Choi, Yoonjeong Kim, Seong A. Jung, Hanul Kim, Eunhae Kim, Yoon Kyoung Kim, Seohyun Kim, Jaehyun Lee, Yeji Jo, Min Kyoung Woo, Jiwan Cho, Yakdol Lee, Dongjoo Choi, Hongyoon Jeong, Cherlhyun Nam, Gi-Hoon Kwon, Minsu Kim, In-San 2024-09-06T06:00:25Z 2024-09-06T06:00:25Z 2024-09-05 2024-07 2051-1426 https://pubs.kist.re.kr/handle/201004/150553 Background Triple-negative breast cancer (TNBC) poses unique challenges due to its complex nature and the need for more effective treatments. Recent studies showed encouraging outcomes from combining paclitaxel (PTX) with programmed cell death protein-1 (PD-1) blockade in treating TNBC, although the exact mechanisms behind the improved results are unclear. Methods We employed an integrated approach, analyzing spatial transcriptomics and single-cell RNA sequencing data from TNBC patients to understand why the combination of PTX and PD-1 blockade showed better response in TNBC patients. We focused on toll-like receptor 4 (TLR4), a receptor of PTX, and its role in modulating the cross-presentation signaling pathways in tumor-associated macrophages (TAMs) within the tumor microenvironment. Leveraging insights obtained from patient-derived data, we conducted in vitro experiments using immunosuppressive bone marrow-derived macrophages (iBMDMs) to validate if PTX could augment the cross-presentation and phagocytosis activities. Subsequently, we extended our study to an in vivo murine model of TNBC to ascertain the effects of PTX on the cross-presentation capabilities of TAMs and its downstream impact on CD8+ T cell-mediated immune responses. Results Data analysis from TNBC patients revealed that the activation of TLR4 and cross-presentation signaling pathways are crucial for the antitumor efficacy of PTX. In vitro studies showed that PTX treatment enhances the cross-presentation ability of iBMDMs. In vivo experiments demonstrated that PTX activates TLR4-dependent cross-presentation in TAMs, improving CD8+ T cell-mediated antitumor responses. The efficacy of PTX in promoting antitumor immunity was elicited when combined with PD-1 blockade, suggesting a complementary interaction. Conclusions This study reveals how PTX boosts the effectiveness of PD-1 inhibitors in treating TNBC. We found that PTX activates TLR4 signaling in TAMs. This activation enhances their ability to present antigens, thereby boosting CD8+ T cell antitumor responses. These findings not only shed light on PTX’s immunomodulatory role in TNBC but also underscore the potential of targeting TAMs’ antigen presentation capabilities in immunotherapy approaches. English BioMed Central Novel insights into paclitaxel's role on tumor-associated macrophages in enhancing PD-1 blockade in breast cancer treatment Article 10.1136/jitc-2024-008864 1 Journal for ImmunoTherapy of Cancer, v.12 Journal for ImmunoTherapy of Cancer 12 Y scie scopus 001300487100001 2-s2.0-85199015383 Oncology Immunology Oncology Immunology Article CROSS-PRESENTATION COMBINATION CELLS DELIVERY RECEPTOR SIGNALS TLR4 Combination therapy Immune Checkpoint Inhibitor Macrophage Toll-like receptor - TLR Breast Cancer