[Inhitibion of FGF23 activities as a possible new treatment for patients with FGF23-related hypophosphatemic diseases].

Excessive actions of fibroblast growth factor 23(FGF23)result in several kinds of hypophosphatemic rickets and osteomalacia. A combination of oral active vitamin D3 and phosphate is the current standard therapy for FGF23-related hypophosphatemia. However, these medications can lead to long-term complications, such as secondary hyperparathyroidism and renal impairment. Therefore, safer and more efficient therapy to correct excessive actions of FGF23 is needed. X-linked hypophosphatemic rickets(XLHR)is the most prevalent form of FGF23-related hypophosphatemia. The efficacy of anti-FGF23 antibody was confirmed in a Hyp mouse, a murine model of XLHR. A recent phase 1 double-blind, placebo-controlled study and the subsequent open-label phase 1/2 study in adults with XLHR showed the safety and the efficacy of human anti-FGF23 antibody, KRN23. KRN23 has a potential for effectively treating patients with XLHR and other types of FGF23-related hypophosphatemia as well.