Recent Advances in Treatment Approaches of Mucopolysaccharidosis VI

Mucopolysaccharidosis VI is caused by accumulation of the glycosaminoglycan dermatan sulfate in all tissues due to decreased activity of the enzyme arylsulfatase B. Patients exhibit multisystemic signs and symptoms in a chronic and progressive manner, especially with changes in the skeleton, cardiopulmonary system, cornea, skin, liver, spleen and meninges. Patients usually have normal intelligence. In the past, treatment of mucopolysaccharidoses was limited to palliative medical care. The outcome for affected patients improved with the introduction of new technologies as hematopoietic stem cell transplantation, relegated to specific situations after enzyme replacement therapy (ERT) became available. The specific ERT for MPS VI, galsulfase (Naglazyme®, Biomarin Pharmaceutical) was approved in 2005 by FDA and in 2006 by EMEA, and three clinical studies including 56 patients have evaluated the efficacy and safety. Long-term follow up data with patients treated up to 5 years showed that ERT is well tolerated and associated with sustained improvements in the patients' clinical condition. Intrathecal ERT may be considered in situations of high neurosurgical risk but still it is experimental in humans, as is intra-articular ERT. It is possible that the full impact of this therapy will only be demonstrated when patients are identified and treated soon after birth, as it was shown that early introduction of ERT produced immune tolerance and improved enzyme effectiveness in the cat model. New insights on the pathophysiology of MPS disorders are leading to alternative therapeutic approaches, as gene therapy, inflammatory response modulators and substrate reduction therapy.