Poly(adenosine diphosphate-ribose) polymerase-1 (PARP1) inhibitors have improved ovarian cancer treatment outcomes. However, clinical response remains heterogeneous. Existing biomarkers, mainly breast cancer susceptibility genes 1 and 2 (BRCA1/2), are suboptimal. New tools are needed to guide patient selection. In this study, [18F]fluorthanatrace ([18F]FTT), a PET radiotracer for imaging PARP1, was compared with [18F]FDG and tumor features commonly assessed in ovarian cancer. Methods: Subjects with epithelial ovarian cancer underwent both [18F]FTT and [18F]FDG PET before new oncologic treatment. The SUVmax of [18F]FTT and [18F]FDG was compared between lesions. [18F]FTT SUVmax was compared with tumor location, tumor grade, and germline or somatic BRCA1/2 status. Linear mixed models were fitted to identify subject-level differences. Results: Fifty-five lesions were identified in 14 subjects. No correlation was found between [18F]FTT SUVmax and [18F]FDG SUVmax per lesion, supporting distinct molecular targets. [18F]FTT uptake varied widely across lesions, with no significant differences between mean SUVmax and tumor location, grade, or BRCA1/2 status. Conclusion: Our findings suggest that [18F]FTT PET may provide unique information on ovarian cancer distinct from [18F]FDG PET and commonly assessed tumor features. Our results imply a wide range of PARP1 expression in the studied ovarian tumors not explained by [18F]FDG PET, location, grade, or mutational status.
Keywords: BRCA; PARP1; [18F]FTT; [18F]fluorthanatrace; ovarian cancer.
© 2025 by the Society of Nuclear Medicine and Molecular Imaging.