Etelcalcetide, a novel calcimimetic agent, is safe and efficacious long-term for the treatment of secondary hyperparathyroidism (SHPT) in patients on hemodialysis, according to study findings presented at the European Renal Association-European Dialysis and Transplant Association 53rd Congress in Vienna.
In a phase 3 open-label single-arm extension study, David A. Bushinsky, MD, of the University of Rochester in New York, and colleagues identified no new safety concerns and found that the significant reductions in parathyroid hormone (PTH), serum corrected calcium, and phosphorus associated with etelcalcetide observed in 3 26-week phase 3 trials were sustained over a 52-week treatment period.
The extension study enrolled 891 subjects, of whom 77% completed the 52-week treatment period. Treatment-emergent adverse events (AEs) and serious AEs developed in 90% and 40% of patients, respectively. Investigator-reported mild, moderate, severe, and life-threatening AEs were noted for 13%, 39%, 32%, and 7% of patients, respectively. In addition, 5% of patients had AEs that led to discontinuation of etelcalcetide. The most common AEs were asymptomatic decreases in blood calcium (43% of patients), diarrhea (11%), and vomiting (10%). The most frequently reported serious AEs were hyperkalemia (3%) and congestive heart failure (2%). The most frequently reported treatment-related AEs were decreased asymptomatic blood calcium (37%), symptomatic hypocalcemia (4%), muscle spasms (3%), nausea (2%), paraesthesia (2%), and decreased blood PTH.
Anti-etelcalcetide antibodies developed in 27 patients during the study; in 11 cases, this antibody response was transient.
Dr. Bushinsky’s group also compared the efficacy of etecalcetide during 2 efficacy assessment phases (EAPs): the last 6 weeks prior to stopping the drug in patients treated for a minimum of 8 weeks (EAP) and from weeks 46 to 53, inclusive (EAP12).
The proportion of patients who had a greater than 30% reduction in mean PTH levels was 68% at both EAPs. The proportion of patients with a PTH level of 300 pg/mL or less was 57% and 56%, respectively, at EAP and EAP12. Mean PTH levels had decreased by 26% at EAP and 30% at EAP12. The changes in mean serum corrected calcium (8% decrease) and phosphorus (4% decrease) were the same at both EAPs.