Since the first EGFR targeting antibody panitumumab (Vectibix) from humanized mice has obtained regulatory approval in 2005, dozens of additional transgenic mouse-derived mAbs have entered human clinical testing, i.e., CD20 (Ofatumumab), CD4 (Zanolimumab), CD70, etc. These genetically "humanized" animals have become one of the most powerful strategies for therapeutic/ diagnostic antibody development, which is now the fastest growing group of mAb drugs in clinical trials currently.