Orlando—Researchers led by Sunfa Cheng, MD, recently conducted an analysis of data from a 52-week open label extension trial and an open label extension trial of up to 2.5 years of etelcalcetide, an intravenous calcimimetic that reduced secondary hyperparathyroidism in hemodialysis patients. The efficacy of etelcalcetide in reducing parathyroid hormone was demonstrated in three phase 3 trials.
The researchers reported results of the analysis during a poster session at the NKF 2017 Spring Clinical Meetings. The poster was titled Analysis of a Single-Arm Extension Study Evaluating Etelcalcetide Starting Dose for Treatment of Secondary Hyperparathyroidism in Patients on Hemodialysis.
In the open label extension 2.5-year trial, patients enrolling from the etelcalcetide versus cinacalcet phase 3 trial had a washout period of 4 weeks, followed by treatment with etelcalcetide at 5.0 mg (original protocol) or 2.5 mg (protocol amendment). Etelcalcetide dose was titrated to achieve parathyroid hormone ≥2 times to ≤9 times the upper limit of normal (ULN). The current analysis aimed to evaluate the relationship between the etelcalcetide starting dose on adverse events, the ability to maintain parathyroid hormone targets, and phosphate level ≤ULN at months 6, 12, and 18.
At the start of the open label extension 2.5-year trial, mean parathyroid hormone was 709.5 pg/mL for participants with starting etelcalcetide dose of 2.5 mg and 651.2 pg/mL for those with starting dose of 5.0 mg. Decrease in asymptomatic calcium (with serum corrected calcium less than lower limit of normal) in the 2.5-mg dose group was 27%; in the 5.0-mg dose group, the decrease was 40%. In the 2.5-mg group, 1% had symptomatic hypocalcemia; no one in the 5.0-mg group had symptomatic hypocalcemia (also with serum corrected calcium less than lower limit of normal).
At month 6, parathyroid hormone ≥2 times and ≤9 times the ULN occurred in 134 of 216 patients (62%) in the 2.5-mg starting dose group and in 87/137 (64%) of patients in the 5.0-mg starting dose group. Results at month 12 were 118 of 184 (64%) in the 2.5-mg starting dose group and 87 of 124 (70%) in the 5.0-mg starting dose group; at 18 months, results were 28 of 39 (72%) in the 2.5-mg starting group and 52 of 77 (68%) in the 5.0-mg starting dose group.
At month 6, 82 of 204 participants (40%) in the 2.5-mg starting dose group had phosphate level ≤ULN, as did 44 of 132 (33%) in the 5.0-mg starting dose group. Results at month 12 were 65 of 167 (39%) in the 2.5-mg starting dose group and 37 of 111 (33%) in the 5.0-mg starting dose group. At month 18, results were 14 of 37 (38%) in the 2.5-mg starting dose group and 23 of 72 (32%) in the 5.0-mg starting dose group.
In summary, the researchers said, “Etelcalcetide prescribed at a starting dose of either 5 mg or 2.5 mg demonstrated similar safety and efficacy over 18 months.”
Source: Cheng S, Block G, Dehmel B, Deng H, Chertow G. Analysis of a single-arm extension study evaluating etelcalcetide starting dose for treatment of secondary hyperparathyroidism in patients on hemodialysis. Abstract of a poster presented at the National Kidney Foundation 2017 Spring Clinical Meetings, April 19-22, 2017, Orlando, Florida. This study was supported by Amgen Inc.