CEACAM5 and neoplasm: The molecular targets for nanobody-based tumor imaging are summarized in Table 1, including epidermal growth factor receptor (EGFR1 or HER1) [26–29], HER2 [23, 30–33], HER3 [34], hepatocyte growth factor (HGF) [35], and carcinoembryonic antigen (CEA) [36].