Evaluation of apoptosis imaging biomarkers in a genetic model of cell death

Purpose We have previously developed the caspase-based radiotracer, 18 F-ICMT-11, for PET imaging to monitor treatment response. We further validated 18 F-ICMT-11 specificity in a murine melanoma death-switch tumour model with conditional activation of caspase-3 induced by doxycycline. Methods Caspase-3/7 activity and cellular uptake of 18 F-ICMT-11, 18 F-ML-10 and 18 F-FDG were assessed in B16ova and B16ovaRevC3 cells after death-switch induction. Death-switch induction was confirmed in vivo in xenograft tumours, and 18 F-ICMT-11 and 18 F-ML-10 biodistribution was assessed by ex vivo gamma counting of select tissues. PET imaging was performed with 18 F-ICMT-11, 18 F-ML-10 and 18 F-FDG. Caspase-3 activation was confirmed by immunohistochemistry. Results Significantly increased caspase-3/7 activity was observed only in B16ovaRevC3 cells after death-switch induction, accompanied by significantly increased 18 F-ICMT-11 ( p