TAT-10: Development of Effective Chelators for Th227 to be Used in Targeted Thorium Conjugates

Kanazawa, Japan (UroToday.com) Ra223 represents a breakthrough in alpha therapy after FDA approval in May 2013 of Ra223 – dichloride (XOFIGO) for the treatment of metastatic castration-resistant prostate cancer. As a calcium analog, Ra223 is well-suited for treatment of bone metastases but the absence of efficient chelators limit its use in other types of radiotherapy. The same generators used for Ra223 production can be also be used for highly purified Th-227. This study aims to produce efficient chelators for Th227.

Chelators such as DOTA exits but the harsh conditions required for labeling are not compatible with stability of antibodies. Attempts at amelioration typically result in poorer yield, efficiency, and specific activity.

We have developed an octadentate chelator using 3-hydroxy-N-methyl_2-pyridinone (Me-3, 2-HOPO) that can form extremely stable thorium complexes. Th227-[Me-3,2-HOPO]-antibody shows great promise for targeted alpha therapy of a variety of cancers.

Presented By: Olav B. Ryan from Bayer AS, Oslo, Norway

Written By: William Carithers, Lawrence Berkeley National Laboratory

at the 10th International Symposium on Targeted Alpha Therapy (TAT-10)  May 31 - June 1, 2017 - Kanazawa, Japan.