CD4 and breast cancer: Additionally, using in vitro assembloids that replicate the TME of HER2 + breast cancer, as shown in Fig. 5, using either miR-19a-3p-expressing or non-expressing modified cells (including HER2 + tumor cells, NK cells, CD8 + CTL, CD4 + Th1 cells, and macrophages), can provide further insights into the cellular origin of circulating miR-19a-3p and the macrophage-mediated ADCC and ADCP [73, 112, 113].