Abstract 3624: Activation of tumor specific antibody response following systemic delivery of receptor targeted nanoparticles into Balb/c mice bearing mouse mammary tumors
Authors: Ward Christina , Qian Weiping , Yang Emmy , Bozeman Erica , Wang Y. Andrew , Yang Lily 
Published: May 2015

Abstract
Targeted nanoparticles (NP) offer a great opportunity for developing new cancer imaging agents and targeted drug delivery carriers. Although increasing evidence supports the potential of the targeted NP for early cancer detection and drug delivery, the impact of systemic delivery of targeted NP on the immune response in the tumor has yet to be addressed. The possible immune enhancement effect of NP has attracted great attention to apply various NP for vaccine development since NP can be nonspecifically taken up by macrophages. In this study, we developed epidermal growth factor receptor (EGFR) receptor-targeted dual imaging modality magnetic iron oxide NP (IONP) using single chain antibody to EGFR (ScFvEGFR) without or with chemotherapy drug doxorubicin (Dox) for targeted tumor imaging and therapy of triple negative breast cancer. The NP were injected into normal Balb/c mice or mice bearing 4T1 mammary tumors once per week for three weeks, then serum and tumors were collected. Systemic delivery of the receptor-targeted NP led to accumulation of NP in the tumors and inhibited tumor growth. Using ELISA on tumor cell lysates and intact tumor cells, we found that mouse serum from targeted IONP had the highest level of mammary tumor specific antibody titers compared to mice that received Dox only, non-targeted NP and no treatment control. However, the antibody titer was decreased in the mice that received ScFvEGFR-IONP-Dox. To understand the antibody activation mechanism by targeted delivery of ScFvEGFR-IONP but not ScFvEGFR-IONP-Dox, we examined changes in the amount, phenotype, and localization of antigen presenting macrophages using a pan-macrophage (CD68) and M2 macrophage (CD163) and also dendritic cells (CD83) markers in frozen tumor tissue sections. Results of double labeling immunofluorescence against CD68 and CD163 showed the majority macrophage subtype at the tumor edge was M2 for the tumors treated with ScFvEGFR-IONP with and without Dox. However, in the central tumor area M1 macrophages was the main phenotype in ScFvEGFR -IONP-Dox treated tumors while ScFvEGFR -IONP still expressed majority M2. Also, a higher level of CD83+ cells infiltrated into the central tumor area of ScFvEGFR-IONP compared to ScFvEGFR-IONP-Dox. Results of our study suggest that targeted delivery of ScFvEGFR-IONP into tumor is able to activate intratumoral macrophages and dendritic cells to antigen presentation and stimulate tumor specific antibody responses while ScFvEGFR-IONP-Dox had decreased amounts of CD163 and CD83. Therefore, targeted delivery of NP into tumors and infiltration of antigen-presenting macrophages into the center of tumors are important for the activation of tumor specific antibody responses. This study could have clinical implications in development of NP imaging and therapy agents for cancer detection and treatment.
Citation Format: Christina Ward, Weiping Qian, Emmy Yang, Erica Bozeman, Y. Andrew Wang, Lily Yang. Activation of tumor specific antibody response following systemic delivery of receptor targeted nanoparticles into Balb/c mice bearing mouse mammary tumors. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3624. doi:10.1158/1538-7445.AM2014-3624