Development of high sustained anti-drug antibody titers and corresponding clinical decline in a late-onset Pompe disease patient after 11+ years on enzyme replacement therapy

A late-onset Pompe disease patient developed high sustained antibody titers (HSAT) of ≥51,200 after 11+ years on alglucosidase alfa and previous tolerance. There was a corresponding worsening of motor function and rise in urinary glucose tetrasaccharide (Glc(4)). Following immunomodulation therapy, HSAT were eliminated with improved clinical outcomes and biomarker trends. This report highlights the importance of continued surveillance of antibody titers and biomarkers, the negative impact of HSAT, and improved outcomes with immunomodulation therapy.