Abstract A11: Targeting vascular endothelial growth factor in myeloid cells enhances natural killer cell responses to chemotherapy and ameliorates cachexia

Chemotherapy remains a mainstay of cancer treatment but its use is often limited by the development of adverse reactions. Severe involuntary loss of body weight (cachexia) is a frequent cause of death in cancer patients and is exacerbated by chemotherapy. We show that, in contrast to antibody-mediated neutralization of Vascular Endothelial Growth Factor (VEGF)-A, genetic inactivation of VEGF-A in tumor-associated myeloid cells prevents chemotherapy-induced cachexia by inhibiting skeletal muscle loss and the lipolysis of white adipose tissue. It also improves clearance of senescent tumor cells by natural killer cells and inhibits tumor regrowth after chemotherapy. The effects depend on the adipokine and chemoattractant chemerin, which is released by the tumur endothelium in response to chemotherapy. The findings define chemerin as a critical mediator of the immune response elicited by chemotherapy as well as an important inhibitor of cancer cachexia. Efficient targeting of VEGF signaling within the tumor microenvironment should impede weight loss that is frequently associated with chemotherapy, thereby dramatically improving the therapeutic outcome.

Citation Format: Magali Castells, Ralph Klose, Dagmar Gotthardt, Eva-Maria Putz, Ewelina Krzywinska, Chahrazade Kantari-Mimoun, Naima Chikdene, Anna-Katharina Meinecke, Katrin Schroedter, Iris Helfrich, Joachim Fandrey, Veronika Sexl, Christian Stockmann. Targeting vascular endothelial growth factor in myeloid cells enhances natural killer cell responses to chemotherapy and ameliorates cachexia. [abstract]. In: Proceedings of the AACR Special Conference: Function of Tumor Microenvironment in Cancer Progression; 2016 Jan 7–10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2016;76(15 Suppl):Abstract nr A11.

Myeloid STAT3 promotes formation of colitis-associated colorectal cancer in mice

Myeloid cells lacking STAT3 promote antitumor responses of NK and T cells but it is unknown if this crosstalk affects development of autochthonous tumors. We deleted STAT3 in murine myeloid cells (STAT3^Δm) and examined the effect on the development of autochthonous colorectal cancers (CRCs). Formation of Azoxymethane/Dextransulfate (AOM/DSS)-induced CRCs was strongly suppressed in STAT3^Δm mice. Gene expression profiling showed strong activation of T cells in the stroma of STAT3^Δm CRCs. Moreover, STAT3^Δm host mice were better able to control the growth of transplanted MC38 colorectal tumor cells which are known to be killed in a T cell-dependent manner. These data suggest that myeloid cells lacking STAT3 control formation of CRCs mainly via cross activation of T cells. Interestingly, the few CRCs that formed in STAT3^Δm mice displayed enhanced stromalization but appeared normal in size indicating that they have acquired ways to escape enhanced tumor surveillance. We found that CRCs in STAT3^Δm mice consistently activate STAT3 signaling which is implicated in immune evasion and might be a target to prevent tumor relapse.

Comparison of three different experimental methods for the assessment of peripheral compartment pharmacokinetics in humans

In many cases the concentration reached in a peripheral effect compartment rather than in plasma determines the clinical outcome of therapy. Therefore, several experimental approaches have been developed for direct assessment of drug kinetics in peripheral compartments. Particularly saliva sampling, skin blister fluid sampling, and in vivo microdialysis are frequently employed for measuring peripheral drug concentrations. However, data derived from these techniques have never been directly compared. In the present study, the tissue kinetics of theophylline were measured following single dose administration simultaneously in cantharides induced skin blisters, saliva and microdialysates of subcutaneous- and skeletal muscle- tissue and compared to plasma concentrations. Theophylline was administered to 9 healthy volunteers as an i.v. infusion of 240 mg. Mean ratio (AUCsaliva/AUCplasma) was 0.63 +/- 0.05, mean ratio (AUCblister/AUCplasma) was 0.69 +/- 0.12, mean ratio (AUCmuscle/AUCplasma) was 0.41 +/- 0.10, mean ratio (AUCsubcutaneous/AUCplasma) was 0.34 +/- 0.07. The time course of the concentration(peripheral)/concentration(plasma)-ratios showed that tissue concentrations obtained by microdialysis were closely correlated to free plasma levels, whereas saliva- and cantharides blister data overestimated the corresponding free plasma concentrations. It is concluded that microdialysis represents a reliable technique for the measurement of unbound peripheral compartment concentrations and is superior to saliva- and skin blister concentration measurements.