Exploratory Study of ^99mTc-EC20 Imaging for Identifying Patients with Folate Receptor–Positive Solid Tumors

Abstract

In vivo imaging with 99mTc-EC20 identified approximately two thirds of patients as having FR-positive tumors. Agreement between imaging and in vitro IHC was poor but was potentially confounded by a lack of correlation between the time of tissue sampling and the time of 99mTc-EC20 imaging, the heterogeneous expression of FR in metastatic lesions from the same patient, and the inability to detect the beta-isoform of FR by IHC. This pilot study of 99mTc-EC20 scintigraphy indicates that the agent is safe and well tolerated and that this noninvasive procedure may have utility in selecting patients likely to benefit from FR-targeted therapy.