Since the millennium, personalized medicine has been at the forefront of therapeutic endeavors in medical oncology. The latest technology has given researchers the ability to define cancer at its molecular core. This has led to the development of “targeted therapies,” designed to eliminate driver mutations while leaving healthy cells unscathed. Unfortunately, more than 10 years into the targeted molecular therapy era, successes have been infrequent, and toxicity remains largely unchanged compared with relatively indiscriminant, traditional chemotherapy. Emerging data suggests that the malignant clonal heterogeneity within solid tumors is so diverse that targeting one or even several mutations is likely to have minimal, transient impact. In recent years, new therapies have emerged that can effectively stimulate the immune system and improve survival in patients with metastatic disease. Through immune activation, there is the potential to target the cancer with a biologic diversity that can potentially rival the multiplicity of malignant mutations within tumors. Stimulating the immune system to become an evolving adversary against malignant cells may revolutionize cancer therapy in the years to come.