Anti-MUC4 antibodies bound to modified lentiviruses drive efficient gene transfer in vivo in CAPAN2 cells. (A) CAPAN2 cells were grafted subcutaneously in the right flanks of immune-deficient recipient mice. When tumors reached about 100 mm3, lentiviruses carrying the luciferase reporter gene combined with anti-MUC4, anti-CLDN18 (PDAC targeting antibodies), anti-HLA (positive control for the targeted gene transfer), rabbit IgGs (ISO, negative control for the targeted gene transfer) or packaged into the broad tropism VSV-G-containing envelope (positive control) were directly injected in the tumors (n = 3 in each group). Two weeks after virus injections luciferase signal was measured in anesthetized live animals with a photon imager apparatus. (B) Quantification of luminescence in photons/steradiant/s (ph/sr/s) was divided by tumor mass in mg, since tumor mass could be very different in individuals after resection, and is expressed as a percentage of VSV-G positive control. Red circles depict the zones used for quantification (same size for all the mice). The black arrow points the area measured for background signal determination. Student’s t tests against the VSV-G condition were statistically different for ISO (p = 0.04) and CLDN18 (p = 0.05). (C) Western-blot analysis of luciferase expression in the previous tumor extracts. The negative control (CTNEG) corresponds to a tumor extract of untransduced CAPAN2 cells. The positive control (CTPOS) was obtained from a tumor derived from CAPAN2 cells transduced with a lentivirus bearing the bicistronic transgene LUCIFERASE-IRES-ZsGREEN. Extracts obtained from tumors transduced by oncospecific lentiviruses are identified according to the target cell surface antigen. ISO: rabbit IgGs.