Terbium emerging as cancer-fighting key for Radiopharm

Radiopharm Theranostics says a new six-patient study shows its terbium-based treatment has superior potential to tackle prostate cancer than lutetium following a head-to-head assessment of the rare earths metals in its therapies.

Management says the results from tests on patients with metastatic “castrate-resistant” cancer vindicate its development of next-generation, terbium-based radiotherapies for the treatment of the often deadly condition and other advanced cancers.

The company considers its “Tb-161” isotope a promising targeted cancer treatment because of its unique radiation characteristics. The study – published by Andrea Schaefer-Schuler and eight others from the Department of Nuclear Medicine at Saarland University Medical Centre in the German town of Homburg – found that Tb-161 delivered a radiation dose to tumour lesions that was on average 2.4 times higher than that of its lutetium-based treatment (Lu-177).

That indicates a stronger ability to kill cancer cells.

Radiopharm says the outcome of the pilot study is of material significance as it is the first direct comparative study undertaken on the two therapies in humans and because two of its existing radiotherapies are terbium-based. The company’s RAD 402 and RAD 502 therapies target advanced prostate cancer and osteosarcoma, respectively.

In August last year, the company revealed an expanded agreement with Netherlands-based TerTherato secure a supply of Tb-161. It says it is the first public company globally to get access to the relatively rare isotope for the clinical development of multiple assets.

Radiopharm Theranostics chief executive officer and managing director Riccardo Canevari said: “Tb-161 holds remarkable promise in nuclear medicine and oncology. It has the strong potential to advance anti-tumour efficacy for not only primary tumours, but also micro-metastatic disease. We are delighted to continue our partnership with TerThera and hopefully bring this highly differentiated technology to eligible advanced cancer patients.”

Prostate cancer continues to rank as the second-most prevalent form of malignant disease among men globally and patients cancer often progress to a stage of metastatic castration-resistant prostate cancer (mCRPC). That is when the patient becomes unresponsive to physical or chemical castration, resulting in relatively poor treatment prognoses and recovery and it usually requires more intense treatment through chemotherapy or radiopharmaceuticals.

The company’s lutetium-based treatment was recently approved by the United States Food and Drug Administration. But Tb-161 has clearly emerged as a new candidate of interest for clinicians and researchers.

Its radiation characteristics include both auger electrons and short-range beta particles. The company says beta radiation travels only a few millimetres, while the auger electronic emission has a higher linear energy transfer that travels less than the width of a single cell.

Radiopharm says Tb-161’s superiority to Lu-177 is potentially due to the auger effect, which increases its potency and efficacy in selectively destroying tumour cells while leaving surrounding healthy tissue largely unaffected.

Every step of the way, legions of cancer sufferers watch with amazement and hope at the giant strides made in human medicine. But for some, the advancements can not come soon enough.

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