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Duchenne Muscular Dystrophy (DMD) includes predictable phases requiring dedicated standard treatments. Therapeutic strategies feature corticosteroids or the more recent gene therapy/stop codon read-through. Ataluren (Translarna®) is an oral drug promoting the readthrough of premature stop codons caused by nonsense mutation (nm) in order to produce full-length dystrophin. It was licensed by EMA in 2014 for ambulatory patients with nmDMD aged ≥ 5 years. Our aim is to report data on long-term ataluren use in Italian patients with nmDMD, with emphasis on continuity of the treatment after loss of ambulation (LoA). Four DMD patients aged between 16 and 24 years who lost ambulation between 12 and 14 years continued to take ataluren after LoA. The oldest patient, aged 24 years, is still taking a few steps. Even in those experiencing motor decline, PUL-test performances were stable and respiratory function satisfactory in all; two patients developed severe cardiomyopathy, stable in one. Therapeutic continuity with ataluren should be offered to all nmDMD patients after LoA given its favourable safety and efficacy profile. However, further research is recommended to identify additional clinically meaningful outcomes and treatment goals following LoA.

Ataluren delays loss of ambulation and respiratory decline in nonsense mutation Duchenne muscular dystrophy patients

Aim: We investigated the effect of ataluren plus standard of care (SoC) on age at loss of ambulation (LoA) and respiratory decline in patients with nonsense mutation Duchenne muscular dystrophy (nmDMD) versus patients with DMD on SoC alone. Patients & methods: Study 019 was a long-term Phase III study of ataluren safety in nmDMD patients with a history of ataluren exposure. Propensity score matching identified Study 019 and CINRG DNHS patients similar in disease progression predictors. Results & conclusion: Ataluren plus SoC was associated with a 2.2-year delay in age at LoA (p = 0.0006), and a 3.0-year delay in decline of predicted forced vital capacity to <60% in nonambulatory patients (p = 0.0004), versus SoC. Ataluren plus SoC delays disease progression and benefits ambulatory and nonambulatory patients with nmDMD. ClinicalTrials.gov: NCT01557400.

A Combined Prospective and Retrospective Comparison of Long-Term Functional Outcomes Suggests Delayed Loss of Ambulation and Pulmonary Decline with Long-Term Eteplirsen Treatment

Background:

Studies 4658-201/202 (201/202) evaluated treatment effects of eteplirsen over 4 years in patients with Duchenne muscular dystrophy and confirmed exon-51 amenable genetic mutations. Chart review Study 4658-405 (405) further followed these patients while receiving eteplirsen during usual clinical care.

Objective:

To compare long-term clinical outcomes of eteplirsen-treated patients from Studies 201/202/405 with those of external controls.

Methods:

Median total follow-up time was approximately 6 years of eteplirsen treatment. Outcomes included loss of ambulation (LOA) and percent-predicted forced vital capacity (FVC%p). Time to LOA was compared between eteplirsen-treated patients and standard of care (SOC) external controls and was measured from eteplirsen initiation in 201/202 or, in the SOC group, from the first study visit. Comparisons were conducted using univariate Kaplan-Meier analyses and log-rank tests, and multivariate Cox proportional hazards models with regression adjustment for baseline characteristics. Annual change in FVC%p was compared between eteplirsen-treated patients and natural history study patients using linear mixed models with repeated measures.

Results:

Data were included from all 12 patients in Studies 201/202 and the 10 patients with available data from 405. Median age at LOA was 15.16 years. Eteplirsen-treated patients experienced a statistically significant longer median time to LOA by 2.09 years (5.09 vs. 3.00 years, p < 0.01) and significantly attenuated rates of pulmonary decline vs. natural history patients (FVC%p change: –3.3 vs. –6.0 percentage points annually, p < 0.0001).

Conclusions:

Study 405 highlights the functional benefits of eteplirsen on ambulatory and pulmonary function outcomes up to 7 years of follow-up in comparison to external controls.

Comparison of Long-term Ambulatory Function in Patients with Duchenne Muscular Dystrophy Treated with Eteplirsen and Matched Natural History Controls

Background:

Duchenne muscular dystrophy (DMD) is a rare, X-linked, fatal, degenerative neuromuscular disease caused by DMD gene mutations. A relationship between exon skipping and dystrophin production in exon 51-amenable patients treated with eteplirsen (EXONDYS 51^®) is established. Once-weekly eteplirsen significantly increased dystrophin, with slower decline in ambulatory function compared to baseline. Long-term treatment with eteplirsen leads to accumulation of dystrophin over time and observed functional benefits in patients with DMD.

Objective:

Compare long-term ambulatory function in eteplirsen-treated patients versus controls.

Methods:

Study 201/202 included 12 eteplirsen-treated patients assessed twice/year for ambulatory function over 4 years. Ambulatory evaluations (6-minute walk test [6MWT], loss of ambulation, and North Star Ambulatory Assessment [NSAA]) were compared with matched controls from Italian Telethon and Leuven registries.

Results:

At Years 3 and 4, eteplirsen-treated patients demonstrated markedly greater mean 6MWT than controls (difference in change from baseline of 132 m [95%CI (29, 235), p = 0.015] at Year 3 and 159 m [95%CI (66, 253), p = 0.002] at Year 4). At Year 4, a significantly greater proportion of eteplirsen-treated patients were still ambulant versus controls (10/12 vs 3/11; p = 0.020). At Year 3, eteplirsen-treated patients demonstrated milder NSAA decline versus controls (difference in change from baseline of 2.6, 95%CI [-6, 11]), however, the difference was not statistically significant; Year 4 control NSAA data were not available.

Conclusion:

In this retrospective matched control study, eteplirsen treatment resulted in attenuation of ambulatory decline over a 4-year observation period, supporting long-term benefit in patients with DMD.

Association of genetic mutations and loss of ambulation in childhood-onset dystrophinopathy

BACKGROUND

Quantifying associations between genetic mutations and loss of ambulation (LoA) among males diagnosed with childhood-onset dystrophinopathy is important for understanding variation in disease progression and may be useful in clinical trial design.

METHODS

Genetic and clinical data from the Muscular Dystrophy Surveillance, Tracking, and Research Network for 358 males born and diagnosed from 1982 to 2011 were analyzed. LoA was defined as the age at which independent ambulation ceased. Genetic mutations were defined by overall type (deletion/duplication/point mutation) and among deletions, those amenable to exon-skipping therapy (exons 8, 20, 44-46, 51-53) and another group. Cox proportional hazards regression modeling was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

Mutation type did not predict time to LoA. Controlling for corticosteroids, Exons 8 (HR = 0.22; 95% CI = 0.08, 0.63) and 44 (HR = 0.30; 95% CI = 0.12, 0.78) were associated with delayed LoA compared to other exon deletions.

CONCLUSIONS

Delayed LoA in males with mutations amenable to exon-skipping therapy is consistent with previous studies. These findings suggest that clinical trials including exon 8 and 44 skippable males should consider mutation information prior to randomization.

Longitudinal timed function tests in Duchenne muscular dystrophy: ImagingDMD cohort natural history

INTRODUCTION

Tests of ambulatory function are common clinical trial endpoints in Duchenne muscular dystrophy (DMD). Using these tests, the ImagingDMD study has generated a large data set that can describe the contemporary natural history of DMD in 5-12.9-year-olds.

METHODS

Ninety-two corticosteroid-treated boys with DMD and 45 controls participated in this longitudinal study. Participants performed the 6-minute walk test (6MWT) and timed function tests (TFT: 10-m walk/run, climbing 4 stairs, supine to stand).

RESULTS

Boys with DMD had impaired functional performance even at 5-6.9 years old. Boys older than 7 had significant declines in function over 1 year for 10-m walk/run and 6MWT. Eighty percent of participants could perform all functional tests at 9 years old. TFTs appear to be slightly more responsive and predictive of disease progression than the 6MWT in 7-12.9 year olds.

DISCUSSION

This study provides insight into the contemporary natural history of key functional endpoints in DMD. Muscle Nerve 58: 631-638, 2018.

Cognitive function is associated with the development of mobility impairments in community-dwelling elders

OBJECTIVE

To examine the association of cognitive function with the risk of incident mobility impairments and the rate of declining mobility in older adults.

DESIGN

Prospective, observational cohort study.

SETTING

Retirement communities across metropolitan Chicago.

PARTICIPANTS

A total of 1,154 ambulatory elders from two longitudinal studies without baseline clinical dementia or history of stroke or Parkinson disease.

MEASUREMENTS

All participants underwent baseline cognitive testing and annual mobility examinations. Mobility impairments were based on annual timed walking performance. A composite mobility measure, which summarized gait and balance measures, was used to examine the annual rate of mobility change.

RESULTS

During follow-up of 4.5 years, 423 of 836 (50.6%) participants developed impaired mobility. In a proportional hazards model controlled for age, sex, education, and race, each 1-unit higher level of baseline global cognition was associated with a reduction to about half in the risk of mobility impairments (hazard ratio = 0.51, 95% confidence interval: 0.40-0.66) and was similar to a participant being about 13 years younger at baseline. These results did not vary by sex or race and were unchanged in analyses controlling for body mass index, physical activity, vascular diseases, and risk factors. The level of cognition in five different cognitive abilities was also related to incident mobility impairment. Cognition showed similar associations with incident loss of the ability to ambulate. Linear mixed-effects models showed that global cognition at baseline was associated with the rate of declining mobility.

CONCLUSIONS

Among ambulatory elders, cognition is associated with incident mobility impairment and mobility decline.