Abstract 3518: Cellular therapy in combination with cytokines improves survival in a xenograft mouse model of ovarian cancer
Authors: Susan Blaydes Ingersoll, Hasina C. McGann, Ahad Ahmed, Sarfraz Ahmad, Neil J. Finkler, John R. Edwards, Robert W. Holloway
Journal: Cancer Research (2012)

Abstract Introduction: Epithelial ovarian cancer is the leading cause of death among gynecologic malignancies, and two-thirds of patients present with stage III and IV disease. Unfortunately, the vast majority of advanced-stage ovarian cancer (OC) patients will relapse, require ongoing treatment, and eventually succumb to chemotherapy-resistant disease. The aim of this study was to test cellular therapy in combination with cytokines (IL-2 and/or pegylated-IFNα-2b) in a xenograft mouse model of OC. Methods: SKOV3-AF2 OC cells (1x106) were injected intraperitoneally (IP) into athymic nude mice (n=40). Day-7 post OC cell injection, mice were IP injected with mononuclear cells (MC; 5x106) and cytokine combinations [IL-2 (4,000 U) ± pegylated-IFNα-2b (IFN; 12,000 U); n=5 per group]. Cytokine injections were continued weekly for IFN and thrice weekly for IL-2. Mice were sacrificed when they became moribund due to tumor burden at which time solid tumor and ascitic fluid was measured and collected. Total RNA was isolated from tumor samples and reverse transcription (RT) reactions were performed. Gene expression of Survivin, DNA mismatch repair homolog (MLH1), cysteine-rich 61 (CCN1), and suppressor of cytokine signaling 1 (SOCS1), which have been shown to play roles in the pathobiology of OC, was analyzed by quantitative (q)RT-PCR using Taqman probes. Results: The in vivo model demonstrated that mice tolerated all the treatment combinations well (PBS, IL-2, IFN, IL-2+IFN, MC, MC+IL-2, MC+IFN, MC+IL-2+IFN) without significant weight loss or other cytotoxicities. Mice receiving MC+IL-2 treatment showed improved survival at 9-weeks post-tumor cell injection (60%, p&amp;lt;0.05) vs. mice without treatment (20%), IL-2 (0%), or MC (20%). There was no significant survival advantage in mice receiving MC+IFN (40%) or MC+IL-2+IFN (20%). Harvested tumors consisted of poorly differentiated surface epithelial carcinoma, growing in solid nests and sheets of large cells with a moderate amount of amphophilic or clear cytoplasm. Tumor cells focally were pleomorphic and multinucleated. Mitoses were frequent with abnormal forms present indicating a high rate of proliferation. We found that all tumors analyzed expressed Survivin, MLH1, CCN1, and SOCS1; however, there was no significant correlation of gene expression level (&amp;gt; 3-fold change) with time to sacrifice, tumor volume, or ascitic fluid production. SOCS1 gene expression, which is known to down-regulate proangiogenic molecules, was up-regulated in IFN treated animals (3-fold increase) but not control animals or animals receiving IL-2. Conclusions: IFNα-2b up-regulates SOCS1 expression in our in vivo mouse model. Cytokine-stimulated cellular immune therapy produces an anti-tumor effect in vivo. This data strongly supports development of cellular therapy (autologous or allogeneic) and is a potentially useful therapeutic strategy for the treatment of OC. 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 3518. doi:1538-7445.AM2012-3518