The long-term objectives of this prject are to produce a radiolabeled monoclonal antibody which will be used for imaging diseased parathyroid tissue. The development of this technology would provide surgeons with preoperative knowledge of the precise location(s) of the parathyroid glands, resulting in shorter and more direct surgical procedures which will provide patients with reduced morbidity. The basis for the proposed technique is monoclonal antibody (Mab) BB5-G1 which has specificity for antigens on the surface of parathyroid tissue, and can be mass produced in proprietary bioreactors by Invitron Corporation. The monoclonal antibody will be labeled with 111In via DTPA technique, and will be injected into patients bearing forearm autografts of parathyroid tissue. As a comparison, the forearm grafts will also be imaged with high resolution ultrasound, and organ dosimetry of the injected radionuclide will be determined. If there are no adverse reactions, a second series of patients with primary hyperparathyroidism will be injected with the previously determined optimum dose of 111In-BB5-G1 and imaged at the appropriate time. Far comparison purposes, these patients will also be imaged with thallium-technetium subtraction imaging. Patients will then have their diseased parathyroid tissue removed and imaging results will be correlated with surgical and pathological findings. Simultaneous with imaging studies, work will proceed on second generation imaging reagent development. These technical improvements will include the use of F(ab')2 fragments, the development of new monoclonal antibodies with improved characteristics, and the development of improved labeling procedures.
