Systemic tumor-cell reprogramming converts solid tumors into in situ biofactories for immunotherapy

A central challenge in oncology is delivering potent drugs to tumors without harming healthy tissues. We therefore asked whether tumor cells themselves could be genetically programmed to produce therapeutic molecules directly within the tumor. We present LENTRA (LENtiviral Tumor-Reprogramming Activator), an antigen-targeted lentiviral platform that enables selective transduction and genetic modification of tumor cells in vivo. Following intravenous administration, LENTRA achieves tumor restricted expression of immune checkpoint inhibitors, cytokines, or therapeutic enzymes in multiple murine solid tumor models. Local production of anti CTLA 4 or IL 12 triggered potent antitumor responses while avoiding systemic toxicities. Tumor restricted secretion of sialidase enhanced dendritic cell and T cell infiltration, and reprogrammed tumor associated macrophages toward an immunostimulatory phenotype, resulting in tumor regression and durable immune memory, including in tumors with heterogeneous antigen expression. In patient derived tumor explants, LENTRA mediated efficient transduction, immune remodeling, and reduced tumor viability. By engineering tumors to produce therapeutic proteins, LENTRA converts resistant tumors into autonomous therapeutic sources and active immune hubs, achieving local TME reprogramming and systemic antitumor immunity with an improved safety profile.