Factors affecting response and tolerability to ferumoxytol in nondialysis chronic kidney disease patients

BACKGROUND: Ferumoxytol is a unique intravenous (i.v.) iron therapy. This report examines factors affecting hemoglobin response to i.v. ferumoxytol, and the relationship between hematologic parameters, concomitant erythropoiesis-stimulating agents (ESA), and adverse events (AEs) in nondialysis CKD patients. METHODS: A series of post-hoc efficacy and safety analyses were performed using pooled data from two identically designed Phase III studies in 608 nondialysis CKD patients randomized to receive two 510 mg i.v. injections of ferumoxytol within 5 ± 3 days versus oral iron. RESULTS: Ferumoxytol resulted in a significant increase in hemoglobin in the presence and absence of ESA, and across a range of baseline hemoglobin, transferrin saturation, ferritin, and reticulocyte hemoglobin content levels. Adverse event rates with ferumoxytol were similar across quartiles of change in hemoglobin; there were no trends suggesting an increased rate of cardiovascular AEs with higher maximum achieved hemoglobin or faster rate of hemoglobin rise. There was no meaningful difference in the rate of AEs, serious AEs, and cardiovascular AEs between patients receiving or not receiving ESA. CONCLUSIONS: These analyses add to the knowledge of predictors of response and safety outcomes associated with i.v. iron therapy in nondialysis CKD patients.