From Radionuclide Isolation to Clinical Innovation: UMC Utrecht Uses the Atley C100 to Pioneer Novel At-211 Therapies

Atley Solutions is proud to spotlight UMC Utrecht and the Princess Máxima Center, where Dr. Arthur Braat and Dr. Alex Poot are pioneering the world’s first clinical translation of Astatine-211 (At-211) therapies. With the Atley C100 module now in routine use, the team is transforming pediatric cancer care by replacing long, isolating treatments with innovative outpatient approaches — marking a new era in targeted alpha therapy.

“We need to do better for these children” – That was the moment everything changed for radiochemist Dr. Alex Poot. After witnessing a young neuroblastoma patient undergo I-131 mIBG therapy—spending a week in radiation isolation—he returned to the lab with a mission: to find a better way.

Today, Poot and his clinical counterpart, Dr. Arthur Braat, are doing exactly that. At UMC Utrecht and the Princess Máxima Center for Pediatric Oncology, the duo is spearheading a new era in targeted alpha therapy using Astatine-211 (²¹¹At) — a radionuclide that combines precision with safety in ways previously unachievable. And with the recent installation of the Atley C100 module, they now have the tools to bring their vision to patients.

“From a medical and emotional perspective, eliminating isolation is a game-changer,” says Dr. Braat. “And from a logistical standpoint, ²¹¹At based therapies allow us to move toward outpatient treatment settings for radiopharmaceuticals — something previously unthinkable.”

A Clinical and Chemical Partnership
Arthur Braat, a nuclear medicine physician and associate professor of translational nuclear oncology, leads the clinical implementation of novel radiopharmaceuticals for pediatric and adult solid tumors at UMC Utrecht and the Princess Máxima Center. Working alongside him is Alex Poot, Associate Professor and Head of Radiopharmaceutical Sciences at UMC Utrecht, specializing in the development of nuclear theranostics for childhood cancers.

Together, they form a unique translational team bridging the bench-to-bedside gap — bringing scientific breakthroughs into clinical care.

Why Astatine-211? A Clinical Need and a Human One
Both researchers were driven by the same frustrating observation: while Iodine-131 therapies remain widely used, they bring profound burdens — especially in pediatrics. The shielding requirements when working with radionuclides that that emit radiation with long pathlengths, like ¹³¹I, mean that patients often require strict radiation isolation. For children undergoing [¹³¹I]mIBG therapy for neuroblastoma, this isolation can last up to a week, limiting contact with family and healthcare providers at a time when emotional support is most critical.

“These kids are often between two and eight years old. They want to hug their parents. They want to be comforted,” says Braat. “Instead, they’re confined to sealed lead-lined rooms, communicating via video calls.”

Isolation is not only emotionally difficult; it also consumes specialized infrastructure, and strains hospital resources. Astatine-211 — thanks to its elegant decay properties and lack of long-range emissions — has the potential to remove this burden altogether.

“Our goal is to enable administration of alpha radiopharmaceuticals in an outpatient setting,” says Braat. “Like with Radium-223, we envision a future where patients can be treated and discharged on the same day.”

Four Clinical Trials, One Shared Vision
The team’s roadmap for ²¹¹At is ambitious and rapidly advancing. Their clinical program already includes four planned Phase I trials, with additional concepts on the horizon:

[²¹¹At]mABG for neuroblastoma (pediatric cancer) primarily run by Princess Máxima Center
[²¹¹At]mABG for pheochromocytoma/paraganglioma (adult cancer)
[²¹¹At]NaAt – Sodium astatide for thyroid cancer
[²¹¹At]APA (TLX102) for glioblastoma – in collaboration with Telix Pharmaceuticals and KWF Dutch Cancer Foundation

Each trial replaces ¹³¹I-based therapies with an ²¹¹At-labeled counterpart. The team is also exploring broader applications of ²¹¹At with novel small molecules and alternative targeting strategies.

“This is just the beginning,” says Braat. “We finally have the tools to do what we’ve talked about for years.”

The Atley C100: From Experimentation to Industrialization
Before receiving the Atley C100, the team manually processed ²¹¹At via wet chemistry— a laborious and technically demanding process with modest yields and complex handling requirements. That changed dramatically when the Atley C100 module arrived in Utrecht.

“The difference is night and day,” says Poot. “From irradiated bismuth target to purified astatine ready for labeling—we now complete the process in 15-20 minutes. And instead of a few megabecquerels of astatine available for radiochemistry, we now have access to hundreds of megabecquerels.”

The dry-distillation process performed by the Atley C100 delivers reproducible yields of pure ²¹¹At with high radiochemical purity. With the additional automated radiolabeling functionality, it standardizes radiopharmaceutical production—paving the way for consistent clinical-grade manufacturing of ²¹¹At radiopharmaceuticals across sites.

“Another benefit is that the Atley C100 is very easy to learn how to use,” adds Poot. “We achieved a more than 75% non-decay corrected yield on our very first try!”

Enabling Global Collaboration
With the C100 now in routine use, UMC Utrecht has seen an immediate increase in collaboration requests from around the world.

“As soon as the word got out that we had installed the Atley C100 module and were running a clinical trial with [²¹¹At]mABG, our inboxes exploded,” says Braat. “There’s huge momentum around neuroblastoma.”

To support this growing interest, the team is building out GMP manufacturing capabilities at UMC Utrecht, further facilitating clinical translation of novel radiopharmaceutical compounds.

Building the Astatine-211 Ecosystem
Beyond their own clinical and research efforts, Braat and Poot are vocal proponents of international coordination across the ²¹¹At community. They participated in the inaugural “mABG for Neuroblastoma” working session organized by Atley Solutions during EANM 2024 and plan to contribute to the follow-up session in Barcelona this year.

“There are still many unknowns with Astatine-211,” says Poot. “From radiochemistry to clinical translation, we need to build this field together.”

Looking Ahead
The next five years will be transformative. The team’s short-term goals include:

Advancing all four clinical trials into Phase I and beyond
Expanding into additional indications, optimizing ²¹¹At radiochemistry toolkits
Establishing GMP-grade supply chains for ²¹¹At therapies.

“We’re just getting started,” says Braat. “But for the first time, we’re not talking about what’s possible — we’re actually doing it.”