Because antiangiogenic therapies inhibit the growth of new tumor-associated blood vessels, as well as prune newly formed vasculature, they would be expected to reduce the supply of oxygen and thus increase tumor hypoxia. However, it is not clear if antiangiogenic treatments lead only to consistent and sustained increases in hypoxia, or transient decreases in tumor hypoxia along with periods of increased hypoxia. We undertook a detailed analysis of an orthotopically transplanted human breast carcinoma (MDA-MB-231) over a 3-week treatment period using DC101, an anti-vascular endothelial growth factor receptor 2 antibody. We observed consistent reductions in microvascular density, blood flow (measured by high-frequency micro-ultrasound), and perfusion. These effects resulted in an increase in the hypoxic tumor fraction, measured with an exogenous marker, pimonidazole, concurrent with an elevation in hypoxia-inducible factor-1A expression, an endogenous marker. The increase in tumor hypoxia was evident within 5 days and remained so throughout the entire course of treatment. Vascular perfusion and flow were impaired at days 2, 5, 7, 8, 14, and 21 after the first injection, but not at 4 hours. A modest increase in the vessel maturation index was detected after the 3-week treatment period, but this was not accompanied by an improvement in vascular function. These results suggest that sustained hypoxia and impairment of vascular function can be two consistent consequences of antiangiogenic drug treatment. The implications of the results are discussed, particularly with respect to how they relate to different theories for the counterintuitive chemosensitizing effects of antiangiogenic drugs, even when hypoxia is increased. (Cancer Res 2006; 66(7): 3639-48)

Metronomic chemotherapy refers to the close, regular administration of comparatively low doses of cytotoxic drugs, with minimal or no drug-free breaks, over prolonged periods. It is thought to have an antiangiogenic basis. However, whereas surprisingly durable and potent tumor responses have been observed in a number of preclinical tumor models, relapses usually eventually occur using this type of treatment strategy. We therefore decided to test modified metronomic chemotherapy regimens that might significantly delay such relapses, but still maintain modest and acceptable toxicity profiles. Here, we show that repeated administration of bolus doses (BDs) of cyclophosphamide every 3 or 6 weeks, combined with a daily oral low-dose metronomic (LDM) regimen (20 mg/kg/d cyclophosphamide), improves efficacy and significantly delays progression of transplanted PC-3 human prostate cancer xenografts, syngeneic transplanted EMT-6 breast tumors, and ''spontaneous'' murine erythroleukemia. Efficacy was superior whereas toxicity was mild and comparable to the LDM regimen, the latter assessed by body weight, neutrophil, lymphocyte, and total white blood counts. Antiangiogenic activity, measured by reduction in circulating endothelial precursor cells, revealed that the greatest degree of suppression occurred using the combination treatment. Overall, our results indicate that the administration of intermittent BD combined with chronic oral LDM cyclophosphamide is a potent treatment regimen for controlling tumor growth, which has a low toxicity profile, over prolonged periods of time. (Cancer Res 2005; 65(16): 7045-51)

The stromal compartments of hematopoietic organs (eg, spleen) are known to influence the viability and growth of diseased hematopoietic progenitors. Here we have used Friend murine leukemia virus (F-MuLV)-induced erythroleukemia to investigate factors of the splenic microenvironment that may make it fertile for the expansion and survival of malignant erythroblasts. We found that splenectomized, erythroleukemic mice exhibited extended survival compared with agematched sham controls. In vitro, the proliferation of primary erythroleukemic cells cocultured with leukemic-derived splenic adherent cells or their conditioned media was found to be significantly higher than that observed in cocultures with healthy-derived adherent splenic cells. Cytokine protein arrays revealed that F-MuLV-infected splenocytes secreted elevated levels of interleukin-6 (IL- 6 IntroductionSolid tumors can be viewed as abnormal organs composed of 3 general cell types: tumor cells, tumor-associated endothelium, and the stroma (reviewed by Liotta and Kohn 1 and Wernert 2 ). The latter serves to nourish and support the growing tumor cell mass, respectively. Similarly, the stroma of hematopoietic organs is known to support the processes of normal and malignant hematopoiesis (ie, "liquid" tumors or leukemias). 3,4 In both cases, support cells are essential for tumor growth and metastasis. However, the changes occurring in their associated endothelial and stromal cells that accelerate the disease process are poorly characterized.A number of hematologic malignancies including chronic lymphocytic leukemia (CLL), marginal zone non-Hodgkin lymphoma (NHL), hairy cell leukemia (HCL), and chronic myelogenous leukemia (CML) display varying propensities for pathological enlargement of the spleen (splenomegaly). 5-7 Thus, splenic involvement appears to be stage specific for each type of disease and is generally considered to take place during the mid to late stages. Particularly for CML, splenomegaly is evident during accelerated disease and blast crisis. 8 Surgical intervention (splenectomy) is typically reserved for patients who are experiencing extreme discomfort or who may benefit from a laparotomy if such a procedure is thought to be useful in governing the therapeutic strategy. 8 These clinical observations suggest mechanistic growth response elements contributed by the spleen, which remain rather enigmatic.Friend murine leukemia virus (F-MuLV)-induced erythroleukemia has been used for decades as a model for analyzing neoplastic transformation, leukemia progression, genetic susceptibility to cancer, and, more recently, erythroid differentiation. 9,10 It is well established that following inoculation of neonates of susceptible murine strains with F-MuLV, infected erythroblasts depart the bone marrow and sequester within the spleen, 11 followed by the development of foci over the following 2 weeks. 12 It has been previously reported that the spleen plays a role in the susceptibility and resistance of the host to Friend virus infection from the polycythe...

BACKGROUND:Autoimmune diseases are a group of illnesses in which autoantibodies are produced against various organs, presenting with a variety of clinical symptoms. In this review, we discuss the different aspects of autoimmune diseases in pregnancy. We also describe experimental models that help to understand the etiology and pathogenesis of the effects of this maternal disease on the developing embryo, fetus and placenta. METHODS:The possible direct effects of sera or IgG obtained from women with systemic lupus erythematosus/antiphospholipid syndrome (SLE/APS) and recurrent pregnancy loss (RPL) were examined on cultured 10.5-and 11.5-day-old rat embryos and on cultured human placental explants, as compared to sera from healthy women or synthetic medium that were used as controls. In addition, we examined the effects of the sera obtained from these women after successful treatment that allowed the birth of normal infants. RESULTS: We observed increased embryonic death and anomalies in embryos cultured on sera and IgG from SLE/APS women. Similarly, when human placental explants were cultured on these sera, trophoblastic cell growth was reduced and apoptotic rate was increased. Successful treatment also reduced the damage caused by the sera from these women in the cultured embryos and placentas. CONCLUSIONS: Our results, and the cited studies, point to the important role of the placental damage in the etiology of RPL associated with SLE/APS. Animal models, both in vivo and in vitro, as well as cultured early human placental explants can be used successfully to understand some of the pathogenic aspects of SLE/APS and RPL.

No abstract

Hepatic metastases of malignant tumors is a major problem in the treatment of cancers for which the liver is the most common site for recurrences. In the present study we describe a selective delivery system to the liver which may facilitate specific hepatic targeting of anti-cancer agents. Avidin and streptavidin are two biotin-binding proteins with extreme resistance to proteolytic activity. Trinitrophenyl (TNP) modification of these two proteins resulted in specific accumulation in mouse liver with levels of 40-50 percent per gram tissue (%/g) during a period of several days. The two modified proteins could target to the liver high doses of covalently bound radionuclide iodine-125, a biotinylated ligand such as biotinyl-tyrosine (BT) or large biotinylated carriers such as carboxymethyl dextran (CMdex, 40kDa). Appropriately derivatized dextrans serve as carriers for various chemotherapeutic drugs, as demonstrated here for cis-dichlorodiammineplatinum (CDDP). Specific liver targeting of CDDP complexed to CMdex-TNP-streptavidin could be monitored by flame atomic absorption spectrometry of the Pt metal: High levels of the Pt drug were concentrated in the liver for at least 15hr following its targeted delivery as compared to essentially undetectable levels after administration of the free drug.

Trinitrophenyl (TNP) modification of streptavidin (St) resulted in high and prolonged accumulation in mouse liver following intravenous administration of radioiodinated TNP streptavidin (TNP-St). Uptake, which is correlated with increased TNP substitution, was first observed at 2-3 h, increased to 40-50% of injected dose/gram tissue (%/g) at 24 h and slowly declined later on. A low degree of accumulation (10%/g) was observed in the spleen. TNP substitution of other proteins such as bovine serum albumin (BSA) or ovalbumin (Ova) led to a transient short-term liver uptake. The enzyme-resistance property of streptavidin and its biotin binding sites render TNP-modified streptavidin a potential targeting vehicle to the liver. 5-Fluorouridine (FUR) was attached to high molecular weight carrier carboxymethyldextran (CMdex, derived from 40 kDa dextran) and the dextran FUR conjugate was charged with 2-4 biotinyl groups (in the form of biotinyl-diaminopropionyl-tyrosine, BDT) for complexing to TNP-St. Biodistribution monitoring of the BDT-CMdex-FUR ligand, radiolabeled at the tyrosyl residue of BDT and targeted via non-radiolabeled TNP-St, showed that ligand accumulation in the liver was similar to TNP-St itself. Liver targeting of FUR was demonstrated by trace-labeling FUR with its structural analog 5,6-[3H]uridine prior to conjugation to dextran hydrazide. Specific liver accumulation of [3H] radioactivity occurred following administration of the conjugate only when complexed to TNP-St. Hepatic levels of [3H] radioactivity were in the range of 25%/g or 35% per whole liver during a period of at least 8 h, as compared to the rapid elimination of free FUR+[3H]uridine (4%/g at 20 min). [3H]-drug radioactivity disappeared at a faster rate as compared to 125I-dextran radioactivity, suggesting that metabolic processes required to generate the 5,6-[3H]uracil-containing active metabolites took place.

<div>Abstract<p>Because antiangiogenic therapies inhibit the growth of new tumor-associated blood vessels, as well as prune newly formed vasculature, they would be expected to reduce the supply of oxygen and thus increase tumor hypoxia. However, it is not clear if antiangiogenic treatments lead only to consistent and sustained increases in hypoxia, or transient decreases in tumor hypoxia along with periods of increased hypoxia. We undertook a detailed analysis of an orthotopically transplanted human breast carcinoma (MDA-MB-231) over a 3-week treatment period using DC101, an anti–vascular endothelial growth factor receptor 2 antibody. We observed consistent reductions in microvascular density, blood flow (measured by high-frequency micro-ultrasound), and perfusion. These effects resulted in an increase in the hypoxic tumor fraction, measured with an exogenous marker, pimonidazole, concurrent with an elevation in hypoxia-inducible factor-1α expression, an endogenous marker. The increase in tumor hypoxia was evident within 5 days and remained so throughout the entire course of treatment. Vascular perfusion and flow were impaired at days 2, 5, 7, 8, 14, and 21 after the first injection, but not at 4 hours. A modest increase in the vessel maturation index was detected after the 3-week treatment period, but this was not accompanied by an improvement in vascular function. These results suggest that sustained hypoxia and impairment of vascular function can be two consistent consequences of antiangiogenic drug treatment. The implications of the results are discussed, particularly with respect to how they relate to different theories for the counterintuitive chemosensitizing effects of antiangiogenic drugs, even when hypoxia is increased. (Cancer Res 2006; 66(7): 3639-48)</p></div>