This article explores the development of T cell-based therapies in Switzerland. These therapies, which elicit the immunological potential of each patient to respond to tumor development, constitute a major promise for so-called ‘precision oncology’. We document how immunological concepts, technologies, and practices are articulated given the centrality of genomics in ‘precision oncology’. We consider ‘precision immunotherapies’ to probe whether and how change ensues in these established sociotechnical regimes of biomedicine. The case of genomics and immunology in oncology offers a unique insight into the conditions of possibility for change in such regimes. How does the present new wave of cancer immunotherapies challenge, integrate, and complement the centrality of genomics in ‘precision oncology’? What are the specific processes that make possible the convergence, competition, or co-existence of distinct conceptions, infrastructures, and programs of innovative cancer medicine? Drawing from observations and interviews with researchers and clinicians, we qualify these sociotechnical processes as hybridizations. Bringing together different sociotechnical regimes of biomedical research is conditional to the articulation of core concepts, technologies, and translational practices of genomics and immunology. Pivotal to this objective are neoantigens, cell surface proteins originating from the somatic genetic mutations of tumors and which activate a patient’s immune response. While neoantigens are an unstable entity in experimentation, they offer a conceptual and material substrate to renegotiate the dominance of cancer genomics, and initiate the production of a new, hybrid regime of ‘immunogenomic precision’ in oncology.