Characteristics of Patients Who Achieve Serum Phosphorus Control on Sucroferric Oxyhydroxide or Sevelamer Carbonate: A post hoc Analysis of a Phase 3 Study.

INTRODUCTION: Control of hyperphosphatemia in patients on dialysis remains a major challenge. OBJECTIVE: This study evaluated predictors of serum phosphorus (sP) control among dialysis patients treated with noncalcium, oral phosphate binder therapy in a phase 3 clinical trial. METHODS: Post hoc analyses were performed using data for patients with hyperphosphatemia who received 52 weeks of treatment with sucroferric oxyhydroxide (SFOH) or sevelamer carbonate (sevelamer). Patients were categorized into those who achieved sP control (n = 302; defined as sP ≤ 5.5 mg/dL at week 52), and those with uncontrolled sP (n = 195; sP >5.5 mg/dL at week 52). Because SFOH and sevelamer have previously demonstrated similar effects on chronic kidney disease-mineral-bone disorder parameters in this study, the treatment groups were pooled. RESULTS: Average age at baseline was higher among sP-controlled versus sP-uncontrolled patients (56.9 vs. 53.4 years; p = 0.005). Baseline sP levels were significantly lower among sP-controlled versus sP-uncontrolled patients (7.30 vs. 7.85 mg/dL; p < 0.001), and sP reductions from baseline were significantly greater in the sP-controlled group (-2.89 vs. -0.99 mg/dL at week 52; p < 0.001). Logistic regression analysis identified higher baseline sP levels (odds ratio [OR] = 0.86, 95% confidence interval [CI]: 0.765-0.960), no concomitant active vitamin D therapy use (OR = 0.51, 95% CI: 0.328-0.804), and higher body mass index at baseline (OR = 0.96, 95% CI: 0.937-0.992) as significant predictors of uncontrolled sP. CONCLUSION: This analysis indicates that sP control may be more challenging in younger patients with high sP levels. Closer monitoring and management of serum phosphorus levels may be required in this population.

PA21, a novel phosphate binder, improves renal osteodystrophy in rats with chronic renal failure.

The effects of PA21, a novel iron-based and non-calcium-based phosphate binder, on hyperphosphatemia and its accompanying bone abnormality in chronic kidney disease-mineral and bone disorder (CKD-MBD) were evaluated. Rats with adenine-induced chronic renal failure (CRF) were prepared by feeding them an adenine-containing diet for four weeks. They were also freely fed a diet that contained PA21 (0.5, 1.5, and 5%), sevelamer hydrochloride (0.6 and 2%) or lanthanum carbonate hydrate (0.6 and 2%) for four weeks. Blood biochemical parameters were measured and bone histomorphometry was performed for femurs, which were isolated after drug treatment. Serum phosphorus and parathyroid hormone (PTH) levels were higher in the CRF rats. Administration of phosphate binders for four weeks decreased serum phosphorus and PTH levels in a dose-dependent manner and there were significant decreases in the AUC0-28 day of these parameters in 5% PA21, 2% sevelamer hydrochloride, and 2% lanthanum carbonate hydrate groups compared with that in the CRF control group. Moreover, osteoid volume improved significantly in 5% of the PA21 group, and fibrosis volume and cortical porosity were ameliorated in 5% PA21, 2% sevelamer hydrochloride, and 2% lanthanum carbonate hydrate groups. These results suggest that PA21 is effective against hyperphosphatemia, secondary hyperparathyroidism, and bone abnormalities in CKD-MBD as sevelamer hydrochloride and lanthanum carbonate hydrate are, and that PA21 is a new potential alternative to phosphate binders.

Efficacy and safety of sucroferric oxyhydroxide compared with sevelamer hydrochloride in Japanese haemodialysis patients with hyperphosphataemia: A randomized, open-label, multicentre, 12-week phase III study.

AIM: We aimed to investigate the non-inferiority of PA21 (sucroferric oxyhydroxide) to sevelamer hydrochloride (sevelamer) in terms of efficacy and safety in Japanese haemodialysis patients with hyperphosphataemia. METHODS: In this Phase III, open-label, multicentre study, 213 haemodialysis patients with hyperphosphataemia were randomized to PA21 or sevelamer treatment for 12 weeks. The primary outcome was adjusted serum phosphorus concentration at the end of treatment; the non-inferiority of PA21 was confirmed if the upper limit of the two-sided 95% confidence interval (CI) is ≤0.32 mmol/L. Secondary outcomes were corrected serum calcium and intact-parathyroid hormone concentrations. Adverse events (AEs) and adverse drug reactions (ADRs) were evaluated. RESULTS: The adjusted mean serum phosphorus concentration at the end of treatment confirmed the non-inferiority of PA21 for lowering serum phosphorus compared with sevelamer (1.62 vs 1.72 mmol/L; difference, -0.11 mmol/L; 95% CI, -0.20 to -0.02 mmol/L). The mean daily tablet intake was 5.6 ± 2.6 and 18.7 ± 7.1 tablets in the PA21 and sevelamer groups, respectively. The incidences of AEs and ADRs were not significantly different between the two groups. CONCLUSION: The non-inferiority of PA21 to sevelamer was confirmed for the treatment of Japanese haemodialysis patients with hyperphosphataemia. PA21 was effective, safe, and well tolerated, while having a considerably lower pill burden than sevelamer.

Efficacy and safety of nicotinamide in haemodialysis patients: the NICOREN study.

BACKGROUND: Nicotinamide (NAM) has been proposed as an alternative treatment to phosphate binders for hyperphosphataemia in chronic kidney disease. METHODS: The NICOREN multicentre, open-label and randomized study was designed to examine non-inferiority and safety of NAM when compared with sevelamer (SEV) in chronic haemodialysis patients. One hundred patients were randomized to either NAM or SEV treatment for 24 weeks. Serum biochemistry and NAM's main metabolite, N -methyl-2-pyridone-5-carboxamide (2PY), were measured to assess compliance, efficacy and safety. RESULTS: After 24 weeks, we observed a comparable decrease in serum phosphorus in the NAM and SEV treatment arms, from 2.1 ± 0.4 to 1.8 ± 0.5 and 2.3 ± 0.5 to 1.7 ± 0.5 mM (P = not significant), respectively. The criterion for non-inferiority was, however, not met due to a more limited number of patients being included than planned. Treatment discontinuation due to adverse events was 1.6 times higher in the NAM than in the SEV group with only 55% of study completers in the NAM arm versus 90% in the SEV arm. Thrombocytopenia was observed in four NAM-treated patients. Serum 2PY levels were comparable at baseline, but increased markedly in the NAM group, but not in the SEV group, at 24 weeks (P < 0.0001). CONCLUSIONS: Thus, both drugs are equally effective in lowering serum phosphorus, but patients' tolerance of NAM was largely inferior to that of SEV. Extremely high 2PY levels may contribute to NAM's side effects.

Preclinical and Healthy Volunteer Studies of Potential Drug-Drug Interactions Between Tenapanor and Phosphate Binders.

Tenapanor (RDX5791, AZD1722), a first-in-class small molecule with minimal systemic availability, is an inhibitor of the sodium/hydrogen exchanger isoform 3. Tenapanor acts locally in the gut, where it reduces absorption of sodium and phosphate. It is being studied in patients with chronic kidney disease requiring dialysis, who are often administered phosphate binders such as sevelamer to help control hyperphosphatemia. We investigated whether coadministration of tenapanor with phosphate binders (sevelamer or calcium-based binders) impacts the pharmacodynamic effects of tenapanor. In vitro studies suggested a binding interaction between tenapanor and sevelamer, but this did not translate into altered pharmacodynamic effects in rats. An open-label, 2-way crossover study was then conducted in healthy volunteers (NCT02346890). This showed that 4 days' treatment with tenapanor hydrochloride (15 mg twice daily) with or without sevelamer carbonate (800 mg 3 times daily) resulted in comparable 24-hour stool and urinary sodium and phosphorus levels. Stool frequency, consistency, and weight were also comparable between the treatments. These results suggest that the binding between sevelamer and tenapanor observed in vitro does not translate into altered pharmacodynamic effects in humans.