Short-Term Intensive Avalglucosidase Alfa Regimen in Late-Diagnosed Infantile Pompe Disease: A Case Report

<b>Background and Clinical Significance</b><b>:</b> Classic infantile-onset Pompe disease (IOPD) is the most severe form of Pompe disease, manifesting within the first months of life with hypertrophic cardiomyopathy and severe hypotonia. Avalglucosidase alfa is a next-generation recombinant human α-glucosidase that was recently approved for use. Clinical trials, conducted on IOPD patients already treated with alglucosidase alfa, have recommended a dosage ranging from 20 to 40 mg/kg every other week. The optimal dosage for treatment-naïve patients has not yet been established. We present a case of a severe IOPD patient who received a short-term high-dose, high-frequency regimen of avalglucosidase alfa (40 mg/kg/week). <b>Case Presentation:</b> The patient, a 3-month-old infant, presented with hypotonia and severe hypertrophic cardiomyopathy (left ventricular mass index (LVMI) of 136 g/m²; ejection fraction (EF) of 60%). Treatment with avalglucosidase alfa was initiated at a dose of 40 mg/kg every other week. After two weeks, cardiac function further deteriorated (LVMI of 168 g/m²; EF of 46%), so the treatment was intensified to a dose of 40 mg/kg weekly for two months. This resulted in significant clinical, biochemical, and motor improvements without adverse reactions. Following this improvement, the dosage of 40 mg/kg every other week was reinstated. At 18 months of age, the patient demonstrated normal motor development, normal cardiac function (LVMI of 49 g/m²; EF of 68%), and normal biomarkers. <b>Conclusions:</b> Although limited to a single patient, this case illustrates that short-term high-dose, high-frequency administration of avalglucosidase alfa could be both effective and safe, even in patients with severe, late-diagnosed IOPD.