DISCUSSION
DMD, deaths, SAEs, fatigue
ADVERSE EVENTS, DISEASE
This was an open-label LTE study that assessed the efficacy and safety of viltolarsen for 192 weeks in boys with DMD. The results of timed function tests, such as TTSTAND, TTRW, and TTCLIMB, are key indicators for assessing the progression of DMD [DMD is a progressive disease with current therapies aiming to delay motor decline for as long as possible, providing meaningful improvement in quality of life. The TTSTAND and TTRW timed function tests in the viltolarsen treatment group showed clear and significant differences over the 4-year study period compared with the CINRG DNHS group, which was matched for key factors, including age, baseline ambulatory ability, steroid use, and geographic location. The TTCLIMB assessment in the viltolarsen treatment group was numerically better (seconds) and significantly better (velocity, weeks 37 and 205) than the CINRG DNHS group, but the overall effect was less pronounced. There may be several reasons for this observation. First, there is greater variability in the TTCLIMB data compared to TTSTAND and TTRW. This may be due, in part, to some boys using a compensation strategy during the TTCLIMB test (eg, using the available handrail to complete the task). Second, fatigue could be a factor since TTCLIMB was not the first test administered. Interestingly, when the seconds measured was transformed to velocity, the viltolarsen-treated group had an essentially flat and stable profile throughout the 205 weeks, whereas the CINRG DNHS group still showed decline, thus indicating a viltolarsen treatment effect.Viltolarsen was well tolerated in this study, with most of the reported TEAEs being mild or moderate with no deaths or study discontinuations. No treatment-related SAEs and no new or unexpected safety findings with viltolarsen were observed in this LTE study. Most adverse events were consistent with conditions expected in a pediatric population with DMD.