In one main study, involving 174 patients aged 5 to 20 years with Duchenne muscular dystrophy who were able to walk, two doses of Translarna (40 mg/kg daily and 80 mg/kg daily) were compared with placebo (a dummy treatment). The main measure of effectiveness was the change in the distance the patient could walk in six minutes after 48 weeks of treatment.

Although an initial analysis of the results of all the data from the study did not show a significant difference in the distances patients in the Translarna and placebo groups could walk, further analyses indicated that walking ability worsened to a lesser extent with 40 mg/kg daily Translarna than with placebo: after 48 weeks of treatment patients receiving 40 mg/kg daily Translarna could walk on average 32 metres more than those given placebo. The effect was more pronounced in a subgroup of patients whose ability to walk was worsening, where patients taking 40 mg/kg daily Translarna could walk on average 50 metres more than those taking placebo. The beneficial effect of the lower dose was also supported by improvements in other measures of effectiveness, including those directly linked to patients’ daily activities. No improvement was seen with the higher dose (80 mg/kg daily).

A further study in 230 patients aged 7 to 14 years with worsening walking ability was completed after initial approval, but its results were considered inconclusive. However, data indicated that Translarna had a positive effect on different measures such as time to run or walk 10 metres, time to climb up and down 4 steps and time to loss of walking ability. In both studies, the beneficial effects of Translarna seemed more evident in patients with moderate decline of their disease.

A small study in children aged 2 to 5 years with Duchenne muscular dystrophy found that the usual dose of Translarna 40 mg/kg daily was sufficient. Translarna seemed effective on an assessment of physical activity in 12 patients when compared with past records of 11 patients of similar age who had not been treated with Translarna.