Biodistribution of 212Pb Conjugated Trastuzumab in Mice

Clinical use of radiolabeled monoclonal antibodies in therapeutic treatment of cancer is increasing. This study demonstrates an increased uptake rate in the tumor over a 72 hr period of observation following a single intravenous injection of 212Pb-trastuzumab in mice. Whereas 212Pb-trastuzumab appeared not to cause systemic toxicity4, there may be concomitant uptake in other organs that should be considered in evaluating the risk of radiation toxicity associated with therapy. Additional laboratory and clinical study with 212Pb-trastuzumab should be conducted to define an optimized therapeutic strategy and determine the radiation doses delivered to non-targeted organs and tissues using microdosimetry methods. Results of this biodistribution study support further investigation of radiolabeled 212Pb-TCMC-trastuzumab, radiobiological organ microdosimetry, and optimal dosing regimens for 212Pb-trastuzumab as a therapeutic agent