Patients with Duchenne muscular dystrophy (DMD) maintained their motor function over more than 2 years of treatment with viltolarsen (Viltepso®) injections, NS Pharma announced. In comparison, the matched DMD historical control group demonstrated functional decline over the same period.

The finding was among the analyses obtained at 109 weeks into an open-label phase 2 trial on the long-term safety and efficacy of viltolarsen. The trial extended a 24-week trial in North America and all 16 participants who were amenable to exon 53 skipping therapy in the short-term trial continued on to the long-term trial.

The motor functional capacity of these individuals was assessed at weeks 37, 49, 73, and 109 and will be subsequently assessed periodically until the trial ends. Assessments at these intervals included Time to Stand, Time to Run/Walk 10 meters, and the 6-Minute Walk Test. 

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The mean change for the Time to Stand from supine at weeks 73 and 109 compared with the baseline measurement was 0.21 seconds and 0.43 seconds, respectively. The control group demonstrated a mean change of 3.6 seconds and 4.3 seconds at weeks 73 and 109, respectively. This reflects a statistically significant difference between the groups (P<.01). 

The Time to Run/Walk 10 meters showed a mean change from baseline (in seconds) of -0.8, -0.9, and -0.4 at weeks 49, 73, and 109, respectively. In the control group, these measurements were 0.5, 1.3, and 1.3 seconds (P <.05). 

Lastly, the 6-Minute Walk Test measured the total distance (in meters) an individual could walk in 6 minutes. The participants who had received the viltolarsen injections showed a mean change from baseline distance at week 109 of 0.9 meters while the control group displayed a loss in function of -65.6 meters (P<.05).

Commonly reported adverse events included cough, rash, emesis, nasopharyngitis, upper respiratory tract infections, and pyrexia. These side effects were mild to moderate and were comparable to those reported in the short-term study. No serious adverse events have been reported during long-term use of viltolarsen, although kidney toxicity is a potential possibility that has yet to be reported. 

The results of this study are critically important to individuals affected by DMD as data analyses regarding viltolarsen injections show promise for disease stabilization and delay of motor function declines.


Viltepso® (viltolarsen) injection: long-term efficacy and safety data presented at the PPMD 2021 virtual annual conference. News release. NS Pharma; July 1, 2021.