FIGURE 2.

Verification of tumor homing ability of IVO phages in vivo. A, IVO phages homed to a variety of human cancer xenografts. SCID mice bearing human lung (H460), colon (HCT116), breast (BT483), prostate (PC3), pancreatic (PaCa-2), and liver (Mahlavu) cancer xenografts were injected intravenously with IVO or control phages. After perfusion with PBS buffer, xenograft tumor masses were removed, and phage titers were measured. Phage titer in control organs compared with tumor tissues is indicated. The level of IVO phage titer in the tumor masses was markedly higher than in the tissues of control organs in all of the human cancer xenografts. B and C, SCID mice bearing lung cancer xenografts were injected intravenously with IVO phages or phages plus peptides, and phages were recovered after perfusion. The titer of IVO phages recovered from tumor tissues was higher than that from control lungs. The targeting activity of IVO phages to tumor tissues was competitively inhibited by their cognate peptide PIVO but not by other peptides.