Many advances in new drugs and devices for the treatment of life-threatening diseases trace their success to a combination of (i) an in depth understanding of the etiology of the disease; (ii) the discovery of how to intervene in a safe and effective way; (iii) the development of a viable product concept and manufacturing process; and (iv) the design and implementation of the development program carefully linked to a commercialization plan that results in sufficient return on invested capital to justify taking financial risk. Innovative and risk-taking approaches are required all along the way. Success depends on the complex interplay of basic science, applied science and engineering, product development, and financial support from both the private and public sector. Notable examples include the discovery of pegylated interferon for treatment of chronic hepatitis C viral infection, the development of monoclonal antibodies, such as Rituxan®, for the treatment of non-Hodgkin's lymphoma, and Epogen®, for anemia. Future successes will come from an even better understanding of the workings of complex biological systems and how to direct them in a clinically meaningful way. One area of personal interest is directing the immune system to prevent and fight diseases. Drugs are in the late stages of clinical development for treatment of cancers and infectious diseases using an “immune engineering” approach.