Since PSMA radioligand therapy (PSMA-RLT) demonstrated remarkable therapeutic efficacy in prostate cancer patients, the question arises whether PSMA-RLT could also achieve beneficial effects in other cancers expressing PSMA on the tumors cells themselves, or in the tumor-associated neovasculature. Expression of PSMA was early-on also identified in kidney, salivary glands, the duodenum and the central and peripheral nervous system. Subsequently, a wide variety of immunohistochemistry (IHC) studies showed PSMA to be upregulated on the endothelial cells of the neovasculature of a wide variety of other solid tumors where it may facilitate endothelial cell sprouting and invasion through its regulation of lytic proteases that have the ability to cleave the extracellular matrix. Similar to the introduction of PSMA-targeting theranostics in prostate carcinoma, overexpression of PSMA on newly formed tumor vessels may serve as a target for imaging and subsequent treatment of cancer through the use of agents that are capable of blocking PSMA in its function or through PSMA-mediated delivery of chemotherapeutics or radiation agents. Preclinical data suggests that PSMA might be involved in cancer-related angiogenesis by degrading the extracellular matrix and participating in integrin signal transduction.
Phase 2 study, single arm trial enrolling patients with a Gallium-68/Fluorine-18 prostate-specific membrane antigen (PSMA) positive positron emission tomography/Computed Tomography (PET/CT) in order to be treated with Lutetium-177 (177Lu) PSMA.~Patients without risk factors for toxicity will receive 7.4 GBq of 177Lu-PSMA while patients with at least 1 risk factor for toxicity will receive 5.5 GBq of 177Lu-PSMA. Patients will receive 4 cycles every 8 weeks (+- 2 weeks)