Abstract 6650: Macrophage pro-inflammatory phenotype skewing by the application of tumor treating fields (TTFields)

Abstract

Abstract Introduction: Tumor Treating Fields (TTFields) are low intensity electric fields that disrupt cellular processes critical for cancer cell viability. TTFields have previously been shown to induce immunogenic cell death, promote dendritic cell maturation, and elicit a systemic anti-cancer immune response in preclinical models. The benefit of applying TTFields together with immune checkpoint inhibitors (ICI) was demonstrated in a phase 3 study in non-small cell lung carcinoma. In the current research, we investigated possible effects of TTFields on regulation of macrophage phenotype. Methods: Bone marrow-derived macrophages (BMDMs) were generated from the femurs and tibias of 5-8-week-old Balb\C mice. LPS+IFN-γ or IL-4 were applied to the BMDMs to induce polarization (M1 and M2, respectively). The BMDMs were then treated with TTFields (150 kHz, 24 h), and then examined by flow cytometry for surface expression of the macrophage biomarker F4/80 and the activation markers CD80, major histocompatibility complex class II (MHC II), inducible nitric oxide synthase (iNOS), CD206, and ARG-1. Cell supernatants were collected and analyzed by multiplexed secretion assay for secretion levels of CXCL1 (KC), IL-18, IL-23, IL-12p70, IL6, TNF-α, IL-12p40, TGF-β1, CCL22 (MDC), IL-10, IL-6, G-CSF, CCL17 (TARC), and IL-1β. Cell lysates were examined using a RhoA activation kit and Western blot to determine GEF-H1, c-Jun, and p65 phosphorylation levels. Results: BMDMs exposed to TTFields demonstrated elevated expression of the pro-inflammatory M1 markers CD80+ and MHC IIhigh, and decreased expression of the M2 markers CD206 and ARG-1. A pro-inflammatory secretion pattern was detected, with increased levels of CXCL1, IL-18, IL-23, IL-12p70, TNF-α, IL-12p40, CCL22, G-CSF, CCL17 and IL-1β. The treated cells further demonstrated RhoA activation and GEF-H1 phosphorylation, with subsequent activation of the transcription factors c-Jun and p65. Conclusions: This study reveals a novel immunomodulatory role for TTFields, promoting in vitro pro-inflammatory polarization of macrophage. Citation Format: Tal Kan, Yiftah Barsheshet, Boris Brant, Tharwat Haj Khalil, Tali Voloshin, Alexandra Volodin, Lilach Koren, Bella Koltun, Anat Klein-Goldberg, Efrat Zemer-Tov, Rom Paz, Adi Haber, Moshe Giladi, Uri Weinberg, Yoram Palti. Macrophage pro-inflammatory phenotype skewing by the application of tumor treating fields (TTFields) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6650.