Abstract 817: Enhancement of paclitaxel and carboplatin therapy by CCL2 blockade in ovarian cancers

Abstract

Abstract Ovarian cancer is strongly associated with a pro-inflammatory leukocyte infiltrate, and very high levels of chemokines are found in ascites, including CCL2. CNTO 888, a neutralizing anti-CCL2 antibody, could inhibit the pro-tumor inflammatory infiltrate and tumor growth, thus providing clinical benefit to ovarian cancer patients. It was reported that CCL2 stimulated tumor cells to produce pro-angiogenic factors instead of directly stimulating bone marrow endothelial cells (Zhang J et al. 2009). The anti-CCL2 antibody CNTO 888 also had no effect as a monotherapy on capillary tube formation; however, CCL2 increased VEGF-A mRNA expression levels in PC-3 cells after 4-6 h of treatment. The induction of VEGF-A mRNA expression in PC-3 cells was blocked by pretreatment with a neutralizing antibody, indicating this induction was mediated by CCL2. CCL2 has been shown to be overexpressed in tumor cell lines resistant to taxanes. CCL2 may be induced by chemotherapy and mediate chemoresistance to taxanes. Moreover, this upregulation of CCL2 by taxane-based chemotherapy has been shown to occur via the JNK pathway. Study design: Our overall hypothesis is that CCL2 neutralization can inhibit tumor growth of taxane resistant metastatic ovarian cancer, and that stroma plays an important role in promoting tumor growth. This project is focused on three pairs of taxane resistant variants developed in the lab: ES-2/TP, MES-OV/TP and OVCAR-3/TP. These three cell models exhibit alterations in tubulin expression and dynamics along with other non-MDR1/P-glycoprotein mechanisms of resistance to taxanes. Using quantitative PCR, we observed elevated CCL2 expression (7x, 45x and 9x, respectively) in these cell models relative to parental controls, and confirmed these findings at the protein level by ELISA. CCR2 expression has been determined as well, by qPCR and by FACS analysis. In order to assess tumor growth by bioluminescent imaging, our taxane variants were transduced with the pHR2-gfp/luc lentiviral vector and were sorted in order to obtain homogenous gfp/luc positive population. These cells have been implanted intraperitoneally (i.p.) and subcutaneously (s.c.) in athymic nude, adult female mice. A pilot study was done to determine the growth of our three cell lines pairs injected subcutaneously or intraperitoneally into mice. Mice were then treated with antibodies to neutralize both the human tumor-derived CCL2 (CNTO 888) and the mouse orthologue of human CCL2, MCP-1 (C1142), with and without chemotherapy (paclitaxel or carboplatin). Bioluminescence images have been acquired in order to evaluate tumor growth during treatment. We observed a significant additive effect on efficacy of paclitaxel and carboplatin when the CCL2 blockade is added, compared to the chemotherapy alone (percent tumor burden at week 7 compared with week 3: paclitaxel 82%, paclitaxel + CNTO888/C1142 19%, carboplatin 74%, carboplatin + CNTO888/C1142 13%). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 817. doi:1538-7445.AM2012-817