Treatment of Infantile-Onset Pompe Disease (GSD Type II) with CRIM-Negative Status

Clinical Scenario

This protocol addresses infants presenting with Pompe disease (Glycogen storage disease Type II) with onset within the first months of life and confirmed or presumed CRIM (Cross Reactive Immune Material) negative status. CRIM-negative patients do not express any GAA protein, placing them at substantially elevated immunological risk during enzyme replacement therapy.

CRIM-Negative Status

Approximately one third of infantile Pompe disease patients, depending on genotype, do not express any GAA protein and are classified as CRIM negative. These patients carry a higher risk of mounting antibody responses against recombinant enzyme, which can significantly compromise treatment outcomes. Because CRIM status must be established quickly, patients with unknown status are typically managed as CRIM negative until confirmed otherwise.

Treatment Approach (Overview)

In CRIM-negative infantile-onset Pompe disease, management requires a prophylactic immune tolerance induction step that must be initiated before the first enzyme replacement infusion. This step involves a combination of immunomodulatory agents, and its timing is critical to reducing the risk of antibody formation once enzyme replacement therapy begins.

The complete regimen — including agent selection, sequencing, and dosing — is available in the full structured protocol below.

Treatment Goals

• Improvement of hypertrophic cardiomyopathy
• Improved gross motor outcomes
• Improved pulmonary function measures