Evaluation of Therapies for Secondary Hyperparathyroidism Associated with Vitamin D Insufficiency in Chronic Kidney Disease.

Introduction: Parathyroid hormone-lowering responses after administration of three different therapies capable of raising serum total 25-hydroxyvitamin D (25OHD) were evaluated in patients with secondary hyperparathyroidism (SHPT), vitamin D insufficiency (VDI), and stage 3 or 4 chronic kidney disease (CKD). Methods: Sixty-nine adult subjects with intact parathyroid hormone (iPTH) ≥85 and <500 pg/mL and VDI (25OHD <30 ng/mL) were randomized after ≥4-week washout to 2 months of open-label treatment with: (1) extended-release calcifediol (ERC) 60 µg/day; (2) immediate-release calcifediol (IRC) 266 µg/month; (3) high-dose cholecalciferol (HDC) 300,000 IU/month; or (4) paricalcitol plus low-dose cholecalciferol (PLDC) 1 or 2 µg and 800 IU/day, used as reference hormone replacement therapy. Serum 25OHD, calcium (Ca), phosphorus (P), plasma iPTH, and adverse events were monitored weekly. No clinically significant differences were observed at baseline between treatment groups. Results: Sixty-two subjects completed the study per protocol (PP; 14-17 per group). Mean (SD) 25OHD and iPTH at baseline were 20.6 (6.6) ng/mL and 144.8 (90) pg/mL, respectively. Mean 25OHD increased at end of treatment (EOT) to 82.9 (17.0) ng/mL with ERC (p < 0.001) and 30.8 (11.6) ng/mL with HDC (p < 0.05), but remained unchanged with IRC and PLDC. EOT 25OHD levels reached ≥30 ng/mL in all subjects treated with ERC and in 44% with HDC. All subjects attained EOT 25OHD levels ≥50 ng/mL with ERC versus none with other therapies. iPTH response rates at EOT (≥10, 20 or 30% below baseline) were similar for ERC and PLDC; rates for IRC and HDC were much lower. No significant changes from baseline were observed in ionized or corrected total Ca or P in any group. One episode of hypercalcemia (>10.3 mg/dL) occurred with PLDC. Hyperphosphatemia (>5.5 mg/dL) occurred once with ERC, eight times with HDC, 3 times with IRC, and twice with PLDC. Conclusion: ERC was highly effective in both raising serum 25OHD and decreasing iPTH in patients with SHPT, VDI, and stage 3 or 4 CKD. iPTH-lowering response rates with ERC were similar to daily PLDC, the reference therapy; rates with IRC or HDC were significantly lower. ERC is an attractive alternative to vitamin D hormone therapy in CKD patients.

Extended-Release Calcifediol Effectively Raises Serum Total 25-Hydroxyvitamin D Even in Overweight Nondialysis Chronic Kidney Disease Patients with Secondary Hyperparathyroidism.

INTRODUCTION: Obesity increases the risk of vitamin D insufficiency, which exacerbates secondary hyperparathyroidism in chronic kidney disease. Recent studies suggest that serum total 25-hydroxyvitamin D (25OHD) levels of ≥50 ng/mL are necessary to produce significant reductions in elevated parathyroid hormone levels in nondialysis patients. Data from real-world and randomized controlled trials (RCTs) involving these patients were examined for (1) relationships between vitamin D treatments and the achieved levels of serum 25OHD and between serum 25OHD and body weight (BW)/body mass index (BMI); and (2) the impact of BW/BMI on achieving serum 25OHD levels ≥50 ng/mL with extended-release calcifediol (ERC) treatment or vitamin D supplementation (cholecalciferol or ergocalciferol). METHODS: Data obtained from nondialysis patients participating in two real-world studies, one conducted in Europe (Study 1) and the other (Study 2) in the USA, and in two US RCTs (Studies 3 and 4) were analyzed for serum 25OHD outcomes after treatment with ERC, vitamin D supplements, or placebo. RESULTS: More than 50% of subjects treated with vitamin D supplements in both real-world studies (Studies 1 and 2) failed to achieve serum 25OHD levels ≥30 ng/mL, a level widely viewed by nephrologists as the threshold of adequacy; only 7.3-7.5% of subjects achieved levels ≥50 ng/mL. Data from the European study (Study 1) showed that serum 25OHD levels had significant and nearly identical inverse relationships with BW and BMI, indicating that high BW or BMI thwarts the ability of vitamin D supplements to raise serum 25OHD. One RCT (Study 3) showed that 8 weeks of ERC treatment (60 µg/day) raised serum 25OHD levels to ≥30 and 50 ng/mL in all subjects, regardless of BW, while cholecalciferol (300,000 IU/month) raised serum 25OHD to these thresholds in 56% and 0% of subjects, respectively. The other RCT (Study 4) showed that ERC treatment (30 or 60 µg/day) successfully raised mean serum 25OHD levels to at least 50 ng/mL for subjects in all BW categories, whereas no increases were observed with placebo treatment. CONCLUSION: Real-world studies conducted in Europe and USA in nondialysis patients (Studies 1 and 2) showed that vitamin D supplements (cholecalciferol or ergocalciferol) were unreliable in raising serum total 25OHD to targets of 30 or 50 ng/mL. In contrast, ERC was demonstrated to be effective in one real-world study (Study 2) and two RCTs (Studies 3 and 4) conducted in US nondialysis patients in raising serum 25OHD to these targeted levels irrespective of BW.

Use of Extended-Release Calcifediol to Treat Secondary Hyperparathyroidism in Stages 3 and 4 Chronic Kidney Disease.

BACKGROUND/AIMS: Vitamin D insufficiency and secondary hyperparathyroidism (SHPT) are associated with increased morbidity and mortality in chronic kidney disease (CKD) and are poorly addressed by current treatments. The present clinical studies evaluated extended-release (ER) calcifediol, a novel vitamin D prohormone repletion therapy designed to gradually correct low serum total 25-hydroxyvitamin D, improve SHPT control and minimize the induction of CYP24A1 and FGF23. METHODS: Two identical multicenter, randomized, double-blind, placebo-controlled studies enrolled subjects from 89 US sites. A total of 429 subjects, balanced between studies, with stage 3 or 4 CKD, SHPT and vitamin D insufficiency were randomized 2:1 to receive oral ER calcifediol (30 or 60 µg) or placebo once daily at bedtime for 26 weeks. Most subjects (354 or 83%) completed dosing, and 298 (69%) entered a subsequent open-label extension study wherein ER calcifediol was administered without interruption for another 26 weeks. RESULTS: ER calcifediol normalized serum total 25-hydroxyvitamin D concentrations (>30 ng/ml) in >95% of per-protocol subjects and reduced plasma intact parathyroid hormone (iPTH) by at least 10% in 72%. The proportion of subjects receiving ER calcifediol who achieved iPTH reductions of ≥30% increased progressively with treatment duration, reaching 22, 40 and 50% at 12, 26 and 52 weeks, respectively. iPTH lowering with ER calcifediol was independent of CKD stage and significantly greater than with placebo. ER calcifediol had inconsequential impact on serum calcium, phosphorus, FGF23 and adverse events. CONCLUSION: Oral ER calcifediol is safe and effective in treating SHPT and vitamin D insufficiency in CKD.