Brookhaven National Lab Upton, USA
Jonathan Fitzsimmons completed his master from Johns Hopkins University in 2000, and received his PhD in radiochemistry in 2005 from University of Missouri-Columbia. He performed postdoctoral studies at Los Alamos National Laboratory and research at the University of North Carolina at Chapel Hill. He is currently a medical scientist at Brookhaven National Laboratory, where he developed a production scale separation of 68Ge, and is part of the TriLab team to develop 225Ac on a production scale. He has published over ten papers in reputed journals, has one patent and is serving on an expert panel for the US Pharmacopeia.
Actinium-225 (225Ac) has a half life of 9.92 days, decaying through multiple intermediate nuclei to a daughter isotope Bismuth-213 (213Bi) with a half life of 45 min. Both isotopes have been investigated for targeted alpha therapy. Researchers have shown 213Bi DOTATOC can shrink tumors in patients that had previously not responded to similar treatments with the beta emitting isotopes 90Y and 177Lu . The United States Department of Energy (US DOE) supplies purified 225Ac from a generator system associated with the parent isotope 229Th, but this approach does not supply enough 225Ac for the applications associated with both 225Ac and 213Bi. To meet this demand the US DOE has initiated a Tri-lab (Los Alamos-Brookhaven-Oak Ridge National Laboratories) effort to develop 225Ac by irradiation of a thorium target with high energy (90-200 MeV) protons. One of the main challenges associated with this production route is isolation of 225Ac from bulk thorium and other radionuclides (~400) formed as a result of fission and other nuclear reactions. In targeted alpha therapy with 225Ac the retention of the multiple daughters of 225Ac at the target site has been problematic. A chemical method to produce a targeting nanochelator to: capture 225Ac, retain the daughters of alpha decay, and target tumors will be discussed.