Endocrine Abstracts

Cinacalcet decreases and normalizes serum calcium levels across a broad severity range of primary hyperparathyroidism (PHPT), slightly reduces parathyroid hormone levels which generally remains elevated, whereas it has no effect on bone mineral density (BMD). Therefore, when administering cinacalcet to a patient with PHPT, concomitant treatment with an anti-catabolic drug should be considered.

An open-labeled, prospective trial was conducted in 32 patients with PHPT with cinacalcet treatment (contraindications to surgery, negative parathyroid imaging, persistent or relapsing PHPT after PTx- and refusal of PTx), to determine whether denosumab, maintains or improves BMD in patients with PHPT after 24 months of treatment.

PHPT patients with low BMD were treated with cinacalcet (Mimpara, Amgen; titrated dose), 25-OH vitamin D (Hidroferol, Faes) and denosumab (Prolia, Amgen) 60 mg sc injections given every 6 months. Serum calcium, phosphorous PTH and bone turnover markers were evaluates every 3 and 6 months. BMD was measured at the lumbar spine (LS) and total femur (TF) by dual-energy X-ray absorptiometry baseline and after 24 months of treatment.

The treatment normalized calcium decreasing 1.7±0.1 mg/dl (P<0,0001) and paratohormone 33.36±21.6 (P<0,05) pg/dl. Bone turnover markers remained suppressed for the duration of the trial. The treatment was also associated with a significant increase after 24 months in vs baseline in LS BMD: 8% (P: 0.037) and in TF BMD: 7% (P: 0.0001), improving to normal BMD in the 45.5%.

Denosumab associated to cinacalcet is an excellent therapeutic option to normalize serum calcium and paratohormone to treat the metabolic bone-disease in patients with PHPT who do not meet criteria for surgical treatment.