Radioligand therapy for the targeted treatment of prostate cancer
177Lu-PSMA-617 is a radioligand therapy (RLT) being developed by Endocyte that utilizes a high affinity targeting ligand to direct potent radiotherapy to prostate cancer cells. The specific targeting of this therapy comes from the “ligand” portion of the RLT, which is a small molecule designed to bind to Prostate Specific Membrane Antigen, or, PSMA, a protein highly expressed on the cell surface of most prostate cancer cells but absent on most normal cells. The PSMA targeting ligand in 177Lu-PSMA-617, is chemically attached to a therapeutic radioactive atom called Lutetium-177 (177Lu), which releases an energetic beta particle to precisely deliver cell killing radiation to the site of disease. Unlike traditional external beam radiotherapy, 177Lu-PSMA-617 is administered as a systemic injection where it can directly target multiple sites of PSMA-positive prostate cancer throughout the body, including the bone and soft tissue, while bypassing the PSMA-negative healthy cells. The expression of PSMA prior to treatment with 177Lu-PSMA-617 can be determined using whole body PSMA-directed imaging, allowing for personalization of treatment so that the best course of therapy might be selected. It is estimated that approximately 80% of men with metastatic castration-resistant prostate cancer (mCRPC) express PSMA on their cancer cells.
PSMA-617 will be evaluated in a Phase 3 registrational study beginning 1H’2018.