The emergence of immunotherapies has represented a powerful addition to the cancer arsenal, but frequently they fail to deliver benefits to patients. Understanding what therapies will benefit which patients remains a challenge because of the complexity of the immune system. Immunai is applying artificial intelligence to map the immune system and understand its complexities at a granular level to better understand its role in health and disease. It is applying what it learns to avoid clinical trial failures, improve combinations of immunotherapies, and guiding future therapeutic development in cancer and a broad range of other conditions. We spoke to Danny Wells, scientific founder of Immunai, about the company’s efforts to map the immune system, the challenges in doing so, and how this has the potential to improve drug development.