The gut microbiota plays a critical role in human health, influencing immune responses, efficacy and toxicity of pharmacological treatments, including chemotherapy. Despite its recognized importance, the precise mechanisms by which the microbiota modulates chemotherapy efficacy and contributes to drug-induced gastrointestinal toxicity (DIGIT) remain unclear. This gap in knowledge mainly due to the poor availability of fully humanized, physiologically relevant multiorgan in vitro models. Building on existing evidence, this work thesis aims to develop a novel triculture human gut model fluidically connected to a 3D breast cancer model, using a multi-compartmental multiorgan on chip platform, resembling both the gut lumen and the circulatory circuit, where cisplatin, a commonly used chemotherapeutic drug, circulates.