Radiopharm Theranostics announces expanded agreement with TerThera

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Radiopharm Theranostics (ASX:RAD) has announced an expanded agreement with TerThera to supply the company with Terbium-161 (Tb-161).

The company said Tb-161 isotope will be linked to a proprietary monoclonal antibody (mAb) to form RAD 402, a radiotherapeutic being developed by Radiopharm to target KLK3 expression. KLK3 is highly expressed in prostate cancer cells but has limited expression in healthy tissue.

Radiopharm said it will initiate a Phase I dose-escalating trial during the second half of 2024 to evaluate the safety and efficacy of RAD 402 in patients with advanced prostate cancer.

“We are excited about bringing this highly differentiated technology (Tb161-RAD402) to patients with advanced prostate cancer. Until now, Prostate-Specific Membrane Antigen (PSMA) targeting agents represent the only theranostic option in the market or in development. RAD has decided to leverage a different mechanism of action by targeting KLK3, and the combination with Tb-161 is unique and highly promising,” said Riccardo Canevari, CEO and managing director of Radiopharm Theranostics.

“Tb-161 has shown superior preclinical results in comparison with Lu-177, which may translate into higher absorbed doses in micrometastatic disease, with less kidney toxicity. This novel radiopharmaceutical has the potential to become the first KLK-based theranostic option for individuals with advanced prostate cancer. We signed a first agreement with TerThera in April 2023 for RAD 602 in brain cancer and now we have decided to amplify, developing a second molecule linked with Terbium-161. We are the first company that has access to Terbium-161 for the clinical development of two different molecules. This is a really exciting innovation!”

Terbium-161 is a highly promising isotope for targeted cancer treatment due to its unique characteristics of radiation emitted, which includes both Auger electrons and short-range beta particles. The beta radiation travels only a few millimetres, and Auger electron emission has a higher linear energy transfer that travels less than the width of a single cell. Tb‑161 has shown excellent bioequivalence presenting a biodistribution comparable to currently used radiolanthanides and is potentially superior to Lutetium-177 (Lu-177) due to Auger effect increasing potency and efficacy in selectively destroying tumor cells while leaving surrounding healthy tissue largely unaffected.1,2

“TerThera is positioned to meet the growing global demand for radioisotopes in oncology by providing a highly sustainable and uninterrupted supply of Terbium-161, a radionuclide that could potentially be positioned right in between conventional Beta- energy emitting therapeutic radionuclides and Alpha energy emitting therapeutic radionuclides. The properties of Tb-161 should make it one of the radionuclides of choice within the current and future theranostic landscape,” said Philippe van Overeem, CEO of TerThera.