RARE DISEASE
Becker muscular dystrophy
Becker muscular dystrophy
Becker muscular dystrophy
Synonyms: BMD, Becker dystrophinopathy
Synonyms: BMD, Becker dystrophinopathy
Synonyms: BMD, Becker dystrophinopathy
Drug discovery
9
drugs
With orphan designations
Overview
Becker muscular dystrophy (BMD) is an X-linked recessive disorder caused by mutations in the DMD gene, leading to reduced or abnormal dystrophin production. It presents with progressive proximal muscle weakness, typically emerging in childhood or adolescence, and progresses slower than Duchenne muscular dystrophy. Cardiac involvement (cardiomyopathy, arrhythmias) and respiratory decline are common, often asymptomatic initially. Diagnosis relies on elevated serum CK, genetic testing, and muscle biopsy. Management focuses on multidisciplinary care, including cardiac surveillance, glucocorticoids, and physical therapy to preserve function [1][5][6][16][17].
Burden
Mobility: Loss of ambulation typically occurs in the 30s–50s; wheelchair dependency in ~40% of cases [11][17].
Mortality: Life expectancy often reduced due to heart failure (leading cause) or respiratory complications [13][17].
Healthcare costs: Requires lifelong multidisciplinary care, cardiac devices, and adaptive equipment [6][8][16].
Therapies
Cardioprotection: ACE inhibitors/beta-blockers initiated at early echocardiogram abnormalities [1][6][13].
Symptomatic care: Glucocorticoids (e.g., prednisone) to delay muscle decline, physical therapy, orthotics, and non-invasive ventilation for respiratory support [6][8][11].
Emerging therapies: Myosin inhibitors (e.g., EDG-5506), follistatin gene therapy, and exon-skipping agents in clinical trials [3][18].
Categories: rare cardiac diseases, rare genetic diseases, rare neurological diseases, rare transplant-related disorders
Research Papers
549 drug discovery papers about Becker muscular dystrophy, with 5 first-in-class and 13 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
549 drug discovery papers about Becker muscular dystrophy, with 5 first-in-class and 13 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
2026-08-11 | Mexico’s First Heart Transplant in a Patient with Becker Muscular Dystrophy Reveals an Overlooked Cause of Idiopathic Dilated Cardiomyopathy
Background: Pathogenic variants in the DMD gene are a frequently overlooked cause of dilated cardiomyopathy (DCM) in idiopathic cases, especially when skeletal myopathy is mild or seemingly absent. Becker muscular dystrophy (BMD) and X-linked dilated cardiomyopathy are at opposite ends of this clinical spectrum but result from pathogenic variants in the same gene. Cardiomyopathy is a major cause of premature death in muscular dystrophies. Case presentation: We describe a 37-year-old man who underwent orthotopic heart transplantation for presumed idiopathic DCM with refractory heart failure. He had a six-year history of progressive proximal weakness, pseudohypertrophy of the calf, a positive Gowers sign, and markedly elevated creatine kinase (6638 IU/L). Multiplex ligation-dependent probe amplification (MLPA) revealed an in-frame deletion of exons 45–47 of DMD [c. (6438+1_6439-1)_(6912+1_6913-1) del; NM_004006.2], confirming BMD. Immunofluorescence showed reduced and patchy dystrophin expression. Conclusions: To our knowledge, this is the first documented heart transplant in a patient with BMD in Mexico. This case demonstrates the value of considering muscular dystrophy in the differential diagnosis of apparently idiopathic dilated cardiomyopathy (DCM), a step that opens the door to accurate diagnosis, carrier screening, and genetic counseling, and supports the view that heart transplantation is a viable option in carefully selected patients with muscular dystrophy cardiomyopathy.
2026-08-04 | Volatile-Free Total Intravenous Anesthesia for Major Gynecologic Surgery in a Manifesting Female Carrier of Becker Muscular Dystrophy: A Case Report
Becker muscular dystrophy (BMD) is a rare X-linked dystrophinopathy caused by dystrophin gene (DMD gene) variants, resulting in reduced or dysfunctional dystrophin. Despite a milder course than Duchenne muscular dystrophy, patients face significant perioperative risk from skeletal muscle degeneration, respiratory weakness, cardiomyopathy, and conduction abnormalities. Succinylcholine and volatile anesthetics have been associated with life-threatening hyperkalemia, rhabdomyolysis, and malignant hyperthermia-like reactions in dystrophinopathies. Clinically manifest BMD in females is exceptionally rare due to skewed X-inactivation, and perioperative data in this population remain scarce. We report a 39-year-old woman with genetically confirmed, clinically manifested BMD who underwent elective left salpingo-oophorectomy with surgical staging for a large adnexal mass. She had severe proximal weakness and was non-ambulatory but had no respiratory, swallowing, or aspiration symptoms. Multidisciplinary preoperative evaluation (neurology, cardiology, hepatology, anesthesiology, gynecologic oncology, intensive care) confirmed preserved cardiac function (ejection fraction >70%), normal conduction, no respiratory compromise evidenced by normal pulmonary function tests, and adequate hepatic reserve. A trigger-free anesthetic strategy was used: the workstation was prepared to eliminate residual volatile agents, and total intravenous anesthesia was maintained with propofol, dexmedetomidine, and midazolam, avoiding succinylcholine and volatile agents. Reduced-dose atracurium provided neuromuscular blockade, and multimodal opioid-sparing analgesia included bilateral rectus sheath blocks and non-opioid analgesics. Surgery was uneventful, with no hemodynamic instability, arrhythmias, hyperkalemia, or rhabdomyolysis. The patient was extubated in the operating room after full neuromuscular recovery, then electively admitted to the ICU for observation given the risk of delayed respiratory compromise. Her postoperative course was uncomplicated, with stable cardiorespiratory function and effective analgesia. Histopathology confirmed an adult granulosa cell tumor of the ovary. This case suggests that major gynecologic surgery can be safely performed in clinically manifest female BMD patients through multidisciplinary planning, trigger-free total intravenous anesthesia, careful neuromuscular blockade, opioid-sparing analgesia, and planned ICU surveillance, offering valuable guidance for this rare, high-risk population.
2026-07-01 | Human Disposition, Metabolism, and Excretion of Sevasemten (EDG‐5506), a Selective Modulator of Fast Myosin in Healthy Volunteers
Abstract Sevasemten (EDG‐5506) is a novel, orally bioavailable, investigational small molecule designed to selectively modulate type II fast skeletal myosin with the goal of protecting dystrophic muscle from contraction‐induced injury. Sevasemten is in clinical development for the treatment of Becker and Duchenne muscular dystrophy. In the current Phase 1 study (NCT05730842), eight participants were dosed with a 20 mg single oral suspension dose of sevasemten containing approximately 500 µCi [ 14 C] sevasemten. Blood and urine samples were collected to evaluate the pharmacokinetics (PK), oral absorption, metabolism, and excretion (AME) of sevasemten and its metabolites. A second cohort of seven participants received a single 20 mg oral dose of sevasemten, followed 2 h later by a single dose of [ 14 C] sevasemten administered as a single intravenous (IV) bolus with approximately 1 µCi [ 14 C] sevasemten to determine absolute bioavailability. Sevasemten was excreted primarily in urine (52.1%) subsequent to CYP3A‐mediated metabolism, and 8.89% was eliminated in the feces, for a total of 61.0% recovered over 840 h post‐dose. Most of the recoverable radioactivity was excreted by 576 h (24 days). However, sevasemten total radioactivity in plasma and whole blood was characterized by a very slow elimination phase of 16.1–20.6 days; total recovery of radioactivity was not achieved. Sevasemten was well tolerated, with no serious adverse events or adverse events leading to study discontinuation. Sevasemten has favorable PK properties for once daily administration and continues to be investigated for the treatment of Becker and Duchenne muscular dystrophies.
2026-06-17 | Effects of sevasemten (EDG-5506) on safety, biomarkers, and functional measures in adults with Becker muscular dystrophy: results of a phase 1b, open-label study.
Sevasemten (EDG-5506) is an orally administered, investigational small molecule that selectively modulates fast muscle fibre contraction by inhibiting fast myosin ATPase. In animal models of Duchenne and Becker muscular dystrophy (DMD and BMD, respectively), sevasemten reduced the muscle contraction injury that leads to inflammation, fibrosis and muscle loss without affecting function. The aim of this study was to evaluate the long-term safety, tolerability, and pharmacokinetics (PK)/pharmacodynamics of sevasemten in adult participants with BMD who had already experienced a decline in function and would be anticipated to continue to decline based on natural history. This open-label, dose escalation, phase 1 b study (NCT05160415) was conducted at a single site and enrolled ambulatory adults with BMD aged 18-55 years; the study is completed. Eligible participants received 10 mg of sevasemten once daily (QD) for 8 weeks, followed by 15 mg QD for 4 months, 20 mg QD for 9 months, and 10 mg QD for 9 months. The primary objective was to assess the safety and tolerability of sevasemten in adults with BMD; endpoints included adverse events (AEs), PK, change from baseline in circulating biomarkers of muscle injury, as well as physical function measures. The study enrolled 12 adults with BMD. Sevasemten was well tolerated; all AEs were mild or moderate in severity and there were no serious AEs or AEs leading to discontinuation. Treatment with sevasemten was associated with reductions in circulating biomarkers of muscle injury that were evident within 4 weeks and sustained for up to 24 months. Physical function, as assessed by North Star Ambulatory Assessment (NSAA), was stable over 24 months. Sevasemten treatment for up to 24 months in adults with BMD was well tolerated and associated with durable reductions in muscle injury biomarkers, consistent with preclinical studies and near maximal with the 10 mg dose, as well as functional stabilisation. Further clinical development is ongoing. Edgewise Therapeutics, Inc.
2026-06-05 | Gene editing restores full-length dystrophin and affects iron homeostasis in hiPSC-derived cardiomyocytes from Becker Muscular Dystrophy patients.
Becker Muscular Dystrophy (BMD) is caused by in-frame mutations in the DMD gene, leading to the production of internally truncated but partially functional dystrophin. Although cardiac involvement is a major contributor to disease burden in BMD, the cellular mechanisms driving cardiomyopathy remain incompletely understood. While emerging evidence suggests that iron imbalance may contribute to oxidative stress and mitochondrial dysfunction in muscular dystrophies, its role in BMD-associated cardiomyopathy has not been defined. Building on our previous findings of dysregulated iron homeostasis in dystrophin-deficient cardiomyocytes from Duchenne muscular dystrophy (DMD), we investigated whether similar alterations are present in BMD using patient-specific and genome-corrected hiPSC-CM models. HiPSC lines derived from two BMD patients and their CRISPR/Cas9-corrected isogenic controls displayed normal karyotype, pluripotency, and efficient differentiation into cardiomyocytes (hiPSC-CMs). BMD hiPSC-CMs showed elevated ROS levels and decreased cytoplasmic and mitochondrial labile iron pools, accompanied by reduced expression of mitoNEET (CISD1), a regulator of mitochondrial iron handling. We also detected changes in the expression of genes involved in iron storage (FTH1), uptake (TFRC), and export (SLC40A1), suggesting a dysregulation of iron trafficking. Importantly, correction of DMD mutation by CRISPR/Cas9 gene editing reversed the effects observed in BMD cardiomyocytes. These results extend our previous observations in DMD to BMD cardiomyocytes and suggest that full-length dystrophin is essential for maintaining cardiac iron homeostasis.
2026-08-11 | Mexico’s First Heart Transplant in a Patient with Becker Muscular Dystrophy Reveals an Overlooked Cause of Idiopathic Dilated Cardiomyopathy
Background: Pathogenic variants in the DMD gene are a frequently overlooked cause of dilated cardiomyopathy (DCM) in idiopathic cases, especially when skeletal myopathy is mild or seemingly absent. Becker muscular dystrophy (BMD) and X-linked dilated cardiomyopathy are at opposite ends of this clinical spectrum but result from pathogenic variants in the same gene. Cardiomyopathy is a major cause of premature death in muscular dystrophies. Case presentation: We describe a 37-year-old man who underwent orthotopic heart transplantation for presumed idiopathic DCM with refractory heart failure. He had a six-year history of progressive proximal weakness, pseudohypertrophy of the calf, a positive Gowers sign, and markedly elevated creatine kinase (6638 IU/L). Multiplex ligation-dependent probe amplification (MLPA) revealed an in-frame deletion of exons 45–47 of DMD [c. (6438+1_6439-1)_(6912+1_6913-1) del; NM_004006.2], confirming BMD. Immunofluorescence showed reduced and patchy dystrophin expression. Conclusions: To our knowledge, this is the first documented heart transplant in a patient with BMD in Mexico. This case demonstrates the value of considering muscular dystrophy in the differential diagnosis of apparently idiopathic dilated cardiomyopathy (DCM), a step that opens the door to accurate diagnosis, carrier screening, and genetic counseling, and supports the view that heart transplantation is a viable option in carefully selected patients with muscular dystrophy cardiomyopathy.
2026-08-04 | Volatile-Free Total Intravenous Anesthesia for Major Gynecologic Surgery in a Manifesting Female Carrier of Becker Muscular Dystrophy: A Case Report
Becker muscular dystrophy (BMD) is a rare X-linked dystrophinopathy caused by dystrophin gene (DMD gene) variants, resulting in reduced or dysfunctional dystrophin. Despite a milder course than Duchenne muscular dystrophy, patients face significant perioperative risk from skeletal muscle degeneration, respiratory weakness, cardiomyopathy, and conduction abnormalities. Succinylcholine and volatile anesthetics have been associated with life-threatening hyperkalemia, rhabdomyolysis, and malignant hyperthermia-like reactions in dystrophinopathies. Clinically manifest BMD in females is exceptionally rare due to skewed X-inactivation, and perioperative data in this population remain scarce. We report a 39-year-old woman with genetically confirmed, clinically manifested BMD who underwent elective left salpingo-oophorectomy with surgical staging for a large adnexal mass. She had severe proximal weakness and was non-ambulatory but had no respiratory, swallowing, or aspiration symptoms. Multidisciplinary preoperative evaluation (neurology, cardiology, hepatology, anesthesiology, gynecologic oncology, intensive care) confirmed preserved cardiac function (ejection fraction >70%), normal conduction, no respiratory compromise evidenced by normal pulmonary function tests, and adequate hepatic reserve. A trigger-free anesthetic strategy was used: the workstation was prepared to eliminate residual volatile agents, and total intravenous anesthesia was maintained with propofol, dexmedetomidine, and midazolam, avoiding succinylcholine and volatile agents. Reduced-dose atracurium provided neuromuscular blockade, and multimodal opioid-sparing analgesia included bilateral rectus sheath blocks and non-opioid analgesics. Surgery was uneventful, with no hemodynamic instability, arrhythmias, hyperkalemia, or rhabdomyolysis. The patient was extubated in the operating room after full neuromuscular recovery, then electively admitted to the ICU for observation given the risk of delayed respiratory compromise. Her postoperative course was uncomplicated, with stable cardiorespiratory function and effective analgesia. Histopathology confirmed an adult granulosa cell tumor of the ovary. This case suggests that major gynecologic surgery can be safely performed in clinically manifest female BMD patients through multidisciplinary planning, trigger-free total intravenous anesthesia, careful neuromuscular blockade, opioid-sparing analgesia, and planned ICU surveillance, offering valuable guidance for this rare, high-risk population.
2026-07-01 | Human Disposition, Metabolism, and Excretion of Sevasemten (EDG‐5506), a Selective Modulator of Fast Myosin in Healthy Volunteers
Abstract Sevasemten (EDG‐5506) is a novel, orally bioavailable, investigational small molecule designed to selectively modulate type II fast skeletal myosin with the goal of protecting dystrophic muscle from contraction‐induced injury. Sevasemten is in clinical development for the treatment of Becker and Duchenne muscular dystrophy. In the current Phase 1 study (NCT05730842), eight participants were dosed with a 20 mg single oral suspension dose of sevasemten containing approximately 500 µCi [ 14 C] sevasemten. Blood and urine samples were collected to evaluate the pharmacokinetics (PK), oral absorption, metabolism, and excretion (AME) of sevasemten and its metabolites. A second cohort of seven participants received a single 20 mg oral dose of sevasemten, followed 2 h later by a single dose of [ 14 C] sevasemten administered as a single intravenous (IV) bolus with approximately 1 µCi [ 14 C] sevasemten to determine absolute bioavailability. Sevasemten was excreted primarily in urine (52.1%) subsequent to CYP3A‐mediated metabolism, and 8.89% was eliminated in the feces, for a total of 61.0% recovered over 840 h post‐dose. Most of the recoverable radioactivity was excreted by 576 h (24 days). However, sevasemten total radioactivity in plasma and whole blood was characterized by a very slow elimination phase of 16.1–20.6 days; total recovery of radioactivity was not achieved. Sevasemten was well tolerated, with no serious adverse events or adverse events leading to study discontinuation. Sevasemten has favorable PK properties for once daily administration and continues to be investigated for the treatment of Becker and Duchenne muscular dystrophies.
2026-06-17 | Effects of sevasemten (EDG-5506) on safety, biomarkers, and functional measures in adults with Becker muscular dystrophy: results of a phase 1b, open-label study.
Sevasemten (EDG-5506) is an orally administered, investigational small molecule that selectively modulates fast muscle fibre contraction by inhibiting fast myosin ATPase. In animal models of Duchenne and Becker muscular dystrophy (DMD and BMD, respectively), sevasemten reduced the muscle contraction injury that leads to inflammation, fibrosis and muscle loss without affecting function. The aim of this study was to evaluate the long-term safety, tolerability, and pharmacokinetics (PK)/pharmacodynamics of sevasemten in adult participants with BMD who had already experienced a decline in function and would be anticipated to continue to decline based on natural history. This open-label, dose escalation, phase 1 b study (NCT05160415) was conducted at a single site and enrolled ambulatory adults with BMD aged 18-55 years; the study is completed. Eligible participants received 10 mg of sevasemten once daily (QD) for 8 weeks, followed by 15 mg QD for 4 months, 20 mg QD for 9 months, and 10 mg QD for 9 months. The primary objective was to assess the safety and tolerability of sevasemten in adults with BMD; endpoints included adverse events (AEs), PK, change from baseline in circulating biomarkers of muscle injury, as well as physical function measures. The study enrolled 12 adults with BMD. Sevasemten was well tolerated; all AEs were mild or moderate in severity and there were no serious AEs or AEs leading to discontinuation. Treatment with sevasemten was associated with reductions in circulating biomarkers of muscle injury that were evident within 4 weeks and sustained for up to 24 months. Physical function, as assessed by North Star Ambulatory Assessment (NSAA), was stable over 24 months. Sevasemten treatment for up to 24 months in adults with BMD was well tolerated and associated with durable reductions in muscle injury biomarkers, consistent with preclinical studies and near maximal with the 10 mg dose, as well as functional stabilisation. Further clinical development is ongoing. Edgewise Therapeutics, Inc.
2026-06-05 | Gene editing restores full-length dystrophin and affects iron homeostasis in hiPSC-derived cardiomyocytes from Becker Muscular Dystrophy patients.
Becker Muscular Dystrophy (BMD) is caused by in-frame mutations in the DMD gene, leading to the production of internally truncated but partially functional dystrophin. Although cardiac involvement is a major contributor to disease burden in BMD, the cellular mechanisms driving cardiomyopathy remain incompletely understood. While emerging evidence suggests that iron imbalance may contribute to oxidative stress and mitochondrial dysfunction in muscular dystrophies, its role in BMD-associated cardiomyopathy has not been defined. Building on our previous findings of dysregulated iron homeostasis in dystrophin-deficient cardiomyocytes from Duchenne muscular dystrophy (DMD), we investigated whether similar alterations are present in BMD using patient-specific and genome-corrected hiPSC-CM models. HiPSC lines derived from two BMD patients and their CRISPR/Cas9-corrected isogenic controls displayed normal karyotype, pluripotency, and efficient differentiation into cardiomyocytes (hiPSC-CMs). BMD hiPSC-CMs showed elevated ROS levels and decreased cytoplasmic and mitochondrial labile iron pools, accompanied by reduced expression of mitoNEET (CISD1), a regulator of mitochondrial iron handling. We also detected changes in the expression of genes involved in iron storage (FTH1), uptake (TFRC), and export (SLC40A1), suggesting a dysregulation of iron trafficking. Importantly, correction of DMD mutation by CRISPR/Cas9 gene editing reversed the effects observed in BMD cardiomyocytes. These results extend our previous observations in DMD to BMD cardiomyocytes and suggest that full-length dystrophin is essential for maintaining cardiac iron homeostasis.
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Drug Discovery Landscape
9 orphan drug designations for Becker muscular dystrophy.
9 orphan drug designations for Becker muscular dystrophy.
Drug | Therapy type | Regulator | Orphan designation | Approval | Sponsor |
|---|---|---|---|---|---|
human allogeneic cardiosphere-derived cells | cell therapies | FDA | 2025-06-13 | — | Capricor, Inc. |
Induced pluripotent stem cells-derived myogenic progenitor cells | cell therapies | EMA | 2025-05-22 | — | Biopatents IP Consultancy |
human induced pluripotent stem cell derived myogenic progenitor cells | cell therapies | FDA | 2024-12-23 | — | IPS HEART |
Sevasemten | small molecules | EMA | 2024-03-21 | — | FGK Representative Service GmbH |
vamorolone | small molecules | FDA | 2023-12-18 | — | ReveraGen BioPharma Inc. |
Dexepicatechin | small molecules | EMA | 2020-06-26 | — | MWB Consulting |
Givinostat | small molecules | EMA | 2018-07-31 | — | Italfarmaco S.p.A. |
adeno-associated virus transgene of follistatin | gene therapies | FDA | 2012-11-19 | — | Milo Biotechnology |
Ataluren [Translarna] | small molecules | EMA | 2012-07-04 | — | PTC Therapeutics International Limited |
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