title: Durable and sustained immune tolerance to ERT in Pompe disease with entrenched immune responses.
abstract: BACKGROUND
  Enzyme replacement therapy (ERT) has prolonged survival and improved clinical outcomes in patients with infantile Pompe disease (IPD), a rapidly progressive neuromuscular disorder. Yet marked interindividual variability in response to ERT, primarily attributable to the development of antibodies to ERT, remains an ongoing challenge. Immune tolerance to ongoing ERT has yet to be described in the setting of an entrenched immune response.
  
  
  METHODS
  Three infantile Pompe patients who developed high and sustained rhGAA IgG antibody titers (HSAT) and received a bortezomib-based immune tolerance induction (ITI) regimen were included in the study and were followed longitudinally to monitor the long-term safety and efficacy. A trial to taper the ITI protocol was attempted to monitor if true immune tolerance was achieved.
  
  
  RESULTS
  Bortezomib-based ITI protocol was safely tolerated and led to a significant decline in rhGAA antibody titers with concomitant sustained clinical improvement. Two of the 3 IPD patients were successfully weaned off all ITI protocol medications and continue to maintain low/no antibody titers. ITI protocol was significantly tapered in the third IPD patient. B cell recovery was observed in all 3 IPD patients.
  
  
  CONCLUSIONS
  This is the first report to our knowledge on successful induction of long-term immune tolerance in patients with IPD and HSAT refractory to agents such as cyclophosphamide, rituximab, and methotrexate, based on an approach using the proteasome inhibitor bortezomib. As immune responses limit the efficacy and cost-effectiveness of therapy for many conditions, proteasome inhibitors may have new therapeutic applications.
  
  
  BACKGROUND
  This research was supported by a grant from the Genzyme Corporation, a Sanofi Company (Cambridge, Massachusetts, USA), and in part by the Lysosomal Disease Network, a part of NIH Rare Diseases Clinical Research Network (RDCRN).
authors: Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA.
authors: Zoheb B
authors: ZB
authors: Kazi
authors: Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA.
authors: Sean N
authors: SN
authors: Prater
authors: Department of Genetics, Kaiser Permanente, San Jose, California, USA.
authors: Joyce A
authors: JA
authors: Kobori
authors: Division of Medical Genetics, Department of Pediatrics, University of Utah, Salt Lake City, Utah, USA.
authors: David
authors: D
authors: Viskochil
authors: Division of Medical Genetics, Department of Pediatrics, University of Utah, Salt Lake City, Utah, USA.
authors: Carrie
authors: C
authors: Bailey
authors: Department of Pediatrics/Human Development, Michigan State University, East Lansing, Michigan, USA.
authors: Renuka
authors: R
authors: Gera
authors: Division of Genetic, Genomic and Metabolic Disorders, Departments of Pediatrics and Internal Medicine, Wayne State University and Children's Hospital of Michigan, Detroit, Michigan, USA.
authors: David W
authors: DW
authors: Stockton
authors: School of Medicine, University of North Carolina at Chapel Hill, North Carolina, USA.
authors: Paul
authors: P
authors: McIntosh
authors: Division of Therapeutic Proteins, Office of Biotechnology Products, Center for Drug Evaluation and Research, United States Food and Drug Administration, Bethesda, Maryland, USA.
authors: Amy S
authors: AS
authors: Rosenberg
authors: Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA.
authors: Priya S
authors: PS
authors: Kishnani