The efficacy and safety of cinacalcet in primary hyperparathyroidism: a systematic review and meta-analysis of randomized controlled trials and cohort studies

Cinacalcet, a positive allosteric modulator of the calcium sensing receptor (CaSR) reduces parathyroid hormone (PTH) secretion by increasing the sensitivity of the CaSR on parathyroid cells. We conducted a systematic review and meta-analysis on the safety and efficacy of cinacalcet in Primary Hyperparathyroidism (PHPT). MEDLINE, Embase, BIOSIS, and the Cochrane Library were searched for published articles (from database inception to Sept 2020). All double-blind RCTs and cohort studies that reported data on the efficacy and safety of cinacalcet therapy in individuals ≥ 18 with PHPT were included. Random effect meta-analysis was performed to estimate the efficacy of cinacalcet in lowering serum calcium and PTH levels compared with placebo. 4 RCTs (177 participants) and 17 cohort studies (763 participants) were eligible for final analysis. Pooled results from the RCTs suggest that, when compared to placebo and administered for up to 28 weeks, cinacalcet normalizes serum calcium (≤ 10.3 mg/dl) in patients with PHPT [RR 20 (95% CI 6.04 – 68.52, I² = 0%, p_{heterogeneity} < 0·00001)]. Serum PTH levels decreased significantly after 2 weeks and up to 28 weeks after treatment with cinacalcet. In the pooled analysis of the 17 cohort studies, serum calcium levels normalized in 76% (95% CI 66% to 86%; I² = 92%, p_{heterogeneity} < 0·00001) of patients regardless of the duration of treatment. In most studies, PTH levels decreased by 13% to 55%. No RCT reported on BMD as a primary or secondary outcome, and no improvement in BMD was noted in the 2 non-randomized studies that reported densitometric findings. No significant difference in urinary calcium was noted with cinacalcet therapy in either the RCTs or non-randomized studies. There was no significant difference in overall adverse events (AE) (RD 0.01, 95% CI –0.07 to 0.26) compared to placebo noted in the RCTs. In the non-randomized studies, pooled weighted AE rate was 45% (95% CI 32 to 59%). Risk of bias was low in 2/4 RCTs and 6/17cohort studies; risk was intermediate in 2/4 RCTs and 8/17 cohort studies, and risk was high in 3/17 cohort studies. In PHPT, cinacalcet lowers serum calcium and PTH with greater effects on calcium than on PTH in the short term. In the doses reported, the drug is safe with tolerable side effects. These findings can help inform targeted medical therapy of PHPT in those for whom lowering the serum calcium is indicated and for whom parathyroidectomy is not an option.