FDA Approves Hyperparathyroidism Drug

The FDA this week approved Parsabiv (etelcalcetide) for the treatment of secondary hyperparathyroidism (HPT) in patients with chronic kidney disease (CKD) who are undergoing hemodialysis.

Parsabiv is the first treatment to receive regulatory approval in the past 12 years, according to a press release from Amgen. The drug is also the only calcimimetic indicated to be administered intravenously 3 times per week at the end of a hemodialysis session.

"We are excited about today's approval of Parsabiv in the US and the opportunity to provide patients and health care providers with a novel option to help treat a complex disease that affects a significant number of patients on hemodialysis," said Sean E. Harper, MD, executive vice president of Research and Development at Amgen. "Parsabiv not only has demonstrated strong efficacy in clinical trials; it also fills an unmet need by putting the delivery of the therapy in the hands of the health care professional."

Secondary HPT refers to the increased secretion of the parathyroid hormone by the parathyroid glands as a response to diminished renal function and impaired mineral metabolism, according to Amgen. This condition is serious, and the number of patients who are unable to meet the recommended HPT lab goals doubled within the last 5 years.

Sensipar (cinacalet) was the first approved calcimimetic, and has been shown to reduce biochemical abnormalities in patients with HPT.

Parsabiv works by binding to and activating the calcium receptor on the gland, which decreases the release of the parathyroid hormone. This drug can be administered intravenously at the conclusion of a hemodialysis session, and can also reduce levels of the biochemical abnormalities for up to 78 weeks in these patients, according to Amgen.

The new approval was based on data from two phase 3 clinical trials, which met their primary endpoints. Included in the trials were 1023 patients with moderate-to-severe HPT who were on hemodialysis. Patients were randomized to receive placebo or Parsabiv 3 times per week, in addition to hemodialysis and other standard of care medications, such as vitamin D or phosphate binders, according to Amgen.

The primary endpoint of the clinical trials was the amount of patients achieving at least a 30% reduction in parathyroid hormone, compared with baseline. Secondary endpoints included the amount of patients with parathyroid hormone less than or equal to 300 pg/mL, and reductions in parathyroid hormone, albumin-adjusted calcium, and phosphate.

Approximately 77% and 79% of patients treated with Parsabiv achieved a reduction of parathyroid hormone greater than 30% in the first and second study, respectively.

Patients treated with Parsabiv were more likely to experience asymptomatic reductions in serum calcium and symptomatic hypocalcemia, according to Amgen. Other common adverse events included muscle spasms, diarrhea, nausea, vomiting, headache, and paresthesia/hypoesthesia.

The cost of Parsabiv will likely be similar to Sensipar, based on expected doses, according to the press release.

"As a physician who cares for patients with advanced chronic kidney disease, I understand the importance of achieving and maintaining simultaneous reductions in a number of complex lab values in the treatment of secondary HPT," said Geoffrey A. Block, MD, nephrologist at Denver Nephrologists, PC, in Colorado. "The ability to provide my patients with an intravenous calcimimetic and help ensure they receive the therapy they need is a tremendous milestone in the management of this frequently undertreated chronic progressive disease."