Cinacalcet Effective for Hypercalcemia in Parathyroid Cancer

NEW YORK SEPT 24, 2007 (Reuters Health) - Cinacalcet effectively lowers serum calcium concentrations in patients with inoperable parathyroid carcinoma, according to a report in the October issue of The Journal of Clinical Endocrinology & Metabolism.

In earlier studies of patients with benign primary hyperparathyroidism, cinacalcet normalized serum calcium and reduced parathyroid hormone (PTH) concentrations for up to 3 years, the authors explain.

Dr. Shonni J. Silverberg from Columbia University College of Physicians & Surgeons, New York and associates investigated the effects of cinacalcet in 29 patients with inoperable metastatic parathyroid carcinoma.

Eighteen of 29 patients experienced a serum calcium decline of at least 1 mg/dL, the authors report. Overall, mean calcium concentrations declined from 14.1 mg/dL at baseline to 12.4 mg/dL after cinacalcet treatment.

Ten patients had sustained declines in serum calcium concentrations lasting a mean of 80 weeks (range, 33-151 weeks).

Patients with the highest baseline calcium levels experienced the greatest reductions, the researchers note, but the absolute level to which the serum calcium declined at the end of the titration phase was similar.

Cinacalcet also reduced the PTH level by an average of 4.6%, the investigators say, but bone turnover markers increased.

Adverse events were common, with two thirds of the patients experiencing nausea and just over half experiencing vomiting. Fracture and hypercalcemia, both affecting 21% of patients, were the most frequent serious adverse events.

There were no significant changes in health-related quality of life.

"These data suggest that treatment can be initiated in the short-term when hypercalcemia persists and after surgical approaches to the disease are no longer indicated or feasible," Dr. Silverberg and associates maintain.

"Because of its novel mechanism of action and the relatively well-tolerated administration demonstrated in this study and in clinical trials in patients with renal disease and primary hyperparathyroidism, cinacalcet offers important benefits in the treatment of hypercalcemia in patients with parathyroid cancer," they conclude.

SOURCE:

• J Clin Endocrinol Metab 2007.