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. (99m)Tc-etarfolatide, a (99m)Tc-labeled folate conjugate, is in late-phase 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.