The results of the open-label, phase II Galactic53 trial suggest that Viltolarsen (Viltepso) is well tolerated by boys and men with Duchenne muscular dystrophy (DMD). There were no new safety signals reported during the trial, offering a glimmer of hope for those living with this devastating disease. The exon-skipping therapy showed a potential clinical benefit in pulmonary function, as indicated by the improvements in percent predicted forced vital capacity (FVC%p) and peak cough flow (PCF). These findings were presented by Michelle Previtera, PhD, and her colleagues at the American Academy of Neurology annual meeting.
Among the participants who were able to walk and received Viltolarsen, 90% experienced either an increase or stabilization in FVC%p from baseline. This improvement was particularly significant at week 49, with a least squares mean change of 8.3%. Even in nonambulatory patients, those receiving Viltolarsen showed an increase in FVC%p compared to a decrease in the control group. This data on pulmonary function is particularly crucial, as it has not been extensively studied in nonambulatory patients with DMD. Combining these results with previous data on motor function, it is clear that Viltolarsen may offer an additional treatment benefit for patients with DMD amenable to exon 53-skipping therapy.
Duchenne muscular dystrophy is a devastating condition with no cure, primarily affecting boys and caused by mutations in the dystrophin gene. This leads to a loss of functional dystrophin and muscle damage over time. As muscle strength decreases, pulmonary function is also impacted, eventually requiring assisted ventilation. Exon-skipping therapies such as Viltolarsen work by skipping parts of the mutated gene, resulting in a shorter but still functional dystrophin protein. The FDA granted accelerated approval to Viltolarsen in 2020, acknowledging its potential to benefit patients with DMD. A confirmatory phase III trial is currently ongoing to further evaluate the clinical benefits of the drug in patients with a confirmed dystrophin gene mutation amenable to exon 53 skipping.
Viltolarsen is not the first exon 53-skipping therapy to receive accelerated approval from the FDA. Golodirsen (Vyondys 53), granted approval in 2019, and eteplirsen (Exondys 51), granted approval in 2016, are also examples of such therapies. These treatments, along with casimersen (Amondys 45), have shown promise in improving outcomes for patients with DMD. In the Galactic53 trial, researchers compared the effects of Viltolarsen on 20 ambulatory and nonambulatory males to a control group from the CINRG DNHS. The results showed promising improvements in pulmonary function and other exploratory endpoints in patients receiving Viltolarsen.
The results of the Galactic53 trial offer new hope for patients with Duchenne muscular dystrophy. The improvements in pulmonary function and overall stability in motor function suggest that Viltolarsen may be a valuable addition to the treatment arsenal for this debilitating disease. Ongoing research, including the phase III trial, will provide more insights into the long-term benefits and safety profile of Viltolarsen. As we continue to fight against DMD, these developments bring us one step closer to improving the lives of those affected by this condition.
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