Feature|Articles|September 17, 2026

10 Years of Progress: A Timeline of FDA Approvals for Duchenne Muscular Dystrophy

Fact checked by: Marco Meglio

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Key Takeaways

Initial DMD disease-targeted approvals relied on accelerated pathways and modest dystrophin increases (eteplirsen, golodirsen, casimersen, viltolarsen), with confirmatory programs such as ESSENCE and mixed functional results.
Deflazacort achieved full approval across genotypes, showing significant short-term preservation of muscle strength versus placebo, and comparative signals favoring 0.9 mg/kg/day versus prednisone through 52 weeks.
Delandistrogene moxeparvovec produced robust micro-dystrophin expression but inconsistent NSAA effects; EMBARK missed NSAA at 52 weeks, while key timed-function secondary endpoints supported expanded approval.
Vamorolone met superiority on TTSTAND velocity at 24 weeks at 6 mg/kg/day and improved multiple secondary measures, positioning a dissociative-steroid approach to balance efficacy with adverse-effect mitigation.
Givinostat, the first nonsteroidal option for all genotypes, slowed decline in stair-climb time and favored secondary measures, including NSAA trajectory and reduced vastus lateralis fat infiltration on background steroids.

In honor of Muscular Dystrophy Awareness Month, held annually in September, NeurologyLive® looks back at the decade-long expansion of the DMD treatment landscape and the data that supports each approval.

Prior to 2016, Duchenne muscular dystrophy (DMD) had no disease-targeted treatment options and at the time, clinicians could offer corticosteroids to slow functional decline but nothing that addressed the underlying dystrophin deficiency driving the disease. That changed in the years since; the FDA has approved a steadily growing roster of exon-skipping therapies, a novel corticosteroid, a first-in-class HDAC inhibitor, and the field's first gene therapy.

In recognition of Muscular Dystrophy Awareness Month, held annually in September, NeurologyLive^® revisited the milestones that built today's DMD treatment paradigm, the data that got each drug across the finish line.

Eteplirsen (Exondys 51) — September 19, 2016

Sarepta Therapeutics' eteplirsen became the first FDA-approved treatment specifically for DMD, clearing the agency via the accelerated approval pathway as an antisense oligonucleotide designed to induce exon 51 skipping in the roughly 13% of patients whose mutation is amenable to that approach.¹ The approval was notable for its controversy, FDA reviewers were sharply divided over whether the surrogate end point of increased dystrophin production justified approval, foreshadowing debates that would recur with several of Sarepta's later exon-skipping drugs.²

The application rested on the placebo-controlled phase 2b Study 201 (NCT01396239) and its open-label extension, Study 202 (NCT01540409), along with the supportive phase 3 PROMOVI study (NCT02255552). Study 201 enrolled just 12 boys, ages 7 to 13, randomized to eteplirsen 30 or 50 mg/kg/week or placebo for 24 weeks before all patients rolled into the open-label extension.³ FDA's approval rested on a modest but statistically significant increase in dystrophin production: from a pretreatment mean of 0.16% of normal to 0.44% of normal after 48 weeks of treatment (P < .05), rising further to a mean of 0.93% of normal by week 180. A clinical benefit, including improved motor function, was not established at the time of approval.⁴

Deflazacort (Emflaza) — February 9, 2017

PTC Therapeutics' deflazacort, a corticosteroid already used off-label and available abroad, received full FDA approval for DMD regardless of genetic mutation, making it the first agent approved for all patients with the disease.⁵The pivotal trial, conducted between 1993 and 1995, was a phase 3, double-blind, randomized, placebo-controlled, multicenter study of 196 boys ages 5 to 15 with DMD onset of weakness before age 5.⁶ Patients received deflazacort (0.9 or 1.2 mg/kg/day), prednisone (0.75 mg/kg/day), or placebo for 12 weeks; placebo patients then crossed over to active treatment for an additional 40 weeks.

On the primary end point, average change in muscle strength from baseline to week 12, all active-treatment arms significantly preserved muscle strength compared with placebo, and deflazacort 0.9 mg/kg/day showed significantly greater improvement than prednisone from week 12 to week 52. A second, smaller trial in 29 boys ages 6 to 12 followed patients for 104 weeks and showed numerically favorable, though not statistically significant, trends in muscle strength and time to loss of ambulation.⁷

Golodirsen (Vyondys 53) — December 12, 2019

Sarepta's second exon-skipping therapy targeted exon 53 skipping, expanding the mutation-specific toolkit for the roughly 8% of patients amenable to that approach.⁸Accelerated approval was based on Study 4053-101 (NCT02310906), a first-in-human, two-part phase 1/2 study in 25 boys ages 6 to 15 with confirmed DMD deletions amenable to exon 53 skipping.

Part 1 was a randomized, placebo-controlled, dose-titration period testing 4 escalating dose levels (4 to 30 mg/kg/week); Part 2 was an open-label evaluation at the 30 mg/kg weekly dose, compared against an untreated group of patients whose mutations were not amenable to exon 53 skipping. At 48 weeks, golodirsen-treated patients showed a statistically significant increase in dystrophin production versus the untreated comparator group.⁹ The postmarketing confirmatory trial, ESSENCE (NCT02500381), was already underway at the time of approval.¹⁰

Viltolarsen (Viltepso) — August 12, 2020

NS Pharma's viltolarsen became the second exon 53-skipping therapy approved for DMD, again via the accelerated pathway.¹¹The FDA based approval on Study NS-065/NCNP-01-201 ("Study 201," NCT02740972), a phase 2, 2-period, dose-finding study in 16 boys ages 4 to 9 with DMD amenable to exon 53 skipping. Patients received weekly intravenous viltolarsen at 40 or 80 mg/kg for 24 weeks.

Both doses produced statistically significant increases in dystrophin: mean levels rose to 5.7% of normal (range, 3.2–10.3) in the 40 mg/kg group and 5.9% of normal (range, 1.1–14.4) in the 80 mg/kg group, with 94% of patients reaching dystrophin levels above 2% of normal.¹² A 144-week open-label extension, Study 202 (NCT03167255), contributed additional safety data, and functional outcomes were contextualized against an external comparator from the CINRG Duchenne Natural History Study. (The confirmatory phase 3 RACER53 trial, NCT04060199, later missed its primary end point of time-to-stand velocity at 48 weeks.)¹³

Casimersen (Amondys 45) — February 25, 2021

Rounding out Sarepta's original exon-skipping trio, casimersen targeted exon 45 skipping, covering an additional 8% of the DMD population.¹⁴Accelerated approval drew on Study 4045-101 (NCT02530905), a phase 1/2, randomized, placebo-controlled, dose-titration study in 12 patients ages 7 to 21 with limited ambulation or nonambulatory DMD amenable to exon 45 skipping,¹⁴ plus interim 48-week data from the global phase 3 ESSENCE trial (NCT02500381).

In ESSENCE, casimersen-treated patients (n = 27) saw dystrophin rise from a baseline of 0.93% of normal to 1.74% of normal—a 0.81-percentage-point increase (P < .001), compared with a nonsignificant 0.22-percentage-point increase in the placebo arm (n = 16).¹⁵ ESSENCE evaluated casimersen (n = 111) and golodirsen (n = 111) together in boys ages 7 to 13.

Delandistrogene moxeparvovec-rokl (Elevidys) — June 22, 2023

Sarepta's SRP-9001 became the first gene therapy approved for DMD, clearing the accelerated approval pathway for ambulatory patients ages 4 to 5 with a confirmed DMD mutation, delivering a transgene coding for a shortened "micro-dystrophin" protein.¹⁶The original accelerated approval rested primarily on three trials: SRP-9001-101 (Study 101, NCT03375164), an open-label Phase 1/2 study in 4 ambulatory boys ages 4 to 7; SRP-9001-102 (Study 102, NCT03769116), a phase 2, double-blind, placebo-controlled, 2-part crossover study in 43 boys ages 4 to 7 (21 placebo, 20 treatment); and ENDEAVOR (SRP-9001-103, NCT04626674), an ongoing open-label Phase 1b study across multiple cohorts.

In Study 102 Part 1, mean micro-dystrophin expression rose to 23.82% of normal by week 12, though the co-primary NSAA end point at week 48 did not reach statistical significance (+1.7 vs +0.9 points, P = .37).¹⁷ In ENDEAVOR Cohort 1 (20 patients), treated patients improved 4 points on the NSAA from baseline compared with a propensity-weighted external control group over 1 year (P < .0001).¹⁸

Vamorolone (Agamree) — October 26, 2023

Catalyst Pharmaceuticals won approval for vamorolone, a first-in-class dissociative steroid for patients 2 years and older, designed to retain corticosteroids' anti-inflammatory activity while reducing their adverse-effect burden.¹⁹The approval was based on the phase 2b VISION-DMD trial (NCT03439670), a randomized, double-blind, placebo- and active-controlled study of 121 ambulatory boys ages 4 to 7 across 33 sites, randomized to placebo, prednisone 0.75 mg/kg/day, or vamorolone 2.0 or 6.0 mg/kg/day.

The primary end point, superiority in change of time-to-stand (TTSTAND) velocity at 24 weeks, was met at the 6.0 mg/kg/day dose, with a difference of 0.06 rises/second versus placebo (95% CI, 0.02–0.10; P = .002). Secondary endpoints, including TTSTAND velocity at the low dose, the 6-minute walk test at both doses, and 10-meter walk/run time at the high dose, were also met, and the open-label extension through 48 weeks showed sustained benefit.

Givinostat (Duvyzat) — March 21, 2024

Italfarmaco's givinostat, an oral HDAC inhibitor, became the first nonsteroidal drug approved for all genetic variants of DMD, regardless of mutation type.²⁰Approval rested on the phase 3 EPIDYS trial (NCT02851797), a randomized, double-blind, placebo-controlled study of 179 ambulant boys ages 6 to 17 (120 in the primary target population), randomized 2:1 to givinostat or placebo on top of standard corticosteroid therapy for an 18-month treatment period.

On the primary end point, mean change from baseline in time to climb 4 stairs, givinostat-treated patients declined by 1.25 seconds versus 3.03 seconds with placebo, a 1.78-second difference (P = .0345). Secondary end points favored givinostat as well, including a roughly 40% slower decline in North Star Ambulatory Assessment (NSAA) scores and a 30% reduction in vastus lateralis muscle fat infiltration.

Elevidys expanded approval — June 20, 2024

Less than a year after its initial clearance, Elevidys received traditional approval for ambulatory patients 4 years of age and older, alongside a new accelerated approval covering non-ambulatory individuals in the same age range.¹⁸The expansion leaned on the phase 3 EMBARK trial (NCT05096221), the postmarketing confirmatory study for the original accelerated approval.²¹

EMBARK's primary end point (change in NSAA score at 52 weeks) was not met, but key secondary end points, time to rise (P = .0025) and 10-meter walk/run time (P = .0048), were statistically significant and consistent across age groups, supporting conversion to traditional approval for ambulatory patients. Extension of accelerated approval to non-ambulatory patients drew on dystrophin expression data from Cohort 3 of the ENDEAVOR study.

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