IMMUNOSCINTIGRAPHY OF BONE SARCOMAS - RESULTS IN 5 PATIENTS

The feasibility of using the murine monoclonal antibody, TP-1, for cli nical immunoscintigraphy was examined in a pilot study involving 5 pat ients with bone sarcomas. I-131-labelled F(ab')(2) antibody fragments were injected in doses of 0.8-1.0 mg (90-130 MBq), and the accumulatio n of radioactivity was examined by scintigraphy, and assessed by direc t measurements on biopsied tumour and normal tissue. One osteosarcoma patient had a primary tumour in the femur, whereas the other 4 had sin gle lung metastases detected by other diagnostic methods. Immunoscinti graphy of the femoral primary was optimally visualised after 22 h. In 2 patients, the method failed to detect lung metastasis, in 1 of the c ases possibly related to less than optimal methodological conditions. In 2 other patients, increased accumulation of radioactivity indicated one and three lung tumours, in addition to the single metastasis obse rved by X-ray and CT scanning, tumours that were later confirmed and r emoved surgically. The concentration of radioactivity in tumour and no rmal tissues 44-72 h after antibody injection could be measured in 4 p atients. The tumour to blood ratios were in the range of 1.2-4.2, comp ared to 0.1-0.8 for various normal tissues. The results indicate that immunoscintigraphy with TP-1 antibody fragments have a potential for e arly detection of lung metastases in patients with bone sarcoma.