In recent years, one of the ex vivo gene therapies, Chimeric Antigen Receptor (CAR)-T cell therapy, has been approved for refractory blood cell cancers, including leukemia, and its clinical use is increasing. CAR-T cells are genetically modified T cells that can bind and kill leukemia cells through the introduction of a CAR gene. Currently CAR-T therapy involves autologous transplantation, whereby T cells are extracted from the patient, the CAR gene is introduced and then the cells are subsequently returned to the patient. The most common method to introduce the CAR gene is through the use of lentiviral vectors. We are engaged in the development of next-generation cancer treatments that employ CAR genes and leverage on the lentiviral vector technologies that we have cultivated in our research for leukemia and cancer. Furthermore, lentiviral vectors, that allow long-term, stable gene expression, are attracting interest in the context of in vivo gene therapy for genetic disorders. In our laboratory, we are developing methods to produce lentiviral vectors that can be administered in vivo, taking advantage of our expertise in the optimization of AAV vector production.