Efficacy and Safety of Vamorolone Over 48 Weeks in Boys With Duchenne Muscular Dystrophy: A Randomized Controlled Trial

BACKGROUND AND OBJECTIVES

Vamorolone is a dissociative agonist of the glucocorticoid receptor that has shown similar efficacy and reduced safety concerns in comparison with prednisone in Duchenne muscular dystrophy (DMD). This study was conducted to determine the efficacy and safety of vamorolone over 48 weeks and to study crossover participants (prednisone to vamorolone; placebo to vamorolone).

METHODS

A randomized, double-blind, placebo-controlled and prednisone-controlled clinical trial of 2 doses of vamorolone was conducted in participants with DMD, in the ages from 4 years to younger than 7 years at baseline. The interventions were 2 mg/kg/d of vamorolone and 6 mg/kg/d of vamorolone for 48 weeks (period 1: 24 weeks + period 2: 24 weeks) and 0.75 mg/kg/d of prednisone and placebo for the first 24 weeks (before crossover). Efficacy was evaluated through gross motor outcomes and safety through adverse events, growth velocity, body mass index (BMI), and bone turnover biomarkers. This analysis focused on period 2.

RESULTS

A total of 121 participants with DMD were randomized. Vamorolone at a dose of 6 mg/kg/d showed maintenance of improvement for all motor outcomes to week 48 (e.g., for primary outcome, time to stand from supine [TTSTAND] velocity, week 24 least squares mean [LSM] [SE] 0.052 [0.0130] rises/s vs week 48 LSM [SE] 0.0446 [0.0138]). After 48 weeks, vamorolone at a dose of 2 mg/kg/d showed similar improvements as 6 mg/kg/d for North Star Ambulatory Assessment (NSAA) (vamorolone 6 mg/kg/d-vamorolone 2 mg/kg/d LSM [SE] 0.49 [1.14]; 95% CI -1.80 to 2.78, p = 0.67), but less improvement for other motor outcomes. The placebo to vamorolone 6 mg/kg/d group showed rapid improvements after 20 weeks of treatment approaching benefit seen with 48-week 6 mg/kg/d of vamorolone treatment for TTSTAND, time to run/walk 10 m, and NSAA. There was significant improvement in linear growth after crossover in the prednisone to vamorolone 6 mg/kg/d group, and rapid reversal of prednisone-induced decline in bone turnover biomarkers in both crossover groups. There was an increase in BMI after 24 weeks of treatment that then stabilized for both vamorolone groups.

DISCUSSION

Improvements of motor outcomes seen with 6 mg/kg/d of vamorolone at 24 weeks of treatment were maintained to 48 weeks of treatment. Vamorolone at a dose of 6 mg/kg/d showed better maintenance of effect compared with vamorolone at a dose of 2 mg/kg/d for most (3/5) motor outcomes. Bone morbidities of prednisone (stunting of growth and declines in serum bone biomarkers) were reversed when treatment transitioned to vamorolone.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov Identifier: NCT03439670.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that for boys with DMD, the efficacy of vamorolone at a dose of 6 mg/kg/d was maintained over 48 weeks.

Towards the harmonization of outcome measures in children with mitochondrial disorders

AIM

A clinical trial is only as reliable as its outcomes, therefore the careful and systematic selection of outcome measures is extremely important. Currently, the selection of outcome measures for clinical trials designed to evaluate new drugs in patients with mitochondrial disorders is inefficient and has not been addressed systematically. Given that meaningful data can be obtained only from trials in which outcomes are assessed using valid instruments, one should first focus on the validation of a set of selected instruments in the target population. The aim of this review is to systematically select a 'toolbox' of robust outcome measures that are relevant to all patients.

METHOD

Using an extensive search of published literature, we systematically compiled a toolbox with outcome measures based on a primary search for possible instruments Subsequently, we reduced this toolbox using strict criteria that were adapted from the United States Food and Drug Administration.

RESULTS

A toolbox with clinically relevant and psychometrically robust instruments for performing clinical research in children with mitochondrial disorders was compiled.

INTERPRETATION

In coming years, more experience using these outcome measures in children with various mitochondrial disease phenotypes must be obtained before reliable conclusions regarding the validity of these instruments can be drawn.

Quantitative ultrasound of the tongue and submental muscles in children and young adults

INTRODUCTION

The purpose of this study was to assess the feasibility of quantitative muscle ultrasound (QMUS) to visualize oral muscles and to establish normative data for muscle thickness and echo intensity of submental and tongue muscles in healthy children and young adults. The data were compared with those of 5 patients with Duchenne muscular dystrophy (DMD).

METHODS

Ultrasound images from the suprahyoid region and from the surface of the tongue were made in 53 healthy subjects aged 5 to 30 years.

RESULTS

All measurements were feasible in all subjects and patients with good reproducibility except for the mylohyoid muscle. Muscle thickness depended on height, and echo intensity depended on weight. Our findings suggest gradual involvement of oral muscles in DMD.

CONCLUSIONS

QMUS in oral muscles is feasible in healthy children, adults and patients with DMD. These data show that it is possible to differentiate between healthy persons and patients with DMD.

Standardized tests of handwriting readiness: a systematic review of the literature

AIM

To establish if there are psychometrically sound standardized tests or test items to assess handwriting readiness in 5- and 6-year-old children on the levels of occupations activities/tasks and performance.

METHOD

Electronic databases were searched to identify measurement instruments. Tests were included in a systematic review if: (1) participants are 5 and 6 years old, (2) the focus was on handwriting readiness, and (3) the measurement was standardized. In the second step a further electronic search was undertaken for selected relevant measurement instruments to evaluate the content, psychometric properties, and feasibility of these instruments.

RESULTS

The search identified 1113 citations. In the final selection 39 articles with information about 12 tests were included. The content, feasibility, and psychometric properties of these 12 tests were evaluated and none of the instruments was satisfactory, according to the specific criteria.

INTERPRETATION

None of the instruments include all necessary components to evaluate writing readiness. Therefore, the development of an all encompassing assessment is necessary to test handwriting readiness and to make tailored interventions possible.

Measurement of decline of functioning in persons with amyotrophic lateral sclerosis: responsiveness and possible applications of the Functional Independence Measure, Barthel Index, Rehabilitation Activities Profile and Frenchay Activities Index

It is important not only to monitor the functional change during the course of ALS, but also to determine whether or not the available help is sufficient. This study was performed to determine which generic assessment instrument is most appropriate. A multicentre cohort of patients with ALS was followed for one year. At baseline, six months, and 1 year four instruments were used: Functional Independence Measure (FIM), Rehabilitation Activities Profile (RAP), Barthel Index (BI), and Frenchay Activities Index (FAI). The responsiveness of the measures was examined using effect sizes and standardized response mean statistics. Seventy-three patients at baseline, 63 after six months and 43 after one year were assessed. If calculated on the group that completed all three assessments, the FIM, BI, and RAP showed moderate effect sizes and standardized response means over a period of six months and large effect sizes over 12 months. Based on their responsiveness FIM, BI, and RAP can be used to evaluate limitations in activities and care needs of persons with ALS and to evaluate treatment results in trials. The FIM was the most responsive instrument, although the BI might be easier to use in clinical practice.

Predictive factors of cessation of ambulation in patients with Duchenne muscular dystrophy

OBJECTIVES

To identify baseline patient and treatment characteristics that can predict wheelchair dependency within 2 yr.

DESIGN

This prospective cohort study included 44 subjects who met study inclusion criteria. The same investigator examined them at 6-mo intervals. Ambulatory status, anthropometric data, muscle strength, range of motion of weight bearing joints, scoliosis, WeeFIM instrument, Functional Status II revised, and use of standing and walking aids. Cox proportional hazards regression analysis and the stepwise technique were used to search for prognostic factors of wheelchair dependency within 2 yr.

RESULTS

Children with impaired hip extension and ankle dorsiflexion strength are 11.5 (95% confidence interval, 3.2-40.5) and 3.7 (95% confidence interval, 1.4-9.7) times, respectively, more likely to stop ambulating within 2 yr.

CONCLUSIONS

This study confirms that strength loss, specifically in hip extension and ankle dorsiflexion, are the primary predictors of loss of ambulation in Duchenne muscular dystrophy. Further research is needed for medical interventions that can improve hip extension or ankle dorsiflexion and actually can improve ambulation.