VPAC1 Receptors for Imaging Breast Cancer: A Feasibility Study

VPAC1 encodes G-protein coupled receptors expressed on all breast cancer (BC) cells at the onset of the disease, but not on benign lesions. Our extensive preclinical studies, have shown that Cu-64-TP3805 has a high affinity for VPAC1, is stable in vivo and has the ability to distinguish spontaneously grown malignant BC masses from benign lesions. Our long term goal is to develop Cu-64-TP3805 as an agent to perform in vivo histology, to distinguish malignant lesions from benign masses noninvasively and thereby avoid patient morbidity and excess economic costs of benign biopsies. METHOD F-18-FDG obtained commercially served as a control. Cu-64-TP3805 was prepared by using a sterile kit containing 20 µg TP3805. Radiochemical purity and sterility were examined. Nineteen consenting females with histologically proved BC were given 370 MBq F-18-FDG. One hr later, 6 of these patients were imaged with PET/CT and 13 with PEM (positron emission mammography). Two to seven days later, 6 PET/CT patients received 111±10% MBq (n=2), 127±10% MBq (n=2) or 148±10% MBq (n=2) Cu-64-TP3805 and imaged 2 hr and 4 hrs later. Thirteen PEM patients received 148±10% MBq Cu-64-TP3805, and imaged at 15 min, 1 hr, 2 hr and 4 hr post injection. For PET/CT patients SUV was calculated and for PEM patients PUV/BGV (PEM uptake value/background value) determined. Tumor volume was also calculated.