IMPROVED STAGING OF B-CELL NON-HODGKINS-LYMPHOMA PATIENTS WITH TC-99M-LABELED LL2 MONOCLONAL-ANTIBODY FRAGMENT

Radioimmunodetection (RAID) with the Tc-99m-labeled Fab' fragment of m onoclonal antibody (MoAb) LL2 has been reported to have a high lesion detection rate for malignant lymph nodes as well as for visceral and s keletal tumor masses (20), Our purpose in this study was to evaluate t he safety and staging efficacy of the Tc-99m-labeled Fab' fragment of MoAb LL2 in patients with various grades and stages of B-cell non-Hodg kin's lymphoma (NHL). Thirty adult patients, 13 male and 17 female, ra nging in age from 20 to 80 years, with at least one biopsy-proved mali gnant node (greater than or equal to O.5 cm) and a Karnofsky performan ce score of greater than or equal to 60% were enrolled in this study. Patients underwent selected planar and single photon emission computed tomographic imaging at 6 and 18 h after receiving an i,v. infusion of 0.25-1 mg of LL2 Fab' fragment labeled with 25-30 mCi of Tc-99m. RAID findings were compared with physical examination, chest radiography, computed tomography, magnetic resonance imaging, and bone and Ga-67 sc an findings, The RAID scan was positive in all but three patients, The sensitivity for known lesions was 90% and for suspected lesions, 89%, with an overall positive predictive value of 96%. Twenty-nine of the 30 patients had either low- or intermediate-grade NHL. Fifteen of 16 ( 94%) low-grade patients were correctly staged by RAID; three of these patients were correctly upstaged, Twelve of the 13 (92%) intermediate- grade patients were correctly staged by RAID; two of these patients we re correctly upstaged, The high-grade NHL patient was staged correctly by RAID. Infused doses of Tc-99m-labeled LL2 Fab' of 0.5 and 1.0 mg d id not affect lesion sensitivity, The RAID sensitivity decreased as th e total tumor burden increased greater than or equal to 100 g. On the basis of these initial results, the Tc-99m-labeled Fab' fragment of Mo Ab LL2 (LymphoScan) seems to yield useful clinical information, especi ally for the staging of B-cell NHL patients who do not have bulky dise ase (Le., tumor burdens of less than or equal to 100 g).