2017 USFDA New Drug Approval: Amgen’s Parsabiv™ (Etelcalcetide)

U.S. Food and Drug Administration (FDA) has approved Amgen’s Parsabiv™ (etelcalcetide) for the treatment of secondary hyperparathyroidism (HPT) in adult patients with chronic kidney disease (CKD) on hemodialysis. Parsabiv is the first therapy approved for this condition in 12 years and the only calcimimetic that can be administered intravenously by the dialysis health care team three times a week at the end of the hemodialysis session.

Parsabiv is a novel calcimimetic agent indicated for the treatment of secondary hyperparathyroidism (HPT) in adult patients with chronic kidney disease (CKD) on hemodialysis.

Parsabiv has not been studied in adult patients with parathyroid carcinoma, primary hyperparathyroidism, or with CKD who are not on hemodialysis and is not recommended for use in these populations.

A calcimimetic is a drug that mimics the action of calcium by activating the calcium-sensing receptors on the parathyroid gland. Parsabiv binds to and activates the calcium-sensing receptor on the parathyroid gland, thereby decreasing PTH levels.

Phase 3 Studies
The approval of Parsabiv in the U.S. was largely based on data from two placebo-controlled Phase 3 studies, both of which met their primary endpoints.

In the two 26-week, randomized, double-blind, placebo-controlled studies, an aggregate of 1,023 patients with moderate-to-severe secondary HPT (PTH greater than 400 pg/mL) on hemodialysis were randomized to receive intravenous Parsabiv or placebo three times a week, at the end of their dialysis sessions in addition to standard of care that could include vitamin D and/or phosphate binders. The primary endpoint of both studies was the proportion of patients achieving greater than 30 percent reduction from baseline in PTH during the Efficacy Assessment Phase (EAP), defined as weeks 20 through 27. Secondary endpoints included the proportion of patients with PTH less than or equal to 300 pg/mL during the EAP; and percent reductions in PTH, albumin-adjusted calcium (cCa), phosphate (P) and cCa x P during the EAP.

The two studies showed that significantly more Parsabiv than placebo patients, respectively, achieved:

A greater than 30 percent reduction from baseline in PTH during the EAP: 77 percent versus 11 percent in Study 1, and 79 percent versus 11 percent in Study 2
PTH levels of 300 pg/mL or less during the EAP: 52 percent versus 6 percent in Study 1, and 56 percent versus 5 percent in Study 2
Additionally, greater percent reduction from baseline was achieved in Parsabiv-treated patients than placebo-treated patients during the EAP, for PTH, corrected calcium and phosphate in both studies.

In a pooled analysis of the two Phase 3 placebo-controlled studies, asymptomatic reductions in serum calcium and symptomatic hypocalcemia occurred more frequently in patients treated with Parsabiv compared to placebo (64 percent versus 10 percent, and 7 percent versus 0.2 percent, respectively). Other commonly reported adverse reactions were muscle spasms (12 percent versus 7 percent), diarrhea (11 percent versus 9 percent), nausea (11 percent versus 6 percent), vomiting (9 percent versus 5 percent), headache (8 percent versus 6 percent), and paresthesia/hypoesthesia (6 percent versus 1 percent).