Abstract: PO0560
Two Siblings with X-Linked Hypophosphatemia (XLH) Treated with Burosumab: Is Therapeutic Regimen Recommended Now Supported by Real-World Data?
Session Information
- Bone and Mineral Metabolism: Clinical
November 04, 2021 | Location: On-Demand, Virtual Only
Abstract Time: 10:00 AM - 12:00 PM
Category: Bone and Mineral Metabolism
- 402 Bone and Mineral Metabolism: Clinical
Authors
- Morita, Hiroyuki, Aichi Ika Daigaku, Nagakute, Aichi, Japan
- Inui, Kiyoko, Showa Daigaku Fujigaoka Byoin, Yokohama, Kanagawa, Japan
- Inoue, Yoshihiko, Showa Daigaku Fujigaoka Byoin, Yokohama, Kanagawa, Japan
- Koiwa, Fumihiko, Showa Daigaku Fujigaoka Byoin, Yokohama, Kanagawa, Japan
- Yoshimura, Ashio, Shinyokohama Daiichi Clinic, Yokohama, Japan
- Takagi, Junko, Aichi Ika Daigaku, Nagakute, Aichi, Japan
Introduction
Burosumab, a human monoclonal antibody to FGF 23, is used now to treat XLH. In phase III study, patients were selected and controlled. What is considered as “recommended” regimen of burosumab in that population within the controlled setting might be different from that in another population in real world. The present study was conducted in an attempt to address this issue.
Case Description
Patient A and patient B with XLH are siblings in their twenties. They were successfully managed in childhood, and have enthesopathy. They had had alpha calciferol and phosphate supplementation, and started to have 1 mg/kg BW burosumab 1.5 years ago. Changes in TmP/GFR, IP, and sCr after burosumab administration are shown (Figure). A significant increase in TmP/GFR (p<0.00001) was seen. IP and sCr levels almost did not change. Nephrocalcinosis, hyperparathyroidism, and vitamin D deficiency were mild and not worsened. Changes in bone mineral density (BMD) were assessed by DEXA scan. In 2018, young adult mean (YAM) of lumbar vertebra were 129% in Patient A, and 138% in Patient B. In 2021, these YAM values increased to 141% in Patient A and 140% in Patient B, respectively.
Figure legend:
Data for the past 6.5 years were retrospectively analyzed and shown as mean (colomn) plus standard deviation (bar). N numbers indicate the time they visited our hospital where they gave blood and spot urine samples. Dimensions of IP, and sCr are mg/dL. TmP/GFR; tubular threshold maximum for phosphorous per glomerular filtration rate.
Discussion
Using real-world data, we confirmed the efficacy and safety of recommended burosumab therapy regimen for 1.5 years, so far as laboratory indices used in phase III study were concerned. However, YAM values were above-the-average and increasing in the presence of hypophosphatemia and low TmP/GFR. The future consequence of this feature in relation to time-elapsed changes in renal physiological parameters including TmP/GFR, Ca, IP, and sCr should be seen.