Abstract 6136: Efficacy of LPS, flagellin, IFN-g, and sCD40L treated bone marrow-derived macrophages in murine mammary carcinoma

Abstract Previously we reported that treating bone marrow-derived macrophages (BMDM) with poly(I:C), IFN-γ, and sCD40L generated BMDM with more consistent anti-tumor activity than BMDM generated with the agonists alone. These BMDM also showed significant anti-tumor activity against the EMT6 and 168 murine mammary carcinoma models. However, the BMDM showed no activity against the 4T1 murine mammary carcinoma model. Here we asked whether BMDM generated with IFN-γ and sCD40L in combination with other TLR agonists would have greater anti-tumor activity than the poly(I:C) generated BMDM. For this purpose we generated BMDM and then activated them with IFN-γ, sCD40L, and either LPS, flagellin or R848. BMDM generated with a combination of four agonists (IFN-γ, sCD40L, LPS and flagellin) were also evaluated. Based on in vitro analysis these treatments led to a significant increase in nitrite and IL-12 production, and the levels of nitrite and IL-12 were significantly greater than the levels produced by the poly(I:C) generated BMDM. All treatments also led to a significant increase in expression of il-1b, il-6, tnf-a, il-18, ccl5, cxcl9, cxcl10 and cxcl11. Moreover, the LPS, flagellin and R848 generated BMDM often expressed a significantly higher level of cytokines than the poly(I:C) generated BMDM. All treatments led to a significant increase in MHC Class II or CD80 expression, but only BMDM generated with IFN-γ, sCD40L, LPS, flagellin and BMDM generated with IFN-γ, sCD40L and LPS showed a significant increase in both MHC Class II and CD80 expression. Furthermore, BMDM generated by these same treatments showed significant anti-tumor activity against all three murine mammary carcinoma models; EMT6, 168, and 4T1. Depletion studies revealed that the BMDM exerted anti-tumor activity against the 4T1 and EMT6 tumors by recruiting CD8+ T cells and NK cells suggesting that expression of ccl5, cxcl9, cxcl10, and cxcl11 may be critical for the in vivo anti-tumor activity of these BMDM. Citation Format: Robert A. Kurt, Joshua Finn, Melissa Lass, Ernesto Oviedo-Bermudez. Efficacy of LPS, flagellin, IFN-g, and sCD40L treated bone marrow-derived macrophages in murine mammary carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6136.