Paricalcitol- or cinacalcet-centred therapy affects markers of bone mineral disease in patients with secondary hyperparathyroidism receiving haemodialysis: results of the IMPACT-SHPT study

BACKGROUND: In this Phase 4 international study, efficacy and safety of paricalcitol-centred therapy were compared with that of cinacalcet-centred therapy for the treatment of chronic kidney disease (CKD)-associated secondary hyperparathyroidism (SHPT) in patients undergoing haemodialysis (ClinicalTrials.gov identifier NCT00977080). METHODS: Patients 6518 years of age with Stage 5 CKD and SHPT [intact parathyroid hormone (iPTH) level of 300-800 pg/mL, calcium level of 8.4-10.0 mg/dL and phosphate concentration of 646.5 mg/dL] who were undergoing haemodialysis were included. Patients were randomized by mode of paricalcitol administration [i.e. intravenous (IV) or oral strata] to receive paricalcitol- or cinacalcet-centred therapy for 6428 weeks. Changes in metabolic markers [total alkaline phosphatase (AP), bone-specific AP and fibroblast growth factor-23 (FGF-23)] and the proportion of patients in each treatment group who achieved an iPTH level of 150-300 pg/mL during Weeks 8, 16 and 21-28 as a composite value were evaluated. RESULTS: Compared with cinacalcet-centred therapy, levels of both bone turnover markers were significantly reduced from baseline with IV and oral paricalcitol-centred treatment (P < 0.05 for both dosing strata) at Weeks 8, 16 and 28. Levels of FGF-23 were increased with paricalcitol versus cinacalcet-centred treatment. A greater proportion of patients receiving paricalcitol-centred therapy achieved target iPTH levels (i.e. 150-300 pg/mL) throughout the study in the IV and oral dosing strata compared with patients receiving cinacalcet-centred treatment. CONCLUSIONS: In patients with CKD and SHPT undergoing haemodialysis, paricalcitol-centred therapy reduced circulating bone turnover markers and iPTH levels and increased FGF-23 levels compared with cinacalcet-centred treatment