BACKGROUND: This report examines (99m)Tc-etarfolatide imaging to identify the 
presence of folate receptor (FR) on tumors of women with recurrent/refractory 
ovarian or endometrial cancer and correlates expression with response to 
FR-targeted therapy (vintafolide).
PATIENTS AND METHODS: In this phase II, single-arm, multicenter study, patients 
with advanced ovarian cancer were imaged with (99m)Tc-etarfolatide before 
vintafolide treatment. Up to 10 target lesions (TLs) were selected based on 
Response Evaluation Criteria In Solid Tumors criteria using computed tomography 
scans. Single-photon emission computed tomography images of TLs were assessed 
for (99m)Tc-etarfolatide uptake as either FR positive or negative. Patients were 
categorized by percentage of TLs positive and grouped as FR(100%), FR(10%-90%), 
and FR(0%). Lesion and patient response were correlated with etarfolatide 
uptake.
RESULTS: Forty-nine patients were enrolled; 43 were available for analysis. One 
hundred thirty-nine lesions were (99m)Tc-etarfolatide evaluable: 110 FR positive 
and 29 FR negative. Lesion disease control rate (DCR = stable or response) was 
observed in 56.4% of FR-positive lesions versus 20.7% of FR-negative lesions (P 
< 0.001). Patient DCR was 57%, 36%, and 33% in FR(100%), FR(10%-90%), and FR(0%) 
patients, respectively. Median overall survival was 14.6, 9.6, and 3.0 months in 
FR(100%), FR(10%-90%), and FR(0%) patients, respectively.
CONCLUSIONS: Overall response to FR-targeted therapy and DCR correlate with FR 
positivity demonstrated by (99m)Tc-etarfolatide imaging.
CLINICAL TRIAL NUMBER: NCT00507741.