Eteplirsen for Duchenne Muscular Dystrophy in Patients Amenable to Exon 51 Skipping
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Horizon Scanning Research January 2016 & Intelligence Centre Eteplirsen for Duchenne muscular dystrophy in patients amenable to exon 51 skipping LAY SUMMARY Duchenne muscular dystrophy is an inherited condition that causes muscle weakness. It affects mainly boys and is caused by a mutation (a change) in the gene that makes dystrophin. Dystrophin is important for protecting muscles from stress and damage during activity. Most This briefing is people with Duchenne muscular dystrophy are diagnosed by the age based on information of 5 years, and need to use a wheelchair by the age of 12 years. Many available at the time will face severe health problems by their late teens as their heart and of research and a chest muscles become weaker, eventually affecting their breathing. limited literature search. It is not Eteplirsen is designed to “skip” a part of the gene that makes intended to be a dystrophin called exon 51. For people who have mutations called definitive statement deletions in certain parts of the dystrophin gene, skipping exon 51 may on the safety, potentially allow the body to produce a shortened, but still working, efficacy or form of the dystrophin protein. Eteplirsen is delivered directly into the effectiveness of the blood stream via a drip, once a week. At the moment, there are no health technology drugs that treat the underlying problem that causes Duchenne covered and should muscular dystrophy. not be used for commercial Eteplirsen is currently being studied to see how well it works and purposes or whether it is safe to use in people with Duchenne muscular dystrophy commissioning amenable to exon 51 skipping. If eteplirsen is licensed for use in the without additional UK, it will offer a new treatment option for this type of Duchenne information . muscular dystrophy NIHR HSRIC ID: 4256 This briefing presents independent research funded by the National Institute for Health Research (NIHR). The views expressed are those of the author and not necessarily those of the NHS, the NIHR or the Department of Health. NIHR Horizon Scanning Research & Intelligence Centre, University of Birmingham. Email: [email protected] Web: www.hsric.nihr.ac.uk Horizon Scanning Research & Intelligence Centre TARGET GROUP • Duchenne muscular dystrophy (DMD); in patients amenable to exon 51 skipping. TECHNOLOGY DESCRIPTION Eteplirsen (AVI-4658) is a phosphorodiamidate morpholine oligomer (PMO) with a charge neutral backbone, that acts as an exon skipping splice switching oligomer (SSO) designed to skip exon 51 of the dystrophin gene, thereby repairing the mutated reading frame in the mRNA coding sequence in patients with a deletion in exons 45-50, 47-50, 48-50, 49-50, 50, 52, or 52-63 of this gene. In doing so, eteplirsen enables the production of an internally truncated, yet functional, dystrophin protein. In phase III clinical trials1, eteplirsen was administered via intravenous (IV) infusion at 30mg/kg, once weekly. Eteplirsen does not currently have Marketing Authorisation in the EU for any indication. INNOVATION and/or ADVANTAGES If licensed, eteplirsen will provide a novel, potentially disease-modifying treatment option for this patient group for whom there are currently no licensed treatments that have an impact on dystrophin protein production. DEVELOPER Sarepta Therapeutics. AVAILABILITY, LAUNCH OR MARKETING In phase III clinical trials. PATIENT GROUP BACKGROUND Muscular dystrophies are a group of genetic disorders that cause muscle weakness and progressive disability 2. DMD is the most common and progresses most rapidly 2. The condition is an X-linked recessive allelic disorder caused by mutations (mainly deletions) in the dystrophin gene, which leads to absence of, or defects in the protein dystrophin 3,4. The absence of functional dystrophin protein leads to progressive muscle necrosis, loss of independent ambulation by early adolescence, cardiomyopathy, respiratory insufficiency and premature death 3. As males have only one X chromosome, and thus one single copy of the dystrophin gene, they have a much higher probability of developing DMD, although a small number of females are also affected 2. Initial symptoms of DMD usually present between the ages of 1 and 3 years and children with the disease may appear weaker than other children, and have difficulty walking, standing, or climbing stairs 2. Affected children may also have behavioural or learning difficulties, and progressive decline in walking ability leads to wheelchair use, typically after 2 Horizon Scanning Research & Intelligence Centre the age of 12 2. Death due to respiratory and/or cardiac failure usually occurs by late teens or early 20s 5, although life expectancy has increased in recent decades due to improved treatments and multidisciplinary care 6. NHS or GOVERNMENT PRIORITY AREA • NHS England. 2013/14 NHS Standard Contract for Neurosciences: Specialised Neurology (Adult). D04/A/a. • NHS England. 2013/14 NHS Standard Contract for Diagnostic Service for Rare Neuromuscular Disorders (All Ages). D04/S(HSS)/a. • NHS England. 2013/14 NHS Standard Contract for Respiratory: Complex Home Ventilation (Adult). A14/S/a. CLINICAL NEED and BURDEN OF DISEASE DMD has an estimated incidence of 1 in 3,500 male births 3. Females who are heterozygous for the defective DMD gene are usually asymptomatic, but a small percentage of female carriers manifest milder forms of the disease 7. The Muscular Dystrophy Campaign estimates that there are approximately 100 boys born with DMD in the UK every year, and there are approximately 2,500 boys living with the condition in the UK at any one time 8,9. Available data suggests around 83% of DMD patients have genotypes amenable to exon skipping, and that 13% of DMD patients have genotypes that are amenable to exon 51 skipping 10 . In 2014-15, there were 1,060 hospital admissions for muscular dystrophy (ICD-10 G71.0; which includes DMD along with other muscular dystrophies) in England, resulting and 1,141 finished consultant episodes and 2,682 bed days 11 . In 2013, 117 deaths (88 men, 29 women) were registered in England and Wales 12 . The population likely to be eligible to receive eteplirsen could not be estimated from available published sources. PATIENT PATHWAY RELEVANT GUIDANCE NICE Guidance • NICE technology appraisal in development. Duchenne Muscular Dystrophy (nonsense mutation) – ataluren (ID428). Expected February 2016. Other Guidance • DMD Care Considerations Working Group. Diagnosis and management of Duchenne muscular dystrophy, part 1: diagnosis, and pharmacological and psychosocial management. 2010 4. • DMD Care Considerations Working Group: Diagnosis and management of Duchenne muscular dystrophy, part 2: implementation of multidisciplinary care. 2010 13 . • British Thoracic Society. Guidelines for respiratory management of children with neuromuscular weakness. 2012 14 . CURRENT TREATMENT OPTIONS Treatment options for DMD predominantly focus on management of symptoms and secondary complications. This requires a multidisciplinary approach involving physicians, 3 Horizon Scanning Research & Intelligence Centre therapists, counsellors, and other specialists to improve the life expectancy and quality of life of patients 13 . Glucocorticoids are the only pharmacological treatments that have been shown to improve skeletal muscle strength and function in reproducible randomised controlled trials; they also reduce the risk of scoliosis, stabilise pulmonary function, and may also improve cardiac function 4,15 . Current guidelines recommend initiation of glucocorticoids (such as prednisolone or deflazacort) once patients reach a plateau of motor skill development, generally at age 4-6 years, but prior to onset of motor decline 15 . Other pharmacologic therapies for DMD are primarily aimed at the management of comorbidities such as cardiomyopathy, osteoporosis, pain management, and respiratory failure 15 . These treatment options include 4: • Angiotensin-converting-enzyme (ACE) inhibitors. • β blockers. • Calcium and vitamin D supplements. • Muscle relaxants. • Non-steroidal anti-inflammatory drugs. Surveillance of the respiratory, cardiac, orthopaedic, nutritional and general medical issues associated with DMD allows anticipation, early detection and treatment of these complications 15 . Supportive care for DMD also includes 4,13 : • Physical therapy. • Occupational therapy. • Orthopaedic surgery. • Genetic counselling. • Invasive and non-invasive ventilation. • Implanted cardiac devices. EFFICACY and SAFETY Trial NCT02255552, 4658-01; NCT01396239, 4658-us- NCT01540409, 4658-us- eteplirsen vs no 201; eteplirsen vs placebo; 202; eteplirsen; phase II intervention; phase III. phase II. extension. Sponsor Sarepta Therapeutics. Sarepta Therapeutics. Sarepta Therapeutics. Status Ongoing. Published. Ongoing. Source of Trial registry 1, Publication 16 , trial Trial registry 18 , information manufacturer. registry 17 , manufacturer. manufacturer. Location USA. USA. USA. Design Non-randomised, Randomised; placebo- Non-randomised; controlled. controlled. uncontrolled. Participants n=160; aged 7-16 years; n=12; aged 7-13 years; n=12 (planned); aged 7-13 males; DMD. males; DMD; mutation years; males; DMD; amenable to exon 51 mutation amenable to exon skipping. 51 skipping; completed 28 weeks treatment (incl placebo) in study NCT01396239. Schedule Eteplirsen, 30mg/kg IV, Randomised to eteplirsen, All participants receive once weekly; or no 30mg/kg or 50mg/kg IV, eteplirsen, 30mg/kg or intervention (for once weekly; or placebo, 50mg/kg IV,