Several analogues were developed for the imaging of carcinoembryonic antigen (CEA) pretargeted with anti-CEA bsmAb [254, 259, 260], and two clinical studies of medullary thyroid carcinoma and breast carcinoma positive for CEA using 68Ga-labelled hapten molecules and bsmAb were initiated [261]. The gene discussed is CEACAM5; the disease is breast carcinoma.