Recent advances in radiopharmaceutical application of matched-pair radiometals

Theranostic medicine is relatively a new term that describes integration of diagnostic and therapeutic functions within the same platform of pharmaceuticals. Such a design may in principle permit the molecular diagnosis, targeted therapy, and simultaneous monitoring and treatment necessary to achieve personalized medicine for cancer. Theranostic radiopharmaceuticals, for instance, carry the properties of both diagnostic radioimaging and radioimmunotherapy (RIT). As nuclear imaging techniques such as positron emission tomography (PET) or single photon emission computed tomography (SPECT) have excellent sensitivity and can provide biochemical information on pathological conditions, much effort has been made in order to accomplish a more effective and powerful theranostic combination. Some recent examples include SPECT-therapy, PET-therapy, and therapy-therapy. In particular, the combined therapy-therapy method is the result of realization that RIT relying on a single radioisotope has an inherent limitation for practical cancer treatment. Thus the success of theranostic nuclear medicine depends on a proper choice of different radioisotopes that will lead to a perfect couple. This pair of radioisotopes is called matched-pair radioisotopes. The structural motif for radiopharmaceuticals based on matched-pair consists of a bifunctional chelator (BFCA) and a biologically active molecule (BAM). This review will focus on recent advances in radiopharmaceutical application of matched-pair radiometals in clinics as well as preclinics.