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

 1. Written informed consent from parent or legal guardian prior to participation

 2. Boys >/= 5 and < 12 years of age and girls >/= 5 and < 10 years of age with open
 growth plates at time of enrollment

 3. Documented history of HPP, as evidenced by:

 1. Presence of HPP-related rickets on skeletal radiographs

 2. Serum alkaline phosphatase (ALP) below age-adjusted normal range

 3. Plasma PLP at least twice the upper limit of normal (>/=220 nM)

 4. Ambulatory without the use of assistive devices

 5. Ability of patient and parent/guardian to comply with study requirements

 Exclusion Criteria:

 1. Serum calcium or phosphorus below age-adjusted normal range

 2. History of sensitivity to any study drug constituent

 3. Medical condition, serious intercurrent illness, or other extenuating circumstance
 that, in the opinion of the investigator, may significantly interfere with study
 compliance, including all prescribed evaluations and follow-up activities

 4. Treatment with an investigational drug within 1 month before start of study drug

 5. Current enrollment in any other study involving an investigational new drug, device,
 or treatment for HPP (eg, bone marrow transplantation)

 6. Current evidence of a treatable form of rickets

 7. Prior treatment with bisphosphonates

 8. Bone fracture or orthopedic surgery within the past 12 months

 9. Major congenital abnormality other than those associated with HPP