title: In vivo biodistribution and lifetime analysis of cy5.5-conjugated rituximab in mice bearing lymphoid tumor xenograft using time-domain near-infrared optical imaging.
abstract: Rituximab is a chimeric monoclonal antibody directed against human CD20 antigen, which is expressed on B-cell lymphocytes and on the majority of B-cell lymphoid malignancies. Herein we report the conjugate of rituximab with the near-infrared (NIR) fluorophore Cy5.5 (RI-Cy5.5) as a tool for in vitro, in vivo, and ex vivo NIR time-domain (TD) optical imaging. In vitro, RI-Cy5.5 retained biologic activity and led to elevated cell-associated fluorescence on tumor cells. In vivo, TD optical imaging analysis of RI-Cy5.5 injected into lymphoma-bearing mice revealed a slow tumor uptake and a specific long-lasting persistence of the probe within the tumor. Biodistribution studies after intraperitoneal and endovenous administration were undertaken to evaluate differences in the tumor uptake. RI-Cy5.5 concentration in the organs after intraperitoneal injection was not as high as after endovenous injection. Ex vivo analysis of biologic tissues and organs by both TD optical imaging and immunohistochemistry confirmed the probe distribution, as demonstrated by imaging experiment in vivo, showing that RI-Cy5.5 selectively accumulated in the tumor tissue and major excretion organs. In summary, the study indicates that NIR TD optical imaging is a powerful tool for rituximab-targeting investigation, furthering understanding of its administration outcome in lymphoma treatment.
authors.affiliation: Optical Imaging Laboratory, CBM, Area Science Park, Trieste, Italy. stefania.biffi@cbm.fvg.it
authors.forename: Stefania
authors.initials: S
authors.lastname: Biffi
authors.forename: Chiara
authors.initials: C
authors.lastname: Garrovo
authors.forename: Paolo
authors.initials: P
authors.lastname: Macor
authors.forename: Claudio
authors.initials: C
authors.lastname: Tripodo
authors.forename: Sonia
authors.initials: S
authors.lastname: Zorzet
authors.forename: Erika
authors.initials: E
authors.lastname: Secco
authors.forename: Francesco
authors.initials: F
authors.lastname: Tedesco
authors.forename: Vito
authors.initials: V
authors.lastname: Lorusso
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D058846:Antibodies, Monoclonal, Murine-Derived; D001665:Binding Sites; D002232:Carbocyanines / Q000493:pharmacokinetics* / Q000627:therapeutic use; D002455:Cell Division / Q000187:drug effects; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007408:Intestinal Absorption; D008198:Lymph Nodes / Q000473:pathology; D008223:Lymphoma / Q000473:pathology*; D051379:Mice; D016513:Mice, SCID; D009368:Neoplasm Transplantation / Q000379:methods; D000069283:Rituximab; D014183:Transplantation, Heterologous / Q000473:pathology*
chemical_list: D000911:Antibodies, Monoclonal; D058846:Antibodies, Monoclonal, Murine-Derived; C098793:CY5.5 cyanine dye; D002232:Carbocyanines; D000069283:Rituximab