Radioimmunoscintigraphy (RIS) with bectumomab (Tc99m labeled IMMU-LL2, Lymphoscan) in the assessment of recurrent non-Hodgkin's lymphoma (NHL)

The efficacy of a Tc99m-labeled anti-lymphoma antibody fragment, bectumomab [LymphoScan], was retrospectively examined in the staging of recurrent or newly diagnosed non-Hodgkin's lymphoma (NHL) [7 patients] and to assess targeting before radioimmunotherapy (RIT) [14 patients]. Performance was graded relative to conventional imaging. Tumors included 7 low-grade, 11 intermediate-grade, and 3 high-grade histologic subtypes. Computed x-ray tomography, radiogallium imaging, FDG-PET, and bone marrow biopsy defined 117 sites. Bectumomab revealed 56% of these sites. In 4 patients bectumomab uncovered five sites not evident by conventional imaging. In addition, it uncovered one site in the brain, an area not covered in the standard work-up of asymptomatic patients. Bectumomab imaging most often failed in central abdominal and thoracic locations, and excelled in revealing disease in the head and neck. Relative to Ga67 citrate imaging, the performance of bectumomab was variable, with no clear relation to anatomic location; there was better targeting of low and intermediate grade NHL. Radiogallium out-performed bectumomab imaging in 23 sites, 19 of which were in patients with high or intermediate-grade disease. Bectumomab was superior to radiogallium at six sites, five of which involved low-grade tumor.

Conclusion: Bectumomab shows promise as a pre-RIT probe for targeting of B-cell NHL. It excelled at defining small volume, low-grade disease. However, as a purely diagnostic agent, its performance was variable.