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

• 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.

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.