David B. Bregman

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.

Clinical efficacy and safety of IV ferric carboxymaltose (FCM) treatment of RLS: a multi-centred, placebo-controlled preliminary clinical trial.

OBJECTIVE Intravenous (IV) iron has been used as a treatment to reduce Restless Legs Syndrome (RLS) symptoms, but two double-blinded trials of a frequently prescribed IV iron formulation, iron sucrose, failed to show lasting efficacy. This study evaluates efficacy and safety of a new IV iron formulation (ferric carboxymaltose, FCM) with molecular properties that may make iron more available for uptake to the brain than iron sucrose does. METHODS In this 28-day, multi-centre, randomised, placebo-controlled trial 46 RLS patients were discontinued from all RLS treatment. Twenty-four received 500 mg FCM in two doses 5 days apart and 22 received a matching placebo. At day 28, those on placebo were given a single 1000 mg IV FCM and those not responding to initial treatment were given a third dose of 500 mg FCM. Patients were followed up for 24 weeks or until needing added RLS treatment. RESULTS FCM significantly improved primary and secondary outcomes compared to placebo: International Restless Legs Syndrome study group severity scale (IRLS) average (SD) decrease of 8.9 (8.52) versus 4.0 (6.11), p=0.040; Clinical Global Inventory of Change (CGI-1) very much or much improved 48.3% versus 14.3%, p=0.004. Quality of life was also significantly improved. Of the 24 with initial iron treatment 45% responded and 29% remitted (IRLS ≤ 10) at day 28, and 25% continued free of other RLS medications at 24 weeks after treatment. The single 1000 mg dose on day 28 produced the same degree of treatment response as the divided dose, but the added 500 mg dose for those not responding to the initial treatment showed little benefit. There were no significant adverse events. CONCLUSIONS IV FCM provided a safe and effective treatment for RLS that lasted for at least 24 weeks for some patients. Larger studies are needed to confirm these results.

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.

Ultraviolet radiation alters the phosphorylation of RNA polymerase II large subunit and accelerates its proteasome-dependent degradation

It has been shown that ultraviolet (UV) radiation induces the ubiquitination of the large subunit of RNA polymerase II (RNAP II-LS) as well as its proteasomal degradation. Studies in mammalian cells have indicated that highly phosphorylated forms of RNAP II-LS are preferentially ubiquitinated, but studies in Saccharomyces cerevisiae have provided evidence that unphosphorylated RNAP II-LS is an equally suitable substrate. In the present study, an antibody (ARNA-3) that recognizes all forms of RNAP II-LS, regardless of the phosphorylation status of its C-terminal domain (CTD), was utilized to evaluate the degradation of total cellular RNAP II-LS in human fibroblasts under basal conditions or after UV-C (10J/m(2)) irradiation. It was found that UV radiation rapidly shifted the phosphorylation profile of RNAP II-LS from a mixture of dephosphorylated and phosphorylated forms to entirely more phosphorylated forms. This shift in phosphorylation status was not blocked by pharmacologic inhibition of either the ERK or p38 pathways, both of which have been implicated in the cellular UV response. In addition to shifting the phosphorylation profile, UV radiation led to net degradation of total RNAP II-LS. UV-induced degradation of RNAP II-LS was also greatly reduced in the presence of the transcriptional and CTD kinase inhibitor DRB. Using a panel of protease inhibitors, it was shown that the bulk of UV-induced degradation is proteasome-dependent. However, the UV-induced loss of hypophosphorylated RNAP II-LS was proteasome-independent. Lastly, UV radiation induced a similar shift to all hyperphosphorylated RNAP II-LS in Cockayne syndrome (CS) cells of complementation groups A or B (CSA or CSB) when compared to appropriate controls. The UV-induced degradation rates of RNAP II-LS were not significantly altered when comparing CSA or CSB to repair competent control cells. The implications for the cellular UV response are discussed.

Yeast Carboxyl-terminal Domain Kinase I Positively and Negatively Regulates RNA Polymerase II Carboxyl-terminal Domain Phosphorylation

Monoclonal antibodies that recognize specific carboxyl-terminal domain (CTD) phosphoepitopes were used to examine CTD phosphorylation in yeast cells lacking carboxyl-terminal domain kinase I (CTDK-I). We show that deletion of the kinase subunitCTK1 results in an increase in phosphorylation of serine in position 5 (Ser5) of the CTD repeat (Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7) during logarithmic growth. This result indicates that CTDK-I negatively regulates CTD Ser5 phosphorylation. We also show thatCTK1 deletion (ctk1Δ) eliminates the transient increase in CTD serine 2 (Ser2) phosphorylation observed during the diauxic shift. This result suggests that CTDK-I may play a direct role in phosphorylating CTD Ser2 in response to nutrient depletion. Northern blot analysis was used to show that genes normally induced during the diauxic shift are not properly induced in a ctk1Δ strain. Glycogen synthase (GSY2) and cytosolic catalase (CTT1) mRNA levels increase about 10-fold in wild-type cells, but this increase is not observed in ctk1Δ cells suggesting that increased message levels may require Ser2 phosphorylation. Heat shock also induces Ser2 phosphorylation, but we show here that this change in CTD modification and an accompanying induction of heat shock gene expression is independent of CTDK-I. The observation that SSA3/SSA4 expression is increased in ctk1Δ cells grown at normal temperature suggests a possible role for CTDK-I in transcription repression. We discuss several possible positive and negative roles for CTDK-I in regulating CTD phosphorylation and gene expression.

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.

Oxaliplatin: A Review of Evolving Concepts

Department of Oncology, Weiler Hospital/Montefiore Medical Center and the Albert Einstein Cancer Center of the Albert Einstein College of Medicine, Room 2S-63, 1825 Eastchester Road, Bronx, NY 10461 Department of Clinical Pharmacokinetics and Drug Metabolism, Sanofi-Synthelabo, 9 Great Valley Parkway, Malvern, Pennsylvania Department of Pathology, Albert Einstein College of Medicine, Bronx, New York Cancer Therapy Evaluation Program of the National Cancer Institute, Bethesda, Maryland Department of Biochemistry and Biophysics, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina

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.