Glycogen storage disease Type II in CRIM-negative infantile-onset Pompe disease — what to do when initial enzyme replacement therapy and immune tolerance induction are insufficient
Infantile-onset Pompe disease arising within the first months of life in a CRIM (Cross Reactive Immune Material) negative patient is a high-risk clinical scenario. This page describes the evidence-based next step when the initial treatment approach does not achieve adequate clinical goals.
Clinical scenario
CRIM-negative status occurs in approximately one third of infantile Pompe disease patients, depending on genotype. These patients express no GAA protein and carry a significantly higher risk of developing antibodies against recombinant enzymes during enzyme replacement therapy. Patients with unknown CRIM status at diagnosis may appropriately be managed as if CRIM negative.
When the initial line is insufficient
Prior treatment: Immune tolerance induction — using variable combinations of rituximab, methotrexate, bortezomib, rapamycin, plasma-exchange, and gamma globulins — started before the first enzyme replacement therapy infusion, together with Alglucosidase alfa.
Escalation trigger: This protocol applies when the prior line did not achieve adequate improvement in hypertrophic cardiomyopathy, gross motor outcomes, or pulmonary function measures — or when a suboptimal response, plateau, or clinical decline subsequently occurs.
Next-step approach (partial)
The next step involves a modification to the Alglucosidase alfa regimen. A higher-dose approach has been associated with improved survival and walking ability compared with the standard initial dose in classic infantile patients.
Full dosing schedule, decision algorithm, and complete regimen details are available in the structured protocol below.
Clinical goals
Key targets of this protocol are improved walking ability and improved gross motor outcomes.
References
DOI: 10.1186/s13023-024-03373-w
About one third of infantile Pompe disease patients, depending on their genotype, do not express any GAA protein and are defined CRIM negative.
CRIM negative patients have a higher risk of producing antibodies against recombinant enzymes when treated with enzyme replacement therapy (ERT).
Therefore, it may be advisable that infantile-onset patients with unknown CRIM status are treated as if they were CRIM negative.
Dose may be increased up to 40 mg/kg/eow or 40 mg/kg/w in patients with classic infantile and in late onset patients showing a suboptimal response, plateau, or clinical decline.
Further, a high-dose regimen of 40 mg/kg week showed a better effect on survival and also on walking ability than the recommend dose in classic infantile patients.
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