PSMA Theranostics: Science and Practice

Prostate cancer (PCa) causes significant morbidity and mortality in men globally. While localized PCa may be managed with curative intent by surgery and/or radiation therapy, the management of advanced hormone resistant metastatic disease (mCRPC) is more challenging. Theranostics is a principle based on the ability to use an organ specific ligand and label it to both a diagnostic and a therapeutic agent. The overexpression of prostate specific membrane antigen (PSMA) on prostate cancer cells creates a unique opportunity for development of targeted radionuclide therapy. The use of both beta and alpha emitting particles has shown great success. Several clinical trials have been initiated assessing the efficacy and safety profile of these radionuclide agents. The results are encouraging with PSMA directed radioligand therapy performing well in patients who have exhausted all other standard treatment options. Future studies need to assess the timing of introduction of these radionuclide therapies in the management schema of mCRPC. Drugs or therapies are not without side effects and targeted radionuclide therapies presents a new set of toxicities including xerostomia and myelosuppression. New therapeutic strategies are being explored to improve outcomes while keeping toxicities to a minimum. This review aims to look at the various PSMA labelled tracers that form part of the theragnostic approach and subsequently delve into the progress made in the area of radionuclide therapy.