Peptide-targeted radioligand therapy reference

A patient with a midgut neuroendocrine tumor undergoes a Ga-68 DOTATATE PET / CT scan. The hepatic metastases light up against the surrounding parenchyma with the high tumor-to-background contrast that somatostatin-receptor-2 overexpression on neuroendocrine tissue produces. Eight weeks later the same patient returns to the nuclear-medicine suite, an amino-acid co-infusion line is started, and 7.4 gigabecquerels of 177Lu-DOTATATE is administered through a slow intravenous push. The targeting peptide is structurally identical to the diagnostic agent. The chelator is identical. The only molecular difference is the radionuclide loaded into the chelator cage: a positron-emitting Ga-68 atom for the imaging scan, a beta-emitting Lu-177 atom for the therapeutic dose. Same vector. Same biology. Different payload. This is the defining architecture of peptide-targeted radioligand therapy, and it is the closest thing modern oncology has produced to the original Ehrlich "magic bullet" — a targeting moiety that delivers a cytotoxic payload to a specific molecular address on tumor tissue, with a companion imaging agent that confirms the address is occupied before treatment is given.

Peptide-targeted radioligand therapy (PRRT) and the broader theranostic framework it sits within is the fastest-growing peptide-pharmacology-adjacent class of the 2020s. The peptide moiety functions as the targeting agent, the radionuclide is the therapeutic payload, and the patient-selection step routes through the imaging companion agent built on the same peptide-chelator backbone. The two clinical platforms that have produced FDA approvals — somatostatin-receptor-targeted PRRT for neuroendocrine tumors (Lutathera, 177Lu-DOTATATE; approved January 2018) and prostate-specific-membrane-antigen-targeted radioligand therapy for prostate cancer (Pluvicto, 177Lu-PSMA-617; approved March 2022) — have produced pivotal-trial evidence at hazard-ratio magnitudes typically associated with first-line standard-of-care regimens, and have prompted a wave of clinical development across additional receptor targets that will reach the clinic over the back half of the 2020s and into the 2030s.

This reference covers the theranostic framework, the chelator chemistry that makes peptide-radionuclide pairing tractable, the radionuclide physics that determine which isotopes serve imaging versus therapeutic roles, the major approved agents and their pivotal trials, the emerging-target landscape, the dosimetry framework that constrains dosing decisions, and the safety profile of the class. It sits alongside the somatostatin analog class peptide page where the receptor pharmacology that licenses DOTATATE is characterized in detail, the peptide receptor pharmacology atlas which walks the broader receptor-target landscape of the peptide field, and the peptide manufacturing technical reference which addresses the radiopharmacy chemistry-and-controls layer beneath any clinical radioligand product. The audience is clinicians and patients trying to read the rapidly accumulating literature; the frame is educational and no therapeutic claims are made beyond what the cited regulatory and peer-reviewed sources document directly. Specific commercial vendors beyond the FDA-registered tradenames (Lutathera, Pluvicto, NETSPOT, Detectnet, Pylarify, Posluma) are not named.