Beyond Lutetium: The Auger Electron Advantage of Terbium-161 in the VIOLET Trial

We are entering a new era of radioligand therapy, moving from Lutetium-177 to Terbium-161 (161Tb).  As noted by Dr. Steven H. Liang of Emory University, in a recent American Journal of Nuclear Medicine and Molecular Imaging editorial, this shift highlights the promising progress of the VIOLET trial conducted at the Peter MacCallum Cancer Centre in Australia.

Why is the focus shifting to Terbium-161?
While similar to 177Lu, 161Tb possesses a significant added advantage: it emits copious short-range, high-LET Auger and internal conversion electrons. This allows for concentrated energy deposition at the subcellular level, thus enhancing tumor cell kill in micrometastases.

This theoretical advantage is now translating into clinical reality.

We are thrilled to see the VIOLET trial results highlighted in the Am J Nucl Med Mol Imaging:

• Cohort: 30 mCRPC patients enrolled at Peter MacCallum Cancer Centre.
• Dosing: Successful escalation through 4.4, 5.5, and 7.4 GBq cohorts.
• Safety Confirmed: The 7.4 GBq dose was established as safe (in 18 subjects during the dose-expansion phase).
• Next Phase: The study is expanding to explore a higher dose cohort of 9.5 GBq to further evaluate efficacy.

These findings establish the feasibility of 161Tb-PSMA-I&T, supporting its continued development in precision oncology.

ISOTOPIA is honored to be the supplier of the 161-Terbium for the VIOLET trial. By resolving the availability challenges associated with this novel isotope, we are helping researchers unlock better dosimetric profiles and improved therapeutic indices for patients.

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