Proceedings of a Parent Project Muscular Dystrophy Bone Health Workshop: Morbidity due to osteoporosis in DMD: The Path Forward May 12-13, 2016, Bethesda, Maryland, USA

Is endocrine surveillance important in the care of Duchenne Muscular Dystrophy? Results from a national survey to patients and families on endocrine complications

Glucocorticoids are standard of care for patients with Duchenne muscular dystrophy (DMD). Although prolonged exposure is associated with multiple endocrine side effects, current guidelines related to monitoring and management of endocrinopathies are suboptimal. We aim to explore community perceptions of endocrine related complications in patients with DMD, assess current level of understanding, and desire for further education. A 31-item online survey was sent through Parent Project to Muscular Dystrophy (PPMD) to Duchenne Registry members to be completed by patients or their caretakers. Response rate was 55% (n = 75). Steroids were taken by 93%, but only 50% were followed by endocrinology and 21% report never been seen by endocrinology. Bone health was discussed with 87% of patients and 60% were diagnosed with osteoporosis. Delayed puberty was discussed with 41% of patients with 23% receiving testosterone therapy. About half the patients reported a diagnosis of slowed growth. Only 51% of the participants recalled discussing adrenal insufficiency. Obesity was discussed with 59% of participants. Families felt education about steroid-induced endocrinopathies to be very or extremely important and prefer to discuss about this at the beginning of their steroid therapy. This demonstrates significant gaps in education and access to endocrine care in patients with DMD.

Long-term safety and functional outcomes of delandistrogene moxeparvovec gene therapy in patients with Duchenne muscular dystrophy: A phase 1/2a nonrandomized trial

INTRODUCTION/AIMS

Delandistrogene moxeparvovec is indicated in the United States for the treatment of ambulatory pediatric patients aged 4 through 5 years with Duchenne muscular dystrophy (DMD) with a confirmed mutation in the DMD gene. Long-term delandistrogene moxeparvovec microdystrophin protein (a shortened dystrophin that retains key functional domains of the wild-type protein) expression may positively alter disease progression in patients with DMD. We evaluated long-term safety and functional outcomes of delandistrogene moxeparvovec in patients with DMD.

METHODS

An open-label, phase 1/2a, nonrandomized controlled trial (Study 101; NCT03375164) enrolled ambulatory males, ≥4 to <8 years old, with DMD. Patients received a single intravenous infusion (2.0 × 1014 vg/kg by supercoiled quantitative polymerase chain reaction) of delandistrogene moxeparvovec and prednisone (1 mg/kg/day) 1 day before to 30 days after treatment. The primary endpoint was safety. Functional outcomes were change from baseline in North Star Ambulatory Assessment (NSAA) and timed function tests.

RESULTS

Four patients (mean age, 5.1 years) were enrolled. There were 18 treatment-related adverse events; all occurred within 70 days posttreatment and resolved. Mean NSAA total score increased from 20.5 to 27.5, baseline to year 4, with a mean (standard deviation) change of +7.0 (2.9). Post hoc analysis demonstrated a statistically significant and clinically meaningful 9-point difference in NSAA score, relative to a propensity-score-weighted external control cohort (least-squares mean [standard error] = 9.4 [3.4]; P = .0125).

DISCUSSION

Gene transfer therapy with delandistrogene moxeparvovec treatment is well tolerated, with a favorable safety profile. Functional improvements are sustained through 4 years, suggesting delandistrogene moxeparvovec may positively alter disease progression.

Variability and trends in corticosteroid use by male United States participants with Duchenne muscular dystrophy in the Duchenne Registry

Background

Treatment options for Duchenne muscular dystrophy remain limited, although consensus treatment guidelines recommend corticosteroid use.

Methods

This retrospective analysis assessed corticosteroid use in ambulatory and nonambulatory US males with Duchenne, age 35 and under, or Becker muscular dystrophy, who enrolled in The Duchenne Registry from 2007 to 2016 (formerly DuchenneConnect).

Results

The mean (SD) age of corticosteroid use initiation was 5.9 (2.5) years, and deflazacort use (54%) was slightly more common than prednisone/prednisolone (46%). Among all responses from those with Duchenne, 63% were currently on corticosteroids, 12% were no longer on corticosteroids, and 25% had never been on corticosteroids. Among those who were nonambulatory, 49% were currently on corticosteroids, 28% had discontinued corticosteroids, and 23% had never used corticosteroids. Primary reasons for never initiating therapy were that corticosteroids were not prescribed or recommended and concerns about side effects. Corticosteroid use was maximal at age 8 (84% on corticosteroids) and gradually declined from age 10 to 19. The primary reasons for corticosteroid discontinuation were problems with side effects (65%) or not enough benefit (28%). Average doses of corticosteroids were below recommended doses. In the 159 responses with Becker muscular dystrophy, 20% were currently using corticosteroids.

Conclusions

Recognizing the self-selected nature of participation, it appears that a considerable proportion of US participants registered with The Duchenne Registry were either not on corticosteroids or not on recommended doses despite consensus recommendations. Side effects were a consideration in initiating and discontinuing treatment.

These data reinforce the need for additional treatment options for those affected by Duchenne.

Increased Rates of Vitamin D Insufficiency in Boys With Duchenne Muscular Dystrophy Despite Higher Vitamin D3 Supplementation

Vitamin D supplementation is important for many chronic pediatric conditions to help maintain bone health; however, there is little evidence about how disease-related factors affect vitamin D status. The objective was to compare 25-hydroxyvitamin D (25(OH)D) concentrations in 3 pediatric cohorts (Duchenne muscular dystrophy [DMD], systemic lupus erythematosus [SLE], and osteogenesis imperfecta [OI]). In a retrospective study of 367 subjects, children with DMD had increased prevalence of vitamin D insufficiency (25% vs 14% [SLE] and 10% [OI], P = .002), despite higher vitamin D₃ supplementation doses. Boys with DMD also had higher weight, fat mass, and lower lean mass percentage Z scores. DMD was associated with having higher rates of vitamin D insufficiency than other comparable pediatric chronic disease cohorts, the effect of which may be modulated by clinical factors such as increased adiposity. While corroboration of these results is needed given baseline differences between the patient groups, greater vitamin D supplementation doses may be required to achieve optimal serum 25(OH)D concentrations in boys with DMD.

Anabolic Therapy for the Treatment of Osteoporosis in Childhood

PURPOSE OF REVIEW

Numerous forms of osteoporosis in childhood are characterized by low bone turnover (for example, osteoporosis due to neuromuscular disorders and glucocorticoid exposure). Anti-resorptive therapy, traditionally used to treat osteoporosis in the young, is associated with further reductions in bone turnover, raising concerns about the long-term safety and efficacy of such therapy. These observations have led to increasing interest in the role of anabolic therapy to treat pediatric osteoporosis.

RECENT FINDINGS

While growth hormone and androgens appears to be relatively weak anabolic modulators of bone mass, emerging therapies targeting bone formation pathways (anti-transforming growth factor beta antibody and anti-sclerostin antibody) hold considerable promise. Teriparatide remains an attractive option that merits formal study for patients post-epiphyseal fusion, although it must be considered that adult studies have shown its effect is blunted when administered following bisphosphonate therapy. Mechanical stimulation of bone through whole body vibration therapy appears to be much less effective than bisphosphonate therapy for treating osteoporosis in children. New anabolic therapies which target important pathways in skeletal metabolism merit further study in children, including their effects on fracture risk reduction and after treatment discontinuation.