What are alpha therapies?
An alpha particle is a helium nucleus — two protons and two neutrons, tightly bound together. Compared with other forms of ionizing radiation, it is relatively massive and carries a double positive charge.
That combination of mass and charge makes alpha particles interact very intensely with the matter they travel through. They lose energy rapidly, which is why their range in tissue is so short. And as they lose that energy, they deposit it in a very dense track of ionization events along an extremely short path.
The result is an extraordinarily high Linear Energy Transfer (LET), the amount of energy deposited per unit of distance travelled.
Alpha particles have a LET hundreds of times higher than that of beta-emitting radionuclides such as Lutetium-177.
In practice, that means alpha particles cause DNA double-strand breaks (DSBs), the most difficult form of DNA damage a cell can sustain. Unlike single-strand breaks, which the cell's repair machinery can often fix, double-strand breaks are very difficult to repair correctly. The cells typically cannot survive them.
Why Targeted Alpha Therapy matters?
The short range of alpha particles, typically 50–100 micrometers in tissue, is what makes Targeted Alpha Therapy (TAT) so compelling.
When an alpha-emitting radionuclide is linked to a targeting molecule and delivered to a tumor cell, its radiation stays to a highly localized area. It does not travel centimeters into surrounding tissue. It deposits its energy and its damage in a sphere roughly the size of a few cells around the target.
This highly localized energy deposition makes alpha emitters particularly attractive for treating micrometastatic disease, small tumor clusters, and disseminated cancer cells that may be challenging to address with surgery or conventional radiotherapy.
The two well-known alpha emitters driving clinical development
Actinium-225 currently leads clinical development in TAT, while Astatine-211 is emerging as one of the most promising next-generation alpha emitters.
- Actinium-225 [²²⁵Ac]
- Alpha emitter with a 9.9-day half-life
- Decays through a cascade of daughter radionuclides, resulting in multiple alpha emissions from a single parent atom
- Being investigated across a broad range of solid tumors and hematological malignancies
- Global production capacity is increasing to meet the projected long-term demand
- Astatine-211 [²¹¹At]
- Alpha emitter with a 7.2-hour half-life
- Produced using high-energy cyclotrons equipped for alpha-particle irradiation
- Particularly attractive for targeting smaller tumors and micrometastatic disease
- Under clinical investigation in several cancer indications, including brain, thyroid, ovarian cancer, and others
- Typically, covalently bonded to targeting molecules
Webinar Alpha Targeted Therapy, Why bother?The Alpha webinar series explores the benefits of Targeted Alpha Therapy (TAT) for cancer, featuring renowned speakers sharing their insights and expertise. In this first webinar, our two experts will delve into TAT distinctive radiobiological effects, its relevance for cancer care as well as the early experience and clinical progress in the field.
This webinar is already ready over. Missed the live webinar or want to rewatch it?
- 28/04/2026
- Prof Dr Ekaterina Dadachova
Expert Spotlight | Alpha emitters and the future of radiopharmaceutical therapyEkaterina (Kate) Dadachova, PhD, joined University of Saskatchewan in Canada late in 2016 as a Fedoruk Center for Nuclear Innovation Chair in Radiopharmacy, and a Professor of Pharmacy.
Before joining University of Saskatchewan, she held a Professorship in Radiology, Microbiology and Immunology at the Albert Einstein College of Medicine in New York, USA from 2000 to 2016.
Her research interests are radioligand therapy of cancer, infections and autoimmune diseases, as well as interaction of melanized fungi with ionizing radiation and melanin-based radioprotectors.
She published more than 210 papers, 13 book chapters, and has 8 US patents. She received several awards such as Philips Young Investigator Award by RSNA, Young Professionals Award from the SNM, Mary Kay Ash Research Award, Top 10 researchers at the Albert Einstein College of Medicine in 2013, 2017 Burroughs Welcome Award, 2020 University of Saskatchewan Distinguished Researcher Award and 2024 Saskatchewan Health Research Foundation (SHRF) Years of Service Award. She is in the top 2% of cited scientists worldwide according to Stanford University 2024 database.
Prof Dr Ekaterina Dadachova, PhD
- Professor, College of Pharmacy and Nutrition
& Editor in Chief, Cancer Biotherapy and Radiopharmaceuticals - Sylvia Fedoruk Center for Nuclear Innovation Chair in Radiopharmacy University of Saskatchewan, Canada
- 29/05/2026
At-211 targeted alpha therapy in Europe: overcoming clinical, regulatory, and infrastructure challengesHugo Levillain, Anne Royer Moës, Cristiana Gameiro-Paris, Antero Abrunhosa, Tom Deakin, Geraldine Gebhart, Matthias M. Herth, Jean-François Gestin, Ferid Haddad, Andreas Ingemann Jensen, Rebecca Lo Bue, Renata Mikolajczak, Adrian Otamendi, Katie Staunton-Mann, Kevin Tabury & Patrick Flamen on behalf of the Accelerate.EU consortium
Targeted Alpha Therapy (TAT) holds considerable promise for precision oncology, yet its clinical deployment in Europe remains limited. Beyond scientific considerations, progress is constrained by fragmentation across the radiopharmaceutical value chain, encompassing radionuclide production, radiochemistry, preclinical validation, clinical development, regulatory frameworks, infrastructure, and workforce training.