A Trial to Assess the Safety and Efficacy of KRN23 in Epidermal Nevus Syndrome (ENS)
Status:
Completed
Trial end date:
2021-08-31
Target enrollment:
Participant gender:
Summary
KRN23 is a fully human immunoglobulin monoclonal antibody (mAb) that binds to and inhibits
the activity of fibroblast growth factor 23 (FGF23), leading to an increase in serum
phosphorus levels. There are multiple disorders that result in unusually high circulating
levels of FGF23, which in turn result in renal phosphate wasting and reduced levels of
1,25-dihydroxy vitamin D (1,25[OH]2D). Across these disorders the clinical symptoms are
similar and often include osteomalacia (and, in children, rickets), muscle weakness, fatigue,
bone pain, and fractures. KRN23 has been studied in one of these disorders, X-linked
hypophosphatemia (XLH). In single- and repeat-dose clinical studies in subjects with XLH,
subcutaneous (SC) administration of KRN23 consistently increased and sustained serum
phosphorus levels and tubular reabsorption of phosphate (TRP) without a major impact on urine
calcium levels or vitamin D metabolism. Positive results were also observed in a nonclinical
pharmacology model of XLH. It is hypothesized that KRN23 may provide clinical benefit in this
patient due to the common underlying feature in this patient and in patients with XLH -
abnormally elevated FGF23 in the context of low age -adjusted serum phosphorous levels. The
primary objective is to study the effect of KRN23 treatment on normalizing age-adjusted
fasting serum phosphorous levels in a single pediatric patient with Epidermal Nevus Syndrome
associated hypophosphatemic rickets.