Astatine-211
Since its discovery in 1940 astatine-211 has been recognized as an ideal candidate for Targeted Radionuclide Therapy. Often referred to as the “Goldilocks” of radionuclides, astatine-211’s physical and chemical properties are “just right” for scalable use in precision oncology. With a half-life that is perfectly balanced—not too short and not too long—a simple and elegant decay chain featuring a single alpha emission per decay, and a scalable, cost-effective manufacturing process, this alpha-emitter has the potential to transform radiopharmaceutical cancer care.
At-211 decays to stable Pb-209 through the emission of a single alpha particle, avoiding “wandering” radiotoxic daughter nuclides and enabling precise, localized radiation delivery. Its alpha emission has an extremely short range, and its low-energy X-ray emission (77–92 keV) poses minimal external exposure risk—reducing shielding needs, eliminating the need for patient isolation and making At-211 ideal for outpatient settings. The characteristic X-rays enables detection via standard equipment as well as SPECT imaging, supporting biodistribution tracking and quantitative dosimetry. This facilitates personalized, data-driven treatment planning and improves safety and efficacy in targeted alpha therapy.
Astatine-211 has a half-life of 7.2 hours—an optimal balance for targeted alpha therapy. It is short enough to minimize radioactive waste and reduce unwanted patient radiation exposure, yet long enough to accommodate manufacturing, quality control, and transport across decentralized supply networks.
This half-life enables outpatient treatment models and reduces infrastructure demands for both radiopharmaceutical manufacturers and healthcare providers. While commercial supply chains for diagnostic isotopes with much shorter half-lives are already well established, At-211 offers significantly greater logistical flexibility—making it well-suited for scalable clinical deployment in real-world healthcare settings.
Astatine is a halogen, like fluorine and iodine. As such, it can form covalent bonds with carrier molecules—eliminating the need for bulky chelators. This makes At-211 ideally suited for use in radiopharmaceuticals based on small molecules and peptides, where chelators could otherwise disrupt pharmacokinetics.
As the only alpha-emitting halogen, astatine-211 is a natural therapeutic counterpart to diagnostic radiopharmaceuticals labeled with fluorine-18 or iodine-123/124, enabling streamlined theranostic approaches that integrate diagnosis and treatment on a single chemical platform.
Astatine-211 can be reliably manufactured using particle accelerators. In this process, alpha particles (helium nuclei) are accelerated to approximately 30 MeV and directed at “targets” coated with bismuth-209 (Bi-209). This induces the 209Bi(α,2n)211At reaction, producing At-211.
Because bismuth is a monoisotopic, naturally abundant, and low-cost raw material, At-211 is one of the few alpha-emitters with a truly scalable and sustainable production route. It also supports both supply chain redundancy and independency. This is a stark contrast to most other medical isotopes that rely on isotopically enriched raw materials that are expensive and often depend on international supply chains that are vulnerable to sanctions.
Cost-efficient astatine supply chain for long-term scalability – enabled by Atley Solutions
Atley Solutions is actively developing optimized At-211 supply chains in partnership with accelerator and radiopharmacy networks, as well as radiopharmaceutical companies. The optimized At-211 supply chain favors efficiency, scalability, and reliability:
1. Target manufacturing and shipment
Bi-209 targets are manufactured centrally and shipped to accelerator sites.
2. Irradiation and isotope production
At these sites, At-211 is produced by irradiating the Bi-209 targets.
3. Radiopharmaceutical manufacturing
Irradiated targets are transported to radiopharmaceutical production sites, where At-211 is purified and labeled to the carrier molecule.
4. Dose formulation and delivery
The final radiopharmaceutical dose is prepared and delivered to the point of care for patient administration.
This distributed but highly coordinated supply model ensures both reliability and redundancy—enabling consistent access to At-211-based radiopharmaceuticals at scale. Atley Solutions is committed to delivering a supply-chain-spanning solution, allowing its customers to focus on what they do best: developing and delivering breakthrough cancer treatments.
Atley Solutions enables the At-211 supply chain by delivering automated radiopharmaceutical manufacturing equipment like the Atley C100, and Atley Targets—customized Bi-209 targets optimized for At-211 manufacturing across a range of accelerator types and facilities.