Impact of safety concerns and regulatory changes on the usage of erythropoiesis-stimulating agents and RBC transfusions

PURPOSE

Safety concerns raised in the recent oncology trials with erythropoiesis-stimulating agents (ESAs) have led to regulatory restrictions on their use. We wished to determine the impact of these changes on the use of ESAs and RBC transfusions.

METHODS

In a retrospective observational study of patients treated at a comprehensive cancer center in 2006-2008, data on all ESA doses dispensed, RBCs transfused, and hemoglobin levels on the days of transfusions and ESA initiations were analyzed.

RESULTS

Compared with 2006, the total patients treated was 14% higher (28,339 versus 24,806) in 2007 and 22% higher (30,254) in 2008. Patients receiving ESAs decreased by 26% and 61%, and ESA units dispensed decreased by 29% (from 30,206 units to 21,409 units) and 80% (6,102 units) in 2007 and 2008, respectively. However, RBC transfusions increased by only 2% (from 38,218 units to 38,948 units) in 2007 and by 8% (41,438) in 2008. The mean hemoglobin on the day of transfusion was the same for each year (8.4 g/dl); however, an increasing proportion of patients initiated ESAs at lower hemoglobin (< 10 g/dl) levels. After adjusting for demographics and diagnostic variables for 3 years (n = 83,399), a multivariate logistic regression showed a significant decline in ESA use (p < .0001) without an increase in RBC transfusions.

CONCLUSIONS

Recent ESA safety concerns and regulatory restrictions have significantly decreased ESA use. The lack of a significant impact on transfusions may be related to a lower hemoglobin threshold used to initiate ESAs or treatment of patients less likely to respond.

Sensitivity of digoxigenin and biotin labelled probes for detection of human papillomavirus by in situ hybridisation

The sensitivity of digoxigenin and biotin labelled DNA probes for the detection of human papillomavirus (HPV) by dot blotting and in situ hybridisation was compared in tissues from cervical, laryngeal, and anogenital neoplasia. Probes were either labelled with digoxigenin by the random primer technique and detected with anti-digoxigenin antibody, or labelled with biotin by nick translation and detected with streptavidin, both methods having a common final visualisation procedure using alkaline phosphatase. Digoxigenin labelled probes proved two to 10-fold more sensitive by quantitative dot blotting and four-fold more sensitive in detecting HPV 16 DNA in a series of 31 anal carcinomas, compared with biotinylated probes. The digoxigenin method also produced less non-specific background staining of tissue sections than biotin labelled probes. It is concluded that digoxigenin DNA labelling and detection provides a simple, reliable, and efficient alternative to the use of biotin or radioactive isotopes for the detection of HPV DNA by in situ hybridisation. Digoxigenin labelled probes also offer the possibility of double labelling in situ hybridisation procedures when used with biotin labelled probes to provide simultaneous identification of different DNA sequences.

Limitation of differential expression of HLA-A,B,C antigens on choriocarcinoma cell lines by messenger RNA for HLA heavy chain but not by beta 2-microglobulin

The relative amounts of HLA-A,B,C antigens, beta 2-microglobulin (beta 2m), and trophoblast antigens (Trop-1 and Trop-2) were determined on nine choriocarcinoma cell lines including seven lines of gestational origin and two lines of nongestational origin (from ovary and stomach) by quantitative immunofluorescence analysis using a fluorescence-activated cell sorter. Most of these lines expressed surface HLA to variable extents, but one had none detectable. However, all lines secreted readily measurable amounts of beta 2m. We analyzed total RNA extracted from these lines using northern blot molecular hybridization with HLA-A,B,C- and beta 2m-specific complementary DNA probes. We found no messenger RNA species which hybridized with the HLA probe in cells with no detectable HLA surface antigen and only small amounts of HLA-specific RNA in cells with low levels of HLA membrane antigen. Cells exhibiting surface HLA levels greater than about 30% of that on lymphocytes had much higher amounts of HLA-specific RNA than did choriocarcinoma cells with no or low HLA antigen expression. In contrast, RNA hybridizing with beta 2m-specific probes was present at the 20% level or higher (relative to lymphocytes) in all the cell lines tested. Thus, the expression of HLA-A,B,C is apparently limited in choriocarcinoma cells by the level of HLA heavy-chain RNA and not by the level of beta 2m RNA. We discuss these findings in relation to the normal trophoblastic or other origins of this tumor type and with respect to the regulation and function of HLA in trophoblasts.

Alteration of membrane phospholipid bilayer organization in human erythrocytes during drug-induced endocytosis

Our plan was to evaluate the potentially important role of phospholipids in erythrocyte shape alterations by determining if their orientation was altered during endocytosis. Stomatocytosis and endocytosis were induced in normal intact human erythrocytes by incubation with three agents: primaquine, vinblastine, and chlorpromazine, each of which has its own requirements and time course for producing endocytosis. The organization of the phospholipid bilayer was assessed by measuring the extent of degradation of phophatidylcholine (PC), phophatidylethanolamine (PE), phosphatidylserine (PS), and sphingomyelin (SM) produced by exposure of erythrocytes to a nonpenetrating protease-free phospholipase A2 alone or in combination with a purified sphingomyelinase as well. The induction of stomatocytosis did not change this orientation. However, correlating with the onset of endocytosis but not its extent, there was an increase in PE degradation, which could be detected regularly only by use of phospholipase A2 alone. Use of the combination of phospholipase A2 and sphingomyelinase showed that the extent and course of endocytosis was paralleled by an apparent movement of PC and SM from the outer to the inner half of the lipid bilayer. Since no further PE was hydrolyzed and because no PS was ever degraded, this inward movement of PC and SM did not represent the establishment of complete symmetry in the membrane. By adjusting the experimental design it was possible to implicate the endocytic process, and not insertion of drug in the membrane, as the cause of the alterations in phospholipid organization seen. Our findings indicate that the phospholipid orientation is very closely involved in the endocytosis process and that specific states of phospholipid asymmetry may be related to identifiable membrane events.

Correlation of plasma phenformin concentration with metabolic effects in normal subjects

1. Circulating concentrations of intermediary metabolites have been measured after administration of 50 mg of phenformin to normal subjects. 2. Phenformin caused a significant increase in blood lactate, alanine and the lactate/pyruvate ratio but did not affect blood glucose or serum insulin concentrations. 3. There was a significant correlation between the increase in blood lactate concentration after phenformin and the plasma concentration of the drug.