Theranostics in prostate cancer

SummaryThis review summarizes current evidence of “theranostics” for patients with prostate cancer. Prostate-specific membrane antigen (PSMA) is a glycoprotein which can be labeled with positron-emitting tomographic (PET) tracers like fluorine-18, gallium-68, or copper-64 and can be labeled with beta emitters like lutetium-177 to treat patients with metastatic castration-resistant prostate cancer (mCRPC). PSMA PET/CT has been shown to be superior to computer tomography (CT) and bone scintigraphy in accuracy, sensitivity, and specificity in the evaluation of metastatic tumor sites and may change treatment management. However, outcome studies showing an improvement in progression-free survival (PFS) and/or overall survival (OS) after management change is missing. PSMA PET/CT is highly recommended in prostate cancer patients with biochemical recurrence (PSA > 0.2 ng/ml). Patients presenting with high PSMA expression in PSMA PET/CT may be favorably treated with 177lutetium-617. In the TheraP study, a multicenter phase 2 trial, patients with mCRPC were randomly assigned to receive either 177lutetium-617 or cabazitaxel. The results indicate fewer treatment-related adverse events in patients treated with 177lutetium-617, an improvement in PSA response, but no improvement in OS after 36 months follow-up. In the VISION trial, a phase 3 international study, patients with mCRPC were randomly assigned to receive either 177lutetium-617 and standard of care (SOC) or SOC alone. At 12 months, radiographic PFS or PSA-PFS was 18% in patients treated with 177lutetium-617 and 3% in patients treated with SOC alone. The real status of 177lutetium-617 in the sequel of treatment regimens remains unclear and additional studies are therefore warranted.