Improved Staging of B-Cell Non-Hodgkin's Lymphoma Patients with 99mTc-labeled LL2 Monoclonal Antibody Fragment

Radioimmunodetection (RAID) with the 99mTc-labeled Fab′ fragment of monoclonal antibody (MoAb) LL2 has been reported to have a high lesion detection rate for malignant lymph nodes as well as for visceral and skeletal tumor masses (20). Our purpose in this study was to evaluate the safety and staging efficacy of the 99mTc-labeled Fab′ fragment of MoAb LL2 in patients with various grades and stages of B-cell non-Hodgkin's lymphoma (NHL). Thirty adult patients, 13 male and 17 female, ranging in age from 20 to 80 years, with at least one biopsy-proved malignant node (≥0.5 cm) and a Karnofsky performance score of ≥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 99mTc. RAID findings were compared with physical examination, chest radiography, computed tomography, magnetic resonance imaging, and bone and 67Ga scan 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 were correctly upstaged. The high-grade NHL patient was staged correctly by RAID. Infused doses of 99mTc-labeled LL2 Fab′ of 0.5 and 1.0 mg did not affect lesion sensitivity. The RAID sensitivity decreased as the total tumor burden increased ≥100 g. On the basis of these initial results, the 99mTc-labeled Fab′ fragment of MoAb LL2 (LymphoScan) seems to yield useful clinical information, especially for the staging of B-cell NHL patients who do not have bulky disease ( i.e. , tumor burdens of ≤100 g).