Synthetic RNA-based regulatory systems are used to program higher-level biological functions that could be exploited, among many applications, for in vivo diagnostic and therapeutic applications. Chen and colleagues have recently reported a significant technological advance by producing an RNA modular device based on a hammerhead ribozyme and successfully tested its ability to control the proliferation of mammalian T lymphocytes. Like all exciting research, this work raises a lot of significant questions. How quickly will such knowledge be translated into clinical practice? How efficient will this system be in human clinical trials involving adaptive T-cell therapy? We discuss the possible advantages of using such new technologies for specific therapeutic applications.