, ,

Viltolarsen, exon 53 skipping therapy, approved

Viltolarsen exon 53 skipping DMD La Force

N.S. Pharma’s VILTEPSO™ (viltolarsen) injection now FDA-Approved in the U.S. for the treatment of Duchenne muscular dystrophy in patients amenable to exon 53 skipping therapy.


  • Patients taking VILTEPSO showed an increase in dystrophin expression to an average of 5.9% of normal after 20-24 weeks of treatment.
  • Overall, in a pivotal study of VILTEPSO, 100% of patients showed an increase in dystrophin levels after treatment, and 88% of patients showed dystrophin levels of 3% of average or higher.

Press release > PARAMUS, NJ: August 12, 2020 – N.S. Pharma, Inc.


N.S. Pharma announced that the U.S. Food & Drug Administration (FDA) has approved VILTEPSO™ (viltolarsen) injection for patients with Duchenne muscular dystrophy (DMD) who are amenable to exon 53 skipping therapy. VILTEPSO received an Accelerated Approval by the FDA based on an increase in dystrophin, an essential protein for supporting muscle health. Since a lack of dystrophin is the underlying cause of DMD, increasing dystrophin as much and as early as possible is a key goal in the treatment of DMD. VILTEPSO is the first and only exon 53 skipping therapy to demonstrate an increase in dystrophin in children as young as four years old. The continued approval of VILTEPSO may be contingent on confirmation of a clinical benefit in the Phase 3 confirmatory trial.


More about the study

The VILTEPSO New Drug Application (NDA) submission included results from a Phase 2, a two-period study in patients aged four to less than ten years of age conducted in North America (Study 1, N=16) and a multicenter, open-label study in boys five to less than 18 years of age conducted in Japan (Study 2, N=16).

In Study 1, of those patients who received the recommended dose of 80 mg/kg/wk (N=8), 100% of patients (8/8) showed an increase in dystrophin levels after treatment with VILTEPSO and 88% of patients (7/8) showed dystrophin levels of 3% or greater than normal. Overall, after 20-24 weeks of treatment, a mean increase in dystrophin expression to nearly 6% of normal was observed with VILTEPSO (80 mg/kg/wk) versus 0.6% at baseline. The most common side effects of VILTEPSO included upper respiratory tract infection, injection site reaction, cough and fever.


Vamshi Rao, MD, Ann & Robert H. Lurie Children’s Hospital of Chicago – “For decades, neurologists who treat DMD have hoped for the discovery of therapies capable of significantly improving dystrophin production, and the magnitude of dystrophin increases observed with VILTEPSO are impressive. The approval of VILTEPSO is an exciting development for DMD patients amenable to exon 53 skipping therapy and may rapidly become a foundational treatment for these patients.”


  • In clinical studies, no patients experienced kidney toxicity during treatment with VILTEPSO. However, kidney toxicity from drugs like VILTEPSO may be possible. Your doctor may monitor the health of your kidneys before starting and during treatment with VILTEPSO.
  • The most common side effects of VILTEPSO included upper respiratory tract infection, injection site reaction, cough and fever.
  • For additional safety information, please see the full Prescribing Information.

N.S. Pharma continues to study the safety and efficacy of VILTEPSO in the confirmatory Phase 3 RACER53 trial. This study was initiated in October 2019 and is currently enrolling. The purpose of this Phase 3 trial is to confirm the clinical findings that were submitted under the Accelerated Approval pathway.


About VILTEPSO™ (viltolarsen) injection

Before its approval in the U.S., VILTEPSO was granted Priority Review as well as Rare Pediatric Disease, Orphan Drug and Fast Track Designations. In March 2020, VILTEPSO was approved in Japan for the treatment of patients with DMD who are amenable to exon 53 skipping therapy. Before its approval in Japan, VILTEPSO was granted the SAKIGAKE designation, Orphan Drug designation, and designation of Conditional Early Approval System.

VILTEPSO is indicated for the treatment of Duchenne muscular dystrophy (DMD) in patients who have a confirmed mutation of the DMD gene that is amenable to exon 53 skipping. This indication is approved under Accelerated Approval based on an increase in dystrophin production in skeletal muscle observed in patients treated with VILTEPSO. Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial. It is an infusion that doctors administer into the bloodstream.


How Viltolarsen works

Viltolarsen contains an artificial piece of mRNA that masks exon 53, causing cells to “skip” this exon when they are making mature mRNA. This skip restores the so-called “reading frame” of the mRNA molecule. In other words, it ensures that the remaining exons fit together again, allowing a cell’s protein-making machinery to synthesize a shorter but working dystrophin protein.

Because viltolarsen is specific to exon 53, the treatment is effective only in those DMD patients who have a mutation that is amenable to exon 53 skipping. Thanks to Muscular Dystrophy News Today for this description.


N.S. Pharma

NS Pharma, Inc. is a wholly-owned subsidiary of Nippon Shinyaku Co., Ltd. For more information, please visit www.nspharma.com. N.S. Pharma is a registered trademark of the Nippon Shinyaku group of companies.

N.S. Pharma will provide families, physicians and healthcare professionals dedicated and individualized resources every step of the way through the N.S. Support program. N.S. Pharma will be hosting a series of webinars on the comprehensive care coordination available through N.S. Support. Follow them on LinkedIn and Twitter for information and registration for upcoming webinars.


Tsugio Tanaka, President, NS Pharma, Inc. – “On behalf of NS Pharma and Nippon Shinyaku, I would like to express our deepest gratitude to the families and physicians who participated in our clinical trials and made today’s approval possible. We are proud to now offer an important new treatment option to help address the significant unmet needs caused by this devastating disease.”


More about DMD

DMD is caused by genetic mutations that prevent dystrophin production. Patients with DMD experience progressive and irreversible muscle loss with symptoms appearing as early as two years of age. 

Duchenne muscular dystrophy occurs primarily in males. Early signs of DMD may include delayed ability to sit, stand or walk. There is a progressive loss of mobility, and by adolescence, patients with DMD may require the use of a wheelchair. Cardiac and respiratory muscle problems begin in the teenage years and lead to serious, life-threatening complications. Read more here.

0 replies

Leave a Reply

Want to join the discussion?
Feel free to contribute!

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.