Radioligand therapy (RLT) using Lu-177 labelled PSMA is a novel and promising therapeutic approach to treat metastatic prostate cancer. We explain how the therapy works.
Lu-177 PSMA Therapy is an emerging therapeutic method for the palliative treatment of advanced metastatic prostate cancer, which is offered as an individual medical treatment. An individual medical treatment is the application of an effective but not (yet) approved therapy, which can be carried out in individual cases and in patients where other therapeutic measures have been exhausted. An individual medical treatment is clearly to be differentiated from a clinical trial and is not part of the medical standard of care, as side effects and risks are not yet fully understood. Initial clinical results on Lu-177 PSMA therapy, however, confirm acceptable rates of side effects with good therapeutic results12.
How does the therapy work?
Prostate-derived cancer cells usually have the prostate-specific membrane antigen (PSMA) incorporated in their cell surface. This antigen can act as a magnetic docking site, which can bind so-called PSMA ligands. These ligands can be chemically combined with therapeutically effective beta emitters (Lu-177). This allows the beta emitter to unfold its effect directly on the cancer cell. Since the radioactive radiation only reaches a few mm in human tissue, a higher and therefore more effective dosage of radiation can be applied directly towards the tumor cells compared to radiation therapy from the outside.
Who is suited for Lu-177 PSMA Therapy?
Patients who are unresponsive to other treatments such as hormone therapy, chemotherapy, or external radiation therapy are potential candidates for the therapy. Lu-177 PSMA therapy is possible in patients with prostate cancer whose cells have a sufficient expression of PSMA on the cell surface. To determine if the therapy can be performed, the PSMA status needs to be checked in a first step using a Ga-68 PSMA ligand PET/CT. In addition to other physical health requirements, which must be individually assessed in advance by the treating physician, it is also necessary that the patient has fully functioning kidneys.
Rahbar, K., et al., German multicenter study investigating 177Lu-PSMA-617 radioligand therapy in advanced prostate cancer patients. J Nucl Med, 2016.
Fendler, W.P., et al., Preliminary experience with dosimetry, response and patient reported outcome after 177Lu-PSMA-617 therapy for metastatic castration-resistant prostate cancer. Oncotarget, 2016