A South Korean team conducted a trial of 6′-sialyllactose (6SL) in GNE myopathy for almost two years (96 weeks) in 20 participants aged between 24 and 58 with an average disease duration of 8.6±5.1 years:
- seven participants received 3g/d of 6SL (low dose), seven others 6g/d (high dose) and six others placebo for three months before three of them received the low dose of 6SL and the other three the high dose.
- levels of free sialic acid were significantly increased at 12 weeks in participants taking 6SL, while levels of sialic acid bound to red blood cell membranes were significantly increased after three months only in the high-dose group.
- 6SL was well tolerated, with a few gastrointestinal side-effects (diarrhoea, constipation) or intermittent headaches in the first six weeks.
- although muscle strength showed no difference between the three groups after 12 weeks, the strength of the proximal muscles of the high-dose participants tended to increase at 96 weeks, starting at 48 weeks for shoulder abduction and elbow flexion.
- a composite score for upper limb strength showed no significant improvement, while that for lower limb strength showed a trend towards improvement at both low and high doses, where it reached the threshold of significance.
- there was no decrease in the fat fraction of the middle thigh and calf on MRI during the first 12 weeks in any of the three groups of participants. Overall, the increase in fat fraction was stabilised by both low- and high-dose 6SL in the latter part of the study, except for the anterior thigh compartment;
- a randomised placebo-controlled trial in 11 patients over 48 weeks confirmed the biological (re-sialylation of red blood cells) and MRI (trend towards slower fat degeneration from the 24th week) trends in the 6g/d 6SL group.
In the authors’ view, these changes suggest a potential long-term benefit of 6SL in GNE myopathy.
