Development of Novel Radiopharmaceuticals: Problems, Decisions and More Problems

Abstract

The development of new tumor targeting radiopharmaceuticals also named tracers relies on the identification and validation of new target structures or processes in close conjunction with the application of new techniques for the development of new biocompatible molecules. A radiopharmaceutical/tracer consists of a carrier molecule which transports the tracer to the target and the radioactive isotope which allows visualization and/or therapy. These techniques either use known lead structures for further refinement or try to identify new lead compounds which is then followed by the screening of various derivatives of these molecules. Their further evaluation and optimization consist in the characterization of the structure-function relationships and subsequent improvement with respect to binding, internalization and biodistribution by rational design of corresponding analogues. However, during this process several decisions have to be made with regard to the nature of the disease process which should give some hints for useful targets, the method for identification of the target and the choice to follow or skip a project. This is usually based on reasonable choices based on the evidence available to minimize the risk for failure. Sometimes this may result in selection without preferences.