Addition Of ¹³¹I MIBG To PRRT (⁹⁰Y DOTATOC) For Personalized Treatment of Selected Patients with Neuroendocrine Tumors

Abstract

INTRODUCTION: PRRT is an effective treatment for metastatic neuroendocrine tumors (NETs). Delivering sufficient tumor radiation dose remains challenging due to critical organ dose-limitations. Adding ¹³¹I MIBG to PRRT may be advantageous in this regard. METHODS: A phase 1 clinical trial was initiated for patients with non-operable progressive NETs using a combination of ⁹⁰Y DOTATOC plus ¹³¹I MIBG. Treatment cohorts were defined by radiation dose limits to kidneys and bone marrow. Subject specific dosimetry was used to determine the administered activity levels. RESULTS: The first cohort treated subjects to 1900 cGy kidneys and 150 cGy marrow. No dose limiting toxicities were observed. Tumor dosimetry estimates demonstrated an expected dose increase of 43-83% using combination therapy as opposed to ⁹⁰Y DOTATOC PRRT alone. CONCLUSION: These findings demonstrate the feasibility of using organ dose for a phase 1 escalation design and suggest the safety of using ⁹⁰Y DOTATOC and ¹³¹I-MIBG.