Developing and applying cancer genomics in both research and healthcare has been a French national priority for more than ten years. In 2006, following the first authorization to market a targeted therapy conditioned on a genetic test, and a competitive call for proposals, the French National Cancer Institute (INCa) and the French Ministry of Health set up a national network of 28 approved regional molecular genetics platforms (Nowak et al, 2012). These platforms are funded annually to perform the molecular tests needed to deliver targeted therapies to all patients in their respective regions, regardless of the institution where they are treated. Although these platforms all respect the quality insurance and organizational guidelines drafted by INCa, they vary in their institutional trajectory, size and modes of organization.To better understand how genomic platforms function on a daily basis, we conducted a collective exploratory ethnographic study of one of these regional platforms, located in a public university hospital of the Auvergne‐Rhône‐Alpes region (CHU de Grenoble). Based in a general hospital that is not a comprehensive cancer centre, this platform provides a relevant site for observing and analysing the organizational, professional and epistemic issues that are raised by the routinization of oncogenomics.In this presentation, we describe and analyse the trajectory of a solid tumour biopsy from its entry into the platform to the writing of the molecular report sent to prescribing clinicians. Our analysis focuses on key moments in the course of this trajectory. We highlight the ways in which the platform brings together social worlds with little previous collaborative experiences. We describe the negotiations and efforts to coordinate the work of different sites and forms of expertise in a context where novel genomic technologies must be “domesticated”. We show how local context and history influence the solutions adopted and report the importance of tinkering practices. Interestingly, strategies to manage varying degrees of personal engagement appear to be central to the success of this collective implementation of personalized medicine.