iMMune profiling comes of age. The study by Bruins et al provides evidence that immune profiling, even when solely focused in a single subset such as T cells, can be a proxy for overall biological health and uncover immune suppressive states resulting from host, tumor, and treatment-related factors. The authors show further evidence that when immune profiling is converted into a composite metric of immune age, it can help predict the risk of infection, treatment discontinuation, and survival better than the patients’ calendar age.