We use genetic engineering technologies in human tissue and patient-derived cancer cells to provide cost-effective in vitro assays to predict the efficacy and safety of drugs in human cells and organs. In addition, these genetically engineered human patient-derived cells can be transplanted back into rodent models to study and optimize RNAi and CRISPR-based therapeutics in a whole organism. Mirimus' in vitro assays empower researchers to investigate factors that underpin pathogenesis, resistance, and susceptibility to cancer, and to discover entirely new set of potential targets.