The anaemia of cancer: death by a thousand cuts

Recombinant epoetins do not stimulate tumor growth in erythropoietin receptor–positive breast carcinoma models

We investigated the significance of erythropoietin receptor (EPOR) expression following treatment with recombinant human erythropoietin (rHuEPO; epoetin alpha) and the effect of recombinant epoetins (epoetin alpha, epoetin beta, and darbepoetin alpha) alone or in combination with anticancer therapy on tumor growth in two well-established preclinical models of breast carcinoma (MDA-MB-231 and MCF-7 cell lines). Expression and localization of EPOR under hypoxic and normoxic conditions in MDA-MB-231 and MCF-7 cells were evaluated by immunoblotting, flow cytometry, and immunohistochemistry. EPOR binding was evaluated using [125I]rHuEPO. Proliferation, migration, and signaling in MDA-MB-231 and MCF-7 cells following treatment with rHuEPO were evaluated. Tumor growth was assessed following administration of recombinant epoetins alone and in combination with paclitaxel (anticancer therapy) in orthotopically implanted MDA-MB-231 and MCF-7 breast carcinoma xenograft models in athymic mice. EPOR expression was detected in both tumor cell lines. EPOR localization was found to be exclusively cytosolic and no specific [125I]rHuEPO binding was observed. There was no stimulated migration, proliferation, or activation of mitogen-activated protein kinase and AKT following rHuEPO treatment. In mice, treatment with recombinant epoetins alone and in combination with paclitaxel resulted in equivalent tumor burdens compared with vehicle-treated controls. Results from our study suggest that although EPOR expression was observed in two well-established breast carcinoma cell lines, it was localized to a cytosolic distribution and did not transduce a signaling cascade in tumors that leads to tumor growth. The addition of recombinant epoetins to paclitaxel did not affect the outcome of paclitaxel therapy in breast carcinoma xenograft models. These results show that recombinant epoetins do not evoke a physiologic response on EPOR-bearing tumor cells as assessed by numerous variables, including growth, migration, and cytotoxic challenge in preclinical in vivo tumor models.

Anemia in the elderly: current understanding and emerging concepts

Anemia is currently defined by the World Health Organization (WHO) as a hemoglobin (Hb) level <13 g/dL in men and <12 g/dL in women. While estimates vary widely, nearly one quarter of community-based octagenerians and one half of the chronically ill elderly have Hb levels that satisfy a diagnosis of anemia according to these criteria. A growing body of evidence has linked adverse events with even "mild" anemia or low-normal Hb in the elderly. Recent studies suggest strongly that aging is associated with dysregulation of pro-inflammatory cytokines, most notably interleukin-6 (IL-6), which may negatively impact hematopoiesis, either by inhibition of erythropoietin (EPO) production or interaction with EPO receptors. Anemia in older individuals is associated with a very wide range of complications, including increased risk for mortality, cardiovascular disease, cognitive dysfunction, longer hospitalization for elective procedures and comorbid conditions, reduced bone density, and falls and fractures. Not surprisingly, anemia also has a significant effect on quality of life (QOL) in the elderly. Most anemia in older individuals results from iron deficiency, chronic inflammation, or chronic kidney disease, or it may be unexplained. Future research on anemia in the elderly should focus on the age-related physiologic changes underlying this condition and whether anemia correction can reduce anemia-associated risks, and improve QOL.

Epoetin beta in oncology: examining the current evidence

Anemia is highly prevalent in patients with cancer and its impact on quality of life and long-term outcome in these patients is well documented. Recombinant human erythropoietins, or epoetins, have been used to treat cancer-related or antitumor therapy-induced anemia for many years. Through a combination of clinical studies and extensive experience in the real-life clinical setting, epoetin beta has been shown to be efficacious and well tolerated, increasing hemoglobin levels, reducing the need for transfusion and improving quality of life. This favorable efficacy and safety profile has been demonstrated across a broad range of malignancy types, irrespective of the treatment used (platinum or nonplatinum based). The effect of treatment with epoetin beta is rapid, with mean hemoglobin increases of 1 g/dl seen as early as 4 weeks following the start of therapy. Furthermore, there is no evidence that epoetin beta negatively affects overall survival or tumor progression in anemic patients with cancer. The approved 30,000 IU once-weekly dosing regimen (as opposed to the 10,000 IU three-times weekly regimen) provides greater convenience and may result in improved treatment compliance.

In vitro dual effect of arsenic trioxide on hemopoiesis: inhibition of erythropoiesis and stimulation of megakaryocytic maturation

Although the arsenic compounds are now widely utilized in clinics in the treatment of various tumors, their effects on normal hematopoiesis do not seem to have been explored. In the present study, we provide evidence that arsenic trioxide (As(2)O(3)) exerts in vitro a potent inhibitory effect on normal erythropoiesis and a stimulatory action on megakaryocytic differentiation. The effect of As(2)O(3) on erythroid and megakaryocytic differentiation was evaluated on both erythroleukemic cell lines K562 and HEL and on normal hemopoietic progenitor cells (HPCs) induced to selective erythroid or megakaryocytic differentiation. The inhibitory effect of As(2)O(3) on erythropoiesis is related to: (a) the inhibition of Stat5 activation with consequent reduced expression of the target genes Bcl-X(L) and glycophorin-A; (b) the activation of an apoptotic mechanism that leads to the cleavage of the erythroid transcription factors Tal-1 and GATA-1, whose integrity is required for erythroid cell survival and differentiation; (c) the reduced expression of heat shock protein 70, required for GATA-1 integrity. The stimulatory effect of As(2)O(3) on normal megakaryocytopoiesis is seemingly related to upmodulation of GATA-2 expression and to stimulation of MAPK activity. These observations may have implications for the patients undergoing anti-leukemic treatment with this compound.

Signaling by Kit protein-tyrosine kinase--the stem cell factor receptor

Signaling by stem cell factor and Kit, its receptor, plays important roles in gametogenesis, hematopoiesis, mast cell development and function, and melanogenesis. Moreover, human and mouse embryonic stem cells express Kit transcripts. Stem cell factor exists as both a soluble and a membrane-bound glycoprotein while Kit is a receptor protein-tyrosine kinase. The complete absence of stem cell factor or Kit is lethal. Deficiencies of either produce defects in red and white blood cell production, hypopigmentation, and sterility. Gain-of-function mutations of Kit are associated with several human neoplasms including acute myelogenous leukemia, gastrointestinal stromal tumors, and mastocytomas. Kit consists of an extracellular domain, a transmembrane segment, a juxtamembrane segment, and a protein kinase domain that contains an insert of about 80 amino acid residues. Binding of stem cell factor to Kit results in receptor dimerization and activation of protein kinase activity. The activated receptor becomes autophosphorylated at tyrosine residues that serve as docking sites for signal transduction molecules containing SH2 domains. The adaptor protein APS, Src family kinases, and Shp2 tyrosyl phosphatase bind to phosphotyrosine 568. Shp1 tyrosyl phosphatase and the adaptor protein Shc bind to phosphotyrosine 570. C-terminal Src kinase homologous kinase and the adaptor Shc bind to both phosphotyrosines 568 and 570. These residues occur in the juxtamembrane segment of Kit. Three residues in the kinase insert domain are phosphorylated and attract the adaptor protein Grb2 (Tyr703), phosphatidylinositol 3-kinase (Tyr721), and phospholipase Cgamma (Tyr730). Phosphotyrosine 900 in the distal kinase domain binds phosphatidylinositol 3-kinase which in turn binds the adaptor protein Crk. Phosphotyrosine 936, also in the distal kinase domain, binds the adaptor proteins APS, Grb2, and Grb7. Kit has the potential to participate in multiple signal transduction pathways as a result of interaction with several enzymes and adaptor proteins.

Chemotherapy-induced anaemia during adjuvant treatment for breast cancer: development of a prediction model

BACKGROUND

At present, oncologists prescribe chemotherapy according to standard dose schedules, and as a result many patients develop serious, dose-limiting toxic effects such as anaemia. We aimed to develop a prediction model for anaemia in patients with breast cancer who were receiving adjuvant chemotherapy.

METHODS

We reviewed medical records of 331 patients who had received adjuvant chemotherapy for breast cancer. Patients were divided randomly into a derivation sample (n=221) and internal-validation sample (n=110). An external sample of 119 patients enrolled onto the control group of a randomised trial of epoetin alfa was used to validate the model further. Multivariable logistic regression was applied to develop the initial model. We then developed a risk-scoring system, ranging from 0 (low risk) to 50 (high risk), based on the final regression variables. A receiver operating characteristic (ROC) curve analysis was done to measure the accuracy of the scoring system when applied to both validation samples.

FINDINGS

The risk of anaemia increased as the pretreatment haemoglobin concentration decreased and was reduced with successive chemotherapy cycles. Risk was also predicted by a platelet count of 200x10(9) cells/L or less before chemotherapy, age 65 years or older, type of adjuvant chemotherapy, and use of prophylactic antibiotics. ROC analysis had acceptable areas under the curve of 0.88 for the internal-validation sample and 0.84 for the external validation sample. A risk score of > or = 24 to < 25 before chemotherapy was identified as the optimum cut-off for maximum sensitivity (83.5%) and specificity (92.3%) of the prediction model.

INTERPRETATION

The application and continued refinement of this prediction model will help oncologists to identify patients at risk of developing anaemia during chemotherapy for breast cancer, and might enhance patient-centred care by the application of anaemia treatment in a proactive and appropriate way.