Recombinant Human Parathyroid Hormone Effective for Hypoparathyroidism

CHICAGO — In patients with hypoparathyroidism, recombinant human parathyroid hormone was effective and well-tolerated through 52 weeks, according to data presented at ICE/ENDO 2014, the joint meeting of the International Congress of Endocrinology and the Endocrine Society.

The ongoing, open-label RACE study is designed to evaluate long-term safety and efficacy of subcutaneous recombinant human parathyroid hormone (rhPTH[1-84]) treatment at 25 mcg, 50 mcg, 75 mcg and 100 mcg per day.

In the study, rPTH(1-84) titration occurred from 25 mcg to 50 mcg day and up to 50 mcg, 75 mcg and 100 mcg per day if active vitamin D and oral calcium could be reduced while maintaining serum calcium levels at or above baseline.

The composite endpoint was defined as an at least 50% reduction in oral calcium, or 500 mg per day or lower, and an at least 50% reduction in active vitamin D, or 0.25 mcg per day or lower, while maintaining serum calcium of at least 7.5 mg/dL.

Data from the interim 52-week analysis included information from 53 patients with hypoparathyroidism (women, 83%; mean age, 48 years) who had a mean duration of disease of 16 years. Patients were enrolled at 13 centers in the United States.

Forty-nine patients continued through 52 weeks, with none discontinuing as a result of adverse events. Eight percent of patients experienced serious adverse events, but none were related to treatment. 

Ninety-six percent of patients reported at least one adverse event, with the most common including muscle spasm, hypocalcemia, paresthesia, nausea, headache, arthralgia and constipation, according to the results.

The efficacy endpoint was met in 74% (95% CI, 59-85) of patients who completed 52 weeks.

At baseline, mean dose of oral calcium was 2,203 mg per day. This dose fell by 67% by week 52, according to the researchers.

Similarly, mean dose of vitamin D at baseline was 0.7 mcg per day and declined by 73% by week 52.

At 52 weeks, serum phosphate levels were also lower as compared with baseline, with a mean change of –0.73 mg/dL.

“These results confirm and extend our experience with rhPTH(1-84) as an effective treatment for hypoparathyroidism,” the researchers wrote in their abstract.

Reference

1. Mannstadt M et al. Poster SUN-0210. Presented at: ICE/ENDO 2014; June 20-24, 2014; Chicago, IL.