IGFBP7 and neoplasm: As sdAbs have a blood half-lives in the range of 20–30 min and are completely cleared from the blood within the first few hours (Iqbal et al, 2010) after injection, the high tumour signal detected at 4 and 24 h with anti-IGFBP7 sdAb-Cy5.5, which was competitively attenuated in the presence of the excess of unlabelled anti-IGFBP7 sdAb, indicates retention of the antibody in the tumour due to its binding to the tumour-expressed antigen.