“Incredibly encouraging” first results of Terbium prostate cancer therapy
03 June 2025
An experimental therapy involving radioactive Terbium, and designed to seek out and kill prostate cancer cells wherever they are in the body, has shown very positive initial results in a first-in-human clinical trial at Peter Mac.
The VIOLET trial, which involved 30 patients whose advanced prostate cancers were progressing despite standard therapies, investigated the safety and efficacy Terbium-161 (¹⁶¹Tb) targeted radioligand therapy.
Results of this single-centre, phase I/II study have just been presented at the American Society of Clinical Oncology (ASCO) 2025 Annual Meeting in Chicago, and due to simultaneously publish in the journal Lancet Oncology.
Critically, the therapy was seen to trigger dramatic reductions of “PSA” (prostate specific antigen), the biomarker for active prostate cancer, in the blood indicating a potent anti-cancer effect for most patients.
Read the abstract, as presented by Dr James Buteau at, ASCO here and key findings include:
- 70% of patients experienced a reduction in PSA levels of 50% or greater, and 40% of patients experienced a PSA reduction of 90% or greater
- A maximum tolerated dose (MTD) of 7.4 GBq was established
- Median radiographic progression-free survival (rPFS) was 11.1 months
- Low rates of side-effects.
Lead Investigator Professor Michael Hofman, Director of the Prostate Cancer Theranostics and Imaging Centre of Excellence (ProsTIC) at Peter Mac, said: “These first-in-human results are incredibly encouraging”.
“Terbium-161 therapy shows the potential to be a valuable new treatment option for patients with advanced prostate cancer. We are particularly excited by the low rates of side effects and the high response rate we observed.”
Importantly, Terbium-161 is seen as having advantages over another radioactive agent - lutetium-177 – which is the mainstay of similar infused radioactive therapy now emerging as standard-of-care in advanced prostate cancer.
Terbium-161 emits beta radiation similar to lutetium-177, but also Auger electrons which deposit highly concentrated energy over very short distances. The result is anti-cancer effect that is both more potent and precise.
Peter Mac medical oncologist Professor Arun Azad added: “This study marks an important step forward in our understanding of targeted radionuclide therapy”.
“The unique properties of Terbium-161 offer a promising avenue for more effective and precise cancer treatment. The data support further evaluation of this novel therapy in larger phase III trials.”
The Peter MacCallum Cancer Centre expresses gratitude to the patients who participated in the VIOLET trial, their families, and the entire research team.
This research was funded by the Prostate Cancer Foundation (PCF), the Peter MacCallum Foundation, National Health and Medical Research Council (NHRMC) Investigator Grant, and Isotopia Molecular Imaging.
Dr. Eli Shalom, CEO of Isotopia Molecular Imaging, which supplied Terbium-161 and the PSMA-I&T kit, said: “We are thrilled to see the positive results from the VIOLET trial. This research validates the potential of Terbium-161 as a powerful tool in targeted cancer therapy. We look forward to continuing our collaboration with Peter MacCallum Cancer Centre to bring this innovative treatment to more patients.”
Howard Soule, Chief Science Officer of the Prostate Cancer Foundation said: “PCF is proud to have been a funder of the VIOLET Study. We believe that the future of theranostics is based on new targets and new atoms - this trial of Terbium-161 fulfills this vision”.
Craig Connelly, CEO of Peter MacCallum Cancer Foundation, said: “We are thrilled to learn of the excellent results the VIOLET study is seeing for people with advanced prostate cancer. Together with our generous donors, we are determined to support the brilliant researchers at Peter Mac like Professor Michael Hofman and his team to make breakthroughs of global significance”.
< ends >
Contacts:
For more information contact the Peter Mac Communications team on 0417 123 048.
About Peter Mac
Peter MacCallum Cancer Centre is a world leading cancer research, education and treatment centre and Australia’s only public health service dedicated to caring for people affected by cancer. The Prostate Cancer Theranostics and Imaging Centre of Excellence (ProsTIC) at Peter Mac performs state-of-the-art research to deliver new paradigms for treatment of prostate cancer driven by seamless integration of clinical trials, pre-clinical and discovery research. The multi-disciplinary team includes nuclear medicine, medical oncology, radiation oncology, urology and laboratory-based doctors and research with a strong patient-centered philosophy. The Center of Excellence is funded by a grant from the Prostate Cancer Foundation (PCF) with support from the Peter MacCallum Cancer Foundation.
About Isotopia Molecular Imaging
Isotopia Molecular Imaging Ltd. is a leader in the supply of Lu-177 and pioneering in Tb-161 with a global manufacturing footprint in Israel, and the United States. Its development team includes nuclear pharmacists, radiochemists, nuclear engineers, and physicists. Combined with its nuclear pharmacy, cyclotron facility, 177Lu / 161 Tb production sites, and sterile manufacturing plant, Isotopia provides a well-established platform for manufacturing and industry collaborations. Isotopia's collaborations with the scientific and medical communities allow it to further develop and experiment with new markers for imaging applications and molecular therapy.
About the Prostate Cancer Foundation
The Prostate Cancer Foundation (PCF) is the world’s leading philanthropic organization dedicated to funding life-saving prostate cancer research. Founded in 1993 by Mike Milken, PCF has raised over $1 billion, supporting more than 2,250 research projects at 245 leading cancer centers across 28 countries. PCF’s mission is to eliminate death and suffering from prostate cancer by accelerating the development of new treatments and improving patient outcomes. Through its innovative funding model and global collaborations, PCF has significantly advanced the understanding and treatment of prostate cancer, contributing to increased survival rates and enhanced quality of life for patients worldwide.
