In vivo radioimmunodetection of neuroplastoma

Ten children, aged 6 months to 13 years, with histologically confirmed undifferentiated neuroblastoma were tested at diagnosis using radiolabelled monoclonal antibody UJ13A. Six of these patients were also investigated after completion of induction chemotherapy. The purified antibody was labelled with 1 mCi 111In (12 instances) or 0.5 mCi 131I (4 instances). Whole body scans using a gamma camera were obtained between 24 and 72 h after injection. A complete staging including 24 h urinary catecholamines, abdominal ultrasound, CT scan, skeletal survey, bone scan and bone marrow biopsies was performed for each patient during the same time period. Seven children were Evan's stage IV, two stage III and one stage II with lymp-node involvement. At diagnosis, the labelled antibody detected 29 out of 38 know lesions (76%). It also detected 10 lesions not demonstrated by other methods. After completion of induction chemotherapy, the labelled antibody detected 6 out of 10 known lesions (60%) and 4 lesions not shown by conventional methods. In 7 instances (3 at diagnosis and 4 after chemotherapy) radioimmunodetection and conventional techniques were in full agreement. The scintigrams obtained with 111In radiolabelled UJ13A monoclonal antibody offered better quality images. Absence of 111In bladder activity was another advantage over 131I, especially in the patients with pelvic mass. However, uptake of 111In in the reticuloendothelial (RE) system appeared to be more important than RE uptake of 131I