Abstract 2728: Modulation of NFkappaB signaling influences tumor associated macrophage phenotypes in murine models of breast cancer

Abstract Tumor associated macrophages (TAMs) often exist in high densities in breast tumors and are associated with adverse clinical outcomes. TAM repolarization as a strategy to shift the breast cancer microenvironment from immunosuppressive to immunostimulatory is an active area of research. The canonical and non-canonical NfkappaB (NFkB) signaling pathways represent potential points of intervention to influence TAM phenotypes. We have found that upregulation of the canonical NFkB signaling pathway specifically in macrophages can be used to repolarize TAMs toward an M1, anti-tumor phenotype. Using our doxycycline inducible mouse model termed IKFM, we are exploring the effects of macrophage specific upregulation of NFkB signaling on different stages of tumor growth and metastasis. In studies using the IKFM mouse model, we found that doxycycline-induced NFkB activation in macrophages in established orthotopic mammary tumors has therapeutic effects on tumor outcomes. Compared to control mice, we found that IKFM mice have reduced tumor burden in the lung, indicating prevention of metastasis. Ongoing studies are focused on understanding how macrophage specific activation of NFkB influences the metastatic niches of lung and bone; two of the most common sites of breast cancer metastasis. To move our findings towards clinical translation, we have developed an M2-macrophage targeted nanoparticle that activates NFkB signaling by delivering an siRNA against IkappaBalpha, an inhibitor of the pathway. The M2 targeted nanoparticle is currently being tested in murine models of breast cancer metastasis to both lung and bone to translate our findings from the IKFM mouse model to a pharmacological manipulation. Citation Format: Kennady K. Bullock, Dominique Parker, Evan B. Glass, Alyssa Hoover, Alyssa Merkel, Richard Maynard, Andrew Wilson, Todd Giorgio, Julie A. Rhoades, Fiona E. Yull. Modulation of NFkappaB signaling influences tumor associated macrophage phenotypes in murine models of breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2728.