Population pharmacokinetics (PPK) of eribulin mesylate in patients with locally advanced or metastatic breast cancer (MBC)

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Background: Eribulin mesylate (E7389) is a non-taxane microtubule dynamics inhibitor with a novel mechanism of action. A study was conducted to evaluate efficacy, safety and pharmacokinetics of eribulin at a dose of 1.4 mg/m2 for locally advanced or MBC in patients previously treated with an anthracycline, a taxane, and capecitabine. Methods: Eribulin was administered intravenously over 2–5 minutes at a dose of 1.4 mg/m2 on days 1 and 8 of a 21- day cycle to 291 patients. Four plasma samples were collected between 5 min and 120 hours after the first dose. Plasma eribulin concentrations were determined by LC/MS/MS. A total of 774 samples, from 209 patients with complete dose and sampling information were included in the PPK analysis, which was conducted using nonlinear mixed effects modeling (NONMEM). Results: Eribulin PKs were best described by a three-compartment model, with elimination from the central compartment. Distribution was rapid and elimination slow. For a typical patient with AST<ULN and CLCR=101mL/min (Cockroft-Gault), clearance (CL) was 2.98 L/h and central volume of distribution 3.72 L (V1). Volumes and inter-compartmental clearances for the two peripheral compartments were 3.60 L (V2), 126 L (V3), 2.7 L/h (Q2) and 5.6 L/h (Q3). Inter-patient variability on CL was 57%, and ranged from 26- 98% for other parameters. Residual error was 21% (proportional). CL was on average 38% lower in patients with AST>ULN and positively correlated with renal function. The covariate effects only explained a minor fraction of inter-patient variability in this single study dataset. Conclusions: Eribulin PKs were described by a three-compartment model with rapid distribution and slow elimination. Appreciable interpatient PK variability exists, a minor fraction of which was explained by measures of liver and renal function.

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Recombinant bovine interleukin-2 and dry cow therapy: efficacy to cure and prevent intramammary infections, safety, and effect on gestation

Cows from eight commercial dairies were randomly assigned to intrammamary infusions of cephapirin or cephapirin plus interleukin-2 at the end of lactation. During the first phase of the trial, interleukin-2 was administered to 159 cows at a dose of 1 mg per gland by intracisternal infusion immediately after 300 mg of cephapirin were administered. One hundred sixty-one cows received infusions of a placebo (phosphate-buffered saline; PBS) immediately after cephapirin. In the second phase of the trial, 70 cows received 2 mg of interleukin-2 per gland, and 78 cows received the placebo. Cows were observed daily by the participating farmer for 72 h after infusion and also during routine feeding and care during the dry period and at calving. Potential side effects from udder infusions, particularly gross abnormalities of the udder and signs of systemic side effects were monitored. During the first phase, cure rates for intramammary infections caused by Staphylococcus aureus that were present at the end of lactation were 33.3% for quarters treated with cephapirin and 53.6% for quarters treated with cephapirin and interleukin-2. Cure rates did not differ between treatment groups for all other pathogens or during the second phase of the trial. The incidence of new intramammary infections during the dry period was not affected by intramammary infusion of interleukin-2. Eighteen of 229 (7.9%) cows treated with interleukin-2 aborted within 49 d of treatment compared with 4 of 239 (1.7%) cows treated with PBS. Eleven of the 18 (61.1%) abortions by cows treated with interleukin-2 occurred 3 to 7 d after infusion; none of the abortions by cows treated with PBS occurred until wk 7 after infusion.

Absence of IL-1 signaling and reduced inflammatory response in IL-1 type I receptor-deficient mice

IL-1alpha and IL-1beta are potent inflammatory cytokines that contribute to a number of normal physiologic processes and to the development of a number of inflammatory diseases. Two IL-1R, the type I and type II receptors, have been identified. This work describes the derivation and characterization of mice deficient in expression of the type I IL-1R (IL-1RI). IL-1RI-deficient mice were viable and fertile, but failed to respond to IL-1 in a variety of assays, including IL-1-induced IL-6 and E-selectin expression and IL-1-induced fever. Similar to IL-1beta-deficient mice, IL-1RI-deficient mice had a reduced acute phase response to turpentine. In contrast, IL-1RI-deficient mice had a reduced delayed-type hypersensitivity response and were highly susceptible to infection by Listeria monocytogenes. These data demonstrate that the IL-1RI is essential for all IL-1-mediated signaling events examined, and that both IL-1alpha and IL-1beta are critical to the animals' response to injury and infection. These data also demonstrate that IL-1 function is not required for normal development or homeostasis.

Absence of IL-1 signaling and reduced inflammatory response in IL-1 type I receptor-deficient mice

IL-1alpha and IL-1beta are potent inflammatory cytokines that contribute to a number of normal physiologic processes and to the development of a number of inflammatory diseases. Two IL-1R, the type I and type II receptors, have been identified. This work describes the derivation and characterization of mice deficient in expression of the type I IL-1R (IL-1RI). IL-1RI-deficient mice were viable and fertile, but failed to respond to IL-1 in a variety of assays, including IL-1-induced IL-6 and E-selectin expression and IL-1-induced fever. Similar to IL-1beta-deficient mice, IL-1RI-deficient mice had a reduced acute phase response to turpentine. In contrast, IL-1RI-deficient mice had a reduced delayed-type hypersensitivity response and were highly susceptible to infection by Listeria monocytogenes. These data demonstrate that the IL-1RI is essential for all IL-1-mediated signaling events examined, and that both IL-1alpha and IL-1beta are critical to the animals' response to injury and infection. These data also demonstrate that IL-1 function is not required for normal development or homeostasis.

MELAS: Clinical and pathologic correlations with MRI, xenon/CT, and MR spectroscopy

We describe the clinical, imaging, and pathologic findings in a patient with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS). The patient experienced her first stroke-like episode at age forty-four. Brain MRI, obtained at symptom onset, at 3 weeks, and at 1 year, revealed migrating T2-weighted hyperintensities in the temporal/parietal and occipital cortices and later revealed atrophy. Abnormal cerebrovascular reserve was evident on xenon/CT four days after the first MRI. MR spectroscopy at 1 year revealed increased lactate in both the occipital and temporal lobes. Histologic sections demonstrated spongy degeneration of the cortex that was most prominent at the crests of the gyri. Electron microscopy of the blood vessels showed increased numbers of abnormal mitochondria within the vascular smooth muscle and in endothelial cells. We hypothesize that the stroke-like episodes in MELAS may be due to impaired autoregulation secondary to the impaired metabolic activity of mitochondria in the endothelial and smooth muscle cells of blood vessels.

Insertion of a structural domain of interleukin (IL)-1 beta confers agonist activity to the IL-1 receptor antagonist. Implications for IL-1 bioactivity

We showed previously that replacement of Lys-145 in the IL-1 receptor antagonist (IL-1ra) with Asp resulted in an analog (IL-1ra K145D) with partial agonist activity. To identify additional amino acids that affect IL-1 bioactivity, we created second site mutations in IL-1ra K145D. Substitutions of single amino acids surrounding position 145 were made; none of these substitutions increased the bioactivity of IL-1ra K145D. However, the insertion of the beta-bulge (QGEESN) of IL-1 beta at the corresponding region of IL-1ra K145D resulted in a 3-4-fold augmentation of bioactivity. An additional increase in agonist activity was observed when the beta-bulge was co-expressed with a second substitution (His-54 --> Pro) in IL-1ra K145D. We also show that the bioactivity of both IL-1ra K145D and the triple mutant IL-1ra K145D/H54P/QGEESN is dependent on interaction with the newly cloned IL-1 receptor accessory protein.

Efficacy of recombinant bovine interleukin-2 as an adjunct to dry cow therapy

Recombinant bovine interleukin-2 was tested as adjunct therapy to intramammary infusion of antibiotics at drying off. Cows were assigned randomly within three commercial herds to either recombinant bovine interleukin-2 or PBS treatment groups at drying off. Ninety-five cows received intramammary infusions of 1 mg of recombinant bovine interleukin-2 in each quarter immediately preceding intramammary infusion of a product for antibiotic therapy of dry cows. Ninety-four cows received intramammary infusion of 10 ml of endotoxin-free PBS in each quarter immediately preceding the antibiotic therapy. Cure rates for IMI present at drying off did not differ between cows treated with recombinant bovine interleukin-2 and those treated with PBS. Intramammary infusion of recombinant bovine interleukin-2 did not affect the rate of new IMI during the dry period. Milk production and SCC during the first 3 mo of lactation subsequent to therapy did not differ between treatment groups. Intramammary infusion of recombinant bovine interleukin-2 was not effective as an adjunct to antibiotic therapy for dry cows.