TAT-10: Dosimetry and Biodistribution of Pb203-AR-RMX in Patients with Somatostatin Expressing Neuroendocrine Tumors: A Clinical Exploratory Study

Kanazawa, Japan (UroToday.com) This is an exploratory study in patients who had received targeted beta therapy to determine the dosimetry and biodistribution using imaging agents Pb203 and Ga68 in preparation for eventual targeted alpha therapy using Pb212. Six patients with confirmed somatostatin-expressing neuroendocrine tumors were recruited.

All had previously completed four cycles of Lu177-DOTATATE therapy. Approximately 5 miCu of Pb203-AR-RMX were injected by iv and both whole body scans and SPECT/CT scans of the abdomen were obtained. Blood and urine samples were collected up to 48 hours after injection for safety and pharmacokinetic assessment.  Organ doses were calculated using the imaging data. No significant hematological or renal toxicity was observed.

In addition, Ga68-DOTATATE PET/CT scans were obtained. The biodistribution was very similar to that obtained for Pb203-AR-RMX and Lu177-DOTATATE. 

Based on the Pb203-AR-RMX dosimetry, the expected doses for Pb212-AR-RMX are calculated and, as expected, the spleen receives the highest dose though the kidneys are the dose-limiting organ. The first clinical trials for Pb211-AR-RMX targeted alpha therapy are expected in the fourth quarter of 2017.

Presented By: Ebrahim S. Delpassand from RadioMedix Inc., USA

Written By: William Carithers, Lawrence Berkeley National Laboratory