Fuente: WIPO "tomato" A technology is described which provides a platform for improving the penetration into tumors in a subject of cancer treatment and cancer imaging agents for greater patient benefit. The invention in particular overcomes two challenges for use of tumor targeting methods for solid tumors: poor penetration and the immunosuppressive nature of the tumor microenvironment. The platform described here allows long-term, in vivo production of iRGD. In a preferred embodiment, CAR-T cells are engineered to secrete iRGD, a tumor-penetrating peptide to achieve tissue-penetrating delivery of drugs and imaging agents in a tumor-specific manner. The peptide acutely permeabilizes the tumor vasculature by binding to αv integrins and neuropilin, but in a tumor-specific manner. This method produces a modification in the tumor microenvironment that enhances drug access into the tumor, prevents distant metastasis of the tumor cells, and allows long-term iRGD therapy without the need for repeated injections of iRGD.