A Study of KRN23 in Subjects With X-linked Hypophosphatemic Rickets/Osteomalacia

A Phase 1, Multicenter, Open-label, Sequential Dose-escalation, Single-dose Study to Assess the Safety and Tolerability of KRN23 in Subjects With X-linked Hypophosphatemic Rickets/Osteomalacia.

The objective of this study is to assess the safety and tolerability of KRN23 after a single subcutaneous (SC) administration in subjects with X-linked hypophosphatemic rickets/osteomalacia (XLH) in Japan or Korea.

Inclusion Criteria:

1. 18 years or older
2. Patients with XLH

Exclusion Criteria:

1. Have an active infection or chronic inflammatory disease
2. Have uncontrolled hypertension
3. Have uncontrolled diabetes mellitus
4. History of known immunodeficiency
5. Use of a pharmacologic vitamin D metabolite or its analogs within 21 days prior to screening and after screening
6. Use of phosphate, calcium preparation, calcimimetics, aluminum hydroxide antacids, thiazide diuretic, acetazolamide, or phosphate, calcium, and/or vitamin D-containing supplements within 10 days prior to screening and after screening
7. Pregnant or lactating females, women who are possibly pregnant or patients who have no intention of utilizing adequate contraception