Effect of Cefiderocol, a Siderophore Cephalosporin, on QT/QTc Interval in Healthy Adult Subjects.

PURPOSE: Cefiderocol is a novel siderophore cephalosporin with potent activity against gram-negative bacteria, including multidrug-resistant strains. This Phase I study was conducted to assess the tolerability of single-ascending doses of cefiderocol (part 1) and the effect of cefiderocol on cardiac repolarization, assessed using the electrocardiographic corrected QT interval (QTcF) and other ECG parameters (part 2), in healthy adult subjects. METHODS: Part 1 was a randomized, double-blind, placebo-controlled, single-ascending dose study in healthy adult male and female subjects. Part 2 was a 4-period crossover study in which subjects received a single 2-g dose of cefiderocol (therapeutic dose), a single 4-g dose of cefiderocol (supratherapeutic dose), or saline (placebo), each infused over 3 hours, and a single oral 400-mg dose of moxifloxacin. In each treatment period, continuous cardiac monitoring was used to assess the effects of cefiderocol on ECG parameters. The QT interval corrected using the Fridericia formula (QTcF) was the primary ECG parameter; the time-matched placebo- and baseline-adjusted (dd)-QTcF interval was the primary end point. The plasma pharmacokinetic properties of cefiderocol were calculated on the basis of concentration-time profiles in all evaluable subjects. FINDINGS: All point estimates for the ddQTcF interval were <5 ms and the upper bound of the 90% CIs were <10 ms at each timepoint after the initiation of the cefiderocol 3-hour infusion. Concentration-effect modeling showed a slightly negative slope and predicted modestly negative values of the ddQTcF interval at the Cmax of cefiderocol. Both doses of cefiderocol were well tolerated. All adverse events were mild in severity, with no deaths or serious adverse events reported. IMPLICATIONS: Overall, therapeutic and supratherapeutic doses of cefiderocol had no apparent clinically significant effect on the QTcF.

Pharmacokinetics, Safety, and Tolerability of Cefiderocol, a Novel Siderophore Cephalosporin for Gram-Negative Bacteria, in Healthy Subjects.

Cefiderocol is a novel parenteral siderophore cephalosporin that shows potent efficacy against various Gram-negative bacteria, including carbapenem-resistant strains, in vitro and in preclinical models of infection. The aim of the present study was to evaluate the pharmacokinetics (PK), safety, and tolerability of cefiderocol after both single and multiple dosing by intravenous infusion over 60 min in healthy adult subjects. A single-ascending-dose study at doses of 100, 250, 500, 1,000, and 2,000 mg was conducted in 40 healthy Japanese males and females (6 individuals receiving the active drug and 2 individuals receiving a placebo per cohort). A multiple-ascending-dose study at doses of 1,000 (two groups) and 2,000 mg every 8 h (q8h) was conducted in 30 healthy Japanese and Caucasian males (8 individuals receiving the active drug and 2 individuals receiving a placebo per cohort). There were no serious or clinically significant adverse events (AEs) observed in either study. A single subject receiving 1,000 mg cefiderocol q8h was withdrawn due to AEs. Dose-proportional increases in the maximum plasma concentration (Cmax), the area under the concentration-time curve (AUC) from time zero to the time of the last quantifiable concentration after dosing, and the area under the concentration-time curve extrapolated from time zero to infinity were observed across the dose range of 100 to 2,000 mg. The mean plasma half-life of cefiderocol was 1.98 to 2.74 h. Cefiderocol was primarily excreted unchanged in the urine (61.5% to 68.4% of the dose). There was little accumulation of Cmax and AUC by dosing q8h, and the PK of cefiderocol did not change with multiple dosing. This study indicates that single and multiple intravenous doses of cefiderocol at up to 2,000 mg are well tolerated in healthy subjects and exhibit linear PK at doses up to 2,000 mg.

Population Pharmacokinetic Analysis of Cefiderocol, a Parenteral Siderophore Cephalosporin, in Healthy Subjects, Subjects with Various Degrees of Renal Function, and Patients with Complicated Urinary Tract Infection or Acute Uncomplicated Pyelonephritis.

Cefiderocol, a novel parenteral siderophore cephalosporin, exhibits potent efficacy against most Gram-negative bacteria, including carbapenem-resistant strains. The aim of this study was to perform a population pharmacokinetic (PK) analysis based on plasma cefiderocol concentrations in healthy subjects, subjects with various degrees of renal function, and patients with complicated urinary tract infection (cUTI) or acute uncomplicated pyelonephritis (AUP) caused by Gram-negative pathogens and to calculate the fraction of the time during the dosing interval where the free drug concentration in plasma exceeds the MIC (fTMIC). Population PK models were developed with three renal function markers, body surface area-adjusted estimated glomerular filtration rate (eGFR), absolute eGFR, and creatinine clearance, on the basis of 2,571 plasma concentrations from 91 subjects without infection and 238 patients with infection. The population PK models with each renal function marker adequately described the plasma cefiderocol concentrations. Clear relationships of total clearance (CL) to all renal function markers were observed. Body weight and disease status (with or without infection) were also significant covariates. The CL in patients with infection was 26% higher than that in subjects without infection. The fTMIC values were more than 75% in all patients (and were 100% in most patients), suggesting that a sufficient exposure to cefiderocol was provided by the tested dose regimens (2 g every 8 h as the standard dose regimen) for the treatment of cUTI or AUP caused by Gram-negative pathogens.

Detection of a Serum Siderophore by LC-MS/MS as a Potential Biomarker of Invasive Aspergillosis.

Invasive aspergillosis (IA) is a life-threatening systemic mycosis caused primarily by Aspergillus fumigatus. Early diagnosis of IA is based, in part, on an immunoassay for circulating fungal cell wall carbohydrate, galactomannan (GM). However, a wide range of sensitivity and specificity rates have been reported for the GM test across various patient populations. To obtain iron in vivo, A. fumigatus secretes the siderophore, N,N',N"-triacetylfusarinine C (TAFC) and we hypothesize that TAFC may represent a possible biomarker for early detection of IA. We developed an ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for TAFC analysis from serum, and measured TAFC in serum samples collected from patients at risk for IA. The method showed lower and upper limits of quantitation (LOQ) of 5 ng/ml and 750 ng/ml, respectively, and complete TAFC recovery from spiked serum. As proof of concept, we evaluated 76 serum samples from 58 patients with suspected IA that were investigated for the presence of GM. Fourteen serum samples obtained from 11 patients diagnosed with probable or proven IA were also analyzed for the presence of TAFC. Control sera (n = 16) were analyzed to establish a TAFC cut-off value (≥6 ng/ml). Of the 36 GM-positive samples (≥0.5 GM index) from suspected IA patients, TAFC was considered positive in 25 (69%). TAFC was also found in 28 additional GM-negative samples. TAFC was detected in 4 of the 14 samples (28%) from patients with proven/probable aspergillosis. Log-transformed TAFC and GM values from patients with proven/probable IA, healthy individuals and SLE patients showed a significant correlation with a Pearson r value of 0.77. In summary, we have developed a method for the detection of TAFC in serum that revealed this fungal product in the sera of patients at risk for invasive aspergillosis. A prospective study is warranted to determine whether this method provides improved early detection of IA.

Model-Based Optimisation of Deferoxamine Chelation Therapy.

PURPOSE: Here we show how a model-based approach may be used to provide further insight into the role of clinical and demographic covariates on the progression of iron overload. The therapeutic effect of deferoxamine is used to illustrate the application of disease modelling as a means to characterising treatment response in individual patients. METHODS: Serum ferritin, demographic characteristics and individual treatment data from clinical routine practice on 27 patients affected by ß-thalassaemia major were used for the purposes of this analysis. The time course of serum ferritin was described by a hierarchical nonlinear mixed effects model, in which compliance was parameterised as a covariate factor. Modelling and simulation procedures were implemented in NONMEM (7.2.0). RESULTS: A turnover model best described serum ferritin changes over time, with the effect of blood transfusions introduced on the ferritin conversion rate and the effect of deferoxamine on the elimination parameter (Kout) in a proportional manner. The results of the simulations showed that poor quality of execution is preferable over drug holidays; and that independently of the compliance pattern, the therapeutic intervention is not effective if >60% of the doses are missed. CONCLUSIONS: Modelling of ferritin response enables characterisation of the dynamics of iron overload due to chronic transfusion. The approach can be used to support decision making in clinical practice, including personalisation of the dose for existing and novel chelating agents.

Metal ions and infectious diseases. An overview from the clinic.

Trace elements (TEs) are required by both humans and bacterial pathogens. Although metal ion homeostasis is tightly controlled in humans, growing evidence suggests that pathogens utilize a variety of means designed to circumvent the sequestration of TEs. Colonizing pathogenic microorganisms employ a variety of strategies to sense, acquire, store, and export metal ions in the vertebrate host which include the biosynthesis and utilization of siderophores, and the expression of high-affinity metal-ion transporters. For iron, selenium, and zinc, significant correlations have been shown between TE levels in plasma, serum, or tissues, and the prevention or treatment of a variety of infectious diseases; fewer such data exist for copper, chromium, or manganese. TEs are often employed as antioxidants, and as supplements in patients with TE-deficient states. The role of TE supplementation in humans as antioxidants remains controversial, but has demonstrated significant benefit in the role of selenium for patients with sepsis, and of zinc for the prevention of several infectious diseases.

Cellular uptake of a catechol iron chelator and chloroquine into Plasmodium falciparum infected erythrocytes.

Our study demonstrates the capacity of FR160, a catechol iron chelator, to reach and accumulate into infected Plasmodium falciparum erythrocytes and parasites (cellular accumulation ratio between 12 and 43). Steady-state FR160 accumulation is obtained after 2 hr of exposure. After 2 hr exposure, it reaches intracellular levels that are 4- to 10-fold higher in infected red blood cells than those attained in normal erythrocytes. There is quite a good correlation between the accumulation of chloroquine and FR160 in the different strains (r=0.939) and in the IC(50) values (r=0.719). In contrast, the accumulation of FR160 and its activity is poorly correlated (r=0.500), suggesting that activity of FR160 may be independent of its penetration into infected erythrocytes. The mechanism of accumulation is yet unknown but based on inhibitor studies, the uptake of FR160 seems to be not associated with the calcium pump or channel, the potassium channel or the Na(+)/H(+) exchanger. Combinations of FR160 with verapamil, diltiazem, clotrimazole, amiloride, diazoxide, 4-aminopyridine, and picrotoxin should be avoided (antagonistic effects). The potent in vitro activity of FR160 on chloroquine-resistant strains or isolates, its lower toxicity against Vero cells, its mechanisms of action, its capacity to reach rapidly and accumulate into infected erythrocytes suggest that FR160 holds much promise as a new structural lead and effective antimalarial agent or at least a promising adjuvant in treatment of malaria.

In vivo antimalarial action of a lipophilic iron (III) chelator: suppression of Plasmodium vinckei infection by reversed siderophore.

We assessed in vivo antimalarial action of a lipophilic iron (III) chelator belonging to a new synthetic family of biomimetic siderophores previously termed reversed siderophores (RSFs). The family member, RSF ileum2, was chosen for its high membrane permeability and fast irreversible inhibition of human malaria parasite growth in vitro. [Shanzer A, et al., Proc Natl Acad Sci USA 88:6585, 1991 and Lytton SD, et al., Blood 81:214, 1993]. The lipophilic drug was administered to Swiss mice by subcutaneous route in fractionated coconut oil at a dosage of 0.37 g/kg every 8 hr with no adverse reactions observed. After 3-4 injections demonstrable suppression of Plasmodium vinckei petteri infection was observed and an additional 3-4 injections resulted in 2-3-fold lower parasitemia with prolonged survival time over sham-injected control mice.