disclosure provides for the therapeutic use of apilectomycin for treating SMA in a patient who is 5-12 years of age and has received at least six months of risperidone prior to starting apilectomycin treatment, wherein apilectomycin treatment comprises intravenous administration of a composition comprising apilectomycin at 10 mg / kg or 20 mg / kg, once every four weeks or once a month. In some embodiments, the present disclosure provides for the therapeutic use of apilectomycin for the treatment of SMA in patients aged 5-12 years who have received nusinirvana, risperidone, and / or sovaprevir for at least 10 months prior to initiating apilectomycin treatment, wherein the apilectomycin treatment comprises intravenous administration of a composition comprising 10 mg / kg or 20 mg / kg of apilectomycin once every four weeks or once monthly (e.g., for at least 52 weeks).

[0247] In some embodiments, the present disclosure provides for the therapeutic use of apilectomycin in treating a patient with late-onset (e.g., type 2 or type 3) SMA who has received at least six months of SMN-targeted therapy (e.g., SMN upregulator / corrector therapy, such as nusindrone, risopram, and / or sovaprevir) prior to starting apilectomycin treatment, wherein apilectomycin treatment comprises intravenous administration of a composition comprising 10 mg / kg or 20 mg / kg of apilectomycin once every four weeks or once a month for at least 52 weeks. In some embodiments, the patient has received at least six months of risopram prior to starting apilectomycin treatment. In some embodiments, the patient has received at least 10 months of nusindrone, risopram, and / or sovaprevir prior to starting apilectomycin treatment. In some embodiments, the subject is 2-21 years old. In some embodiments, the patient starts SMN-targeted therapy before the age of five. In some embodiments, the patient starts SMN-targeted therapy after the age of five. In some embodiments, the subject has not previously received sovaroprevir or apivolumab.

[0248] In some embodiments, the present disclosure provides for the therapeutic use of apivolumab for the treatment of SMA in patients aged 13-21 years who have received risopram for at least six months prior to starting apivolumab treatment and have not previously received sovaprevir or apivolumab, wherein apivolumab treatment comprises intravenous administration of a composition comprising 10 mg / kg or 20 mg / kg of apivolumab once every four weeks or once monthly, for example, for at least 52 weeks. In some embodiments, the patient starts risopram treatment before the age of five. In some embodiments, the patient starts risopram treatment after the age of five.

[0249] In some embodiments, the present disclosure provides for the therapeutic use of apivolumab to treat SMA in patients aged 13-21 years who have received nusindrone, risopram, and / or sovaprevir for at least 10 months prior to starting apivolumab treatment and have not previously received sovaprevir or apivolumab, wherein apivolumab treatment comprises intravenous administration of a composition comprising 10 mg / kg or 20 mg / kg of apivolumab once every four weeks or once monthly, for example, for at least 52 weeks. In some embodiments, the patient starts treatment with nusindrone, risopram, and / or sovaprevir before the age of five. In some embodiments, the patient starts treatment with nusindrone, risopram, and / or sovaprevir after the age of five.

[0250] In some embodiments, the present disclosure provides for the therapeutic use of apilectomycin for the treatment of SMA in patients five years of age or younger, wherein the patient has not received an SMN-targeted therapy (e.g., an SMN upregulator / corrector therapy, such as nusinsen, risopram, or sovaprevir) prior to starting apilectomycin treatment, wherein the treatment comprises concurrent (e.g., simultaneous, separate, or sequential) administration of a composition comprising apilectomycin and a composition comprising an SMN-targeted therapy (e.g., an SMN upregulator / corrector therapy, such as nusinsen, risopram, or sovaprevir). In some embodiments, the composition comprising apilectomycin is administered intravenously. In some embodiments, the composition comprising apilectomycin is administered once every four weeks or once a month.

[0251] In some embodiments, the present disclosure provides for the therapeutic use of apilectomycin for treating SMA in a patient 2 years of age or younger (e.g., newborn to 24 months of age), wherein the patient has not received an SMN upregulator / corrector therapy prior to initiating apilectomycin treatment, wherein the treatment comprises concurrent (e.g., simultaneously, separately, or sequentially) administration of a composition comprising apilectomycin and a composition comprising an SMN-targeted therapy (e.g., an SMN upregulator / corrector therapy such as nusindrone, risperidone, or sovaprevir).

[0252] In some embodiments, the present disclosure provides for the therapeutic use of apilectomycin for the treatment of SMA in patients six years of age or younger (e.g., newborn to six weeks of age), wherein the patient has not received an SMN-targeted therapy (e.g., an SMN upregulator / corrector therapy) prior to starting apilectomycin treatment, wherein the treatment comprises concurrent (e.g., simultaneously, separately, or sequential) administration of a composition comprising apilectomycin and a composition comprising an SMN-targeted therapy (e.g., an SMN upregulator / corrector therapy, such as nusinsen, risperidone, or sovaprevir). In some embodiments, the patient has presymptomatic SMA. In some embodiments, the patient has two copies of the SMN2 gene. In some embodiments, the composition comprising apilectomycin is administered intravenously. In some embodiments, the composition comprising apilectomycin is administered once every four weeks or once a month.

[0253] In some embodiments, the present disclosure provides therapeutic uses of a myostatin selective inhibitor (e.g., apitoquumab, GYM329, or trogelutumab) for treating pre-symptomatic SMA in human patients. In some embodiments, the patient has not previously received an SMN up-regulator / corrector therapy (e.g., SMN1 gene therapy) prior to starting treatment with a myostatin selective inhibitor. In some embodiments, the patient has previously received or is receiving an SMN up-regulator / corrector therapy (e.g., SMN1 gene therapy). In some embodiments, treatment comprises co-administration (e.g., simultaneously, separately, or sequentially) of a composition comprising a myostatin selective inhibitor (e.g., apitoquumab, GYM329, or trogelutumab) and a composition comprising an SMN up-regulator / corrector therapy (e.g., SMN1 gene therapy). In some embodiments, the patient has two copies of the SMN2 gene. In some embodiments, a composition comprising a myostatin selective inhibitor (e.g., apitoquumab, GYM329, or trogelutumab) is administered intravenously. In some embodiments, a composition comprising a myostatin selective inhibitor (e.g., apilectumab, GYM329, or trogelutumab) is administered once every four weeks or once a month. In some embodiments, the myostatin selective inhibitor selectively binds to pre-latent myostatin. In some embodiments, the myostatin selective inhibitor is apilectumab.

[0254] In some embodiments, the present disclosure provides therapeutic uses of a myostatin selective inhibitor (e.g., apitoquumab, GYM329, or trogelutumab) for treating SMA in a patient who is five years of age or younger. In some embodiments, the patient has not previously received an SMN upregulator / corrector therapy (e.g., SMN1 gene therapy) prior to starting treatment with a myostatin selective inhibitor. In some embodiments, the patient has previously received or is currently receiving an SMN upregulator / corrector therapy (e.g., SMN1 gene therapy). In some embodiments, the patient is administered an SMN upregulator / corrector therapy (e.g., SMN1 gene therapy) at age five or younger. In some embodiments, the treatment of SMA comprises co-administration (e.g., simultaneously, separately, or sequentially) of a composition comprising a myostatin selective inhibitor (e.g., apitoquumab, GYM329, or trogelutumab) and a composition comprising an SMN upregulator / corrector therapy (e.g., SMN1 gene therapy). In some embodiments, a composition comprising a myostatin selective inhibitor (e.g., apivolumab, GYM329, or trogeluzumab) is administered intravenously. In some embodiments, the patient has presymptomatic SMA. In some embodiments, the patient has two copies of the SMN2 gene. In some embodiments, a composition comprising a myostatin selective inhibitor (e.g., apivolumab, GYM329, or trogeluzumab) is administered once every four weeks or once per month. In some embodiments, the myostatin selective inhibitor selectively binds to pro / latent myostatin. In some embodiments, the myostatin selective inhibitor is apivolumab.

[0255] In some embodiments, the present disclosure provides therapeutic uses of a myostatin selective inhibitor (e.g., apivolumab, GYM329, or trogeluzumab) for treating SMA in a patient who is two years of age or younger (e.g., newborn to 24 months old). In some embodiments, the patient has not previously received an SMN upregulator / corrector therapy (e.g., SMN1 gene therapy) prior to starting treatment with a myostatin selective inhibitor. In some embodiments, the patient has previously received or is currently receiving an SMN upregulator / corrector therapy (e.g., SMN1 gene therapy). In some embodiments, the patient is administered an SMN upregulator / corrector therapy (e.g., SMN1 gene therapy) when the patient is two years of age or younger (e.g., newborn to 24 months old). In some embodiments, treatment comprises co-administration (e.g., simultaneously, separately, or sequentially) of a composition comprising a myostatin selective inhibitor (e.g., apivolumab, GYM329, or trogeluzumab) and a composition comprising an SMN upregulator / corrector therapy (e.g., SMN1 gene therapy). In some embodiments, the patient has presymptomatic SMA. In some embodiments, the patient has two copies of the SMN2 gene. In some embodiments, a composition comprising a myostatin selective inhibitor (e.g., apivolumab, GYM329, or trogelutumab) is administered intravenously. In some embodiments, a composition comprising a myostatin selective inhibitor (e.g., apivolumab, GYM329, or trogelutumab) is administered once every four weeks or once per month. In some embodiments, the myostatin selective inhibitor selectively binds to pro / latent myostatin. In some embodiments, the myostatin selective inhibitor is apivolumab.

[0256] In some embodiments, the present disclosure provides for the therapeutic use of a myostatin selective inhibitor (e.g., apitoquumab, GYM329, or trogelutumab) for treating SMA in a patient who is six weeks old or younger (e.g., newborn to six weeks old), wherein the treatment comprises co-administration (e.g., simultaneously, separately, or sequentially) of a composition comprising a myostatin selective inhibitor (e.g., apitoquumab, GYM329, or trogelutumab) and a composition comprising an SMN upregulator / corrector therapy (e.g., SMN1 gene therapy). In some embodiments, the patient has not previously received an SMN upregulator / corrector therapy (e.g., SMN1 gene therapy) prior to starting treatment with the myostatin selective inhibitor. In some embodiments, the patient has previously received or is currently receiving an SMN upregulator / corrector therapy (e.g., SMN1 gene therapy). In some embodiments, the patient has presymptomatic SMA. In some embodiments, the patient has two copies of the SMN2 gene. In some embodiments, the composition comprising a myostatin selective inhibitor (e.g., apivolumab, GYM329, or trogelutumab) is administered intravenously. In some embodiments, the composition comprising a myostatin selective inhibitor (e.g., apivolumab, GYM329, or trogelutumab) is administered once every four weeks or once a month. In some embodiments, the myostatin selective inhibitor selectively binds to pre-latent myostatin. In some embodiments, the myostatin selective inhibitor is apivolumab.

[0257] In some embodiments, the present disclosure provides a myostatin selective inhibitor and SMN upregulator / corrector therapy (e.g., SMN1 gene therapy) for use in treating presymptomatic SMA in a patient, wherein the treatment comprises administering a myostatin selective inhibitor and SMN upregulator / corrector therapy (e.g., SMN1 gene therapy) to the presymptomatic patient in an amount effective to treat SMA. In some embodiments, the patient has two copies of the SMN2 gene, and / or wherein the patient is six weeks old or younger when the SMN upregulator / corrector therapy (e.g., SMN1 gene therapy) is administered. In some embodiments, the myostatin selective inhibitor is apilectomycin, GYM329, or trogelutumab.

[0258] In some embodiments, the present disclosure provides a myostatin selective inhibitor and SMN upregulator / corrector therapy (e.g., SMN1 gene therapy) for use in treating presymptomatic SMA in a patient, wherein the treatment comprises administering a myostatin selective inhibitor and SMN upregulator / corrector therapy (e.g., SMN1 gene therapy) to the presymptomatic patient in amounts effective to treat SMA, wherein the patient has two copies of the SMN2 gene, wherein at the time of administration of the SMN upregulator / corrector therapy (e.g., SMN1 gene therapy), the patient is six weeks of age or younger, and wherein the myostatin selective inhibitor is apilectomy, GYM329, or trogeluzumab.

[0259] In some embodiments, the present disclosure provides a myostatin selective inhibitor for use in treating presymptomatic SMA in a patient, wherein the treatment comprises administering to the presymptomatic patient a myostatin selective inhibitor in an amount effective to treat SMA. In some embodiments, the patient has two copies of the SMN2 gene. In some embodiments, the patient is administered an SMN upregulator / corrector therapy (e.g., SMN1 gene therapy) at six weeks of age or younger. In some embodiments, the myostatin selective inhibitor is apilectumab, GYM329, or trogeluzumab.

[0260] In some embodiments, the present disclosure provides a myostatin selective inhibitor for use in treating presymptomatic SMA in a patient, wherein the treatment comprises administering the myostatin selective inhibitor to the presymptomatic patient in an amount effective to treat SMA, wherein the patient has two copies of the SMN2 gene, wherein the patient is administered an SMN upregulator / corrector therapy (e.g., SMN1 gene therapy) at six weeks of age or younger, and wherein the myostatin selective inhibitor is apilectumab, GYM329, or trogeluzumab.

[0261] In some embodiments, the present disclosure provides for the therapeutic use of an SMN upregulator / corrector therapy (e.g., SMN1 gene therapy) for the treatment of presymptomatic SMA in a human patient, wherein the treatment comprises co-administration (e.g., simultaneously, separately, or sequentially) of a composition comprising an SMN upregulator / corrector therapy (e.g., SMN1 gene therapy) and a composition comprising a myostatin selective inhibitor (e.g., apivolumab, GYM329, or trogelumab). In some embodiments, prior to starting the SMN upregulator / corrector therapy, the patient had not previously received a myostatin selective inhibitor, such as apivolumab, GYM329, or trogelumab. In some embodiments, the patient had previously received or is currently receiving a myostatin selective inhibitor, such as apivolumab, GYM329, or trogelumab. In some embodiments, the patient was administered an SMN upregulator / corrector therapy (e.g., SMN1 gene therapy) at age five or younger. In some embodiments, the patient is administered an SMN upregulator / corrector therapy (e.g., SMN1 gene therapy) at age two years or younger (e.g., newborn to 24 months old). In some embodiments, the patient is administered an SMN upregulator / corrector therapy (e.g., SMN1 gene therapy) at age six weeks or younger (e.g., newborn to six weeks old). In some embodiments, the patient has two copies of the SMN2 gene. In some embodiments, a composition comprising a myostatin selective inhibitor (e.g., apivolumab, GYM329, or trogelutumab) is administered intravenously. In some embodiments, a composition comprising a myostatin selective inhibitor (e.g., apivolumab, GYM329, or trogelutumab) is administered once every four weeks or once a month. In some embodiments, the myostatin selective inhibitor selectively binds to pre-latent myostatin. In some embodiments, the myostatin selective inhibitor is apivolumab.

[0262] In some embodiments, myostatin selective inhibitors are used to treat SMA in patients two months of age or older who are being treated with SMN therapy (such as nusindrocin, risperidone, or sovaprevir). In some embodiments, apilectomycin is administered as an adjunct to SMN upregulator therapy (including nusindrocin, risperidone, or sovaprevir).

[0263] In some embodiments, a myostatin selective inhibitor is used to treat presymptomatic SMA in a patient who has up to three copies (e.g., two copies, three copies) of the SMN2 gene, or who has been diagnosed with SMA type 1, wherein the patient has received or is currently receiving gene therapy, such as sovaraprevir. Optionally, the patient is six weeks old or younger. Further optionally, the patient weighs between 2.6 kg and 21.0 kg.

[0264] In some embodiments, the present disclosure provides an SMN1 upregulator / corrector therapy (e.g., SMN1 gene therapy) for use in treating presymptomatic SMA in a patient, wherein the treatment comprises administering an SMN1 upregulator / corrector therapy (e.g., SMN1 gene therapy) to the presymptomatic patient in an amount effective to treat SMA, wherein the patient is administered the SMN1 upregulator / corrector therapy (e.g., SMN1 gene therapy) at six weeks of age or younger, wherein the patient is further treated with a myostatin selective inhibitor, and wherein the myostatin selective inhibitor is apilectomy, GYM329, or trogeluzumab.

[0265] The data disclosed herein further support the concept that myostatin inhibitors help improve SMA treatment in patients receiving SMN therapy. In particular, the data suggest that subgroups of patients experiencing or suffering from certain types of disease-related symptoms may be particularly benefited from myostatin inhibitor therapy, which points to considerations for patient selection. Certain SMA patient subgroups that may particularly benefit from myostatin inhibitors include, but are not limited to, the following patient cohorts exhibiting specified disease-related symptoms: patients with muscle weakness and / or tightness; patients with severe fatigue (e.g., as assessed by art-recognized measurement tools such as PROMIS); patients with difficulty or impairment of bulbar function (e.g., coughing, difficulty swallowing / eating, difficulty chewing or smiling); patients susceptible to respiratory infections; and / or patients with difficulty or disordered emptying (e.g., urinary and / or bowel movements, urgency and frequency). Therefore, in some embodiments, a myostatin inhibitor is used to treat SMA in a patient, wherein the treatment comprises administering a myostatin inhibitor to treat SMA, wherein the patient has bulbar dysfunction, wherein optionally, the patient has difficulty coughing, difficulty swallowing or eating, and / or difficulty chewing or smiling. In some embodiments, the myostatin inhibitor is used to treat SMA in a patient, wherein the treatment comprises administering the myostatin inhibitor to treat SMA, wherein the patient is susceptible to respiratory infections. In some embodiments, the myostatin inhibitor is used to treat SMA in a patient, wherein the treatment comprises administering the myostatin inhibitor to a patient suffering from severe fatigue, wherein the severity of fatigue is optionally assessed by PROMIS. In some embodiments, the myostatin inhibitor is used to treat SMA in a patient, wherein the treatment comprises administering the myostatin inhibitor to a patient suffering from difficult or impaired emptying (e.g., urinary and / or frequent bowel movements).

[0266] Therefore, the present disclosure provides patient selection considerations intended to help identify SMA patients who are more likely to benefit from muscle enhancement therapies (such as myostatin inhibitors). According to the present disclosure, myostatin inhibitors are used to treat SMA in patients receiving SMN therapy, wherein the patient suffers from muscle weakness / tightness, fatigue, bulbar dysfunction (optionally coughing, and / or difficulty swallowing or eating), and / or emptying disorders (optionally, urgent and frequent urination and / or defecation). In some embodiments, myostatin inhibitors include agents that inhibit myostatin, GDF11, and activin A. In some embodiments, myostatin inhibitors include agents that inhibit myostatin and GDF11 but do not inhibit activin A. In preferred embodiments, myostatin inhibitors are agents that selectively inhibit myostatin (i.e., myostatin selective inhibitors) that do not bind to or inhibit GDF11 or activin A. Myostatin selective inhibitors include neutralizing antibodies or antigen-binding fragments thereof that selectively bind to myostatin but not to GDF11 or activin A, as well as antibodies or antigen-binding fragments thereof that bind to promyostatin / latent myostatin and thereby inhibit activation of mature myostatin. The latter include, for example, apivolumab (SRK-015), GYM329 (RO7204239), variants thereof, or antibodies that cross-block or cross-compete for antigen binding with apivolumab or GYM329. In the most preferred embodiment, the myostatin selective inhibitor is apivolumab. Additional indications

[0267] The data presented herein suggest that the disclosed apilectomycin treatment regimens (e.g., including dose selection) may provide clinical benefit to human patients other than SMA patients. Apilectomycin may provide clinical benefit to human patients diagnosed with other indications that share certain attributes of SMA. These attributes include one or more of the following criteria, such as: a disease with a relatively young patient population, a disease with preserved muscle structure or function, a disease that affects fast-twitch fibers, and a disease that relies on the availability of established endpoints for fast-twitch fibers.

[0268] In addition to SMA, additional indications that may benefit from treatment with the antibodies disclosed herein (e.g., apivolumab) include, but are not limited to, dystrophies such as Becker muscular dystrophy, Becker muscular dystrophy with dystrophin mini-gene therapy, Duchenne muscular dystrophy, Duchenne muscular dystrophy with dystrophin mini-gene therapy, facioscapulohumeral muscular dystrophy (FSHD), and other muscular dystrophies, as well as Pompe disease, Pompe disease with enzyme replacement therapy (including but not limited to alglucosidase α (Lumizyme) and efavirenz α (Nexviazyme), late-onset Pompe disease, post-cancer muscle recovery, and glucocorticoid-induced myopathy (e.g., in a subset of patients who cannot interrupt steroid therapy). Becker muscular dystrophy may be particularly suitable for treatment with the antibodies disclosed herein (e.g., apivolumab). Patients with Becker muscular dystrophy typically have higher levels of circulating myostatin compared to patients with Duchenne muscular dystrophy (see, e.g., Burch et al. (2017) J Neurol. 264(3):541-553; Mariot et al. (2017) Nat Commun. 8:1859). In other embodiments, the indication for treatment is amyotrophic lateral sclerosis (ALS). In other embodiments, the indication for treatment is post-cancer muscle recovery, such as post-cancer muscle recovery in pediatric patients (because some children may develop severe muscle wasting due to chemotherapy). The antibodies disclosed herein (e.g., apilectomycin) can be used as monotherapy or as an add-on therapy to provide a muscle-targeted approach to enhance other stabilization therapies (e.g., therapies such as gene therapy for Duchenne muscular dystrophy or enzyme replacement therapy for lysosomal storage disorders). Dose selection and administration

[0269] In various embodiments of the methods, uses, and compositions disclosed herein, an effective amount of an anti-promyostatin / latent myostatin antibody (e.g., apilectumab) is administered to a human subject in need of treatment via intravenous administration (e.g., by continuous infusion over a period of time).

[0270] In some embodiments, apivolumab is administered to the patient as a weight-based dose, i.e., the dose depends on the patient's weight. In some embodiments, a suitable dose of apivolumab includes greater than 2 and up to 20 mg / kg, optionally about 5, 10, 15, or 20 mg / kg. In some embodiments, the therapeutic dose of apivolumab is 10 mg / kg. In some embodiments, the therapeutic dose of apivolumab is 20 mg / kg. In some embodiments, a dose greater than 20 mg / kg can be used while maintaining a similar safety profile, although the need for higher doses may be reduced in view of the surprisingly good therapeutic and PK profiles (e.g., 20 mg / kg and 2 mg / kg, respectively).

[0271] PK analysis of apivolumab showed a correlation between drug clearance and age. These data suggest that younger patients (lower body weight) clear apivolumab more slowly than older patients (heavier body weight). This finding may point to appropriate intermediate dose selection, such as 5 mg / kg, 7.5 mg / kg, 10 mg / kg, 12 mg / kg, 15 mg / kg, etc. Apivolumab exhibited linear pharmacodynamics in both healthy volunteers and subjects receiving apivolumab, with a mean terminal half-life of 23-40 days.

[0272] Target engagement analysis in the 6- and 12-month studies demonstrated that 20 mg / kg of apilectomycin achieved target saturation, while 2 mg / kg of apilectomycin showed partial target engagement. In some embodiments, because target saturation was achieved at 20 mg / kg, a lower dose, e.g., 10 mg / kg, was used. Target engagement analysis after 24 months was consistent with earlier studies and further demonstrated that apilectomycin target engagement was associated with improved motor function. When normalized for the age at which subjects began treatment, both the amount of latent myostatin and the fold change in latent myostatin provided pharmacodynamic markers of improved motor function.

[0273] In some embodiments, a suitable dose of apivolumab is 20 mg / kg. In some embodiments, a suitable dose of apivolumab is 10 mg / kg. In some embodiments, apivolumab is administered intravenously to the patient at 5 mg / kg, 7.5 mg.kg, 10 mg / kg, or 12 mg / kg every four weeks or monthly.

[0274] In some embodiments, apivolumab is administered to patients at a dose of 20 mg / kg. In some embodiments, apivolumab may be administered to patients at a dose exceeding 20 mg / kg, for example, where the dose is up to 30 mg / kg, for example, 25 mg / kg, due to its favorable safety profile when administered at a dose of 20 mg / kg. In some embodiments, apivolumab is administered to patients at a dose exceeding 20 mg / kg (e.g., about 25 mg / kg, about 30 mg / kg). In some embodiments, apivolumab is administered intravenously to patients at a dose of 10-20 mg / kg, every four weeks or every month.

[0275] In some embodiments, apivolumab is initially administered to the patient at 2 mg / kg, and if additional motor improvement is needed, the dose is then increased to a dose of at least 10 mg / kg (e.g., 10 mg / kg, 15 mg / kg, 20 mg / kg). In some embodiments, the dose is increased to at least 10 mg / kg after the patient has been treated with 2 mg / kg apivolumab for at least four months. In some embodiments, the dose is increased to at least 10 mg / kg after the patient has been treated with 2 mg / kg apivolumab for at least six months. In some embodiments, the dose is increased to at least 10 mg / kg after the patient has been treated with 2 mg / kg apivolumab for at least 12 months. In some embodiments, the dose is increased to at least 10 mg / kg after the patient has been treated with 2 mg / kg apivolumab for at least 24 months. In some embodiments, increasing the dose of apilectomycin from 2 mg / kg to at least 10 mg / kg (e.g., 10 mg / kg, 15 mg / kg, 20 mg / kg) produces a dose response, e.g., as determined by the subject's latent myostatin concentration. In some embodiments, motor improvement is measured by RULM. In some embodiments, motor improvement is measured by RHS. In some embodiments, motor improvement is measured by HFMSE.

[0276] In some embodiments, apilectomycin is administered to a patient about once every four weeks, once a month, etc. Such antibodies can be administered by intravenous injection / infusion (e.g., by intravenous infusion) or another suitable route of administration (e.g., subcutaneous (e.g., under the skin) or intrathecal (e.g., within the spinal cord)). Similarly, SMN upregulators (e.g., splicing modifiers) can be administered orally (e.g., by mouth), or another suitable route of administration.

[0277] In some embodiments, the subject has received an SMN upregulator prior to administration of apivolumab. In some embodiments, the subject receives an SMN upregulator concurrently with administration of apivolumab. In some embodiments, the subject will receive an SMN upregulator after administration of apivolumab.

[0278] In some embodiments, a subject receiving an SMN upregulator is administered apilectomycin at least 24 hours (e.g., at least 36 hours, at least 48 hours, or longer) prior to a dose (e.g., a maintenance dose) of the SMN upregulator (e.g., nusinsen, risapram, and / or sovaprevir). In some embodiments, a subject receiving an SMN upregulator is administered apilectomycin at least 14 days (e.g., at least 21 days, or longer) after a dose (e.g., a maintenance dose) of the SMN upregulator (e.g., nusinsen, risapram, and / or sovaprevir).

[0279] In some embodiments, the subject receives an SMN upregulator within six months of administration of apivolumab. In some embodiments, the subject receives an SMN upregulator within three months of administration of apivolumab. In some embodiments, the subject receives an SMN upregulator within six months, five months, four months, three months, two months, or one month of administration of apivolumab. In some embodiments, the subject receives an SMN upregulator within four weeks, three weeks, two weeks, or one week of administration of apivolumab. In some embodiments, the subject receives an SMN upregulator on the same day of administration of apivolumab.

[0280] In some embodiments, the subject is expected to receive an SMN upregulator within six months of administration of apivolumab. In some embodiments, the subject is expected to receive an SMN upregulator within three months of administration of apivolumab. In some embodiments, the subject is expected to receive an SMN upregulator within six months, five months, four months, three months, two months, or one month of administration of apivolumab. In some embodiments, the subject is expected to receive an SMN upregulator within four weeks, three weeks, two weeks, or one week of administration of apivolumab.

[0281] In some embodiments, the SMN upregulator is an antisense nucleotide and is administered to the central nervous system of the subject via intrathecal injection. In some embodiments, the antisense nucleotide is administered to the subject every few months, for example, every month, every two months, every three months, every four months, every five months, every six months, or every 12 months. In other embodiments, initial treatment may involve more frequent dosing, followed by less frequent maintenance doses.

[0282] In some embodiments, the SMN upregulator is a small molecule and is administered orally to the subject. In some embodiments, the small molecule is administered to the subject daily. In other embodiments, the small molecule is administered to the subject weekly, biweekly, or monthly.

[0283] In some embodiments, the SMN upregulator is a gene therapy and is administered via intravenous injection. In some embodiments, the SMN upregulator is a gene therapy and is administered via intrathecal injection. In some embodiments, initial treatment may include more frequent dosing followed by less frequent maintenance doses. To avoid an inappropriate immune response to the gene therapy, less frequent maintenance doses may be preferred.

[0284] In some embodiments, apitalizumab is administered to the subject via intravenous administration (e.g., by intravenous infusion). In some embodiments, apitalizumab is administered to the subject once every four weeks or once a month. In some embodiments, initial treatment may involve more frequent administration, followed by less frequent maintenance doses. In some embodiments, apitalizumab may initially be administered at a higher dose (e.g., a loading dose), followed by one or more lower doses (e.g., one or more maintenance doses). In some embodiments, one or more initial doses of apitalizumab may be administered at 20 mg / kg, followed by one or more lower doses (e.g., 15 mg / kg, 10 mg / kg, 5 mg / kg, 2 mg / kg, or 1 mg / kg), for example, four weeks or one month after administration of the initial 20 mg / kg dose, for example, wherein once every four weeks or once a month thereafter, or one or more lower doses are administered at intervals longer than for the loading dose.

[0285] In some embodiments, the SMA therapy comprises intravenous administration of greater than 2 mg / kg and up to 20 mg / kg of apivolumab every four weeks or monthly. In some embodiments, the SMA therapy comprises intravenous administration of about 20 mg / kg of apivolumab every four weeks or monthly. In some embodiments, the SMA therapies disclosed herein (e.g., SMA therapies comprising apivolumab) can achieve disease stabilization, such that the patient's motor function is maintained over time, or in other words, prevented from declining, which is contrary to the natural history of the disease (which predicts disease progression over time). In some embodiments, a net zero change in motor function score relative to an appropriate baseline reflects disease stabilization.

[0286] In some embodiments, SMA therapy comprises administering greater than 2 mg / kg and up to 20 mg / kg of apivolumab intravenously every four weeks or monthly. In some embodiments, SMA therapy comprises administering about 20 mg / kg of apivolumab intravenously every four weeks or monthly. In some embodiments, SMA therapy comprises administering a therapeutically effective amount of apivolumab such that the administration is sufficient to increase the subject's motor function by at least one milestone according to the WHO motor development milestones. In some embodiments, SMA therapy comprises administering a therapeutically effective amount of apivolumab such that the administration is sufficient to increase the subject's motor function by one, two, or three milestones according to the WHO motor development milestones. In some embodiments, the WHO motor development milestones include one or more of the ability to walk independently, the ability to stand independently, standing with assistance, crawling on hands and knees, and / or walking with assistance.

[0287] In some embodiments, the SMA therapies disclosed herein (e.g., SMA therapies comprising apivolumab) can help maintain the disease state in a patient population receiving apivolumab compared to a control group that did not receive apivolumab. Maintenance of the disease state refers to preventing further deterioration of the affected muscles in these patients, as assessed by changes in motor function over time. In some embodiments, treatment can slow disease progression, for example, as assessed by a slower rate of change in disease function compared to a suitable baseline (e.g., untreated patients). Therefore, even in the absence of improvement in motor function test scores, apivolumab may also provide clinical benefits by combating the progression of the disease. Therefore, compared to a control group, this clinical benefit may exist for a longer observation time when the patient population treated with apivolumab maintains the previous test score or shows a slower rate of score decline over time. In some embodiments, patients or patient populations receiving or requiring treatment with apivolumab can be compared with control patients or patient populations. In some embodiments, the control patients or patient populations are patients or patient populations that have not received apivolumab.

[0288] In some embodiments, an SMA therapy disclosed herein (e.g., an SMA therapy comprising apilectomycin) can slow disease progression, for example, by delaying the decline in motor function (as measured by a decrease in HFMSE, RHS, MFM, MyoGrip, or MyoPinch scores), and / or by delaying the transition from ambulatory to nonambulatory, delaying the need for respiratory assistance or intervention, etc.

[0289] Based on the surprising degree of clinical benefit achieved by selective inhibition of myostatin in human patients as demonstrated herein, it is expected that different myostatin selective inhibitors (in addition to apilectumab) can be used to treat SMA or other muscle disorders. Accordingly, the present disclosure includes myostatin selective inhibitors for use in treating a muscle disorder (such as SMA) in a human subject, wherein optionally, the subject is further treated with a motor neuron-directed therapy, wherein further optionally, the motor neuron-directed therapy comprises an SMN upregulator therapy (such as an SMN2 upregulator therapy) and an SMN1 gene therapy. Biological effects of treatment

[0290] The SMA therapies disclosed herein (eg, SMA therapies comprising apilectumab) may be suitable for treating any form of SMA in human subjects, particularly late-onset forms of SMA.

[0291] Patient populations that may benefit from the therapies described herein include patients with nonambulatory SMA and patients with ambulatory SMA. In some embodiments, the SMA therapies disclosed herein are considered to be applicable to nonambulatory forms of SMA (e.g., Type 2) and nonambulatory Type 3 SMA. In other embodiments, the SMA therapies disclosed herein are considered to be applicable to ambulatory forms of SMA, such as ambulatory Type 3 SMA.

[0292] Genotype-based diagnosis allows the identification of patients carrying SMA gene mutations, including those who may be presymptomatic (not showing an obvious disease phenotype). In some embodiments, subjects suitable for treatment with the SMA therapies disclosed herein have a directed diagnosis of an SMN1 mutation (e.g., a chromosome-directed diagnosis of 5q SMA). In some embodiments, in addition to a diagnosis based on motor phenotype, the subject is also diagnosed with 5q SMA. In some embodiments, subjects suitable for treatment with the SMA therapies disclosed herein do not have an SMN1 mutation (e.g., a chromosome-directed diagnosis of 5q SMA). In some embodiments, the subject is not diagnosed with 5q SMA. In some embodiments, the subject is diagnosed with non-5q SMA.

[0293] In some embodiments, the subject with SMA is two years old or older. In some embodiments, the subject with SMA is 2 to 12, 5 to 21, 13 to 21 or 2 to 21 years old. In some embodiments, the subject with SMA is under two years old. The clinical effects of anti-myostatin / latent myostatin antibodies (e.g., apitalin) administered alone or in combination with SMN upregulators can be monitored and / or evaluated in various ways. Exemplary such biological effects are provided herein. Biological effects beneficial to the subject can be achieved by administering anti-myostatin / latent myostatin antibodies (e.g., apitalin) (as a monotherapy or in combination with SMN upregulators). In some embodiments, apitalin, as a monotherapy or in combination with SMN upregulators, is administered in an amount effective to cause one or more of the following biological effects.

[0294] The ability of the functional scale that can be reliably measured in SMA patients can be used to track the disease progression of patients and the treatment effect over time. Although muscle function can be assessed by physiological measurements (such as muscle strength and force generation), the motor function scale monitors disease progression in a manner related to the patient's daily life function and is more meaningful and relevant than the measurement of quantitative strength itself. In some embodiments, patients who need treatment or are receiving SMA treatment are assessed using a functional scale, such as any one or more of the motor function assessment tests or functional outcome measures described herein (for example, one or more of HFMSE, RHS, 6MWT, WHO motor milestones, RULM, 30 seconds sit-stand, motor function measurement (MFM), CHOP-INTEND, endurance shuttle nine-hole plug test [ESNHPT], and / or endurance shuttle box block test [ESBBT]).

[0295] In some embodiments, RHS is used to assess patients with SMA (e.g., late-onset SMA). In some embodiments, the execution of RHS includes standing up from the floor regularly and a 10-meter walk / run test. In some embodiments, RHS is a 36-item clinical assessment of the physical fitness of patients with type 2 SMA and patients with ambulatory and nonambulatory type 3 SMA. RHS includes 33 items graded on a scale of 0, 1, 2, where 0 represents the lowest level of ability / function and 2 represents the highest level of ability (Ramsey et al. (2017) PLoS One. [Public Library of Science: Comprehensive] 12 (2): e0172346). The remaining three items are scored with 0 and 1, where 0 represents that it cannot be achieved and 1 represents that it can be achieved. The highest achievable score is 69.

[0296] In some embodiments, patients to be treated with apivolumab (e.g., patients with ambulatory SMA) have a baseline RHS score of 26 or higher prior to treatment. In some embodiments, patients have a baseline RHS score of 63 or less. In some embodiments, patients have a baseline RHS score ranging from 26-63. In some embodiments, patients have ambulatory SMA, e.g., ambulatory type 3 SMA. In some embodiments, treatment with apivolumab improves the patient's RHS score. In some embodiments, apivolumab continues to improve the patient's RHS score over a 24-month treatment period. In some embodiments, apivolumab maintains an increased RHS score over a 24-month treatment period.

[0297] In some embodiments, patients with SMA (e.g., late-onset SMA) are evaluated using a 10-meter walk / run test. In some embodiments, the 10-meter walk / run test is an enhancement of the RHS for ambulatory patients with Type 3 SMA. The 10-meter walk / run test measures the time it takes to walk / run 10 meters. In some embodiments, treatment with apilectomycin improves a patient's 10-meter walk / run test score.

[0298] In some embodiments, patients with SMA (e.g., late-onset SMA) are evaluated using the timed floor rise test. In some embodiments, the timed floor rise test is an enhancement of the RHS for ambulatory patients with type 3 SMA. The timed floor rise test measures the time it takes to rise from the floor to standing. In some embodiments, treatment with apilectomycin improves a patient's timed floor rise test score.

[0299] In some embodiments, patients with SMA (e.g., late-onset SMA) are evaluated using the 6-minute walk test (6MWT). The 6MWT is an assessment of motor ability and fatigue that has been used in clinical studies of ambulatory late-onset SMA patients (Young et al. (2016). Muscle Nerve. [Muscle Nerve] 54 (5): 836-842). Patients are instructed to walk as fast as possible along a 25-meter route within six minutes. The minute distance and the total distance of the six-minute walk are measured. In some embodiments, treatment with apivolumab improves the patient's 6MWT score.

[0300] In some embodiments, patients with SMA (e.g., late-onset SMA) are evaluated using a 30-second sit-stand test. Researchers and clinicians use the 30-second sit-stand test to assess functional lower extremity strength (Jones et al. (1999) ResQ Exerc Sport. 70: 113-119). For the ambulatory SMA population, this test is modified based on a modified 30-second sit-stand study, which is a reliable, feasible tool for use in the general elderly population with lower functional levels (McAllister and Palombaro (2019). J Geriatr Phys Ther. [Journal of Geriatric Physical Therapy] 0(0): 1-6), and is associated with fall risk in veterans who lack self-care ability (Applebaum et al. (2017). PLoS One. [Public Library of Science: Comprehensive] 12(5): e0176946; Le Berre et al. (2016) PerceptMot Skills. [Perception and Motor Skills] 123: 138-152). This test measures the maximum number of times a patient can go from sit to stand in 30 seconds. In some embodiments, treatment with apivolumab improves the patient's 30-second sit-stand score.

[0301] In some embodiments, patients to be treated with apivolumab (e.g., patients with nonambulatory SMA (such as Type 2 and nonambulatory Type 3 SMA)) have a baseline HFMSE score of 12 or more prior to treatment. In some embodiments, the patient has a baseline HFMSE score of 44 or less. In some embodiments, the patient has a baseline HFMSE score ranging from 12-44. In some embodiments, the patient has nonambulatory SMA. In some embodiments, the patient has Type 2 SMA. In some embodiments, the patient has nonambulatory Type 3 SMA. In some embodiments, treatment with apivolumab improves the patient's HFMSE score.

[0302] In some embodiments, patients with SMA (e.g., late-onset SMA) are assessed using the Revised Upper Limb Module (RULM). RULM is a 20-item assessment of upper limb function in patients with SMA (children and adults) who are unable to walk (Mazzone et al. (2017) Muscle Nerve. [Muscle Nerve] 55(6):869-874). 19 scoring items test functions related to daily life, such as putting hands on knees, pressing buttons, and picking up objects. Items are scored as 0, 1, and 2, where 0 means unable, 1 means able after modification, and 2 means able and without difficulty. The highest achievable score is 37. In some embodiments, RULM is used to assess patients with SMA who are unable to walk. In some embodiments, for example, RULM is completed by patients who are 30 months of age or older at baseline assessment. In some embodiments, treatment with apivolumab improves the patient's RULM score.

[0303] In some embodiments, patients with SMA (e.g., late-onset SMA) are assessed using the World Health Organization (WHO) motor milestones. The WHO Multicenter Growth Reference Study (MGRS) generates growth curves for assessing the growth and development of infants and young children worldwide (de Onis et al. (2004) Food Nutr Bull. 25 Suppl: S1-89). The primary goal of the MGRS is to construct curves and related tools to assess the growth and development of children from birth to five years of age. Another feature of the MGRS is that it includes the collection of ages at completion of motor milestones, including gross motor development milestones such as sitting without support, crawling on hands and knees, standing with assistance, walking with assistance, standing alone, and walking alone (Wijnhoven et al. (2004) Food Nutr Bull. 25(1 Suppl): S37-45; WHO Multicentre Growth Reference Study Group (2006) Acta Paediatr Suppl; 450: 86-95). In some embodiments, the WHO MGRS gross motor development performance criteria are used to assess motor development milestones in patients, for example, with type 2 and nonambulatory type 3 SMA. In some embodiments, treatment with apilectomycin improves the patient's WHO MGRS score.

[0304] In some embodiments, the Motor Function Measure (MFM) is used to assess patients with SMA (e.g., late-onset SMA). The MFM assesses motor function in three areas: (1) standing, walking ability, and transfers; (2) axial and proximal motor function; and (3) distal motor function (Annoussamy et al. (2020) Annals of Clinical and Translational Neurology 8:359-373). The MFM was originally designed for children seven years of age or older and has 32 items across three functional areas. The MFM-20 is a modified version of the MFM scale that removes some difficult items to make it suitable for younger children. It contains 20 items and is suitable for children two years of age and older (Pierzchiewicz et al., Child Neurology Open (2021) 8:1-9). In some embodiments, the MFM20 is used to assess patients with SMA (e.g., late-onset SMA). In some embodiments, treatment with apilectomy improves the patient's MFM20 score.

[0305] In some embodiments, patients with SMA (e.g., early-onset or type 1 SMA) are evaluated using the CHOP-INTEND test (Glanzman et al. (2010) Neuromus. Disord. 20(3):155-161). CHOP-INTEND measures five parameters of observed and evoked motor activity: (1) spontaneous movements of the left and right upper limbs; (2) spontaneous movements of the left and right lower limbs; (3) hand grasping; (4) head positioned in the midline with visual stimulation; and (5) hip adduction. Each item is scored on a scale of 0-4, where 0 indicates no response, 1 indicates minimal response, 2 indicates partial response, 4 indicates almost complete response, and 4 indicates complete response. The maximum score is 64. CHOP-INTEND is targeted at infants with SMA and has been validated (Alfano et al. (2021) Pediatric Neurology 122:21-26).

[0306] Healthy babies typically achieve a maximum CHOP-INTEND score of 64 at three to six months of age. Most patients received nusindrone (Duong et al. (2021) Neuromuscul Dis, 8(1), 63-77; Pechmann et al. (2018) J Neuromuscul Dis, 5(2), 135-143; Aragon-Gawinska et al. (2018) Neurology, 91:14), lisapranolol (Baranello et al. (2021) N Engl J Med, 384(10), 915-923; Darras et al. (2021) N Engl J Med, 385(5), 427-435), and sovaroprevir (Mendell et al. (2021) JAMA Neurol 78(7), 834-841; EMA / 200482 / 2020 (2020) Zolgensma EPAR [European Public Assessment Report]) reaches a plateau with a CHOP-INTEND score of less than 50 within the first three years of life.

[0307] In some embodiments, patients evaluated with CHOP-INTEND are under the age of two. In some embodiments, patients evaluated with CHOP-INTEND have early-onset SMA or SMA Type 1. In some embodiments, patients evaluated with CHOP-INTEND have a baseline score of 40 or less.

[0308] In some embodiments, patients with SMA (e.g., late-onset SMA) are assessed using the Endurance Shuttle Nine-Hole Peg Test (ESNHPT). The ESNHPT is an endurance test for patients severely affected by SMA. Patients are instructed to repeat an initial nine-hole peg test at 75% of their individual maximum speed. Shuttles are performed at a set speed marked by an auditory cue, where the test ends when the patient misses two consecutive beeps. The primary outcome parameter is the "limit time (Tlim)", which is the time the task can be maintained at a preset intensity. The maximum test duration is 20 minutes (Stam et al. (2018) BMJ Open. [BMJ Open Access Journal] 8(7):e019932). In some embodiments, the ESNHPT is used to assess patients with non-ambulatory SMA. In some embodiments, the ESNHPT is completed by patients eight years of age or older. In some embodiments, treatment with apivolumab improves the patient's ESNHPT score.

[0309] In some embodiments, patients with SMA (e.g., late-onset SMA) are assessed using the endurance shuttle box-block test (ESBBT). The ESBBT is a muscle endurance tool that measures the rate at which a subject's proximal arm muscles fatigue. The patient can be instructed to repeat the initial box-block test at 75% of their individual maximum speed. Shuttles are performed at a set speed marked by an auditory cue, where the test ends when the patient misses two consecutive beeps. The primary outcome parameter is the "limit time (Tlim)", which is the time the task can be maintained at a preset intensity. The maximum test duration is 20 minutes (Stam et al. (2018) BMJ Open. [BMJ Open Access Journal] 8(7):e019932). The ESBBT has been validated in SMA (Bartels et al. (2020) Orphanet J Rare Dis [Orphan and Rare Diseases Journal] 15:75). The ESSBT is the first validated and sensitive fatigability test of proximal arm muscle function in SMA, and by adding an endurance dimension, the results complement those obtained with other measures of arm motor function, such as the RULM.

[0310] In some embodiments, the ESBBT is used to assess nonambulatory SMA patients. In some embodiments, the ESBBT is completed by patients eight years of age or older. In some embodiments, treatment with apilectomycin improves the patient's ESBBT score.

[0311] In some embodiments, treatment with apivolumab for 12 months is sufficient to increase the subject's ESBBT score by at least 109.1 points (e.g., to increase the subject's ESBBT score by about 110 points to about 239 points). In some embodiments, treatment with apivolumab for 24 months is sufficient to increase the subject's ESBBT score by at least 147.9 points (e.g., to increase the subject's ESBBT score by about 150 points to about 300 points). In some embodiments, the subject has nonambulatory SMA type 2 or type 3 and is 5-21 years old and has previously received SMN upregulator / corrector therapy (e.g., nusinsen, risopram, and / or sovaprevir), wherein the subject was first treated with SMN upregulator / corrector therapy (e.g., nusinsen, risopram, and / or sovaprevir) after the age of five.

[0312] Clinical benefits of SMA treatment may include 1) improved motor function, 2) maintenance of motor function (disease stable), 3) delayed disease progression, or (4) improved quality of life.

[0313] Motor function can be assessed by a suitable means (such as HFMSE and / or RHS), the latter of which is typically used to assess motor function in ambulatory patients. In some embodiments, HFMSE is more commonly used to assess motor function in patients who cannot ambulatory. An increase in the corresponding score over an appropriate baseline indicates an improvement in motor function. In some embodiments, the increase is at least one point, at least two points, at least three points, at least four points, or at least five points. In some embodiments, the increase is one point or more, two points or more, three points or more, four points or more, or five points or more. In some embodiments, the SMA therapies disclosed herein (e.g., SMA therapies comprising apivolumab) enhance motor function such that the HFMSE score or RHS score (e.g., HFMSE score) measured six months, 12 months, or 24 months after the start of treatment is at least 1, 3, 5, 7, or 10 points higher than the baseline, and wherein the baseline is obtained at or before the start of treatment. In some embodiments, an SMA therapy disclosed herein (e.g., an SMA therapy comprising apivolumab) produces an increase in HFMSE score of at least five points relative to a baseline score after at least 12 months of treatment (e.g., after at least 24 months). In some embodiments, an SMA therapy disclosed herein (e.g., an SMA therapy comprising apivolumab) produces an increase in HFMSE score of 6-20 points or more relative to a baseline score after at least 12 months of treatment (e.g., after at least 24 months). In some embodiments, an SMA therapy disclosed herein (e.g., an SMA therapy comprising apivolumab) produces an increase in HFMSE score of at least seven points relative to a baseline score after at least 12 months of treatment (e.g., after at least 24 months or at least 36 months).

[0314] In some embodiments, the SMA therapies disclosed herein (e.g., SMA therapies comprising apivolumab) enhance motor function such that the HFMSE score or RHS score (e.g., HFMSE score) measured 24 months after the start of treatment is at least 1, 3, 5, 7, or 10 points higher than baseline, and wherein the baseline is obtained at or before the start of treatment. In some embodiments, after at least 24 months of treatment, the SMA therapies disclosed herein (e.g., SMA therapies comprising apivolumab) increase the HFMSE score by at least five points relative to the baseline score. In some embodiments, after at least 24 months of treatment, the SMA therapies disclosed herein (e.g., SMA therapies comprising apivolumab) increase the HFMSE score by 6-20 points or more relative to the baseline score. In some embodiments, after at least 24 months of treatment, the SMA therapies disclosed herein (e.g., SMA therapies comprising apivolumab) increase the HFMSE score by at least seven points relative to the baseline score. In some embodiments, an SMA therapy disclosed herein (e.g., an SMA therapy comprising apivolumab) results in an increase in HFMSE score of at least 2 points (e.g., at least 3 points, at least 4 points, or at least 5 points, at least 6 points) relative to baseline after 12 months of apivolumab treatment, wherein the increase in HFMSE score is maintained at 24 months after initiating apivolumab treatment, optionally wherein the increase in HFMSE score is maintained at 36 months after initiating apivolumab treatment. In some embodiments, the improved HFMSE score relative to baseline in a subject as measured 12 months after initiating apivolumab treatment is maintained or further increased at 24 months. In some embodiments, the improved HFMSE score relative to baseline in a subject as measured 12 months after initiating apivolumab treatment is maintained or further increased at 36 months.

[0315] In some embodiments, improvements in motor function scores (e.g., HFMSE or RHS scores) may be positively correlated with the severity of SMA and / or the length of treatment with SMN corrector therapy (e.g., nusinsen, risperidone and / or sovaprevir). In some embodiments, improvements in motor function scores (e.g., HFMSE or RHS scores) may be negatively correlated with age and / or features of advanced disease. In some embodiments, features of advanced disease include scoliosis and / or joint contractures. In some embodiments, shortening of muscles, tendons, and ligaments can lead to joint contractures, resulting in deformities, and symptoms include joint pain and loss of movement. In some embodiments, a method of treating SMA comprises administering apilectomycin therapy to a patient lacking scoliosis and / or joint contractures, either as a monotherapy or in combination with another therapy (or combination). In some embodiments, apilectomycin is used to treat SMA in patients lacking scoliosis and / or joint contractures, either as a monotherapy or in combination with another therapy (or combination).

[0316] In some embodiments, an SMA therapy disclosed herein (e.g., an SMA therapy comprising apilectomycin) stabilizes disease progression such that the HFMSE score or RHS score measured at six months or 12 months after the start of treatment is no less than baseline or no more than a 0.1, 0.2, 0.3, 0.4, or 0.5 point decrease, and wherein the baseline is obtained at or before the start of treatment, and optionally wherein the stabilization is durable for at least 24 months of treatment. In some embodiments, an SMA therapy disclosed herein (e.g., an SMA therapy comprising apilectomycin) stabilizes disease progression such that the RHS score comprises a decrease in the RHS score of less than one, two, or three points relative to the baseline score after at least 12 months of treatment, and optionally wherein the stabilization is durable for at least 24 months of treatment.

[0317] In some embodiments, an SMA therapy disclosed herein (e.g., an SMA therapy comprising apivolumab) stabilizes disease progression such that the HFMSE score or RHS score measured 24 months after the start of treatment is no less than baseline or decreases by no more than 0.1, 0.2, 0.3, 0.4, or 0.5 points, and wherein the baseline is obtained at or before the start of treatment. In some embodiments, an SMA therapy disclosed herein (e.g., an SMA therapy comprising apivolumab) stabilizes disease progression such that the RHS score after at least 24 months of treatment comprises a decrease in the RHS score of less than one, two, or three points relative to the baseline score.

[0318] In some embodiments, an SMA therapy disclosed herein (e.g., an SMA therapy comprising apivolumab) results in an increase in RULM score of at least 0.5 points (e.g., at least 0.75, 1, 1.25, 1.5, 2, 2.25, or 2.5 points) relative to baseline at 12 months after starting apivolumab treatment. In some embodiments, the increase in RULM score compared to baseline is maintained at 24 months after starting apivolumab treatment. In some embodiments, the RULM score relative to baseline at 24 months after starting apivolumab treatment is further increased compared to the RULM score at 12 months after starting apivolumab treatment. In some embodiments, the improved RULM score relative to baseline in a subject measured at 12 months after starting apivolumab treatment is maintained or further increased at 24 months. In some embodiments, the improved RULM score relative to baseline in a subject measured at 12 months after starting apivolumab treatment is maintained or further increased at 36 months.

[0319] In some embodiments, an SMA therapy disclosed herein (e.g., an SMA therapy comprising apilectomycin) improves muscle function such that the patient's HFMSE score increases by at least 2 points (e.g., at least 3, 4, 5, or 6 points) at 24 months of treatment compared to baseline. In some embodiments, the patient's RULM score increases by at least 0.5 points (e.g., at least 0.75, 1, 1.25, 1.5, 2, 2.25, or 2.5 points) at 24 months of treatment compared to baseline. Quality of life

[0320] Although several previous studies have reported on the effects of SMA treatments (e.g., nusindrone) on overall quality of life, those results have so far shown mixed results, with no conclusive evidence of significant improvements in quality of life. For example, Montes et al. measured the six-minute walk test (6MWT) and fatigue in 14 ambulatory children aged 2-15 years with SMA type II(1) or III(13) after receiving their first dose of nusindrone. Fatigue was defined as the difference between meters walked in the first minute and meters walked in the sixth minute. They observed only a modest reduction or stabilization of 6MWT fatigue after nusindrone treatment and concluded that this modest effect may represent a nusindrone treatment response, but endorsed the finding by noting that further understanding of the underlying mechanisms of fatigue may help to explain the only modest effect (Montes et al. (2019) Muscle Nerve 60(4):409-414).

[0321] Yao et al. evaluated the quality of life of children 17 years of age or younger who were diagnosed with SMA and treated with nusindrone. Children who received nusindrone had higher mean scores in the Neuromuscular Diseases and Family Resources domain of the Pediatric Quality of Life Inventory 3.0 Neuromuscular Module (PedsQL NMM) compared to children who did not receive nusindrone. However, the study authors cautioned that the results may not be conclusive due to the small sample size of children treated with nusindrone (n=6). (Yao et al. (2021) Orphanet Journal of Rare Diseases 16:7.)

[0322] Mix et al. evaluated overall quality of life, health-related quality of life, and depressive symptoms in adolescents and adults with SMA who were treated with nusindrome and reported improvements in subjective well-being during the first six months of treatment, but not in subjective well-being (Mix et al. (2021) Front Neurol 12:626787).

[0323] Other studies reported no changes in the quality of life of SMA patients as a result of the therapies provided in the reported clinical trials. A literature review of quality of life studies in SMA patients (Landfeldt et al. (2019) Eur. J. Paediatric Neurology 23:347) found four relevant publications from reported clinical trials: a phase 1 trial of nusinsen, a phase 2 trial of olesoxime, and a phase 2 trial of L-carnitine and valproic acid. None of the studies reported any significant changes in quality of life.

[0324] Thimm et al (2022) Frontiers in Neurology 12:8120 studied adult patients with type 2 or 3 SMA treated with nusindrone who were prospectively included in the assessment of health-related quality of life using the short form Neuro-QoL, which measures upper and lower limb function, before starting treatment and after 2, 6, 10, and 14 months of nusindrone treatment. The study did not show improvement at any of the measured time points.

[0325] An early study reported on HRQoL in children aged 2-4 years diagnosed with type II or type III SMA, where a mild but nonsignificant increase was observed after 85 days of treatment with nusin (Chiriboga et al. (2016) Neurology 86:890-7). A comprehensive literature review (Yang et al. (2022) Adv Ther 39:1915) found that while SMN-targeted therapies improved survival outcomes in SMA patients, no other treatments besides Chiriboga's showed significant improvements in HRQoL.

[0326] In contrast, in some embodiments, the present disclosure demonstrates that apilectomycin is the first muscle-targeted treatment for SMA that provides improvements in quality of life for SMA patients. In some embodiments, these improvements can be sustained over a treatment period of at least 24 months.

[0327] In some embodiments, quality of life is assessed by interviewing the subject using a semi-structured interview guide that includes questions about the subject's expectations of meaningful improvement in their condition and their perspectives on why they experienced or did not experience meaningful improvement. The subject may be interviewed about their experience with SMA and their treatment in certain areas of their life, such as physical function, social impact, and emotional impact. The subject may be asked to rate their quality of life by providing a score (e.g., on a scale of 0-10), where zero indicates minimal impact on quality of life and ten indicates an extremely severe impact on quality of life.

[0328] In some embodiments, patients with SMA (e.g., late-onset SMA) are assessed using one of the tools developed by EUROQOL, such as the EQ-5D-3L. EQ-5D-5L, EQ-5D-Y, and EQ-HWB are multifunctional tools that measure health-related quality of life. For example, the EQ-5D-5L is a descriptive system that includes dimensions such as mobility, self-care, daily activities, pain / discomfort, and anxiety / depression.

[0329] In some embodiments, treatment with apivolumab improves the subject's Clinical Global Impression of Change (CGI-C). The CGI-C scores the clinician's impression of the subject's overall health changes (Staunton et al. (2021) HealthQual Life Outcomes [Health Quality Life Results] 19: 184). In some embodiments, treatment with apivolumab improves the subject's Pediatric QoL Scale (PedsQL). The PedsQL consists of a universal core scale and disease-specific modules (e.g., a neuromuscular module), which can be used to assess the health-related QoL of children aged 2-18 years with neuromuscular diseases (including SMA) (Iannaccone et al. (2009) Neuromus Disord. [Neuromuscular Disease] 19: 805-812). In some embodiments, treatment with apivolumab improves the subject's neuromuscular gross motor outcome (GRO) score. The GRO is a gross motor outcome measure designed to assess all levels of whole-body strength and function across the lifespan of patients with neuromuscular diseases and has been validated in SMA types 1-3 (Alfano et al. (2021) Pediatric Neurology 122:21-26).

[0330] In some embodiments, treatment with apilectomycin is sufficient (e.g., 24 months after initiating apilectomycin treatment and / or 36 months after initiating apilectomycin treatment) to improve one or more measures of quality of life in an SMA subject.

[0331] In some embodiments, patients with SMA (e.g., late-onset SMA) are evaluated using the Patient Reported Outcomes Measurement Information System (PROMIS), e.g., before and / or after treatment comprising apivolumab. PROMIS is a person-centered measure designed to be completed by the patient or parent proxy without the assistance of anyone else (Ader (2007) Med Care. [Medical] 5(5): S1-S2). The fatigue profile domain measures a range of symptoms, from mild subjective fatigue to overwhelming, debilitating, and persistent exhaustion. Self-report measures are suitable for children aged 8-17 years, and parent proxy report measures are suitable for children aged 5-17 years. Patients aged 18-21 years can complete the adult version of PROMIS. In some embodiments, PROMIS is completed by patients aged ≥2 years, ≥5 years, or 5-21 years. In some embodiments, treatment with apivolumab improves the patient's PROMIS score.

[0332] The Pediatric Disability Assessment Inventory Computer Adaptive Test (PEDI-CAT) is a questionnaire administered by caregivers to assess a patient's ability to perform daily functions (Haley et al. (2005) Arch Phys Med Rehabil. 86(5):932-939). The domain for activities of daily living (ADL) contains 68 items covering areas such as dressing, keeping clean, and household tasks. The domain for mobility contains 75 items covering areas such as basic movements and transfers, standing and walking, and steps and ramps. Responses are scored on a four-point scale (not able to easily), and the test is suitable for assessing function from newborns to 21 years of age. The characteristics of the PEDI-CAT have been studied in the SMA population, and the test has been validated in the SMA population; Rasch analysis showed that the distribution of abilities in the mobility and ADL domains in the PEDI-CAT was best reflected in the Type 2 and Type 3 populations (Pasternak et al. (2016) Muscle Nerve. 54(6):1097-1107).

[0333] In some embodiments, PEDI-CAT is used to assess patients with SMA (e.g., late-onset SMA). In some embodiments, a caregiver (who may or may not be a parent and / or legal guardian) completes the PEDI-CAT assessment. In some embodiments, if a caregiver is not present, the patient is not assessed with the PEDI-CAT. In some embodiments, the PEDI-CAT is completed by the caregiver in a setting where they do not observe the patient undergoing any functional assessment tests. In some embodiments, treatment with apilectomycin improves the patient's PEDI-CAT score.

[0334] In some embodiments, treatment with apivolumab improves the subject's quality of life as assessed on the PEDI-CAT scale, wherein, optionally, the subject's PEDI-CAT score can include a PEDI-CAT activity score and a PEDI-CAT mobility score. In some embodiments, treatment with apivolumab improves the subject's quality of life as measured by assessing the subject's fatigue level, wherein, optionally, the subject's fatigue can be assessed by a Patient Reported Outcomes Measurement Information System (PROMIS) score and / or an Endurance Shuttle Box Block Test (ESBBT) score. In some embodiments, treatment with apilectomycin for 12 months is sufficient to increase the subject's PEDI-CAT activity score by at least 1.9 points (e.g., increase the subject's PEDI-CAT activity score by about 2 points to about 4 points), increase the subject's PEDI-CAT mobility score by at least 0.4 points (e.g., increase the subject's PEDI-CAT mobility score by about 0.5 points to about 3 points), and / or decrease the subject's PROMIS score by at least 5.5 points (e.g., decrease the subject's PROMIS score by about 6 points to about 10 points), wherein, optionally, the subject has nonambulatory type 2 SMA and is at least two years of age. In some embodiments, the subject's PEDI-CAT activity score is further increased at 24 months compared to 12 months after initiating apilectomycin treatment. In some embodiments, the subject has previously received SMN upregulator / corrector therapy (e.g., nusindrone, risopram, and / or sovaprevir), wherein the subject was first treated with SMN upregulator / corrector therapy (e.g., nusindrone, risopram, and / or sovaprevir) before the age of five years.

[0335] In some embodiments, treatment with apilectomycin for 12 months is sufficient to increase the subject's PEDI-CAT activity score by at least 0.9 points (e.g., increase the subject's PEDI-CAT score by about 1 point to about 3 points) and / or decrease the subject's PROMIS score by at least 0.6 points (e.g., decrease the subject's PROMIS score by about 1 point to about 6 points, or about 4 points to about 35 points), wherein, optionally, the subject has nonambulatory type 2 SMA and is 5 to 21 years of age. In some embodiments, the subject's PROMIS score is further reduced at 24 months compared to 12 months after initiating apilectomycin treatment. In some embodiments, the subject has previously received SMN upregulator / corrector therapy (e.g., nusinsen, risopram, and / or sovaprevir), wherein the subject was first treated with SMN upregulator / corrector therapy (e.g., nusinsen, risopram, and / or sovaprevir) after the age of five.

[0336] In some embodiments, treatment with apilectomycin for 24 months is sufficient to increase the subject's PEDI-CAT activity score by at least 1.8 points (e.g., increase the subject's PEDI-CAT activity score by about 2 points to about 4 points), increase the subject's PEDI-CAT mobility score by at least 0.4 points (e.g., increase the subject's PEDI-CAT mobility score by about 0.4 points to about 5 points), and / or decrease the subject's PROMIS score by at least 5.0 points (e.g., decrease the subject's PROMIS score by about 5 points to about 9 points), wherein, optionally, the subject has nonambulatory SMA type 2 and is at least two years old. In some embodiments, the subject has previously received SMN upregulator / corrector therapy (e.g., nusinsen, risopram, and / or sovaprevir), wherein the subject was first treated with SMN upregulator / corrector therapy (e.g., nusinsen, risopram, and / or sovaprevir) before the age of five years.

[0337] In some embodiments, treatment with apilectomycin for 24 months is sufficient to increase the subject's PEDI-CAT activity score by at least 0.7 points (e.g., increase the subject's PEDI-CAT activity score by about 1 point to about 3 points) and / or decrease the subject's PROMIS score by at least 1.3 points (e.g., decrease the subject's PROMIS score by about 2 points to about 7 points, or about 4 points to about 10 points), wherein, optionally, the subject has nonambulatory SMA Type 2 and is 5 to 21 years of age. In some embodiments, the subject has previously received SMN upregulator / corrector therapy (e.g., nusinsen, risopram, and / or sovaprevir), wherein the subject was first treated with SMN upregulator / corrector therapy (e.g., nusinsen, risopram, and / or sovaprevir) after the age of five years.

[0338] In some embodiments, treatment with apilectomycin is sufficient to increase the subject's PEDI-CAT Activities of Daily Living score at 12 months, compared to baseline, wherein, optionally, the subject's PEDI-CAT Activities of Daily Living score is further increased at 24 months, compared to 12 months. In some embodiments, treatment with apilectomycin is sufficient to increase the subject's PEDI-CAT Mobility score at 12 months, compared to baseline, wherein, optionally, the subject's PEDI-CAT Mobility score is further increased at 24 months, compared to 12 months.

[0339] In some embodiments, treatment with apilectomycin is sufficient to reduce the subject's PROMIS fatigue score at 12 months compared to baseline, wherein, optionally, the subject's PROMIS fatigue score is further reduced at 24 months compared to 12 months. In some embodiments, the improvement in the subject's PROMIS fatigue score is maintained at 36 months.

[0340] In some embodiments, treatment with apilectumab is sufficient to increase the subject's ESBBT score at 12 months compared to baseline, wherein, optionally, the subject's ESBBT score is further increased at 24 months compared to 12 months.

[0341] The Columbia-Suicide Severity Rating Scale (C-SSRS) measures suicidal ideation, intensity of ideation, and suicidal behavior. It has been validated in different populations, including five-year-old children (Salvi (2019) Emerg Med Pract 21(5):CD3-CD4). In some embodiments, treatment with apilectomycin improves the subject's C-SSRS score.

[0342] In some embodiments, treatment with apilectomycin improves the subject's quality of life as assessed by the severity of muscle function-related symptoms. In some embodiments, muscle function-related symptoms include muscle function severity, fatigue severity, bulbar function severity, and / or emptying severity. In some embodiments, muscle function-related symptoms are measured by the subject's symptom severity rating on a scale from 0 to 10, where zero indicates the lowest severity and ten indicates high severity.

[0343] In some embodiments, treatment with apivolumab improves the subject's quality of life as assessed by the severity of fatigue-related symptoms. In some embodiments, fatigue-related symptoms are measured by the subject's symptom severity rating on a scale from 0 to 10, where zero indicates minimal severity and ten indicates high severity.

[0344] In some embodiments, treatment with apivolumab improves the subject's quality of life, as assessed by symptoms related to bulbar function. Bulbous function refers to functions controlled by areas of the brainstem; "bulb" is an archaic term for the medulla. Bulbous function includes swallowing, masticatory motor function and strength, coughing, breathing, snoring, and range of mandibular motion. Bulbar dysfunction affects these activities. Bulbous dysfunction remains a significant complication in most type 1 patients treated with apivolumab; only 4 of 24 patients remained orally fed after 24 months, as assessed by p-FOIS (Westrate et al. (2022) Dev Med Child Neurol 64:907-914). Similarly, patients with type 2 and type 3 who received treatment with nivolumab did not show improvements in bulbar function after 6 or 14 months of nivolumab treatment compared to what was observed before treatment, whereas nivolumab was observed to improve their HFMSE scores (Brakemeier et al. (2021) Brain Sci 11:1244). In some embodiments, treatment with nivolumab improves bulbar function in patients.

[0345] In some embodiments, bulbar function-related symptoms are measured by the subject's symptom severity rating on a scale from 0 to 10, where zero indicates lowest severity and ten indicates high severity.

[0346] In some embodiments, bulbar function in patients with SMA is assessed using the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (AMLFRSR), a questionnaire-based scale that measures physical function in performing activities of daily living and has been shown to correlate with quality of life (Cedarbaum et al. (1999) J. Neurolog. 169:13-21).

[0347] In some embodiments, bulbar function in patients with SMA is assessed using the Sydney Swallowing Questionnaire (SSQ), a tool that assesses the severity of oral and pharyngeal dysphagia (Dwivedi et al. (2010) Oral Oncol. E10-e14).

[0348] In some embodiments, patients with SMA are assessed using the MD Anderson Dysphagia Inventory (MDADI), a questionnaire that assesses the relationship between swallowing and quality of life (Chen et al. (2001) Arch Otolaryngol Head Neck Surg 127(7):870-876).

[0349] In some embodiments, patients with SMA are assessed using the SWAL-QoL, a 93-item quality of life outcome instrument that measures dysphagia (McHorney et al. (2002) Dysphagia 17:97-114).

[0350] In some embodiments, patients with SMA are evaluated through qualitative, semi-structured interviews with the patients or their caregivers.

[0351] In some embodiments, patients with SMA (e.g., early-onset SMA, including but not limited to SMA Type 1) are assessed using the Pediatric Functional Oral Intake Scale (p-FOIS). The p-FOIS is a tool that assesses changes in functional eating ability using a 6-point, ordinal, clinician-rated outcome measure for use in the pediatric feeding disorder population.

[0352] In some embodiments, treatment with apilectomycin improves the subject's quality of life as assessed by symptoms related to voiding. In some embodiments, symptoms related to voiding are measured by the subject's symptom severity rating on a scale from 0 to 10, with zero indicating minimal severity and ten indicating high severity.

[0353] In some embodiments, treatment with apivolumab improves the subject's quality of life as assessed by the severity of symptoms associated with the impact on daily life. In some embodiments, the impact on daily life can be assessed by physical function, balance, daily activities, mobility, sleep, transfers, and / or falls. In some embodiments, symptom severity is measured by the subject's symptom severity rating on a scale from 0 to 10, where zero indicates the lowest severity and ten indicates high severity.

[0354] In some embodiments, SMA subjects selected for treatment with a myostatin inhibitor (e.g., a selective myostatin inhibitor, e.g., apilectomycin) have reported at least one of muscle weakness or tightness, fatigue, pain, voiding dysfunction, or bulbar dysfunction. In some embodiments, symptoms of bulbar dysfunction include respiratory infections; use of assistive devices; inability to cough and clear lung secretions; difficulty breathing; difficulty eating / swallowing; difficulty speaking; and snoring. In some embodiments, symptoms of muscle weakness or tightness include balance problems, muscle and tendon tightness, decreased muscle tone, and difficulty chewing or smiling. In some embodiments, symptoms of voiding dysfunction include difficulty urinating and difficulty defecating. In some embodiments, treatment with a myostatin inhibitor (e.g., a selective myostatin inhibitor, e.g., apivolumab) surprisingly results in an improvement in the quality of life of such patients (e.g., after 24 months of apivolumab treatment), wherein the improvement includes an improvement in at least one of symptoms of muscle weakness or tightness, fatigue, pain, voiding dysfunction, or bulbar dysfunction as reported by the subject or the subject's caregiver. Methods, uses, and compositions for treating SMA

[0355] In various embodiments, to achieve an average serum concentration (C) between about 25 and 250 μg / mL 波谷 ). In some embodiments, the amount of apilectomycin to achieve a mean serum concentration (C max ) in an amount greater than or equal to 1% of the dose administered to the patient (alone or in combination with at least one additional therapy).

[0356] In some embodiments, the present disclosure provides a method of treating SMA in a human subject, the method comprising administering to the subject a composition comprising apiltuzumab by intravenous infusion every four weeks or monthly for at least six months or 12 months in an amount sufficient to prevent or delay a decrease in the RHS score relative to a pre-treatment baseline score. In some embodiments, the present disclosure provides a composition comprising apiltuzumab for use in treating SMA in a human subject, wherein the subject is administered apiltuzumab by intravenous infusion every four weeks or monthly for at least six months, 12 months, or 24 months in an amount sufficient to prevent or delay a decrease in the RHS score relative to a pre-treatment baseline score. In some embodiments, the present disclosure provides a use of a composition comprising apiltuzumab for treating SMA in a human subject, wherein the subject is administered apiltuzumab by intravenous infusion every four weeks or monthly for at least six months, 12 months, or 24 months in an amount sufficient to prevent or delay a decrease in the RHS score relative to a pre-treatment baseline score. In some embodiments, the present disclosure provides use of apilectomycin in the manufacture of a composition for treating SMA in a human subject, wherein apilectomycin is administered to the subject by intravenous infusion every four weeks or monthly for at least six, 12, or 24 months in an amount sufficient to prevent or delay a decrease in RHS score relative to a pre-treatment baseline score.

[0357] In some embodiments, the SMA is late-onset SMA. In some embodiments, the SMA is ambulatory type 3 SMA. In some embodiments, the subject is 2 to 12, 5 to 21, 13 to 21, or 2 to 21 years old. In some embodiments, the sufficient amount is a dose of greater than 2 mg / kg and up to 20 mg / kg, optionally about 5, 10, 15, or 20 mg / kg. In some embodiments, the sufficient amount is a dose of 10 mg / kg or 20 mg / kg of apilectomycin every four weeks or monthly.

[0358] In some embodiments, for example, after at least 12 months of treatment, Apitogumab is administered in an amount that stabilizes the RHS score or reduces the RHS score by less than 0.4 points. In some embodiments, Apitogumab is administered in an amount that generates an average increase of at least 0.2 points relative to the baseline score before treatment, optionally an average increase of 0.3 points, 0.5 points, at least 0.7 points, at least 1 point, at least 2 points, or at least 3 points (e.g., an average increase in a cohort of at least 11 subjects) relative to the baseline. In some embodiments, Apitogumab is administered in an amount that generates an average increase of at least 1 point relative to the baseline in the RHS score (e.g., an average increase in a cohort of at least 11 subjects). In some embodiments, Apitogumab is administered in an amount that generates an average increase of at least 3 points relative to the baseline in the RHS score (e.g., an average increase in a cohort of at least 11 subjects). In some embodiments, for example, Apitogumab is administered in an amount that stabilizes the RHS score as assessed after at least 12 months of treatment relative to the baseline. In some embodiments, for example, apilectomycin is administered in an amount that limits a decrease in RHS score of about 0.5, 0.4, 0.3, 0.2, or 0.1 as assessed after at least 12 months of treatment relative to baseline.

[0359] In some embodiments, the subject is treated with an SMN upregulator therapy. In some embodiments, the SMN upregulator therapy is nusin or risperidone. In some embodiments, the subject is treated with gene therapy. In some embodiments, the gene therapy is sovarprevir. In some embodiments, the SMN upregulator therapy is nusin. In some embodiments, the subject starts SMN upregulator therapy at or after the age of five. In some embodiments, for example, as assessed after at least 12 months of treatment relative to baseline, apivolumab is administered in an amount that stabilizes the RHS score. In some embodiments, for example, as assessed after at least 12 months of treatment relative to baseline, apivolumab is administered in an amount that limits a decrease in the RHS score by about 0.5, 0.4, 0.3, 0.2, or 0.1. In some embodiments, apivolumab is administered in an amount that produces an average increase in the RHS score of at least 0.3 points relative to baseline (e.g., an average increase in a cohort of at least 11 subjects). In some embodiments, apilectomycin is administered in an amount that produces a mean increase in RHS score of at least 0.3 points relative to baseline after eight weeks (e.g., a mean increase in a cohort of at least 11 subjects). In some embodiments, the amount is a dose of 20 mg / kg of apilectomycin every four weeks or monthly.

[0360] In some embodiments, the subject is not treated with SMN up-regulator therapy. In some embodiments, for example, as assessed after treatment relative to a baseline for at least 12 months, Apital is administered in an amount that stabilizes the RHS score. In some embodiments, for example, as assessed after treatment relative to a baseline for at least 12 months, Apital is administered in an amount that limits the RHS score to be reduced by about 0.5, 0.4, 0.3, 0.2, or 0.1. In some embodiments, Apital is administered in an amount that produces an average increase of at least 0.7 points in the RHS score relative to the baseline (for example, an average increase in a cohort of at least 11 subjects). In some embodiments, Apital is administered in an amount that produces an average increase of at least 0.7 points in the RHS score relative to the baseline (for example, an average increase in a cohort of at least 11 subjects) after eight weeks. In some embodiments, the amount is a dosage of 20 mg / kg Apital every four weeks or every month.

[0361] In some embodiments, to achieve a serum concentration (C) of at least about 100 μg / mL, e.g., about 100 to 500 μg / mL (e.g., about 100, 200, 300, 400, or 500 μg / mL). 波谷 ) is administered in an amount, e.g., as determined as an average over a course of at least 12 months. In some embodiments, the serum concentration (C 波谷 ) is about 100-450 micrograms / ml. In some embodiments, the amount is a dose of 20 mg / kg of apilectumab every four weeks or monthly.

[0362] In some embodiments, to achieve a serum concentration (C max ) is administered in an amount, e.g., as determined as an average over a course of at least 12 months. In some embodiments, the serum concentration (C max ) is at least about 300-1100 μg / ml, for example, 300-800. In some embodiments, the serum concentration (C max ) is at least 600 micrograms of apilectomycin / ml (e.g., at least 600, 700, 800, 900, 1000 micrograms / ml or more). In some embodiments, the serum concentration is between about 600-1000 micrograms / ml. In some embodiments, the serum concentration is a steady-state serum concentration. In some embodiments, apilectomycin is administered in an amount that achieves a steady-state serum concentration after about 112 days. In some embodiments, the amount is a dose of 20 mg / kg of apilectomycin every four weeks or every month.

[0363] In some embodiments, apilectomycin is administered in an amount sufficient to achieve target engagement as measured by a serum latent myostatin concentration of at least about 100 ng / ml, as determined at steady state over a course of at least 12 months. In some embodiments, apilectomycin is administered in an amount sufficient to achieve target engagement as measured by a serum latent myostatin concentration of at least about 250 ng / ml, as determined at steady state over a course of at least 12 months. In some embodiments, apilectomycin is administered in an amount sufficient to achieve target engagement as measured by a serum latent myostatin concentration of at least about 400 ng / ml. In some embodiments, apilectomycin is administered in an amount sufficient to achieve target engagement as measured by a serum latent myostatin concentration of at least 500 ng / ml (e.g., at least 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, or 1100 ng / ml). In some embodiments, the serum latent myostatin concentration is between about 550-2400 ng / ml. In some embodiments, the serum latent myostatin concentration is the steady-state concentration measured at the trough. In some embodiments, the amount is a dose of 20 mg / kg of apilectomycin every four weeks or every month.

[0364] In some embodiments, apilectomycin is administered in an amount that achieves one or more of the following in a subject: maintaining motor function compared to a decline in a control, delaying disease progression, delaying or preventing ambulatory Type 3 SMA patients from becoming nonambulatory, delaying or preventing the need for respiratory assistance or intervention, reducing the rate of decline in one or more motor function scores compared to a control, and / or maintaining at least a net zero change in one or more motor function scores compared to baseline. In some embodiments, the amount is a dose of 20 mg / kg of apilectomycin every four weeks or monthly. In embodiments, the control refers to the natural history of a subject with untreated SMA.

[0365] In some embodiments, the present disclosure provides a method of treating SMA in a human subject, the method comprising administering to the subject a composition comprising apilectumab and a composition comprising an SMN up-regulator, wherein apilectumab is administered to the subject by intravenous infusion every four weeks or monthly for at least 6, 12, or 24 months in an amount sufficient to produce a mean increase in HFMSE score of at least 0.5 or 1 point (e.g., at least 2, 3, 4, 5, or 6 points) relative to a baseline score before treatment, e.g., a mean increase in a cohort of at least 13 or 14 subjects. In some embodiments, the present disclosure provides a composition comprising apilectumab for use in treating SMA in a human subject receiving an SMN upregulator, wherein apilectumab is administered to the subject by intravenous infusion every four weeks or monthly for at least 6, 12, or 24 months in an amount sufficient to produce an average increase of at least 0.5 or 1 point (e.g., at least 2, 3, 4, 5, or 6 points) in HFMSE score relative to a pre-treatment baseline score (e.g., an average increase in a cohort of at least 13 or 14 subjects). In some embodiments, the present disclosure provides a composition comprising apilectumab for use in treating SMA in a human subject receiving an SMN upregulator, wherein apilectumab is administered to the subject by intravenous infusion every four weeks or monthly for at least 6, 12, or 24 months in an amount sufficient to produce an average increase of at least 0.5 or 1 point (e.g., at least 2, 3, 4, 5, or 6 points) in HFMSE score relative to a pre-treatment baseline score (e.g., an average increase in a cohort of at least 13 or 14 subjects). In some embodiments, the present disclosure provides use of apilectomycin in the manufacture of a composition for treating SMA in a human subject receiving an SMN upregulator, wherein apilectomycin is administered to the subject by intravenous infusion every four weeks or monthly for at least 6, 12, or 24 months in an amount sufficient to produce a mean increase in HFMSE score of at least 0.5 or 1 point (e.g., at least 2, 3, 4, 5, or 6 points) relative to a pre-treatment baseline score (e.g., a mean increase in a cohort of at least 13 or 14 subjects).

[0366] In some embodiments, the SMA is late-onset SMA. In some embodiments, the SMA is type 2 SMA. In some embodiments, the SMA is non-ambulatory type 3 SMA. In some embodiments, the subject is 2 to 12, 5 to 21, 13 to 21, or 2 to 21 years old. In some embodiments, the SMN upregulator therapy is nusindrome or lisapram. In some embodiments, the gene therapy is sovaprevir. In some embodiments, the SMN upregulator therapy is nusindrome. In some embodiments, a sufficient amount is a dose greater than 2 mg / kg and up to 20 mg / kg, optionally about 5, 10, 15, or 20 mg / kg. In some embodiments, a sufficient amount is a dose of 10 mg / kg or 20 mg / kg of apilectomycin every four weeks or monthly.

[0367] In some embodiments, apivolumab is administered in an amount that produces an increase of at least 0.5 points or 1 point in the HFMSE score relative to baseline after 16 weeks (e.g., the average increase in a cohort of at least 13 or 14 subjects). In some embodiments, apivolumab is administered in an amount that produces an increase of at least 2 points, at least 3 points, at least 4 points, or at least 5 points in the HFMSE score relative to baseline (e.g., the average increase in a cohort of at least 13 or 14 subjects). In some embodiments, apivolumab is administered in an amount that produces an increase of at least 3 points in the HFMSE score relative to baseline (e.g., the average increase in a cohort of at least 13 or 14 subjects). In some embodiments, apivolumab is administered in an amount that produces an increase of at least 5 points in the HFMSE score relative to baseline (e.g., the average increase in a cohort of at least 13 or 14 subjects). In some embodiments, the amount is a dose of 20 mg / kg of apivolumab every four weeks or every month.

[0368] In some embodiments, the serum concentration (C max ). In some embodiments, apivolumab is administered in an amount that achieves a serum concentration of at least 600 micrograms of apivolumab / ml (e.g., at least 600, 700, 800, 900, 1000 micrograms / ml or more). In some embodiments, the serum concentration is between about 600-1000 micrograms / ml. In some embodiments, the serum concentration is a steady-state serum concentration. In some embodiments, apivolumab is administered in an amount that achieves a steady-state serum concentration after about 112 days. In some embodiments, the amount is a dose of 20 mg / kg of apivolumab every four weeks or monthly.

[0369] In some embodiments, to achieve a serum concentration (C 波谷 In some embodiments, the amount is a dose of 20 mg / kg of apivolumab every four weeks or monthly.

[0370] In some embodiments, apilectomycin is administered in an amount sufficient to achieve target engagement as measured by a serum latent myostatin concentration of at least about 250 ng / ml (e.g., at least about 400 or 500 ng / ml (e.g., at least 500, 550, 600, or 650 ng / ml)). In some embodiments, the serum latent myostatin concentration is between about 550-1650 ng / ml. In some embodiments, the serum latent myostatin concentration is the steady-state concentration measured at the trough. In some embodiments, the amount is a dose of 20 mg / kg of apilectomycin every four weeks or every month.

[0371] In some embodiments, apilectomycin is administered in an amount that achieves one or more of the following in a subject: maintaining motor function compared to a decline in a control, delaying disease progression, delaying or preventing ambulatory Type 3 SMA patients from becoming nonambulatory, delaying or preventing the need for respiratory assistance or intervention, reducing the rate of decline in one or more motor function scores compared to a control, and / or maintaining at least a net zero change in one or more motor function scores compared to baseline. In some embodiments, the amount is a dose of 20 mg / kg of apilectomycin every four weeks or monthly.

[0372] In some embodiments, the present disclosure provides a method of treating SMA in a human subject, the method comprising administering to the subject a composition comprising apilectumab and a composition comprising an SMN up-regulator, wherein apilectumab is administered to the subject by intravenous infusion every four weeks or monthly for at least six, 12, or 24 months in an amount sufficient to produce a mean increase in HFMSE score of at least two points relative to a pre-treatment baseline score (e.g., a mean increase in a cohort of at least eight or nine subjects), and wherein the subject initiates the SMN up-regulator therapy before the age of five years.

[0373] In some embodiments, the present disclosure provides a composition comprising apilectumab for use in treating SMA in a human subject receiving an SMN upregulator, wherein apilectumab is administered to the subject by intravenous infusion every four weeks or monthly for at least six, 12, or 24 months in an amount sufficient to produce a mean increase of at least two points in HFMSE score relative to a pre-treatment baseline score (e.g., a mean increase in a cohort of at least eight or nine subjects), and wherein the subject initiated the SMN upregulator therapy before the age of five years.

[0374] In some embodiments, the present disclosure provides for the use of a composition comprising apilectumab for treating SMA in a human subject receiving an SMN upregulator, wherein apilectumab is administered to the subject by intravenous infusion every four weeks or monthly for at least six, 12, or 24 months in an amount sufficient to produce a mean increase of at least two points in HFMSE score relative to a pre-treatment baseline score (e.g., a mean increase in a cohort of at least nine subjects), and wherein the subject initiated the SMN upregulator therapy before the age of five years.

[0375] In some embodiments, the present disclosure provides use of apilectomycin in the manufacture of a composition for treating SMA in a human subject receiving an SMN upregulator, wherein apilectomycin is administered to the subject by intravenous infusion every four weeks or monthly for at least six, 12, or 24 months in an amount sufficient to produce a mean increase of at least two points in HFMSE score relative to a pre-treatment baseline score (e.g., a mean increase in a cohort of at least eight or nine subjects), and wherein the subject initiated the SMN upregulator therapy before the age of five years.

[0376] In some embodiments, SMA is late-onset SMA. In some embodiments, SMA is type 2 SMA. In some embodiments, the subject is 2 years of age or older. In some embodiments, the SMN upregulator therapy is nusindrome or lisapram. In some embodiments, the gene therapy is onasemnogene abeparvovec. In some embodiments, the SMN upregulator therapy is nusindrome. In some embodiments, a sufficient amount is greater than 2 mg kg and up to 20 mg / kg, optionally a dose of about 5, 10, 15, or 20 mg / kg. In some embodiments, a sufficient amount is a dose of 10 mg / kg or 20 mg / kg of apilectomycin every four weeks or monthly.

[0377] In some embodiments, apivolumab is administered in an amount that produces an average increase of at least two points in HFMSE scores relative to baseline after 12 months or 24 months (e.g., an average increase in a cohort of at least eight or nine subjects). In some embodiments, apivolumab is administered in an amount that produces an average increase of at least three points, at least four points, at least five points, at least six points, or at least seven points in HFMSE scores relative to baseline (e.g., an average increase in a cohort of at least eight or nine subjects) (e.g., after at least 12 months of treatment, e.g., after at least 24 months of treatment). In some embodiments, apivolumab is administered in an amount that produces an average increase of at least three points in HFMSE scores relative to baseline (e.g., an average increase in a cohort of at least eight or nine subjects). In some embodiments, apivolumab is administered in an amount that produces an average increase of at least five points in HFMSE scores relative to baseline (e.g., an average increase in a cohort of at least eight subjects). In some embodiments, apilectomycin is administered in an amount that produces a mean increase in HFMSE score of at least six points relative to baseline (e.g., the mean increase in a cohort of at least eight or nine subjects). In some embodiments, apilectomycin is administered in an amount that produces a mean increase in HFMSE score of at least seven points relative to baseline (e.g., the mean increase in a cohort of at least eight or nine subjects). In some embodiments, the amount is a dose of 20 mg / kg of apilectomycin every four weeks or every month.

[0378] In some embodiments, to achieve a serum concentration (C) of at least about 25-1100 μg apilectomycin / mL max ). In some embodiments, apivolumab is administered at 2 mg / kg to obtain a serum concentration of about 25-55 micrograms / ml. In some embodiments, apivolumab is administered at greater than 2 mg / kg and up to 20 mg / kg to obtain a serum concentration of about 250-1100 micrograms / ml. In some embodiments, the serum concentration is 600 micrograms of apivolumab / ml (e.g., at least 600, 700, 800, 900, 1000 micrograms / ml or more). In some embodiments, the serum concentration is between about 600-1000 micrograms / ml. In some embodiments, the serum concentration is a steady-state serum concentration. In some embodiments, apivolumab is administered in an amount that reaches a steady-state serum concentration after about 112 days or after about five half-lives. In some embodiments, an amount greater than 2 mg / kg and up to 20 mg / kg is a dose of apivolumab of 20 mg / kg every four weeks or every month. In some embodiments, increasing the dose of apivolumab produces a serum concentration (C 最大 ) dose response, for example, increasing the dose tenfold from 2 mg / kg up to 20 mg / kg will produce C 最大 tenfold increase.

[0379] In some embodiments, to achieve a serum concentration (C 波谷 In some embodiments, apivolumab is administered at 2 mg / kg to achieve a serum concentration of about 25-55 micrograms / ml. In some embodiments, apivolumab is administered at greater than 2 mg / kg and up to 20 mg / kg to achieve a serum concentration of about 100-400 micrograms / ml. In some embodiments, the amount greater than 2 mg / kg and up to 20 mg / kg is a dose of 20 mg / kg of apivolumab every four weeks or monthly. In some embodiments, increasing the dose of apivolumab produces a serum concentration (C 波谷 ) dose response, for example, increasing the dose tenfold from 2 mg / kg up to 20 mg / kg will produce C 波谷 tenfold increase.

[0380] In some embodiments, apilectomycin is administered in an amount sufficient to achieve target engagement as measured by a serum latent myostatin concentration of at least about 250 ng / ml (e.g., at least about 400 ng / ml or 500 ng / ml (e.g., at least 500, 550, 600, or 650 ng / ml). In some embodiments, the serum latent myostatin concentration is between about 550-1100 or 600-1000 ng / ml. In some embodiments, the serum latent myostatin concentration is the steady-state concentration measured at the trough. In some embodiments, the amount is a dose of 20 mg / kg of apilectomycin every four weeks or every month.

[0381] In some embodiments, apilectomycin is administered in an amount that achieves one or more of the following in a subject: maintaining motor function compared to a decline in a control, delaying disease progression, delaying or preventing ambulatory Type 3 SMA patients from becoming nonambulatory, delaying or preventing the need for respiratory assistance or intervention, reducing the rate of decline in one or more motor function scores compared to a control, and / or maintaining at least a net zero change in one or more motor function scores compared to baseline. In some embodiments, the amount is a dose of 20 mg / kg of apilectomycin every four weeks or monthly.

[0382] In some embodiments, the present disclosure provides a method of treating SMA, the method comprising administering a composition comprising apivolumab to a patient population, wherein apivolumab is administered to the patient population by intravenous infusion every four weeks or monthly for at least six, 12, or 24 months in an amount sufficient to increase the clinical response rate (proportion of responders) in the patient population, and wherein the clinical response rate is measured by a 6-minute walk test and / or a 30-second sit-stand test. In some embodiments, the present disclosure provides a composition comprising apivolumab for use in treating SMA, wherein apivolumab is administered to the patient population by intravenous infusion every four weeks or monthly for at least six, 12, or 24 months in an amount sufficient to increase the clinical response rate (proportion of responders) in the patient population, and wherein the clinical response rate is measured by a 6-minute walk test and / or a 30-second sit-stand test. In some embodiments, the present disclosure provides the use of a composition comprising apilectumab for treating SMA, wherein apilectumab is administered to the patient population by intravenous infusion every four weeks or monthly for at least six months, 12 months, or 24 months in an amount sufficient to increase the clinical response rate (proportion of responders) in the patient population, and wherein the clinical response rate is measured by a 6-minute walk test and / or a 30-second sit-stand test. In some embodiments, the present disclosure provides the use of apilectumab in the manufacture of a composition for treating SMA, wherein apilectumab is administered to the patient population by intravenous infusion every four weeks or monthly for at least six months, 12 months, or 24 months in an amount sufficient to increase the clinical response rate (proportion of responders) in the patient population, and wherein the clinical response rate is measured by a 6-minute walk test and / or a 30-second sit-stand test.

[0383] In some embodiments, the patient population is a late-onset SMA population. In some embodiments, the patient population is an ambulatory type 3 SMA population. In some embodiments, the patient population comprises human subjects aged 5 to 21 years. In some embodiments, the patient population is treated with SMN upregulator therapy. In some embodiments, the SMN upregulator therapy is nusindrome or lisprolan. In some embodiments, the gene therapy is onasemnogene abeparvovec. In some embodiments, the SMN regulator therapy is nusindrome. In some embodiments, the patient population starts SMN upregulator therapy after the age of five. In some embodiments, a sufficient amount is a dose greater than 2 mg / kg and up to 20 mg / kg, optionally about 5, 10, 15, or 20 mg / kg. In some embodiments, a sufficient amount is a dose of 10 mg / kg or 20 mg / kg of apilectomycin every four weeks or monthly.

[0384] In some embodiments, apivolumab is administered in an amount to achieve a serum concentration of at least 600 micrograms of apivolumab / ml (e.g., at least 600, 700, 800, 900, 1000 micrograms / ml or more). In some embodiments, the serum concentration is between about 600-1000 micrograms / ml. In some embodiments, the serum concentration is a steady-state serum concentration. In some embodiments, apivolumab is administered in an amount that achieves a steady-state serum concentration after about 112 days. In some embodiments, the amount is a dose of 10 mg / kg or 20 mg / kg of apivolumab every four weeks or every month.

[0385] In some embodiments, apilectomycin is administered in an amount sufficient to achieve target engagement as measured by a serum latent myostatin concentration of at least 500 ng / ml (e.g., at least 500, 550, 600, or 650 ng / ml). In some embodiments, the serum latent myostatin concentration is between about 550-1100 or 600-1000 ng / ml. In some embodiments, the serum latent myostatin concentration is the steady-state concentration measured at the trough. In some embodiments, the amount is a dose of 10 mg / kg or 20 mg / kg of apilectomycin every four weeks or every month.

[0386] In some embodiments, apilectomycin is administered in an amount that achieves one or more of the following in a subject: maintaining motor function compared to a decline in a control, delaying disease progression, delaying or preventing ambulatory Type 3 SMA patients from becoming nonambulatory, delaying or preventing the need for respiratory assistance or intervention, reducing the rate of decline in one or more motor function scores compared to a control, and / or maintaining at least a net zero change in one or more motor function scores compared to baseline. In some embodiments, the amount is a dose of 10 mg / kg or 20 mg / kg of apilectomycin every fou...

Claims

1. A composition comprising apivolumab for use in treating spinal muscular atrophy (SMA) in a human subject, wherein the treatment comprises administering apivolumab intravenously in an amount of 20 mg / kg at intervals of once every four weeks for at least 24 months or two years.

2. The composition for use according to claim 1, wherein the apiltimumab is administered as a monotherapy or as an add-on therapy to SMN therapy.

3. A composition for use as claimed in claim 2, wherein the SMN therapy comprises (i) SMN2 splicing modifier; (ii) smn1 gene replacement or gene therapy; (iii) smn1 or smn2 transcription enhancer (iv) SMN protein translation enhancer; or (v) SMN protein stabilizer.

4. A composition for use according to any one of the preceding claims, wherein the SMN therapy comprises nusinsan or lisapram.

5. A composition for use as claimed in any preceding claim, wherein the treatment is sufficient to enhance motor function in the human subject compared to baseline as measured at 24 months after initiation of apivolumab administration.

6. The composition for use of any one of the preceding claims, wherein the treatment is sufficient to delay the loss of motor function in the human subject compared to baseline as measured at 24 months after initiation of apivolumab administration.

7. A composition for use as claimed in claim 5 or claim 6, wherein the enhancement of motor function or the delay of motor function loss is measured by the following: Hammersmith Functional Motor Scale Extended (HFMSE) score, Revised Hammersmith Scale (RHS) score, Revised Upper Limb Module (RULM) score or WHO Motor Development Milestones.

8. The composition for use of claim 7, wherein the enhancement of motor function is an increase of at least 1, 2, 3 or 4 points in the subject's HFMSE score compared to baseline at 24 months after initiation of apivolumab administration.

9. The composition for use of claim 7, wherein the enhancement of motor function is an increase of at least 1 point, 2 points, 3 points or 4 points in the subject's HFMSE score at 24 months compared to 12 months after starting apivolumab administration.

10. The composition for use of any one of the preceding claims, wherein the improvement in the subject's motor function relative to baseline is correlated with the level of target engagement relative to baseline as measured at 24 months after initiation of apivolumab administration.

11. A composition for use as claimed in any preceding claim, wherein the subject is at least 2 years old, optionally wherein the subject is 2-12 years old or 5-21 years old.

12. The composition for use according to any one of claims 5 to 11, wherein the enhancement of motor function refers to an increase in both the subject's HFMSE score and the Revised Upper Limb Module score as measured 24 months after initiation of apivolumab administration.

13. A composition for use as claimed in any preceding claim, wherein the subject suffers from ambulatory SMA.

14. A composition for use as claimed in any preceding claim, wherein the subject suffers from nonambulatory SMA.

15. A composition for use as claimed in any preceding claim, wherein the treatment is sufficient to improve the quality of life of the human subject as measured at 24 months after initiation of apivolumab administration.

16. The composition for use of claim 15, wherein the quality of life is measured by Pediatric Disability Evaluation Inventory Computer Adaptive Test (PEDI-CAT), Patient Reported Outcomes Measurement Information System (PROMIS), Endurance Shuttle Box and Block Test (ES-BBT).

17. The composition for use of claim 15 or claim 16, wherein the subject's PEDI-CAT activities of daily living score is increased compared to baseline at 12 months after initiation of apivolumab administration, and wherein the subject's PEDI-CAT activities of daily living score is further increased at 24 months after initiation of apivolumab treatment compared to the 12-month score.

18. The composition for use according to any one of claims 15-17, wherein the subject's PEDI-CAT mobility score is increased compared to baseline at 12 months after initiation of apivolumab administration, and wherein the subject's PEDI-CAT mobility score is further increased at 24 months after initiation of apivolumab treatment compared to the 12-month score.

19. The composition for use according to any one of claims 15-18, wherein the subject's PROMIS fatigue score is reduced compared to baseline at 12 months after initiation of apivolumab administration, and wherein the subject's PROMIS fatigue score is further reduced at 24 months after initiation of apivolumab treatment compared to the 12-month score.

20. The composition for use of any one of claims 15-19, wherein the subject's ES-BBT score is increased compared to baseline at 12 months after initiation of apivolumab administration, and wherein the subject's ES-BBT score is further increased at 24 months after initiation of apivolumab treatment compared to the 12-month score.

21. A composition for use as claimed in any one of the preceding claims, wherein the subject is 2-21 years old.

22. A myostatin inhibitor for use in treating SMA in a subject receiving SMN therapy, wherein the treatment comprises administering the myostatin inhibitor to a subject suffering from fatigue, bulbar dysfunction (optionally, cough, swallowing and / or eating difficulties), and / or voiding disorders (optionally, urinary and / or bowel movement urgency and frequency) as measured by subject or caregiver reported outcomes.

23. The myostatin inhibitor for use according to claim 22, wherein the myostatin inhibitor inhibits myostatin, GDF11 and activin A.

24. The myostatin inhibitor for use according to claim 22, wherein the myostatin inhibitor inhibits myostatin and GDF11 but does not inhibit activin A.

25. The myostatin inhibitor for use according to claim 22, wherein the myostatin inhibitor is a selective inhibitor of myostatin and does not bind to or inhibit GDF11 or Activin A, wherein optionally, the myostatin selective inhibitor is: (i) a neutralizing antibody or antigen-binding fragment thereof that selectively binds to myostatin but not to GDF11 or activin A; or (ii) an antibody or antigen-binding fragment thereof that binds to pro-myostatin / latent-myostatin.

26. The myostatin inhibitor for use according to claim 25, wherein the myostatin inhibitor inhibits activation of mature myostatin.

27. The myostatin inhibitor for use according to claim 25 or claim 26, wherein the myostatin selective inhibitor is Apitalugumab (SRK-015), GYM329 (RO7204239), a variant of Apitalugumab or GYM329, or an antibody that cross-blocks or cross-competes for antigen binding with Apitalugumab or GYM329.

28. The myostatin inhibitor for use according to any one of claims 22 to 26, wherein: a) the subject suffers from type 2 SMA or type 3 SMA; b) the subject has 2 copies, 3 copies, 4 copies or 5 copies of the smn2 gene; c) the subject suffers from ambulatory SMA or non-ambulatory SMA; and / or, d) the subject is 2 years of age or older when administration of the myostatin inhibitor is initiated.

29. The myostatin inhibitor for use according to claim 28, wherein the subject is 2-13 years old.

30. A myostatin inhibitor for use as claimed in claim 28 or claim 29, wherein the subject is 2-21 years old.

31. The myostatin inhibitor for use according to any one of claims 22 to 30, wherein: The SMN therapy is either an smn2 splicing modifier or an smn1 gene therapy.

32. A method for treating SMA in a subject, the method comprising administering to a subject diagnosed with Type 2 or nonambulatory Type 3 SMA a composition comprising apivolumab in an amount sufficient to achieve the following at 24 months after initiation of apivolumab administration: a) PEDI-CAT activities of daily living (ADL) score increased by at least one point compared with baseline; b) an increase in PEDI-CAT mobility score of at least one point compared to baseline; and / or, c) A decrease of at least one point in the PRIMIS fatigue score compared to baseline.

33. A method for treating SMA in a subject, the method comprising administering to a subject diagnosed with Type 2 or nonambulatory Type 3 SMA a composition comprising apivolumab in an amount sufficient to achieve an increase of at least two points from baseline in the subject's RULM score as measured 24 months after initiation of apivolumab administration.

34. A method for determining the therapeutic efficacy of a myostatin inhibitor treatment in a subject with SMA, the method comprising: i) determining a baseline level of serum creatinine in a serum sample collected from the subject prior to initiating the myostatin inhibitor treatment; ii) determining the level of serum creatinine in a serum sample collected from the subject after initiation of the myostatin inhibitor treatment; iii) comparing the serum creatinine level of step (ii) with the baseline serum creatine level of step (i); wherein a change in the serum creatinine level of step (ii) compared to the serum creatinine level of step (i) is indicative of efficacy.

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