We have created a genetically engineered machine to identify, isolate and eliminate Cancer Stem Cells (CSCs). According to the latest Cancer Stem Cell Theory, not all the cancer cells have the same ability to generate new tumors. Tumor growth is mostly driven by a small proportion of cells, the CSCs. In addition to having high proliferation rates, CSCs are more resistant to chemotherapy. This indicates that while regular cancer cells are killed, CSCs may remain unaffected and give rise to new tumors once the treatment stops. CSCs produce increased levels of a particular enzyme, Aldehyde Dehydrogenase. We have identified its 3 most frequent isoforms (ALDH1A1, ALDH1A3 and ALDH3A1)in aggressive types of cancer, and used their gene promoters to build our CSC-targeting constructs: the iSTEM -Intelligent Synthetic Tumor Eliminating Machine.