Radioimmunodetection of non-Hodgkin`s lymphoma with radiolabelled LL2 monoclonal antibody. Preliminary results

Radioimmunodetection (RAID) with 99m technetium labelled B cell lymphoma monoclonal antibody (MAb) (IMMU-LL2 Fab`, Immunomedics, Inc., Morris Plains, N.J.) was investigated in 8 patients (5 female and 3 male; age range 20-72 years) with histologically proven non-Hodgkin`s lymphoma (NHL). Of the 8 lymphomas, 5 were intermediate grade and 3 low grade. Whole body images with multiple planar views were obtained at 30 min, 4-6 and 24 hours after the I.V. injection of 1 mg LL2-Fab` labelled with 20-25 mCi (740-925 MBq) {sup 99}Tc. SPECT of chest or abdomen was performed at 5-8 hours after injection in all patients. No adverse reactions were observed in any patient after MAb infusion and no appreciable changes were seen in the blood counts, renal and liver function tests. A total of 17 of 18 (94.4%) lymphoma lesions were detected by RAID. All the tumor localizations were confirmed by clinical examination and with other imaging techniques, such as CT scan, MRI or gallium scan. In this series of patients no false positive results were noted and only 1 false negative resulted in a patient who had a mediastinal bulky disease. As regard the biodistribution of the immunoreagent we can make the following conclusions: (1) nomore » appreciable bone marrow activity was seen, (2) splenic targeting was demonstrated in all patients, (3) tumor-to-non tumor ratios ranged from 1.2 to 2.8 as measured by ROI technique, (4) no difference of uptake was noted for different tumor grades. The images performed 24 hours after injection did not detect new lesions, but areas of doubtful uptake were seen as positive focal areas in the delayed scan. In these preliminary results the LL2-Fab` MAb seems to be useful for detection, staging and follow up of NHL patients.« less