Effect of rapid cessation of enzyme replacement therapy: A report of 5 cases and a review of the literature

Enzyme replacement therapy (ERT) is a treatment modality available for several of the lysosomal storage diseases including mucopolysaccharidosis type II (MPS II). We report a series of patients with MPS II (n=5, age range at the start of ERT 11-21 years, median 15 years) and the effects of ERT cessation (range 2-8 months, median 3 months) on their clinical status. Additionally, we review previously published cases. In our series, a worsening of the patients' clinical status was observed. Symptoms after ERT discontinuation included recurrent respiratory infections (severe pneumonia) with respiratory insufficiency (80%), difficulty with walking/standing (60%), increased joint stiffness (40%), but also decreased hematological parameters (40%), renal insufficiency (40%) and death (20%). The literature review confirms that the beneficial clinical effects of ERT are soon lost if treatment is discontinued in MPS I and Pompe patients. Conclusions: 1. Rapid cessation of ERT results not only in the loss of the beneficial effects, but in a significant worsening of the patient's clinical status. 2. Decisions about the introduction of ERT, especially in patients severely affected, should be made carefully. 3. Once started, it is essential to keep an adequate administration schedule of ERT to maintain the clinical benefits of enzyme therapy. (C) 2012 Elsevier Inc. All rights reserved.