Imaging the Folate Receptor on Cancer Cells with 99mTc-Etarfolatide: Properties, Clinical Use, and Future Potential of Folate Receptor Imaging

Folate receptor (FR) can be used as a therapeutic target because of its expression on different epithelial cancers, such as ovarian, non-small cell lung, endometrial, and breast cancer. Assessing FR expression in tumors may help to identify patients who can benefit from FR-targeted therapeutics, such as vintafolide and farletuzumab. Different methods exist to detect FR expression. Tissue sampling has limited clinical utility, mainly because it requires an invasive procedure. Tc-99m-etarfolatide, a Tc-99m-labeled folate conjugate, is in latephase trials in Europe and the United States. It allows noninvasive, whole-body imaging of the FR. This review focuses on this FR-imaging agent and how it may be used to direct FR-targeted therapy.