SLC28A3 genotype and gemcitabine rate of infusion affect dFdCTP metabolite disposition in patients with solid tumours.

BACKGROUND: Gemcitabine is used for the treatment of several solid tumours and exhibits high inter-individual pharmacokinetic variability. In this study, we explore possible predictive covariates on drug and metabolite disposition. METHODS: Forty patients were enrolled. Gemcitabine and dFdU concentrations in the plasma and dFdCTP concentrations in peripheral blood mononuclear cell were measured to 72 h post infusion, and pharmacokinetic parameters were estimated by nonlinear mixed-effects modelling. Patient-specific covariates were tested in model development. RESULTS: The pharmacokinetics of gemcitabine was best described by a two-compartment model with body surface area, age and NT5C2 genotype as significant covariates. The pharmacokinetics of dFdU and dFdCTP were adequately described by three-compartment models. Creatinine clearance and cytidine deaminase genotype were significant covariates for dFdU pharmacokinetics. Rate of infusion of <25 mg m(-2) min(-1) and the presence of homozygous major allele for SLC28A3 (CC genotype) were each associated with an almost two-fold increase in the formation clearance of dFdCTP. CONCLUSION: Prolonged dFdCTP systemic exposures (≥72 h) were commonly observed. Infusion rate <25 mg m(-2) min(-1) and carriers for SLC28A3 variant were each associated with about two-fold higher dFdCTP formation clearance. The impacts of these covariates on treatment-related toxicity in more selected patient populations (that is, first-line treatment, single disease state and so on) are not yet clear.

Phase I study of bortezomib and cetuximab in patients with solid tumours expressing epidermal growth factor receptor.

Bortezomib inhibits nuclear factor-kappaB (NF-kappaB). Cetuximab is a chimeric mouse-human antibody targeted against epidermal growth factor receptor (EGFR). We hypothesised that concomitant blockade of NF-kappaB and EGFR signalling would overcome EGFR-mediated resistance to single-agent bortezomib and induce apoptosis through two molecular pathways. The aim of this phase I trial was to establish the maximum tolerated dose (MTD) for bortezomib plus cetuximab in patients with EGFR-expressing epithelial tumours. The 21-day treatment cycle consisted of bortezomib administered on days 1 and 8 through dose escalation (1.3-2 mg m(-2)). Cetuximab was delivered at a dose of 250 mg m(-2) on days 1, 8 and 15 (400 mg m(-2) day 1 cycle 1). A total of 37 patients were enroled and given a total 91 cycles. No grade > or =3 haematological toxicity was noted. Non-hematological grade > or =3 toxicities included fatigue (22% of patients), dyspnoea (16%) and infection (11%). The MTD was not reached at the highest tested bortezomib dose (2.0 mg m(-2)). Efficacy outcomes included disease progression in 21 patients (56.7%) and stable disease (SD) at 6 weeks in 16 patients (43.3%). Five of the six patients with SD at 12 weeks were diagnosed with cancers of the lungs or head and neck. This combination therapy was moderately effective in extensively pretreated patients with non-small cell lung or head and neck cancers and warrants further investigation.

Thrombotic stroke associated with the use of porcine factor VIII in a patient with acquired haemophilia.

Porcine factor VIII (pFVIII), which is used to control bleeding in patients with congenital or acquired haemophilia who have high-titre neutralizing antibodies to human FVIII, is not known to increase the risk of arterial or venous thrombosis. We have recently encountered a patient with acquired haemophilia who developed a thrombotic left middle cerebral artery distribution stroke while being treated with pFVIII. To our knowledge, this is the first such reported thrombotic event. We speculate that platelet activation induced by pFVIII may have contributed to thrombosis and suggest that pFVIII be used with caution in elderly patients with pre-existing cardiovascular risk factors.

Apoptosis is associated with increased cell surface tissue factor procoagulant activity.

Tissue factor (TF), the physiologic initiator of coagulation, is present on the surface of cells but is not fully active unless the cell is lysed. This phenomenon, termed TF encryption, may be regulated by changes in membrane structure. Because apoptosis is associated with cell membrane alterations and conditions associated with apoptosis have also been associated with TF de-encryption, we hypothesized that apoptosis would result in enhanced TF procoagulant activity. Cultured human fibroblasts and endotoxin-stimulated endothelial cells were treated to induce apoptosis as evidenced by morphologic and DNA changes. Under the same conditions, changes in the level of TF activity were measured. Conditions that resulted in endothelial apoptosis were associated with de-encryption of TF activity. Similar results were obtained in fibroblasts except that only the morphologic changes, not the alterations in DNA size characteristic of apoptosis in other cells, were found. The data suggest an association between apoptosis and expression of cell surface tissue factor activity. Because of the recognized linkage of the coagulation system with wound healing and neoplasia, we speculate that this association may help to regulate the flux of cells in tissues being remodelled by apoptosis.

Exchange transfusion the hard way: massive hemolysis following transplantation of bone marrow with minor ABO incompatibility.

BACKGROUND: Bone marrow transplantation using donors with minor ABO incompatibility may result in the rapid production of donor-derived red cell isohemagglutinins, causing hemolysis of recipient red cells. CASE REPORT: The transplant of sibling-donor marrow with minor ABO incompatibility (group O donor marrow to group A recipient), using FK-506 as an immunosuppressant to prevent graft-versus-host disease, is reported. Following early myeloid engraftment, the recipient developed hemolysis of her entire A red cell population between Day 8 and Day 11. This brisk hemolytic anemia was due to rapid donor lymphoid engraftment that resulted in the explosive production of donor-derived anti-A. CONCLUSION: Patients undergoing the transplantation of marrow from donors with minor ABO incompatibility in which the donor cells can produce isohemagglutinins against the recipient's red cells must be kept under vigilant observation for the possible development of severe hemolysis, particularly in the setting of profound T-cell suppression without B-cell suppression.

Lupus inhibitors following bone marrow transplant.

Lupus inhibitors have been reported in a number of pathologic states in which there is a disruption of normal immunoregulation. We report here the development of new lupus inhibitors following bone marrow transplantation. Retrospective analysis of 1292 patients undergoing transplantation at the University of Minnesota over a 10 year period demonstrated newly recognized lupus inhibitors in 3% of the patients. These inhibitors were usually detected in the first 1-2 months after transplant. They occurred more frequently in children, with a particularly high incidence in patients with Hurler syndrome. The development of inhibitors was associated with the use of cyclosporine A (CsA) or T depletion for GVHD prophylaxis, with the use of busulfan/cytoxan as a preparative regimen (which includes phenytoin for seizure prophylaxis) and with the occurrence of viral infections. Lupus inhibitors were not associated with development of GVHD, or with any diagnosis other than Hurler syndrome. Thrombotic complications were rare as would be expected in this severely thrombocytopenic population. The incidence of lupus inhibitors that we recognized may substantially underestimate the true incidence as frequent routine coagulation studies were not performed in these patients. Prospective evaluation of lupus inhibitors during bone marrow transplant may provide insight into the pathogenesis of these inhibitors in other disease states.

Functional neurokinin 1 receptors for substance P are expressed by human vascular endothelium.

Substance P (SP), a neurotachykinin, is important in a number of inflammatory processes in which the endothelial cell also plays a critical role. SP receptors have previously been identified only on arterial endothelium, and the scant in vitro evidence for direct effects of SP on human endothelium is based on studies using nonarterial cells. To better understand SP's role in inflammation, we sought to identify functional SP receptors on human endothelium in situ and in culture. Autoradiographic ligand binding to human umbilical cord sections demonstrates the presence of SP binding sites with characteristics of the neurokinin 1 (NK-1) receptor (displacement by GTP analogues and the NK-1 specific antagonist CP-96,345) on human umbilical arterial, but not venous, endothelium. In culture, human umbilical venous endothelial cells (HUVECs) and human aortic endothelial cells express low levels of available SP binding sites. However, HUVECs, which are serum starved and refed, undergo a dramatic increase in SP binding. SP binding to starved/refed HUVECs induces a transient increase in intracellular calcium. This calcium flux is dose dependent over appropriate SP concentrations and can be blocked by NK-1 specific antagonists. The proinflammatory effects of SP may be mediated in part through the NK-1 receptor on endothelium.