Progress on Production of Alpha-Emitting Radioisotopes for Cancer Therapy

High yield production of Actinium-225 and Radium-223 achieved by high energy proton bombardment of natural thorium targets.

The Science

DOE Laboratory scientists measured data showing the potential production efficiency of key alpha-emitting radionuclides at a variety of accelerated proton energies using bombardment of stacked thorium foils. The results of this work show that Ac-225 may be produced effectively at accelerated proton beam energies greater than 100 MeV.

The Impact

Alpha emitting radioisotopes have great potential for effective and safe treatment of a wide variety of cancer types. High-yield production of nuclides such as Ac-225 for application in emerging treatment of metastatic cancer via targeted alpha-immunotherapy and Ra-223 for the treatment of metastatic bone cancer would accelerate development of the promising clinical applications.

Summary

Ac-225 is a rare but medically-prized radioactive isotope, since it has the ability to precisely destroy cancerous cells without damaging healthy surrounding cells. It also has a short half-life, which means it ceases to be radioactive after a short period of time. However, production of the isotope has been costly and meager, too meager to support essential clinical trials of medicines based on the isotope. Those shortages of Ac-225 could be significantly lessened by this research. Using proton beams, lab researchers demonstrated that the current annual supply of Ac-225 can be produced in less than a week. Beyond their expected use in treating common cancers, new medicines made with Ac-225 are likely to be especially effective at treating diffuse cancers, which have spread through healthy tissue instead of staying concentrated in a single tumor. Diffuse cancers are among the most difficult to treat, and in many cases are considered untreatable. A collaborative project among Los Alamos, Brookhaven, and Oak Ridge National Laboratories is underway to develop production scale targetry and chemical processing as continuation of this research.

Contact

F. Meiring Nortier
Los Alamos National Laboratory
[email protected]

Funding

Basic Research (Cross Section Data): DOE Office of Science, Office of Nuclear Physics, Isotope Program Applied Research (Production Scale Targetry and Chemical Processing): DOE Office of Science, Office of Nuclear Physics, Isotope Program

Publications

J. W. Weidner, et al., “Proton-induced cross sections relevant to production of ²²⁵Ac and ²²³Ra in natural thorium targets below 200 MeV,” Applied Radiation and Isotopes 70 (2012) 2602–2607. J. W. Weidner, et al., “²²⁵Ac and ²²³Ra production via 800 MeV proton irradiation of natural thorium targets,” Applied Radiation and Isotopes 70 (2012) 2590–2595.