Rationale & objective: Hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) may offer an alternative erythropoiesis-stimulating agents (ESA) for the treatment of anemia in the setting of CKD. To investigate the efficacy and safety of conversion from long-acting erythropoiesis-stimulating agent (ESA) methoxy polyethylene glycol-epoetin beta (MPG-EPO) to the oral hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHI) vadadustat 3-times-weekly versus maintenance on MPG-EPO.
Study design: Phase 3b, open-label, noninferiority trial.
Setting & participants: Multicenter study in United States; 456 patients adults with anemia and dialysis-dependent chronic kidney disease.
Intervention: Participants were randomized 1:1:1 either to vadadustat (starting dose: 600 mg thrice weekly), vadadustat (starting dose: 900 mg thrice weekly), or MPG-EPO, for up to 52 treatment weeks and 4 safety follow-up weeks after the end of treatment or early termination.
Outcomes: Primary and secondary efficacy endpoints were the mean change in hemoglobin from baseline during primary (weeks 20-26) and secondary (weeks 46-52) evaluation periods, respectively. Noninferiority was specified as a lower bound of the 95% CI above -0.75 g/dL for the difference in mean change in hemoglobin from baseline. Other efficacy endpoints were the proportion of participants with hemoglobin levels within the target range and the proportions of participants requiring ESA or red blood cell transfusion rescue for anemia during the evaluation periods. Transfusion rates were low and occurred at similar rates across treatment groups (2.7% and 4.0% in the combined vadadustat and MPG-EPO groups, respectively). Primary safety endpoints were any treatment-emergent and serious adverse events (AEs).
Results: After combining the vadadustat groups (600 mg and 900 mg thrice weekly, n=304), vadadustat was noninferior to MPG-EPO (n=152) for both primary (least squares mean treatment difference, -0.33; 95% CI, -0.53 to -0.13) and secondary efficacy endpoints (-0.33; -0.56 to -0.09). Mean hemoglobin concentrations were stable for all groups, except for an initial slight decline in the vadadustat 600 mg group, which stabilized by week 12. ESA rescue for anemia was more frequent in the MPG-EPO group (primary evaluation period, 27.7%; secondary evaluation period, 16.2%) than in the combined vadadustat (14.2%; 7.3%) groups. The incidences of any treatment-emergent and serious treatment-emergent AEs were similar across treatment groups.
Limitations: Potential errors in attribution of AEs as drug related.
Conclusions: Three-times-weekly vadadustat was noninferior to MPG-EPO on their effect on hemoglobin levels without detectable differences in AEs.
Keywords: HIF-PHI; MPG-EPO; chronic kidney disease; erythropoiesis-stimulating agent; vadadustat.
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