Date of publication: December 11, 2017

News & Views

ASN Kidney Week 2017: New Real-World Data on Phosphate Control

In this article, the COMPACT RENAL team provides a summary of key presentations from American Society of Nephrology Kidney Week 2017 relating to CKD-MBD, including real-world evidence on the phosphate binder sucroferric oxyhydroxide.

KDIGO update

An update to the KDIGO CKD-MBD guidelines was published earlier this year, in response to new evidence and topics identified at a Controversies Conference in 2013. At Kidney Week 2017 Dr Mary Leonard, USA presented the guideline changes, also outlining the evidence behind the Work Group’s decisions.[1] A summary of the KDIGO update has been published previously on COMPACT RENAL, and a Speaker’s Guide is also available for download.

New real-world data on sucroferric oxyhydroxide

Despite the availability of phosphate treatments, many dialysis patients experience uncontrolled serum phosphorus levels. At Kidney Week 2017, several posters presented real-world data recorded following a switch to sucroferric oxyhydroxide (SFOH) from an alternative phosphate binder. Results following such a switch included:

  • an increased proportion of patients achieving phosphorus ≤5.5 mg/dL,[2,3]
  • a reduction in serum calcium and intact parathyroid hormone (iPTH) in those achieving serum phosphorus targets,[4]
  • an increase in serum albumin in patients with low albumin levels at baseline,[5] and
  • a significantly reduced pill burden and improved adherence.[2,6]

In addition, Dr Marc Vervloet, The Netherlands, presented interim data analysis from the VERIFIE study, a prospective, European, observational study investigating the effectiveness and safety of SFOH in haemodialysis patients with hyperphosphataemia.[7]

In the VERIFIE study, a switch from previous phosphate binder treatment to SFOH resulted in:

  • Mean change in serum phosphorus at 6 months from baseline of -1.1 mg/dL
  • Increase in the proportion of patients with serum phosphorus ≤5 mg/dL from 26.9% at baseline to 46.5% at 3 months and 38.2% at 6 months
  • Pill burden of 2.6 pills/day at last observation[7]

The authors concluded that SFOH was found to be effective and well-tolerated, with no new safety concerns identified from the real-world setting.[7]

Therapies in development for CKD-MBD

ASN Kidney Week 2017 also featured data on therapies in development for CKD-MBD, as well as study results on extended-release calcifediol, a therapy for secondary hyperparathyroidism (sHPT) recently approved by the FDA.

Tenapanor hydrochloride is a potential new treatment for hyperphosphatemia which works by blocking the sodium-hydrogen type 3 exchanger (NHE3) in the gastrointestinal tract to inhibit the absorption of dietary sodium. It has also been shown to reduce absorption of phosphate, but the exact mechanism of action is being investigated. Dr Geoffrey Block, USA presented two posters on a randomized, double-blind study:

  • Significant reductions in serum phosphate were reported with 3 mg, 10 mg and 30 mg doses of tenapanor compared with placebo.[8]
  • A safety analysis found tenapanor to be well tolerated in haemodialysis patients, with diarrhoea as the main treatment-related adverse event.[9]

Post-hoc analyses of randomized controlled trial data[10] for extended-release calcifediol (ERC) were also presented in poster format. Kopyt et al. found that baseline serum calcium (Ca) levels affected serum 1,25 dihydroxyvitamin D (1,25D) and intact PTH (iPTH) responses to ERC treatment. ERC-induced increases in 1,25D and decreases in iPTH were greatest in subjects with the lowest baseline Ca levels. The smaller increase in serum 1,25D in subjects with higher Ca suggests that active Vitamin D remains under physiological control during treatment with ERC.[11] Reduction in iPTH with ERC was proportional to baseline iPTH levels, with the greatest effect seen in patients with the highest baseline iPTH, suggesting a mechanism of action involving physiological regulation of iPTH modulated by SHPT severity.[12]

 

References

  1. KDIGO Guideline and Conference Updates.LeonardM. ASN Kidney Week 2017.
  2. Two Year Follow Up on Chronic Hemodialysis (HD) Patients Prescribed SucroferricOxyhydroxide as Part of Routine Care. Sprague SM. Et al. ASN Kidney Week 2017, TH-PO1030.
  3. Effectiveness of SucroferricOxyhydroxide (SO) in Lowering Serum Phosphorus (sP) in 4,925 Chronic Hemodialysis (HD) Patients Prescribed SO as Part of Routine Care. Coyne DW. Et al. ASN Kidney Week 2017, TH-PO1031.
  4. Changes in Mineral Bone Disease (MBD) Markers in Hemodialysis (HD) Patients Switched to SucroferricOxyhydroxide (SO). Shori S. et al. ASN Kidney Week 2017, TH-PO1032.
  5. Serum Albumin and Serum Phosphorus among Hemodialysis Patients after Initiating SucroferricOxyhydroxide (SO).   Kalantar-Zadeh K. et al. ASN Kidney Week 2017, TH-PO1033.
  6. Changes in Serum Phosphorus, Pill Burden, and Medication Possession Ratio among Chronic Hemodialysis Patients Who Converted to SucroferricOxyhydroxide as Part of Routine Care. Gray K. et al. ASN Kidney Week 2017, TH-PO785.
  7. Evaluating the Real-World Safety and Effectiveness of Sucroferric Oxyhydroxide in Dialysis Patients: An Interim Analysis of the VERIFIE Study.Vervloet M. et al. ASN Kidney Week 2017, FR-PO886.
  8. Efficacy of Tenapanor to Treat Hyperphosphatemia in Patients on Hemodialysis. Block G. et al. ASN Kidney Week 2017, TH-PO1046.
  9. Gastrointestinal Tolerability of Tenapanor to Treat Hyperphosphatemia in Patients on Hemodialysis. Block G. et al. ASN Kidney Week 2017, TH-PO1045.
  10. Use of ExtendedRelease Calcifediol to Treat Secondary Hyperparathyroidism in Stages 3 and 4 Chronic Kidney Disease. Sprague SM. et al. Am J Nephrol. 2016;44(4):316-325. Epub 2016 Sep 28.
  11. Effect of Baseline Serum Calcium on Responses to Extended-Release Calcifediol (ERC) in Stage 3-4 CKD. Kopyt NP. et al. ASN Kidney Week 2017, TH-PO513.
  12. PTH Suppression with Extended-Release Calcifediol (ERC) Is Directly Proportional to Severity of Secondary Hyperparathyroidism (SHPT). Sprague SM. et al. ASN Kidney Week 2017, TH-PO515.

 

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