NATIONAL HARBOR, Md.—An investigational treatment safely and effectively lowers elevated plasma intact parathyroid hormone (iPTH) levels in patients with stage 3 or 4 chronic kidney disease and vitamin D deficiency, researchers reported at the National Kidney Foundation 2012 Spring Clinical Meetings.

The treatment, CTAP101 Capsules, is a first-in-class, modified-release oral formulation of calcifediol that is being developed as a treatment for secondary hyperparathyroidism (SHPT).

Stuart Sprague, DO, of NorthShore University Health System in Evanston, Ill., and colleagues tested CTAP101 Capsules in a Phase 2b, randomized, double-blind, placebo-controlled study that included 78 stage 3 or 4 CKD patients with vitamin D insufficiency and SHPT. Subjects were assigned to receive one of three formulations of the active drug (30, 60, or 90 mcg) or a matching placebo for six weeks. Serum total 25-hydroxyvitamin D (25D), plasma iPTH, serum calcium, and serum phosphorus were monitored at least weekly.

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Compared with placebo, the capsules increased serum total 25D and decreased plasma iPTH significantly. Low serum total 25D was corrected to adequate levels (30 ng/mL or higher) in nearly every treated subject. Plasma iPTH was decreased by 30% or more from pre-treatment levels in 39%, 65%, and 63% of subjects treated with doses of 30, 60, and 90 mcg, respectively. CTAP101 had no adverse effects on serum calcium, serum phosphorus, or urinary calcium throughout the six-week treatment period or the six-week follow-up period.

The product is being developed by Cytochroma, whose president and CEO Charles W. Bishop, MD, stated in a press release that CTAP101 Capsules performed well above expectations. “No marketed therapy both effectively controls elevated serum parathyroid hormone levels and corrects the underlying vitamin D insufficiency in CKD patients,” he said. “These strong data indicate that CTAP101 Capsules is a highly differentiated product compared to current treatment options. We look forward to initiating Phase 3 trials later this year.”