Optical imaging with A11 Mb-IRDye800CW enabled detection of orthotopically implanted intraprostatic tumors and metastatic lesions in human PSCA knock-in transgenic mice. A, bioluminescence image of the prostate tumor and metastasis (red arrow) (left top panel). Optical images of the orthotopic tumor, mesentery (yellow arrowhead) and lumbar LNs (yellow dotted line) metastases under bright field and fluorescence. Fluorescence imaging with A11 Mb-IRDye800CW detected the orthotopic tumor and multiple LNs metastases. Nonspecific fluorescent signals in the liver and kidneys are due to the clearance of probe. B, ex vivo optical imaging for evaluation of probe biodistribution in transgenic mouse. C, H&E and IHC staining for human PSCA confirmed the presence of tumor cells and PSCA expression in the prostate and metastatic lumbar LNs. B, bladder; P, prostate tumor; L, liver; K, kidney; LN, lymph node.