OPKO Health, Inc., a multi-national biopharmaceutical and diagnostics company, has completed patient recruitment in the first phase III trial of Rayaldy to treat patients with secondary hyperparathyroidism (SHPT), stage 3 or 4 chronic kidney disease (CKD) and vitamin D insufficiency. This trial is the first of two identical randomized, double-blind, placebo-controlled, multi-site studies intended to establish the safety and efficacy of Rayaldy as a new treatment for SHPT in the targeted population.

The endpoints of both studies, which are being conducted in parallel, include vitamin D status and changes in serum calcium, serum phosphorus and plasma intact parathyroid hormone (PTH).

Each of the two pivotal phase III trials involves approximately 210 patients recruited at approximately 40 sites in the United States. Patients are being stratified by CKD stage and randomized in a 2:1 fashion to receive six months of treatment with either Rayaldy or placebo. Top-line data from both trials are expected in mid-2014.

The two pivotal trials are being followed by an open-label extension study in which patients are treated, at their election, for an additional six months with Rayaldy. To date, 129 patients have enrolled in this open-label study.

Rayaldy is a first-in-class oral vitamin D prohormone treatment being developed for SHPT in stage 3 and 4 CKD patients with vitamin D insufficiency. It has a proprietary modified-release formulation designed to gradually and reliably raise serum total 25-hydroxyvitamin D (prohormone) concentrations to targeted levels (at least 30 ng/mL) while avoiding upregulation of CYP24, a cytochrome P-450 enzyme that reduces the PTH lowering potency of current vitamin D supplements. Activation of calcifediol, the active ingredient in Rayaldy, by the kidney is tightly regulated, preventing excessive elevation of serum calcium and related side effects which encumber current vitamin D hormone therapies and promote vascular and renal calcification. Once approved, Rayaldy is expected to address CKD stage 3 and 4 patients in the US and elsewhere, with SHPT and vitamin D insufficiency.