The Duchenne muscular dystrophy (DMD) treatment landscape is undergoing a transformation, with new therapies offering options to patients with this rare disease and their caregivers. Traditionally managed with corticosteroids, care of boys with DMD is now expanding to include next-generation steroids, exon-skipping drugs, and even gene therapy.
However, challenges such as side effects, insurance hurdles, and uncertain long-term efficacy continue to shape the market. As investment in DMD research accelerates, the market is projected to grow to more than $7 billion by 2034, signaling a future of innovation and evolving treatment strategies.
While a rare muscle disorder, DMD is the most common genetic disorder, affecting one in 1,350 boys born each year worldwide. Due to a defect in the gene that makes a key protein called dystrophin, patients suffer gradual muscle wasting, and most patients are wheelchair-bound by the age of 12 years.
Until the last decade, innovation in DMD drug development was largely unproductive, leaving patients with few treatment choices beyond corticosteroids such as prednisone. Today, however, several alternative treatments are on the market for DMD, and the innovation pipeline is growing.
Yet efforts to develop and market non-steroid drugs and one-time cures such as gene therapy have faced obstacles. Hence, steroids remain the standard of care for DMD, and improving on steroid treatments is a major focus of drug developers.
Combating Steroid Side Effects for DMD Therapy
Patients and caregivers have abandoned steroid treatments due to side effects, including excessive weight gain, gastrointestinal upset, cardiac issues and bone-density declines. Steroids can also cause diabetes — another factor widely cited by respondents as a reason for discontinuation.
Next-generation steroid treatments are designed to match or exceed the efficacy of older steroids and reduce the risk of side effects.
Emflaza (deflazacort), approved by the FDA in 2017, has a slightly different structure than prednisone, which makes it less soluble in lipids. Studies have shown that deflazacort has less of an effect on glucose metabolism than prednisone does, potentially lowering the risk of diabetes.
Agamree (vamorolone), approved by the FDA in 2023, also has structural differences designed to minimize side effects. In clinical trials, it was effective as prednisone but less likely to cause negative changes in bone density.
One obstacle facing those seeking therapy with these next-gen steroids is insurance hurdles, including pre-authorization processes.
DMD patients often face “step edit” or “fail first” policies, whereby insurers only agree to cover vamorolone after a patient tries and fails to respond to less costly medicines. This process is burdensome to physicians, who must document the failures and present proof to insurers.
Continuing research will be key to easing payer concerns and shaping the future market for next-generation steroids, particularly if they prove superior efficacy or safety to existing treatments.
Vamorolone developer Santhera Pharmaceuticals is sponsoring a long-term study of DMD patients that will be completed in 2028. Separately, Santhera’s marketing partner, Catalyst Pharmaceuticals, is collecting data from 25 treatment sites in a DMD patient registry. The company’s goal is to track 250 patients ages 2 years and older who are treated with Vamorolone from 2024 through 2030.
Innovation is Expanding the DMD Treatment Toolbox
Several biopharmaceutical innovators are pursuing the quest to develop non-steroid treatments for DMD — contributing to a large and growing market. One recent estimate predicts the market for DMD treatments, valued at $2.2 billion in 2023, to grow to $7.4 billion by 2034. and growing at a compound annual rate of 11.7 percent. This growth is driven by a combination of increasing global rates of DMD and advances in genetic research spurring the development of new therapies.
Drug developers working in the DMD field are pursuing several approaches for restoring or replacing dystrophin, reducing muscle inflammation and improving the growth and protection of muscle. But early approaches have faced numerous challenges.
Four drugs that employ a mechanism called “exon skipping” to restore dystrophin are on the market: Amondys 45 (casimersen), Exondys 51 (eteplirsen), Viltepso (viltolarsen) and Vyondys 53 (golodirsen),, but a 2024 study found that they are frequently discontinued. This led the authors to question whether patients and caregivers are seeing enough clinical benefits from the drugs to justify their high costs, which can be upwards of $300,000 per year per patient.
Improving clinical benefits is prompting development of newer exon-skipping therapies, with modified technologies to improve targeted delivery within the body or for specific genetically defined patients with DMD. At least nine investigational exon-skipping therapies are in the pipeline, including those from Avidity Biosciences, Biomarin, Dyne Therapeutics, Entrada Therapeutics, NS Pharma, PepGen and Wave Life Sciences.
In 2023, the FDA granted an accelerated approval for the first gene therapy for DMD, Elevidys (delandistrogene moxeparvovec-rokl), which is designed to deliver a short version of the dystrophin gene in the hopes it will deliver enough of the protein to delay muscle decline.
The initial approval granted use for ambulatory individuals aged 4 to 5 years with confirmed DMD gene mutation. In June 2024, the FDA expanded the approval for ambulatory and non-ambulatory patients aged 4 years and older with the mutation. In January 2025, Elevidys’s developer, Sarepta Therapeutics, announced positive top line results for the second part of its global phase 3 study, which documenting the therapy’s impact on disease stabilization of DMD, with functional benefits, compared to a placebo.
In July 2024, a new drug designed to improve muscle growth and protection in DMD patients came to market. Duvyzat (givinostat), marketed by ITF Therapeutics LLC, works by inhibiting histone deacetylase (HDAC), a major culprit in muscle decline. In a study leading to the drug’s approval, patients taking the drug showed a meaningful improvement in their ability to complete a short stair climb.
A Look to the Future for DMD Therapy
As some innovators continue to pursue gene-based approaches to replacing dystrophin, others are focusing on improving muscle health and longevity in DMD patients. The early development pipeline includes cell therapies to spur muscle growth and non-steroid drugs to reduce muscle inflammation.
References:
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