Preliminary evaluation of the potential of ^99mTc carbonyl–DTPA–Rituximab as a tracer for sentinel lymph node detection

Preliminary work with ^99mTc carbonyl–DTPA–Rituximab was attempted to test its feasibility as a sentinel lymph node (SLN) tracer for patients with breast cancer. ^99mTc labeling of DTPA–Rituximab conjugate was carried out via ^99mTc carbonyl synthon which exhibited >95% radiochemical purity and good in vitro stability. In vitro studies of ^99mTc carbonyl–DTPA–Rituximab in normal and malignant B cells showed higher binding in malignant cells. In vivo distribution of ^99mTc carbonyl–DTPA–Rituximab in Wistar rat footpad model indicated good retention by B-cells present in the sentinel lymph node. - Highlights: • Proposal of ^99mTc-labeled Rituximab as a sentinel lymph node (SLN) tracer. • ^99mTc carbonyl DTPA–Rituximab obtained in good radiochemical purity. • In vitro cell binding studies confirmed presence of higher CD20 receptor density on malignant cells. • Tested in Wistar rat using footpad model (popliteal node uptake). • Significant SLN uptake and retention of ^99mTc carbonyl labeled Rituximab in animal model.