Switching Epoetin Alfa and Epoetin Zeta in Patients with Renal Anemia on Dialysis: Posthoc Analysis

Introduction: Epoetin zeta is a recently introduced recombinant erythropoietin, designed to be biologically similar to epoetin alfa. This posthoc analysis evaluated the impact of switching patients with chronic kidney disease (CKD) on hemodialysis from epoetin alfa to epoetin zeta, or vice versa, on hemoglobin concentration, epoetin dose, and patient safety. Methods: Data were analyzed from three published trials: two 24-week randomized, double-blind (maintenance and induction) studies and a 56-week, open-label, follow-on study involving adult patients with CKD stage 5, maintained on hemodialysis, and receiving epoetin alfa or epoetin zeta. Patients had either completed and switched treatments within the maintenance study, or had completed the induction or maintenance study on epoetin alfa and then switched to, and completed at least 12 weeks of follow-up treatment on, epoetin zeta. Mean hemoglobin levels and epoetin dose were evaluated pre- (0-4 weeks before) and post- (8-12 weeks after) switch, and were considered equivalent for the two treatments if the upper and lower limits of the 95% confidence intervals (CIs) for the intraindividual differences in mean values fell within accepted limits. Results: Overall, 481 patients were included in the analysis. Mean hemoglobin concentration was maintained at target levels (10.5-12.5 g/dL) throughout the drug switch. The mean differences in hemoglobin concentration and associated 95% CIs following the switch remained within prespecified equivalence limits (+/- 1.0 g/dL). The 95% CIs of the mean difference in weekly epoetin dose postswitch also remained within prespecified equivalence margins (+/- 45 IU/kg; upper limit 17.83 IU/kg, lower limit -10.91 IU/kg). Both treatments were similarly well tolerated. Conclusion: Our data suggest that epoetin alfa and epoetin zeta therapy can be interchanged without any clinically significant alteration in efficacy, safety, or epoetin dose, in patients with CKD on dialysis receiving stable epoetin maintenance therapy.