Safety and Efficacy Study of ENB-0040 in Juvenile Patients With Hypophosphatasia (HPP)

Overview

This Clinical Trial is being conducted to study Hypophosphatasia (HPP), a bone disorder caused by gene mutations or changes. These gene mutations cause low levels of an enzyme needed to harden bone. The purpose of this study is to test the safety of the study drug called ENB-0040 and see what effects is has on human juveniles and HPP.

Hypophosphatasia (HPP) is a rare inherited form of rickets and osteomalacia caused by inactivating mutations in the gene encoding the tissue-nonspecific isoenzyme of alkaline phosphatase (TNSALP). The prevalence of the disease is thought to be about 1:100,000 although it is markedly higher in a small Canadian Mennonite population (Fraser 1957, Chodirker 1990). Inheritance can be autosomal recessive or dominant, and penetrance is variable resulting in a wide range of clinical expressivity. HPP differs from other forms of rickets and osteomalacia in that serum levels of calcium and phosphorus are generally normal or even elevated (Whyte 2002). Low circulating levels of alkaline phosphatase with elevated serum or urine levels of the TNSALP substrates inorganic pyrophosphate (PPi), pyridoxal 5'-phosphate (PLP) and phosphoethanolamine (PEA) are the biochemical hallmarks of this inborn error of metabolism. Disease severity in HPP is inversely related to the age at symptom presentation. The most severe cases occur in utero and almost invariably result in death, generally due to pulmonary compromise. Infants who present in the first six months of life have about 50% mortality. Children and adults have less severe disease but can have frequent fractures, bone pain, bowing of the long bones and muscle weakness, and morbidity is generally cumulative. Some patients cannot ambulate independently and end up wheelchair-bound.

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Outcomes