Radiopharm Theranostics set to revolutionise prostate cancer treatment with Terbium-161

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By Imelda Cotton - 
Radiopharm Theranostics ASX RAD prostate cancer trial terbium 161

A recent medical publication into prostate cancer has validated the development by clinical-stage biotech Radiopharm Theranostics (ASX: RAD) of its first-in-class Terbium-161 (Tb-161).

The publication reported the results of six metastatic castration-resistant prostate cancer patients who were treated with Tb-161 and lutetium chloride (Lu-177).

It demonstrated that Tb-161 could deliver markedly higher tumor-absorbed doses compared to Lu-177.

The dosage with Tb-161 delivered a radiation hit to tumor lesions that was an average of 2.4 times higher than that of Lu-177.

Radiopharm said the results “strongly support” Tb-161 as a potential candidate for use in the radiotherapeutic targeting of advanced cancers.

Targeted cancer treatment

Tb-161 is a “highly promising” isotope for targeted cancer treatment due to its unique characteristics of emitted radiation including Auger electrons and short-range beta particles.

The beta radiation travels only a few millimeters, while Auger electronic emission has a higher linear energy transfer that travels less than the width of a single cell.

Previously, Tb-161 has shown excellent bioequivalence comparable to currently-used radiopharmaceuticals.

Its superiority to Lu-177 is believed to be due to the Auger effect – a sub-atomic electronic process – increasing its potency and efficacy in selectively destroying tumor cells while leaving surrounding healthy tissue largely unaffected.

First access

Radiopharm is believed to be the first public company worldwide with access to Tb-161 for the clinical development of multiple assets.

In August, the company extended an agreement with Dutch radionuclide producer TerThera for the supply of Tb-161 in the development of Radiopharm’s lead candidate RAD402 to treat advanced prostate cancer.

Tb-161 will be linked to a proprietary monoclonal antibody to form RAD402 for targeting the KLK3 gene, which is highly expressed in prostate cancer cells but limited in healthy tissue.

Anti-tumour efficacy

Radiopharm managing director Riccardo Canevari said Tb-161 holds “remarkable promise” in nuclear medicine and oncology.

“[Tb-161] has the strong potential to advance anti-tumour efficacy for not only primary tumours but also micrometastatic disease,” he said.

“We are delighted to continue our partnership with TerThera and hopefully bring this highly-differentiated technology to eligible advanced cancer patients.”