A 3E8.scFv.Cys-IR800 Conjugate Targeting TAG-72 in an Orthotopic Colorectal Cancer Model.

ABSTRACT: PURPOSE:Optical surgical navigation (OSN) will be a potent tool to help surgeons more accurately and efficiently remove tumors. The purpose of this study was to evaluate a novel humanized 3E8 antibody (3E8 MAb) fragment site-specifically conjugated with IR800, 3E8.scFv.Cys-IR800, as a potential OSN agent to target colorectal adenocarcinoma. PROCEDURES:An engineered single-chain variable fragment of 3E8 MAb (targeted to TAG-72), appending a C-terminal cysteine residue (3E8.scFv.Cys), was created and reacted with IRDye800-maleimide. 3E8.scFv.Cys-IR800 identity and purity were verified by MALDI-TOF mass spectra and 800 nm detected size exclusion column HPLC. In vitro human colon adenocarcinoma LS-174 T cells binding and competition assay validated biological functionality. We further evaluated the imaging ability and receptor-specific binding of 3E8.scFv.Cys-IR800 in an orthotopic LS-174 T mouse model. RESULTS:A 1:1 dye to protein conjugate was achieved at greater than 90 % HPLC purity. A 1 nmol dose of 3E8.scFv.Cys-IR800 via intraperitoneal injection administration was sufficient to produce high tumor to background fluorescence contrast. Blocking competition studies both in vitro and in vivo using a different blocking protein, 3E8?CH2, demonstrated 3E8.scFv.Cys-IR800 binding specificity for TAG-72 antigen. CONCLUSIONS:3E8.scFv.Cys-IR800 shows properties useful in a clinically viable OSN agent for colorectal cancer.

SUBMITTER: Gong L 

PROVIDER: S-EPMC5885140 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature