Todd A. Koch

Effects of iron deficiency anemia and its treatment on fibroblast growth factor 23 and phosphate homeostasis in women

Fibroblast growth factor 23 (FGF23) is an osteocyte‐derived hormone that regulates phosphate and vitamin D homeostasis. Through unknown mechanisms, certain intravenous iron preparations induce acute, reversible increases in circulating FGF23 levels that lower serum phosphate in association with inappropriately low levels of calcitriol, similar to genetic diseases of primary FGF23 excess. In contrast, studies in wild‐type mice suggest that iron deficiency stimulates fgf23 transcription but does not result in hypophosphatemia because FGF23 is cleaved within osteocytes by an unknown catabolic system. We tested the association of iron deficiency anemia with C‐terminal FGF23 (cFGF23) and intact FGF23 (iFGF23) levels in 55 women with a history of heavy uterine bleeding, and assessed the longitudinal biochemical response over 35 days to equivalent doses of randomly‐assigned, intravenous elemental iron in the form of ferric carboxymaltose (FCM) or iron dextran. Iron deficiency was associated with markedly elevated cFGF23 (807.8 ± 123.9 relative units [RU]/mL) but normal iFGF23 (28.5 ± 1.1 pg/mL) levels at baseline. Within 24 hours of iron administration, cFGF23 levels fell by approximately 80% in both groups. In contrast, iFGF23 transiently increased in the FCM group alone, and was followed by a transient, asymptomatic reduction in serum phosphate <2.0 mg/dL in 10 women in the FCM group compared to none in the iron dextran group. Reduced serum phosphate was accompanied by increased urinary fractional excretion of phosphate, decreased calcitriol levels, and increased parathyroid hormone levels. These findings suggest that iron deficiency increases cFGF23 levels, and that certain iron preparations temporarily increase iFGF23 levels. We propose that intravenous iron lowers cFGF23 in humans by reducing fgf23 transcription as it does in mice, whereas carbohydrate moieties in certain iron preparations may simultaneously inhibit FGF23 degradation in osteocytes leading to transient increases in iFGF23 and reduced serum phosphate.

Hepcidin levels predict nonresponsiveness to oral iron therapy in patients with iron deficiency anemia

Levels of hepcidin, a major regulator of iron homeostasis, may identify patients with iron deficiency anemia (IDA) who will not respond to oral iron therapy. In this study, IDA patients underwent a 14‐day trial (run‐in) course of ferrous sulfate therapy. Nonresponders (Hgb increase <1 g/dL with 67% compliance rate) were randomized to IV ferric carboxymaltose (FCM; two injections of 750 mg) or further oral iron for 14 days. Screening hepcidin levels were 38.4 versus 11.3 ng/mL, P = 0.0002 in nonresponders versus responders to a trial of oral iron. Hepcidin of > 20 ng/mL, showed sensitivity of 41.3%, specificity of 84.4%, and positive predictive value of 81.6% for predicting nonresponsiveness to oral iron. PPVs for ferritin> 30 ng/mL or transferrin saturation (TSAT)>15% were 59.2 and 55%, respectively. Negative predictive values for hepcidin, ferritin, and TSAT were 46.3, 22.7, and 19.7, respectively. FCM versus oral iron showed Hgb increases of ≥1 gm/dL in 65.3% versus 20.8% (P < 0.0001) and Hgb increases of 1.7 ± 1.3 versus 0.6 ± 0.9 g/dL (P = 0.0025), respectively. We conclude that hepcidin predicts nonresponsiveness to oral iron in patients with IDA and is superior to TSAT or ferritin for this purpose. Nonresponse to oral iron therapy does not rule out IDA, since two‐thirds of patients subsequently responded to intravenous iron. Am. J. Hematol. 88:97–101, 2013.

A multicenter, randomized, active‐controlled study to investigate the efficacy and safety of intravenous ferric carboxymaltose in patients with iron deficiency anemia

Many patients receiving oral iron for iron deficiency anemia (IDA) cannot tolerate or fail to respond to therapy, and existing intravenous (IV) iron formulations often require repeated administrations. Ferric carboxymaltose (FCM), a nondextran IV formulation, permits larger single doses.

Ferric carboxymaltose in patients with iron-deficiency anemia and impaired renal function: the REPAIR-IDA trial

BACKGROUND Iron-deficiency anemia in non-dialysis-dependent chronic kidney disease (NDD-CKD) frequently requires parenteral iron replacement, but existing therapies often require multiple administrations. We evaluated the efficacy and cardiovascular safety of ferric carboxymaltose (FCM), a non-dextran parenteral iron permitting large single-dose infusions, versus iron sucrose in patients with iron-deficiency anemia and NDD-CKD. METHODS A total of 2584 participants were randomized to two doses of FCM 750 mg in one week, or iron sucrose 200 mg administered in up to five infusions in 14 days. The primary efficacy endpoint was the mean change to highest hemoglobin from baseline to Day 56. The primary composite safety endpoint included all-cause mortality, nonfatal myocardial infarction, nonfatal stroke, unstable angina, congestive heart failure, arrhythmias and hyper- and hypotensive events. RESULTS The mean hemoglobin increase was 1.13 g/dL in the FCM group and 0.92 g/dL in the iron sucrose group (95% CI, 0.13-0.28). Similar results were observed across all subgroups, except Stage 2 CKD. More subjects in the FCM group achieved a hemoglobin increase of ≥ 1.0 g/dL between baseline and Day 56 (48.6 versus 41.0%; 95% CI, 3.6-11.6%). There was no significant difference between FCM and iron sucrose recipients with respect to the primary composite safety endpoint, including the major adverse cardiac events of death, myocardial infarction, or stroke. A significant difference in the number of protocol-defined, predominantly transient hypertensive episodes was observed in the FCM group. CONCLUSIONS Two 750-mg infusions of FCM are a safe and effective alternative to multiple lower dose iron sucrose infusions in NDD-CKD patients with iron-deficiency anemia.

Intravenous ferric carboxymaltose versus standard medical care in the treatment of iron deficiency anemia in patients with chronic kidney disease: a randomized, active-controlled, multi-center study

BACKGROUND Currently available intravenous (IV) iron agents vary in indication, dosing regimens and safety profiles. Ferric carboxymaltose (FCM) is a stable, non-dextran-containing iron formulation developed for rapid IV administration in high doses with controlled delivery of iron into target tissues. The objective of the present study was to evaluate the safety of FCM compared with standard medical care (SMC) in dialysis (HD) and non-dialysis-dependent (NDD) chronic kidney disease (CKD) patients. METHODS Adults 18-85 years of age with CKD were enrolled. NDD-CKD (n = 204) patients received an undiluted IV dose of FCM (15 mg/kg to a maximum of 1000 mg IV) and HD-CKD (n = 50) patients received an undiluted IV push of 200 mg ~30-60 min into the dialysis session. Subjects randomized to the SMC group (n = 259) received treatment determined by the investigator that could include oral iron, IV iron or no iron. RESULTS Single doses of FCM of 200 mg in HD-CKD patients and up to 1000 mg in NDD-CKD patients were well tolerated. Incidences of treatment-emergent adverse events were similar between the groups: 30.3% (77 of 254) in the FCM group and 32.8% (85 of 259) in the SMC group. Incidences of serious adverse events were higher in the SMC group overall and in patients receiving iron sucrose or sodium ferric gluconate. There were no clinically significant differences in laboratory or clinical chemistry values or vital signs between the groups. There were no statistically significant differences between the FCM and SMC groups in indices of hemoglobin (Hb) improvement, including proportions of patients achieving a ≥ 1 g/dL increase in Hb and proportions of patients achieving Hb level of >12 g/dL. CONCLUSION FCM in doses of 200 mg for HD-CKD patients and up to 1000 mg in NDD-CKD patients were well tolerated and displayed comparable efficacy to other IV iron formulations.

Direct Comparison of the Safety and Efficacy of Ferric Carboxymaltose versus Iron Dextran in Patients with Iron Deficiency Anemia

Several intravenous iron complexes are available for the treatment of iron deficiency anemia (IDA). Iron dextran (DEX) is associated with an elevated risk of potentially serious anaphylactic reactions, whereas others must be administered in several small infusions to avoid labile iron reactions. Ferric carboxymaltose (FCM) is a nondextran intravenous iron which can be administered in high single doses. A randomized, open label, and multicenter comparison of FCM to DEX in adults with IDA and baseline hemoglobin of ≤11.0 g/dL was conducted. A total of 160 patients were in the safety population (FCM n = 82; DEX n = 78). Adverse events, including immune system disorders (0% in FCM versus 10.3% in DEX, P = 0.003) and skin disorders (7.3% in FCM versus 24.4% in DEX, P = 0.004), were less frequently observed in the FCM group. A greater portion of patients in the FCM group experienced a transient, asymptomatic decrease in phosphate compared to patients in the DEX group (8.5% in FCM versus 0% in DEX, P = 0.014). In the FCM arm, the change in hemoglobin from baseline to the highest observed level was 2.8 g/dL, whereas the DEX arm displayed a change of 2.4 g/dL (P = 0.20). Treatment of IDA with FCM resulted in fewer hypersensitivity-related reactions than DEX.

Safety and Efficacy of Intravenous Ferric Carboxymaltose (750 mg) in the Treatment of Iron Deficiency Anemia: Two Randomized, Controlled Trials

Background. Iron deficiency anemia (IDA) is a common hematological complication with potentially serious clinical consequences that may require intravenous iron therapy. Ferric carboxymaltose (FCM) is a stable, nondextran iron formulation administered intravenously in large single doses to treat IDA. Objective. Two open-label, randomized, placebo-controlled trials evaluated safety of multiple or single 750 mg FCM doses compared to standard medical care (SMC) in IDA patients. Secondary endpoints were improvements in hemoglobin and iron indices. Design and Patients. Adults with hemoglobin ≤12 g/dL, ferritin ≤100 or ≤300 ng/mL with transferrin saturation ≤30% were randomized to receive single (n = 366) or weekly (n = 343) FCM or SMC (n = 360 and n = 366). Results. Significantly greater (P ≤ 0.001) increases in hemoglobin and iron indices occurred in FCM groups versus SMC. In the multidose study, up to two infusions of FCM were needed to reach target iron levels versus 3–5 of intravenous iron comparators. FCM and SMC groups had similar incidences and types of adverse events and serious adverse events. Transient hypophosphatemia not associated with adverse events or clinical sequelae occurred in the FCM groups. Conclusion. Intravenous FCM is safe, well tolerated, and associated with improvements in hemoglobin and iron indices comparable to SMC when administered in single doses of up to 750 mg at a rate of 100 mg/min. Fewer FCM infusions were required to reach target iron levels compared to other intravenous iron preparations.

Intravenous Iron Therapy in Patients with Iron Deficiency Anemia: Dosing Considerations

Objective. To provide clinicians with evidence-based guidance for iron therapy dosing in patients with iron deficiency anemia (IDA), we conducted a study examining the benefits of a higher cumulative dose of intravenous (IV) iron than what is typically administered. Methods. We first individually analyzed 5 clinical studies, averaging the total iron deficit across all patients utilizing a modified Ganzoni formula; we then similarly analyzed 2 larger clinical studies. For the second of the larger studies (Study 7), we also compared the efficacy and retreatment requirements of a cumulative dose of 1500 mg ferric carboxymaltose (FCM) to 1000 mg iron sucrose (IS). Results. The average iron deficit was calculated to be 1531 mg for patients in Studies 1–5 and 1392 mg for patients in Studies 6-7. The percentage of patients who were retreated with IV iron between Days 56 and 90 was significantly (p < 0.001) lower (5.6%) in the 1500 mg group, compared to the 1000 mg group (11.1%). Conclusions. Our data suggests that a total cumulative dose of 1000 mg of IV iron may be insufficient for iron repletion in a majority of patients with IDA and a dose of 1500 mg is closer to the actual iron deficit in these patients.

Randomized Evaluation of efficacy and safety of ferric carboxymaltose in Patients with iron deficiency Anaemia and Impaired Renal function (REPAIR-IDA): rationale and study design

BACKGROUND Patients with iron deficiency anaemia (IDA) in the setting of non-dialysis-dependent chronic kidney disease (NDD-CKD) may benefit from treatment with intravenous (IV) iron. Ferric carboxymaltose (FCM) is a novel IV iron formulation designed to permit larger infusions compared to currently available IV standards such as Venofer(R) (iron sucrose). METHODS The primary objective of REPAIR-IDA is to estimate the cardiovascular safety and efficacy of FCM (two doses at 15 mg/kg to a maximum of 750 mg per dose) compared to Venofer(R) (1000 mg administered as five infusions of 200 mg) in subjects who have IDA and NDD-CKD. REPAIR-IDA is a multi-centre, randomized, active-controlled, open-label study. Eligible patients must have haemoglobin (Hgb) < or = 11.5 g/dL and CKD defined as (1) GFR < 60 mL/min/1.73 m(2) on two occasions or (2) GFR < 90 mL/min/1.73 m(2) and either evidence of renal injury by urinalysis or elevated Framingham cardiovascular risk score. Two thousand and five hundred patients will be randomized to FCM or Venofer(R) in a 1:1 ratio. The primary efficacy endpoint is mean change in Hgb from baseline to the highest observed Hgb between baseline and Day 56. The primary safety endpoint is the proportion of subjects experiencing at least one of the following events: death due to any cause, non-fatal myocardial infarction, non-fatal stroke, unstable angina requiring hospitalization, congestive heart failure requiring hospitalization or medical intervention, arrhythmias, hypertension or hypotension during the 120 days following randomization. CONCLUSION REPAIR-IDA will assess the efficacy and safety of two 750-mg infusions of FCM compared to an FDA-approved IV iron regimen in patients with NDD-CKD at increased risk for cardiovascular disease.