Abstract 5196: CSFR-1R a potential therapeutic target in 4T1 xenograft breast cancer model

The 4T1 cell line is a mouse mammary carcinoma which can mimic stage IV breast cancer in humans. When these cells are xenografted into a BALB/c mouse there is an infiltration of macrophages into the spleen, bone marrow and blood which was observed 11 days after engraftment. Increased cell proliferation was also detected in the spleen and blood. We found that 4T1 cells produced high levels of M-CSF in culture. In this study we attempt to neutralize the secreted cytokine from the tumor cells with anti-M-CSF (clone, A10603L) or to block the receptor with anti-M-CFR (CSF-1R) (clone, AFS98). Mice were xenografted with 4T1 cells then given one dose of 100 ug of neutralizing antibodies to either anti-M-CSF or anti-CSF-1R two days post tumor engraftment. Animals were sacrificed at multiple time points between 1-3 weeks. Treatment with one dose of anti-M-CSF showed minimal to no difference compared to the 4T1 xenograft group. Treatment with anti-CSF-1R showed reduced macrophage infiltration in the bone marrow, spleen and blood at day 11. BrdU incorporation levels dropped in the spleen and blood of these animals. Spleen size and total cell numbers were also reduced by 40% compared to the 4T1 xenograft group. Citation Format: Jeanne Elia, Hong Zhang, Chiaokai Wen, Xifeng Yang. CSFR-1R a potential therapeutic target in 4T1 xenograft breast cancer model [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5196.