The insulin-like growth factor 1 receptor (IGF-1R) mostly employs in the Ras/MAPK and phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) pathways. IGF-1R also cross-talks with the EGFR pathway. This receptor is overexpressed in different human cancers, such as breast, colorectal, lung, and prostate. mAb with inhibitory effect on IGF-1R signaling are classified in two categories, including mAb against IGF-1R and mAbs against IGF-1R ligands (IGF-1 and IGF-2).