Cinacalcet HCl prevents development of parathyroid gland hyperplasia and reverses established parathyroid gland hyperplasia in a rodent model of CKD.
BACKGROUND
Secondary hyperparathyroidism (sHPT) represents an adaptive response to progressively impaired control of calcium, phosphorus and vitamin D in chronic kidney disease (CKD). It is characterized by parathyroid hyperplasia and excessive synthesis and secretion of parathyroid hormone (PTH). Parathyroid hyperplasia in uremic rats can be prevented by calcium-sensing receptor (CaSR) activation with the calcimimetic cinacalcet (Sensipar®/Mimpara®); however, it is unknown, how long the effects of cinacalcet persist after withdrawal of treatment or if cinacalcet is efficacious in uremic rats with established sHPT.


METHODS
We sought to determine the effect of cinacalcet discontinuation in uremic rats and whether cinacalcet was capable of influencing parathyroid hyperplasia in animals with established sHPT.


RESULTS
Discontinuation of cinacalcet resulted in reversal of the beneficial effects on serum PTH and parathyroid hyperplasia. In rats with established sHPT, cinacalcet decreased serum PTH and mediated regression of parathyroid hyperplasia. The cinacalcet-mediated decrease in parathyroid gland size was accompanied by increased expression of the cyclin-dependent kinase inhibitor p21. Prevention of cellular proliferation with cinacalcet occurred despite increased serum phosphorus and decreased serum calcium.


CONCLUSIONS
The animal data provided suggest established parathyroid hyperplasia can be reversed by modulating CaSR activity with cinacalcet and that continued treatment may be necessary to maintain reductions in PTH.
Department of Metabolic Disorders, Amgen Inc, Thousand Oaks, CA, USA.
Gerald
G
Miller
James
J
Davis
Edward
E
Shatzen
Matthew
M
Colloton
David
D
Martin
Charles M
CM
Henley
D000818:Animals; D002118:Calcium / Q000097:blood; D049109:Cell Proliferation / Q000187:drug effects; D000069449:Cinacalcet; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004195:Disease Models, Animal; D006962:Hyperparathyroidism, Secondary / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D006965:Hyperplasia / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D007676:Kidney Failure, Chronic / Q000150:complications* / Q000473:pathology; D008297:Male; D009281:Naphthalenes / Q000627:therapeutic use*; D010280:Parathyroid Glands / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D010281:Parathyroid Hormone / Q000097:blood; D010758:Phosphorus / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley; D014511:Uremia / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*
D050759:Cyclin-Dependent Kinase Inhibitor p21; D009281:Naphthalenes; D010281:Parathyroid Hormone; D010758:Phosphorus; D002118:Calcium; D000069449:Cinacalcet