In the first experiment, breast cancer cells (BT474 cell line, representative of HER2 + breast cancer subtype) were co-cultured in 3D biomimetic gels, within microfluidic devices, with immune cells (PBMCs, peripheral blood mononuclear cells from healthy donors); the addition of an immunotherapy drug, the Trastuzumab (brand name Herceptin), increases cancer-immune cell interactions12. Here, ERBB2 is linked to breast cancer.