The promise of stem cell therapy for various clinical applications seems getting realistic. An increasing number of researchers, from virtually every discipline of natural sciences, are flocking into this new world. Only ten years ago, gene therapy was the medicine for the 21st century. The possibility was endless. Although the science itself underlying gene therapy was very young, the field was exploding under the optimism that this new medicine would revolutionize both the basic and clinical sciences. For many reasons, the initial target was cancer. Here, we will focus on the results of cancer gene therapy clinical trials using liposome or nonviral gene carrier, hoping that the lesson from here will be a guideline for the new generation of cell-based therapies.