CRIM-negative infantile Pompe disease: characterization of immune responses in patients treated with ERT monotherapy

Purpose: Enzyme replacement therapy (ERT) with recombinant human acid α-glucosidase (rhGAA) prolongs survival in infantile Pompe disease (IPD). However, the majority of cross-reactive immunologic material (CRIM)–negative (CN) patients have immune responses with significant clinical decline despite continued ERT. We aimed to characterize immune responses in CN patients with IPD receiving ERT monotherapy. Methods: A chart review identified 20 CN patients with IPD treated with ERT monotherapy for ≥6 months. Patients were stratified by anti-rhGAA antibody titers: high sustained antibody titers (HSAT; ≥51,200) at least twice; low titers (LT;