Adults with late-onset Pompe disease generally tolerate avalglucosidase alfa well for up to 6.5 years whether or not they have previously been treated with alglucosidase alfa, according to the results of the phase 1 clinical trial called NEO1 and its phase 2 and 3 extensions called NEO-EXT.

During the NEO1 study, 24 participants received 5 mg/kg, 10 mg/kg, or 20 mg/kg of avalglucosidase alfa every other week for 6 months. Of these 10 were treatment-naive while 14 switched from alglucosidase alfa treatment. A total of 19 participants then entered NEO-EXT and continued on their previous dose until all received 20 mg/kg of treatment every 2 weeks for 6 months.

Based on results from 17 patients who remained on avalglucosidase alfa treatment for up to 6.5 years, researchers reported that the treatment was generally well-tolerated during the extension study and the safety profile was consistent with that in the NEO1 study.

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The researchers also reported no treatment-related life-threatening serious adverse events or deaths. However, 18 participants developed antidrug antibodies, but these had no apparent impact on clinical outcomes. None of the participants tested developed immunoglobulin E antibodies.

Moreover, upright forced vital capacity percent predicted and 6-Minute Walk Test (6MWT) percent predicted were stable in most patients with improvements observed in 6MWT scores in most patients who were younger than 45 years when they enrolled in the NEO1 study. This was the case regardless of whether or not they had received alglucosidase alfa previously.

Avalglucosidase alfa is a recombinant human lysosomal acid α-glucosidase enzyme replacement therapy designed for better cellular uptake and glycogen clearance in patients with Pompe disease. The results of this study were published ahead of print in the journal Neurology.


Dimachkie MM, Barohn RJ, Byrne B, NEO-EXT investigators. Long-term safety and efficacy of avalglucosidase alfa in patients with late-onset Pompe disease. Neurology. Published online May 26, 2022. doi:10.1212/WNL.0000000000200746