Repurposing [11C]PS13 for PET imaging of cyclooxygenase-1 (COX-1) in ovarian cancer xenograft mouse models.

Cyclooxygenase-1 (COX-1), a biomarker for neuroinflammation, is implicated in ovarian cancer (OvCa) progression and prognosis. This study considered the repurposing of [11C]PS13, a COX-1 PET neuroimaging radiopharmaceutical, in OvCa xenograft mouse models. Methods: [11C]PS13 was evaluated in ICRscid mice with s.c. or i.p. human OVCAR-3 OvCa xenografts by dynamic PET/MR imaging, ex vivo biodistribution and radiometabolite analysis of plasma and tumor. Results: OVCAR-3 xenografts were well visualized with [11C]PS13 in xenograft mouse models. Time-activity curves revealed steady tumor radioactivity accumulation that plateaued from 40-60 min, and was significantly reduced by pre-treatment with ketoprofen (3.56 ± 0.81 and 1.30 ± 0.18 %ID/g, respectively, P = 0.01). Radiometabolite analysis showed that intact [11C]PS13 accounted for >80% of radioactivity in the tumor, with <20% in plasma, at 40 min post-injection. Conclusion: [11C]PS13 shows promise for PET imaging COX-1 in OvCa and rapid translation for clinical cancer research should be considered.