Anti-CD70 immunocytokines for exploitation of interferon-γ-induced RIP1-dependent necrosis in renal cell carcinoma.

Metastatic renal cell carcinoma (RCC) is an incurable disease in clear need of new therapeutic interventions. In early-phase clinical trials, the cytokine IFN-γ showed promise as a biotherapeutic for advanced RCC, but subsequent trials were less promising. These trials, however, focused on the indirect immunomodulatory properties of IFN-γ, and its direct anti-tumor effects, including its ability to kill tumor cells, remains mostly unexploited.

Impact of expression system on the function of the C6.5 diabody PET radiotracer.

The ability of engineered antibodies to rapidly and selectively target tumors that express their target antigen makes them well suited for use as radioimaging tracers. The combination of molecular size and bivalent nature makes diabody molecules a particularly promising structure for use as radiotracers for diagnostic imaging. Previous data have demonstrated that the anti-HER2 C6.

Influence of affinity and antigen internalization on the uptake and penetration of Anti-HER2 antibodies in solid tumors.

Antibody drugs are widely used in cancer therapy, but conditions to maximize tumor penetration and efficacy have yet to be fully elucidated. In this study, we investigated the impact of antibody binding affinity on tumor targeting and penetration with affinity variants that recognize the same epitope. Specifically, we compared four derivatives of the C6.

Evaluation of the anti-HER2 C6.5 diabody as a PET radiotracer to monitor HER2 status and predict response to trastuzumab treatment.

Purpose: The rapid tumor targeting and pharmacokinetic properties of engineered antibodies make them potentially suitable for use in imaging strategies to predict and monitor response to targeted therapies. This study aims to evaluate C6.5 diabody (C6.

Targeting ErbB2 and ErbB3 with a bispecific single-chain Fv enhances targeting selectivity and induces a therapeutic effect in vitro.

Inappropriate signalling through the EGFR and ErbB2/HER2 members of the epidermal growth factor family of receptor tyrosine kinases is well recognised as being causally linked to a variety of cancers. Consequently, monoclonal antibodies specific for these receptors have become increasingly important components of effective treatment strategies for cancer. Increasing evidence suggests that ErbB3 plays a critical role in cancer progression and resistance to therapy.

Effective treatment of established human breast tumor xenografts in immunodeficient mice with a single dose of the alpha-emitting radioisotope astatine-211 conjugated to anti-HER2/neu diabodies.

Purpose: Successful radioimmunotherapy strategies depend on selecting radioisotopes with physical properties complementary to the biological properties of the targeting vehicle. Small, engineered antitumor antibody fragments are capable of rapid, highly specific tumor targeting in immunodeficient mouse models. We hypothesized that the C6.

Quantitative immuno-positron emission tomography imaging of HER2-positive tumor xenografts with an iodine-124 labeled anti-HER2 diabody.

Positron emission tomography (PET) provides an effective means of both diagnosing/staging several types of cancer and evaluating efficacy of treatment. To date, the only U.S.

A single treatment of yttrium-90-labeled CHX-A"-C6.5 diabody inhibits the growth of established human tumor xenografts in immunodeficient mice.

Antitumor diabody molecules are noncovalent single-chain Fv dimers that recapitulate the divalent binding properties of native IgG antibodies. Diabodies are capable of substantial accumulation in tumor xenografts expressing relevant antigens in immunodeficient mouse models. With a Mr of approximately 55,000, diabodies are rapidly cleared from the circulation, resulting in tumor-to-blood ratios that significantly exceed those achieved early after the administration of monoclonal antibodies.

Quantitation of small-animal (124)I activity distributions using a clinical PET/CT scanner.

Unlabelled: Time-dependent PET imaging can be an important tool in the assessment of radiotracer performance in murine models. We have performed a quantitative analysis of PET images of (124)I, acquired on a clinical PET system using a small-animal phantom. We then compared the recovered activity concentrations with the known activity concentration in the phantom spheres.

Phosphomonoester concentrations differ between chronic lymphocytic leukemia cells and normal human lymphocytes.

Levels of phospholipid-related metabolites of chronic lymphocytic leukemia lymphocytes (CLL) and normal human lymphocytes were quantified using phosphorus magnetic resonance spectroscopy. The CLL cells versus normal lymphocytes showed significant increases of phosphoethanolamine(Etn-P) (8.11+/-2.

Delivery of the alpha-emitting radioisotope bismuth-213 to solid tumors via single-chain Fv and diabody molecules.

Intravenously administered anti-tumor single-chain Fv (scFv) and diabody molecules exhibit rapid clearance kinetics and accumulation in tumors that express their cognate antigen. In an attempt to fit the rate of isotope decay to the timing of delivery and duration of tumor retention, anti-HER2/neu CHX-A" DTPA-C6.5K-A scFv and diabody conjugates were labeled with the alpha-particle emitter (213)Bi (t(1/2) = 47 min).

Quantitation of resonances in biological 31P NMR spectra via principal component analysis: potential and limitations.

This paper examines the potential and limitations of peak area quantitation of biological NMR spectra using principal component analysis (PCA), including its requirement for prior knowledge. The principles of the method are presented without in-depth mathematical treatment. PCA is illustrated for simulated data, 31P NMR spectra obtained consecutively over 1-2.

Metabolism of phosphonium choline by rat-2 fibroblasts: effects of mitogenic stimulation studied using 31P NMR spectroscopy.

Phospholipid turnover increases with both mitogenic stimulation and oncogenic transformation (1-9). Recent 31P nuclear magnetic resonance (NMR) spectroscopy studies of human tumors, animal tumor models and cell systems have reported elevated phosphomonoesters with growth and oncogenic transformation, as well as changes in these levels associated with treatment (10). In order to gain insights into the mechanisms underlying these changes, we used a phosphonium analog of choline and 31P NMR spectroscopy to study choline metabolism in quiescent and mitogenically stimulated Rat-2 fibroblasts.

Characterization of a phosphonium analog of choline as a probe in 31P NMR studies of phospholipid metabolism.

Tumors and transformed cells have been shown by 31P NMR to contain elevated concentrations of two phosphomonoesters, phosphorylcholine and phosphorylethanolamine, involved in phospholipid metabolism. In order to understand the biochemical basis for these phenomena new methods are needed to allow for analysis of the relevant metabolic pathways in intact cells. One such promising tool may be phosphonium-choline, a 31P NMR-visible analog of choline in which the trimethyl-ammonium group of choline has been replaced with a trimethyl-phosphonium moiety.

Inositol 1,4,5-triphosphate-induced granule secretion in platelets. Evidence that the activation of phospholipase C mediated by platelet thromboxane receptors involves a guanine nucleotide binding protein-dependent mechanism distinct from that of thrombin.

Phosphoinositide hydrolysis in platelets stimulated by thrombin is thought to be regulated by a pertussis toxin-sensitive guanine nucleotide binding protein (G protein) referred to as Gp. The present studies examine the role of Gp in platelet responses to the thromboxane A2 analogue U46619 and in the pathway by which the phosphoinositide hydrolysis product inositol 1,4,5-triphosphate (IP3) causes secretion. In permeabilized platelets, U46619 caused phosphatidic acid formation and secretion, which were abolished by the G protein inhibitor, guanosine 5'-O-(2-thiophosphate) (GDP beta S).

Self-exchange of sodium in human lymphocytes.

Self-exchanges of Na and K in human lymphocytes were measured by isotopic efflux techniques. In washed cells, K exchanged in a single slow exponential fraction, but the Na exchange had a marked curvature. It was shown that the curvature was not caused by simple bulk-phase diffusion, and it was resolved into three major fractions: fast (F) (half-time, t1/2 = 2-4 min), intermediate (I) (t1/2 = 12 min), and slow (S) (t1/2 = 125 min).

Development of a protocol for photoradiation therapy of malignant brain tumors: part 1. Photosensitization of normal brain tissue with hematoporphyrin derivative.

The successful application of phototherapy to subcutaneous tumors has suggested that a similar procedure should be developed for treating gliomas. As a result, attempts are being made to determine a set of conditions that would optimize the destruction of tumor cells while minimizing injury to surrounding brain tissue. To initiate this task, we developed a novel assay method to assess the amount of phototoxicity induced in normal brain by light exposure of mice treated with hematoporphyrin derivative (HPD).

Effects of valinomycin on lymphocytes independent of potassium permeability.

10(-7) M valinomycin affects human lymphocytes in the following manner: (1) it is non-toxic; (2) it inhibits mitogenesis; (3) it causes a reduction in cell ATP; and (4) it causes a marked increase in steady-state Na+ exchange. However, it has a minimal effect on cell ion (K+, Na+, Ca2+, Mg2+) contents and no effect whatever on K+ exchange. Neither the fast nor the slow fraction of steady-state K+ exchange is affected by 10(-7) M valinomycin.

The effect of metabolic inhibition on ion contents and sodium exchange in human lymphocytes.

Lymphocytes depleted of ATP by incubation in iodoacetate (IAA) and nitrogen (N2) lost K and gained Na. Isotopic Na exchange showed a fast fraction and a slower exponential fraction, the latter conventionally assumed to reflect surface membrane properties. The gain of cell Na was not accounted for by a decrease in 22Na efflux in either the slow or the fast fraction.

Temperature-dependence of ATP level, organic phosphate production and Na,K-ATPase in human lymphocytes.

It was previously shown that human lymphocytes maintain a normal accumulation of K+ and exclusion of Na+ between 37 degrees and 10 degrees C., and a significant net accumulation of K+ and exclusion of Na+ at even lower temperatures. The studies reported here show that the level of ATP is near-normal for at least 24 hours between 37 degrees and 10 degrees C.

Simultaneous net accumulation of both K+ and Na+ by lymphocytes at 0 degrees C.

Human lymphocytes at 0 degrees C in low Na+ medium accumulate both K+ and Na+ to levels higher than in the external medium. This is not due to an impermeable compartment or a Donnan equilibrium, and is incompatible with the membrane Na+-pump concept. In contrast, it supports prior evidence that ion exchange in lymphocytes is mediated by adsorption onto and desorption from fixed anionic sites within the cell.

Multiple fractions of sodium exchange in human lymphocytes.

Human lymphocytes contain a large, saturable fraction of K+ that exchanges slowly with K+ in the external medium, and a small non-saturable fraction that exchanges rapidly. We determined whether or not Na+ exchanges in a similar manner with external Na+. Cells were pre-equilibrated to ensure absence of net ion movements.

A critical temperature transition of K+-Na+ exchange in human lymphocytes.

Human lymphocytes were equilibrated for 48 hours at 5-6 mM K+ ex over a range of temperatures between 0 and 37 degrees C, and at 5 degrees C over a range of external K+ levels between 0 and 32 mM. Cell K+ and Na+ contents are normal between 37 and 10 decrees. Below 10 degrees there is a critical thermal transition in ion content centering around 3 degrees C.