177Lu-TLX250 (177Lu-Lutarex®, 177Lu-Girentuximab), a Lutetium-177-labeled monoclonal antibody is being developed as a potential RIT for various cancers including renal cell carcinoma (RCC). 177Lu-cG250’s development became an extension of the development of the imaging agent 124I-Girentuximab (124I-Redectane®).

G250 (Girentuximab) is a chimeric murine human monoclonal antibody which targets the Carbonic Anhydrase IX (CA-IX) molecule/G250 antigen, expressed on over 90% of clear cell renal cell carcinomas. The cold antibody was developed as a chemotherapeutic for kidney cancer treatment, under the name Rencarex, but this molecule recently failed (2013) during the pivotal Phase III trial. The antibody was labeled with 124I (Redectane®) for diagnosis and 131I or 177Lu (Lutarex®) for kidney cancer therapy.

A Phase I/II safety and efficacy trial with 177Lu-cG250 was initiated in February 2005 in patients with advanced RCC. The dosimetry was determined using 111In-cG250. A Phase II efficacy study was initiated in 2013 in patients with advanced clear cell kidney cancer. The study demonstrated stability in about 75% of the patients.

The development of this molecule is now progressing in a fast way and the diagnostic agent could reach the market before 2022.

Target/Mechanism: CAIX

Leading Emitter: beta electrons (β)