Effects of cinacalcet and concurrent low-dose vitamin D on FGF23 levels in ESRD.
OBJECTIVE
Fibroblast growth factor-23 (FGF23) levels are elevated in ESRD and have been associated with adverse outcomes. The effects of various treatments for secondary hyperparathyroidism on FGF23 levels in ESRD have not been examined in a clinical trial.


METHODS
We assessed intact FGF23 levels in 91 subjects over the course of the ACHIEVE trial, which was designed to compare escalating doses of Cinacalcet plus fixed low-dose calcitriol analogs (Cinaclcet-D) with titration of calcitriol analogs alone (Flex-D) to suppress parathyroid hormone. Between-group and within-group changes in log-transformed FGF23 levels were analyzed. Factors associated with change in FGF23 were assessed using a multiple regression model.


RESULTS
Intact FGF23 levels were markedly elevated in subjects at baseline. A statistically significant difference in percent change in log FGF23 levels was observed between treatment groups (P < 0.002). The Cinacalcet-D group had a significant decrease in percent change in log FGF23 levels (corrected P = 0.021), whereas FGF23 levels trended toward an increase in the Flex-D group. Change in FGF23 level was significantly associated with changes in levels of phosphate (P < 0.0001) and calcium (P = 0.0002) but not parathyroid hormone.


CONCLUSIONS
Treatment with Cinacalcet plus low-dose calcitriol analogs results in lower FGF23 levels compared with a treatment regimen using calcitriol analogs alone in ESRD. The mechanisms underlying the differential effects of these treatment regimens on FGF23 levels and the clinical impact of these changes on FGF23 remain to be defined.
Wetmore
James B
JB
University of Kansas Medical Center, MS 3002, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA. jwetmore@kumc.edu
Liu
Shiguang
S
Krebill
Ron
R
Menard
Rochelle
R
Quarles
L Darryl
LD
D000069449:Cinacalcet; D004359:Drug Therapy, Combination; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood* / Q000187:drug effects*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009281:Naphthalenes / Q000627:therapeutic use*; D016037:Single-Blind Method; D014807:Vitamin D / Q000008:administration & dosage*; D014815:Vitamins / Q000008:administration & dosage*
C000717427:FGF23 protein, human; D009281:Naphthalenes; D014815:Vitamins; D014807:Vitamin D; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D000069449:Cinacalcet