Chimeric antigen receptor (CAR) T cells have proven that engineered immune cells can serve as a powerful new class of cancer therapeutics. Clinical experience has helped to define the major challenges that must be met to make engineered T cells a reliable, safe, and effective platform that can be deployed against a broad range of tumors. Here I will discuss a road opened CAR T cells for cancer that leads to therapies for HIV. The emergence of synthetic biology approaches for cellular engineering is providing us with a broadly expanded set of tools for programming immune cells that can be used to contain or confer elite controller status on patients with HIV. The convergence of the field of HIV and Cancer is driven in part because both are chronic conditions of antigen overload, where chronic infections and tumors can lead to phenocopies of acquired tolerance and antigen escape.