Chronic immune thrombocytopenic purpura (ITP) is characterized by low platelet counts and mucocutaneous bleeding. In previous studies romiplostim (AMG531), a thrombopoiesis-stimulating protein, increased platelet counts in most patients with chronic ITP. This ongoing, long-term open-label, single-arm study investigated safety and efficacy in patients who completed a previous romiplostim study and had platelet counts less than 5 ؋ 10 9 /L. One hundred forty-two patients were treated for up to 156 weeks (mean, 69 weeks). Platelet responses (platelet count > 50 ؋ 10 9 /L and double baseline) were observed in 87% of all patients and occurred on average 67% of the time in responding patients. In 77% of patients, the romiplostim dose remained within 2 g/kg of their most frequent dose at least 90% of the time. Ninety patients (63%) received treatment by selfadministration. Treatment-related serious adverse events were reported in 13 patients (9%). Bone marrow reticulin was observed in 8 patients; marrows were not routinely performed in this study, so the true incidence of this event cannot be determined. Severe bleeding events were reported in 12 patients (9%). Thrombotic events occurred in 7 patients (5%
Management of secondary hyperparathyroidism is challenging with traditional therapy. The calcimimetic cinacalcet HCl acts on the calcium-sensing receptor to increase its sensitivity to calcium, thereby reducing parathyroid hormone (PTH) secretion. This phase 3, multicenter, randomized, placebo-controlled, double-blind study evaluated the efficacy and safety of cinacalcet in hemodialysis (HD) and peritoneal dialysis (PD) patients with PTH >300 pg/ml despite traditional therapy. A total of 395 patients received once-daily oral cinacalcet (260 HD, 34 PD) or placebo (89 HD, 12 PD) titrated from 30 to 180 mg to achieve a target intact PTH (iPTH) level of <250 pg/ml. During a 10-wk efficacy assessment phase, cinacalcet was more effective than control for PTH reduction outcomes, including proportion of patients with mean iPTH levels <300 pg/ml (46 versus 9%), proportion of patients with >30% reduction in iPTH from baseline (65 versus 13%), and proportion of patients with >20, >40, or >50% reduction from baseline. Cinacalcet had comparable efficacy in HD and PD patients; 50% of PD patients achieved a mean iPTH <300 pg/ml. Cinacalcet also significantly reduced serum calcium, phosphorus, and Ca ؋ P levels compared with control treatment. The most common side effects, nausea and vomiting, were usually mild to moderate in severity and transient. Once-daily oral cinacalcet was effective in rapidly and safely reducing PTH, Ca ؋ P, calcium, and phosphorus levels in patients who received HD or PD. Cinacalcet offers a new therapeutic option for controlling secondary hyperparathyroidism in patients with chronic kidney disease on dialysis.
Calcimimetics increase the sensitivity of parathyroid calcium-sensing receptors to extracellular calcium, thereby reducing PTH secretion. This multicenter, randomized, double-blind, placebo-controlled study assessed the ability of the oral calcimimetic cinacalcet HCl to achieve long-term reductions in serum calcium and PTH concentrations in patients with primary hyperparathyroidism (HPT). Patients (n = 78) were randomized to cinacalcet or placebo. Cinacalcet was titrated from 30-50 mg twice daily during a 12-wk dose-titration phase. Efficacy was assessed during 12-wk maintenance and 28-wk follow-up phases. The primary endpoint was the achievement of normocalcemia [serum calcium = 10.3 mg/dl (2.57 mmol/liter)] with at least 0.5 mg/dl (0.12-mmol/liter) reduction from baseline. Plasma PTH, serum and urine biochemistry, biochemical measures of bone turnover, bone mineral density, and safety were also assessed. Seventy-three percent of cinacalcet-treated patients vs. only 5% of placebo-treated patients achieved the primary endpoint (P < 0.001). Fasting predose plasma PTH decreased 7.6% in cinacalcet patients but increased 7.7% in placebo patients (P < 0.01). Bone mineral density was unchanged by cinacalcet, but bone resorption and formation markers increased (P < 0.05). Adverse events were mild and similar between treatment groups. Cinacalcet rapidly normalizes serum calcium and reduces PTH in patients with primary HPT, and these effects are maintained with long-term treatment. Cinacalcet may be an effective, nonsurgical approach for management of primary HPT.
Calcimimetics increase the sensitivity of the calcium-sensing receptor (CaR) to circulating serum calcium, reducing the secretion of PTH and the serum calcium concentration. We evaluated the calcimimetic cinacalcet, a novel therapy for the management of primary hyperparathyroidism. In this randomized, double-blind, dose-finding study, patients (n = 22) with primary hyperparathyroidism were given cinacalcet (30, 40, or 50 mg) or placebo twice daily for 15 d and observed for an additional 7 d. Serum calcium, plasma PTH, and 24-h and fasting urine calcium were measured. Baseline mean serum calcium was 10.6 mg/dl for the combined cinacalcet-treated patients (normal range, 8.4-10.3 mg/dl), compared with 10.4 mg/dl for the placebo group. Mean PTH at baseline was 102 pg/ml (normal range, 10-65 pg/ml) for the combined cinacalcet-treated patients, compared with 100 pg/ml in the placebo group. Serum calcium normalized after the second dose on d 1 and remained normal through d 15 in all cinacalcet dose groups. Maximum decreases in PTH of over 50% occurred 2-4 h after dosing in all cinacalcet-treated groups. The fasting and 24-h urine calcium to creatinine ratios were similar in the cinacalcet and placebo groups. This study demonstrates that cinacalcet safely normalized serum calcium and lowered PTH concentrations without increasing urinary calcium excretion in the study subjects, indicating the potential benefit of cinacalcet as a medical treatment for primary hyperparathyroidism.
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