The FIELD-LAB team selected lead-212 as one of the key isotopes for nuclear medicine by evaluating technical achievability and the potential for medical use:
Unstable isotopes that become stable through the release of alpha-radiation.
Alpha-radiation consists of highly energetic particles, that do not travel far but can create significant damage on their way
Effective cancer therapy by linking an alpha-emitter to a molecule that binds specifically to cancer cells. This so-called “targeting molecule” transports the alpha-emitter to the right location, preventing damage at other locations.
Karlijn van der Schilden
R&D Manager Medical Isotopes
212Pb is generated in the decay chain of 228Th.
228Th is generated when 226Ra, a radioactive isotope that is found in nature, is exposed to neutron irradiation in a nuclear reactor.
After the 228Th is extracted from the material, it is a radioactive source which continuously generates 212Pb through radioactive decay.
212Pb can be generated by:
- Extracting it directly from the 228Th, or
- Extracting it from the intermediate decay product 224Ra, which can be extracted from the 228Th as well.
Because of the significant damage alpha-emitters can cause, the materials need to be handled carefully and in a protected environment.
FIELD-LAB’s radiological laboratories allow for safe handling of alpha-emitters. Here the processes of separation and purification have been developed.
Then, these processes will be transferred to the available alpha-laboratory, where larger amounts of material can be handled and processed.
The first test batch for R&D and pre-clinical purposes will be delivered to FIELD-LAB partners in Q4 2020.
The last phase will be to transfer the processes to (GMP) hot cells. 212Pb, and its mother isotope 224Ra, will be produced in larger quantities and in line with the highest quality standards. This allows the material to be used for patients in a clinical research setting.
The GMP cell environment also allows manufacturing of radiopharmaceutical products, for example by linking the alpha-emitter to a cancer cell targeting molecule (labelling).
“Lead-212 is a very relevant medical isotope with large potential. It is however very difficult to make and have access to. FIELD-LAB allows us to proceed developing and testing the potential applications of 212Pb for effective cancer therapies.”
With the experience collected in the FIELD-LAB partnership, and the infrastructure in Petten that was made available, we have been able to establish the production of Lead-212, a medical isotope with great perspective for cancer therapy with maximal efficiency and minimal side effects.