Evaluating extended-release calcifediol as a treatment option for chronic kidney disease-mineral and bone disorder (CKD-MBD)

Extended-Release Calcifediol: A Data Journey from Phase 3 Studies to Real-World Evidence Highlights the Importance of Early Treatment of Secondary Hyperparathyroidism

BACKGROUND

Early secondary hyperparathyroidism (SHPT) diagnosis and treatment are crucial to delay the progression of SHPT and related complications, in particular, cardiovascular events and bone fractures. Extended-release calcifediol (ERC) has been developed for the treatment of SHPT in patients with stage 3/4 chronic kidney disease (CKD) and vitamin D insufficiency (VDI).

SUMMARY

This review compares baseline characteristics and treatment responses of SHPT patients receiving ERC in phase 3 studies with those treated with ERC in a real-world study. Mean ± standard deviation baseline parathyroid hormone (PTH) levels were 147 ± 56 pg/mL and 148 ± 64 pg/mL in the phase 3 ERC cohorts, and 181 ± 98 pg/mL in the real-world study. Other baseline laboratory parameters were consistent between the clinical and real-world studies. ERC treatment increased 25-hydroxyvitamin D (25(OH)D) and significantly reduced PTH levels, regardless of baseline CKD stage, in all studies. In the pooled phase 3 per-protocol populations, 74% of the ERC cohort were uptitrated to 60 μg/day after 12 weeks at 30 μg/day, 97% attained 25(OH)D levels ≥30 ng/mL, and 40% achieved ≥30% PTH reduction. Despite a much lower rate of uptitration in the real-world study, 70% of patients achieved 25(OH)D levels ≥30 ng/mL, and 40% had a ≥30% reduction in PTH.

KEY MESSAGES

These data establish a "continuum" of clinical and real-world evidence of ERC effectiveness for treating SHPT, irrespective of CKD stage, baseline PTH levels, and ERC dose. This evidence supports early treatment initiation with ERC, following diagnosis of SHPT, VDI, and stage 3 CKD, to delay SHPT progression.

Vitamin Supplement Use in Patients With CKD: Worth the Pill Burden?

All vitamins play essential roles in various aspects of body function and systems. Patients with chronic kidney disease (CKD), including those receiving dialysis, may be at increased risk of developing vitamin deficiencies due to anorexia, poor dietary intake, protein energy wasting, restricted diet, dialysis loss, or inadequate sun exposure for vitamin D. However, clinical manifestations of most vitamin deficiencies are usually subtle or undetected in this population. Testing for circulating levels is not undertaken for most vitamins except folate, B12, and 25-hydroxyvitamin D because assays may not be available or may be costly to perform and do not always correlate with body stores. The last systematic review through 2016 was performed for the Kidney Disease Outcome Quality Initiative (KDOQI) 2020 Nutrition Guideline update, so this article summarizes the more recent evidence. We review the use of vitamins supplementation in the CKD population. To date there have been no randomized trials to support the benefits of any vitamin supplementation for kidney, cardiovascular, or patient-centered outcomes. The decision to supplement water-soluble vitamins should be individualized, taking account the patient's dietary intake, nutritional status, risk of vitamins deficiency/insufficiency, CKD stage, comorbid status, and dialysis loss. Nutritional vitamin D deficiency should be corrected, but the supplementation dose and formulation need to be personalized, taking into consideration the degree of 25-hydroxyvitamin D deficiency, parathyroid hormone levels, CKD stage, and local formulation. Routine supplementation of vitamins A and E is not supported due to potential toxicity. Although more trial data are required to elucidate the roles of vitamin supplementation, all patients with CKD should undergo periodic assessment of dietary intake and aim to receive various vitamins through natural food sources and a healthy eating pattern that includes vitamin-dense foods.

Calcifediol: a review of its pharmacological characteristics and clinical use in correcting vitamin D deficiency

BACKGROUND

In addition to the role of vitamin D in bone mineralization, calcium and phosphate homeostasis, and skeletal health, evidence suggests an association between vitamin D deficiency and a wide range of chronic conditions. This is of clinical concern given the substantial global prevalence of vitamin D deficiency. Vitamin D deficiency has traditionally been treated with vitamin D₃ (cholecalciferol) or vitamin D₂ (ergocalciferol). Calcifediol (25-hydroxyvitamin D₃) has recently become available more widely.

METHODS

By means of targeted literature searches of PubMed, this narrative review overviews the physiological functions and metabolic pathways of vitamin D, examines the differences between calcifediol and vitamin D₃, and highlights clinical trials conducted with calcifediol in patients with bone disease or other conditions.

RESULTS

For supplemental use in the healthy population, calcifediol can be used at doses of up to 10 µg per day for children ≥ 11 years and adults and up to 5 µg/day in children 3-10 years. For therapeutic use of calcifediol under medical supervision, the dose, frequency and duration of treatment is determined according to serum 25(OH)D concentrations, condition, type of patient and comorbidities. Calcifediol differs pharmacokinetically from vitamin D₃ in several ways. It is independent of hepatic 25-hydroxylation and thus is one step closer in the metabolic pathway to active vitamin D. At comparable doses to vitamin D₃, calcifediol achieves target serum 25(OH)D concentrations more rapidly and in contrast to vitamin D₃, it has a predictable and linear dose-response curve irrespective of baseline serum 25(OH)D concentrations. The intestinal absorption of calcifediol is relatively preserved in patients with fat malabsorption and it is more hydrophilic than vitamin D₃ and thus is less prone to sequestration in adipose tissue.

CONCLUSION

Calcifediol is suitable for use in all patients with vitamin D deficiency and may be preferable to vitamin D₃ for patients with obesity, liver disease, malabsorption and those who require a rapid increase in 25(OH)D concentrations.

Effect of calcifediol supplementation on renin-angiotensin-aldosterone system mediators in dogs with chronic kidney disease

Background

Chronic kidney disease (CKD) leads to low serum concentrations of vitamin D metabolites. Thus, hypovitaminosis D associated with CKD might contribute to disease progression via increased concentration of renin angiotensin aldosterone system (RAAS) mediators.

Objectives

To evaluate whether supplementation with calcifediol affects equilibrium concentrations of selected mediators of the RAAS. We hypothesized that vitamin D supplementation will decrease concentration of circulating RAAS mediators in dogs with CKD.

Animals

Six client‐owned adult dogs with IRIS Stage 2 and 3 CKD.

Methods

Prospective study. Serum 25‐hydroxyvitamin D (25[OH]D), 1,25‐dihydroxyvitamin D (1,25[OH]₂D), 24,25‐dihydroxyvitamin D (24,25[OH]₂D), RAAS mediators (angiotensin I/II/III/IV/1‐5/1‐7, and aldosterone), and surrogate angiotensin converting enzyme (ACE) activity (calculated by the ratio of angiotensin II to angiotensin I) were evaluated at baseline, after 3 months of calcifediol supplementation, and 2 months after discontinuing administration of supplement.

Results

All serum vitamin D metabolite concentrations increased significantly by month 3 (P < .001): 25(OH)D (median 250 ng/mL; range, 204‐310), compared to baseline (median 43.2 ng/mL; range, 33.8‐58.3 ng/mL); 1,25(OH)₂D (median 66.1 pg/mL; range, 57.3‐88.1 pg/mL) compared to baseline (median 35.2 pg/mL; range, 29.3‐56.7 pg/mL); 24,25(OH)₂D (median 68.4 ng/mL; range, 22.1‐142.0 ng/mL) compared to baseline (median 14.4 ng/mL; range, 9.0‐21.3 ng/mL). Calculated ACE activity was significantly lower at month 3 (median 0.5; range, 0.4‐1.0) compared to baseline (median 0.7; range, 0.6‐1.3; P = .01). There were no significant differences in any of the evaluated RAAS variables at any other time‐point.

Conclusions and Clinical Importance

Short‐term calcifediol supplementation in this small group of CKD dogs appeared to decrease ACE activity.

Extended-release calcifediol in stage 3-4 chronic kidney disease: a new therapy for the treatment of secondary hyperparathyroidism associated with hypovitaminosis D

A high percentage of patients with chronic kidney disease have hypovitaminosis D, which is a driver of secondary hyperparathyroidism and an important factor in chronic kidney disease-mineral and bone disorder. Vitamin D deficiency (serum total 25-OH vitamin D levels < 30 ng/mL) occurs early in the course of chronic kidney disease and treatment guidelines recommend early intervention to restore 25-OH vitamin D levels as a first step to prevent/delay the onset/progression of secondary hyperparathyroidism. The vitamin D forms administered to replace 25-OH vitamin D include cholecalciferol, ergocalciferol, and immediate- or extended-release formulations of calcifediol. Most patients with intermediate-stage chronic kidney disease will develop secondary hyperparathyroidism before dialysis is required. Control of parathyroid hormone levels becomes a major focus of therapy in these patients. This article focuses on the position of extended-release calcifediol in the treatment of patients with stage 3–4 chronic kidney disease and secondary hyperparathyroidism with hypovitaminosis D. Several characteristics of extended-release calcifediol support its use in the intermediate stages of chronic kidney disease. The pharmacokinetics of extended-release calcifediol make it effective for replenishing 25-OH vitamin D levels, with minimal impact on vitamin D catabolism from fibroblast-growth factor-23 and CYP24A1 upregulation. Extended-release calcifediol increases circulating 25-OH vitamin D levels in a dose-dependent manner and lowers parathyroid hormone levels by a clinically relevant extent, comparable to what can be achieved by administering active vitamin D analogues, though with a lower risk of hypercalcaemia and hyperphosphataemia. Active vitamin D analogues are reserved for patients undergoing dialysis or pre-dialysis patients with severe progressive secondary hyperparathyroidism.

Where are we now? Emerging opportunities and challenges in the management of secondary hyperparathyroidism in patients with non-dialysis chronic kidney disease

Abstract

Rising levels of parathyroid hormone (PTH) are common in patients with chronic kidney disease (CKD) not on dialysis and are associated with an elevated risk of morbidity (including progression to dialysis) and mortality. However, there are several challenges for the clinical management of secondary hyperparathyroidism (SHPT) in this population. While no recognised target level for PTH currently exists, it is accepted that patients with non-dialysis CKD should receive early and regular monitoring of PTH from CKD stage G3a. However, studies indicate that adherence to monitoring recommendations in non-dialysis CKD may be suboptimal. SHPT is linked to vitamin D [25(OH)D] insufficiency in non-dialysis CKD, and correction of low 25(OH)D levels is a recognised management approach. A second challenge is that target 25(OH)D levels are unclear in this population, with recent evidence suggesting that the level of 25(OH)D above which suppression of PTH progressively diminishes may be considerably higher than that recommended for the general population. Few therapeutic agents are licensed for use in non-dialysis CKD patients with SHPT and optimal management remains controversial. Novel approaches include the development of calcifediol in an extended-release formulation, which has been shown to increase 25(OH)D gradually and provide a physiologically-regulated increase in 1,25(OH)₂D that can reliably lower PTH in CKD stage G3–G4 without clinically meaningful increases in serum calcium and phosphate levels. Additional studies would be beneficial to assess the comparative effects of available treatments, and to more clearly elucidate the overall benefits of lowering PTH in non-dialysis CKD, particularly in terms of hard clinical outcomes.

Graphic abstract

Vitamin D Effects on Bone Homeostasis and Cardiovascular System in Patients with Chronic Kidney Disease and Renal Transplant Recipients

Poor vitamin D status is common in patients with impaired renal function and represents one main component of the complex scenario of chronic kidney disease-mineral and bone disorder (CKD-MBD). Therapeutic and dietary efforts to limit the consequences of uremia-associated vitamin D deficiency are a current hot topic for researchers and clinicians in the nephrology area. Evidence indicates that the low levels of vitamin D in patients with CKD stage above 4 (GFR < 15 mL/min) have a multifactorial origin, mainly related to uremic malnutrition, namely impaired gastrointestinal absorption, dietary restrictions (low-protein and low-phosphate diets), and proteinuria. This condition is further worsened by the compromised response of CKD patients to high-dose cholecalciferol supplementation due to the defective activation of renal hydroxylation of vitamin D. Currently, the literature lacks large and interventional studies on the so-called non-calcemic activities of vitamin D and, above all, the modulation of renal and cardiovascular functions and immune response. Here, we review the current state of the art of the benefits of supplementation with native vitamin D in various clinical settings of nephrological interest: CKD, dialysis, and renal transplant, with a special focus on the effects on bone homeostasis and cardiovascular outcomes.

Effects of calcifediol supplementation on markers of chronic kidney disease-mineral and bone disorder in dogs with chronic kidney disease

Background

Chronic kidney disease‐mineral and bone disorder (CKD‐MBD) in dogs is associated with hypovitaminosis D, increased parathyroid hormone (PTH), and increased fibroblast growth factor‐23 (FGF‐23) concentrations. Best practice for vitamin D metabolite supplementation in CKD‐MBD remains unknown.

Objective

To provide an extended‐release calcifediol supplement to dogs with CKD and to measure its effects on variables indicative of CKD‐MBD.

Animals

Ten dogs with International Renal Interest Society stages 2 and 3 CKD.

Methods

In a prospective study, dogs received a calcifediol supplement for 84 days. Serum 25‐hydroxyvitamin D (25[OH]D), 1,25‐dihydroxyvitamin D (1,25[OH]₂D), 24,25‐dihydroxyvitamin D (24,25[OH]₂D), creatinine, calcium, phosphorus, PTH, plasma FGF‐23 concentrations, and urine profiles were measured monthly during supplementation. Urine calcium to creatinine (UCa/Cr) ratios and fractional excretion of calcium, phosphorus, and sodium were determined.

Results

All serum vitamin D metabolite concentrations increased significantly by day 84 (P < .001): [25(OH)D (median 249.9 ng/mL; range, 149.7‐469.9 ng/mL) compared to baseline (median 50.2 ng/mL; range, 31.3‐66.0 ng/mL); 1,25(OH)₂D (median 66.1 pg/mL; range, 56.9‐88.1 pg/mL) compared to baseline (median 37.3 pg/mL; range, 29.3‐56.7 pg/mL); 24,25(OH)₂D (median 81.4 ng/mL; range, 22.1‐151.7 ng/mL) compared to baseline (median 15.4 ng/mL; range, 6.9‐40.6 ng/mL)]. There were no significant differences in calcium, phosphorus, PTH concentrations, UCa/Cr or fractional excretion of calcium. No dog developed ionized hypercalcemia. Plasma FGF‐23 concentrations increased by day 84 (median 1219 pg/mL; range, 229‐8824 pg/mL) compared to baseline (median 798 pg/mL; range, 103‐4.145 pg/mL) (P < .01).

Conclusions and Clinical Importance

Calcifediol supplementation for 84 days was well‐tolerated in dogs with IRIS stages 2 and 3 CKD. It remains to be determined how long‐term supplementation would affect CKD progression and QOL.

Association between Bone Mineral Density and Severity of Chronic Kidney Disease

OBJECTIVE

We sought to evaluate the association between femoral neck (FN) and lumbar spine (LS) bone mineral densities (BMDs) with severity of chronic kidney disease (CKD) and prevalence of osteopenia or osteoporosis (OP) among the CKD group.

METHODS

Cross-sectional data from 11050 participants aged ≥20 years from the National Health and Nutrition Examination Survey (NHANES) were analyzed. Specifically, Pearson correlation was applied to analyze the relationship between BMD and estimated glomerular filtration rate (eGFR). General linear models (GLMs) were adjusted for potential confounders and used to analyze mean BMD, based on CKD and CKD stages.

RESULTS

FN BMD was positively correlated with the eGFR in the total and male CKD, but not in the female CKD population. LS BMD was not significantly associated with eGFR. After controlling for partial correlations, FN T-score was positively correlated with the eGFR in the total at-risk population. According to FN BMD, OP prevalence was positively associated with CKD stage. However, according to LS BMD, there was no significant association between OP and CKD stage.

CONCLUSION

Our results may explain the higher prevalence of hip fracture, relative to that of the spine, among CKD patients and generate meaningful insights to guide care, prevention, and treatment regimens for CKD patients. However, the fact that this was a cross-sectional study may limit the possibility of drawing concrete conclusions. Nevertheless, these findings open up a new frontier for further studies to uncover the higher decrease of FN BMD compared to LS BMD among CKD cases.