Amgen expects a target U.S. market of at least 300,000 patients for its newly approved chronic kidney disease agent Sensipar , the company said.

Sensipar (cinacalcet), which is Amgen's first small molecule drug, cleared FDA March 8 for the treatment of secondary hyperparathyroidism in chronic kidney disease patients on dialysis. The drug is also indicated for the treatment of hypercalcemia associated with parathyroid carcinoma.

"Nearly all of the 300,000 dialysis patients in the U.S. suffer from secondary [hyperparathyroidism]," Amgen said in a ¹ press release. "It is the only available therapy that allows practitioners to reduce parathyroid hormone (PTH) while lowering calcium-phosphorus product," Amgen said.

Approval was based on three flexible-dose pivotal clinical trials. The primary endpoint of the studies was a reduction in PTH to 250 pg/ML or less. Patients received 30 mg once daily and titrated every three to four weeks up to a maximum dose of 180 mg once daily.

In a 410-patient study, split evenly between placebo and Sensipar patient groups, 41% achieved the primary endpoint, compared to 4% for placebo. In a second, 331-patient study, 46% achieved the primary endpoint, compared to 7% for placebo.

In a third study of 395 patients, 35% of patients receiving Sensipar achieved the primary endpoint compared to 6% for placebo.

Clinical trials also measured a reduction in calcium and phosphorus levels as secondary endpoints.

In clinical trials among chronic kidney disease patients on dialysis, the most commonly reported side effects were nausea and vomiting, FDA said in announcing the approval.

The labeling also contains a warning that Sensipar may increase patients' risk of developing seizures, particularly those with a familial history. Labeling states that calcium levels should be closely monitored, particularly in those with a family history of seizures.

Cinacalcet was evaluated under priority review; Amgen filed the NDA in September.

- Lee Kalowski & Sue Sutter

Amgen Sensipar Approved; Target U.S. Market At Least 300,000 Patients

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