English: Key clinical uses of lentiviral vectors. a Correction of primary immunodeficiency. Using a viral vector to deliver the common gamma chain (γc) restores immune function in patients with SCID-X1. b Delivery of a tumor-specific T-cell receptor (TCR). A lentiviral vector can be used to introduce the MART-1 TCR, which recognizes a melanoma antigen, into a patient’s T cells ex vivo. The modified T cells, which now recognize melanoma cells, are administered to the patient as a cancer therapy. c Chimeric antigen receptor (CAR) T-cell therapy. A CAR engineered from three distinct domains (antigen recognition, co-stimulatory signaling, and T-cell signaling) can be introduced into T cells using a lentiviral vector. The cells expressing the modified receptor recognize the antigen of interest and harness the potent cytotoxic activity of T cells to attack tumor cells. Currently, most CAR T-cell therapies in clinical trials target the CD19 antigen, a protein expressed on B cells and B-cell malignancies. SCID severe combined immunodeficiency