In the contemporary landscape marked by simultaneous approvals of new drugs for breast cancer by the FDA, the complexity of determining optimal treatment selection and sequencing for enhanced response rates and prolonged survival has become increasingly pronounced. Our research delves into a personalized approach to cancer care for individuals with breast cancer, leveraging ex-vivo organ cultures alongside extensive analyses of large datasets and clinical databases. The objective is to discern molecular regulators and biomarkers that play pivotal roles in the mechanisms of resistance within breast cancer. By doing so, we aim to optimize drug selection strategies for patients diagnosed with breast cancer, ultimately advancing the precision and effectiveness of treatment protocols.