[Denosumab and fracture risk in kidney transplant]

Background: Kidney transplant patients bear a higher risk of bone disease. The monoclonal antibody Denosumab (Den), by binding RANKL, reduces osteoclastic activity and increases mineral density (BMD), thus limiting the risk of bone fractures. We evaluated the efficacy and safety of Den in kidney transplant patients who developed bone fractures. Methods: Thirteen kidney transplant recipients (aged from 50 to 79 years 7M and 6F, with an average 9,9 years follow up after transplantation, and nearly normal renal function (GFR 62±15 ml/min/1.73m2), who developed low-energy vertebral fractures (21 dorsal and 1 lumbar) after transplantation, had been evaluated for 2 years with Dual-energy X-ray absorptiometry (DEXA) and morphometric absorptiometry (MXA) while receiving Den (four 60-mg doses). Data for vertebral heights and posterior-anterior height ratios (P/A), and BMD values for vertebral, femoral, and radius were obtained. The immunosuppressive regimen consisted of CNI and MMF, and 8 out of 13 were taking prednisone. A fixed dose of 450.000 UI-year of cholecalciferol was prescribed to all patients. Whole-PTH, 25-OHD3, and alkaline phosphatase (ALP) were also evaluated. Results: After 2 years of Den treatment, we observed a significative increase in vertebral T-score (from -2.12±0.35 to -1.67±0.35; p < 0.02), while T score of femoral neck and radius did not show significative variation (-1.86±0.21 versus -1.84±0.23 and -3.04±0.42 versus -3.19±0.45, respectively). We found a lower incidence of fracture/patient-year pre and post Den 0.17 [95 CI 0.11-0.24] vs 0.07 [95% CI 0.02-0.3] respectively. No significative variations were observed in whole-PTH (89.31±19.9 pg/ml versus 68.38±9.8 pg/ml), 25OHD3 (24.02±2.75ug/L versus 26.67±2.29 ug/L) and alkaline phosphatase (78.46±12.73UI/L versus 56.77±7.14UI/L). No adverse events were registered. Conclusions: Treatment with Den improve BMD in vertebral bone and possibly reduces the risk of low-energy vertebral fractures in kidney transplant patients.