ESPE Abstracts

Background: Traditionally patients with X-linked Hypophosphatemic Rickets (XLH) have been treated with conventional therapy, however, in 2018, the FDA approved Burosumab use in XLH patients.

Objective: To investigate Burosumab effectiveness on pediatric patients with XLH by observing an improvement in serum phosphorus concentration and total rickets severity score (RSS) within 12 months period.

Methods: This is a prospective observational study. It took a place at King Faisal Specialist Hospital & Research Centre in Riyadh, Saudi Arabia over one year in duration. We enrolled 19 patients with x-linked hypophosphatemia rickets aged between 1-18 years. Data analysis was done in STATA software version 18. Consent was taken from all participants, and ethical approval was taken from the research committee (reference: 2231069).

Results: A total of 19 patients were included and followed for a year; 5 (26.32%) were males, whereas 14 (73.68%) were females with a median age of 9 years [IQR: 4-10]. Over a one-year period, the height SDS score notably improved in all cases from -2.96 to -2.76 by (6.76%) (P = 0.0029). In addition, all cases reported considerable improvement in biochemical and radiological findings from baseline to the last visit as follows: the serum phosphate (0.78 to 1.03) mmol/l, alkaline phosphate (493.68 to 355.94) IU/L, Albumin (45.40 to 44.46) g/L, urine phosphate (29.47 to 19.51) mmol/L, tubular phosphate reabsorption (0.84 to 0.93), TMP/GFR (0.62 to 1.35), wrist score (3.26 to 0.68), knee score (4.21 to 1.05), and the total rickets severity score (RSS) (7.47 to 1.73) (p-values<0.05). Consequently, only 1(7.14%) had orthopedic surgery during the follow-up period, and three other patients (33.33%) had minor symptoms (headache, vomiting, and diarrhea).

Conclusion: Burosumab therapy is more effective than continuing conventional therapy in improving rickets, linear growth, and lower limb deformity in Pediatrics with XLH. By inhibiting excess FGF23 activity and normalizing renal phosphate excretion, burosumab induced clinically meaningful improvements and has the potential to prevent long-term complications associated with X-linked hypophosphatemia.