Paricalcitol versus cinacalcet plus low-dose vitamin D therapy for the treatment of secondary hyperparathyroidism in patients receiving haemodialysis: results of the IMPACT SHPT study

Optimal treatment for secondary hyperparathyroidism (SHPT) has not been defined. The IMPACT SHPT (ClinicalTrials.gov identifier: NCT00977080) study assessed whether dose-titrated paricalcitol plus supplemental cinacalcet only for hypercalcaemia is superior to cinacalcet plus low-dose vitamin D in controlling intact parathyroid hormone (iPTH) levels in patients with SHPT on haemodialysis. In this 28-week, multicentre, open-label Phase 4 study, participants were randomly selected to receive paricalcitol or cinacalcet plus low-dose vitamin D. Randomization and analyses were stratified by mode of paricalcitol administration [intravenous (IV) or oral]. The primary efficacy end point was the proportion of subjects who achieved a mean iPTH value of 150300 pg/mL during Weeks 2128. Of 272 subjects randomized, 268 received one or more dose of study drug; 101 in the IV and 110 in the oral stratum with two or more values during Weeks 2128 were included in the primary analysis. In the IV stratum, 57.7 of subjects in the paricalcitol versus 32.7 in the cinacalcet group (P 0.016) achieved the primary end point. In the oral stratum, the corresponding proportions of subjects were 54.4 for paricalcitol and 43.4 for cinacalcet (P 0.260). CochranMantelHaenszel analysis, controlling for stratum, revealed overall superiority of paricalcitol (56.0) over cinacalcet (38.2; P 0.010) in achieving iPTH 150300 pg/mL during Weeks 2128. Hypercalcaemia occurred in 4 (7.7) and 0 (0) of paricalcitol-treated subjects in the IV and oral strata, respectively. Hypocalcaemia occurred in 46.9 and 54.7 of cinacalcet-treated subjects in the IV and oral strata, respectively. Paricalcitol versus cinacalcet plus low-dose vitamin D provided superior control of iPTH, with low incidence of hypercalcaemia.