PD-L1 microSPECT/CT Imaging for Longitudinal Monitoring of PD-L1 Expression in Syngeneic and Humanized Mouse Models for Cancer
until further notice
SourceCancer Immunology Research, 7, 1, (2019), pp. 150-161
Article / Letter to editor
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Cancer Immunology Research
SubjectRadboudumc 14: Tumours of the digestive tract RIHS: Radboud Institute for Health Sciences; Radboudumc 19: Nanomedicine RIMLS: Radboud Institute for Molecular Life Sciences; Radboudumc 2: Cancer development and immune defence RIMLS: Radboud Institute for Molecular Life Sciences; Radboudumc 4: lnfectious Diseases and Global Health RIMLS: Radboud Institute for Molecular Life Sciences; Radboudumc 9: Rare cancers RIHS: Radboud Institute for Health Sciences; Radboudumc 9: Rare cancers RIMLS: Radboud Institute for Molecular Life Sciences
Antibodies that block the interaction between programmed death ligand 1 (PD-L1) and PD-1 have shown impressive responses in subgroups of patients with cancer. PD-L1 expression in tumors seems to be a prerequisite for treatment response. However, PD-L1 is heterogeneously expressed within tumor lesions and may change upon disease progression and treatment. Imaging of PD-L1 could aid in patient selection. Previously, we showed the feasibility to image PD-L1(+) tumors in immunodeficient mice. However, PD-L1 is also expressed on immune cell subsets. Therefore, the aim of this study was to assess the potential of PD-L1 micro single-photon emission tomography/computed tomography (microSPECT/CT) using radiolabeled PD-L1 antibodies to (i) measure PD-L1 expression in two immunocompetent tumor models (syngeneic mice and humanized mice harboring PD-L1 expressing immune cells) and (ii) monitor therapy-induced changes in tumor PD-L1 expression. We showed that radiolabeled PD-L1 antibodies accumulated preferentially in PD-L1(+) tumors, despite considerable uptake in certain normal lymphoid tissues (spleen and lymph nodes) and nonlymphoid tissues (duodenum and brown fat). PD-L1 microSPECT/CT imaging could also distinguish between high and low PD-L1-expressing tumors. The presence of PD-L1(+) immune cells did not compromise tumor uptake of the human PD-L1 antibodies in humanized mice, and we demonstrated that radiotherapy-induced upregulation of PD-L1 expression in murine tumors could be monitored with microSPECT/CT imaging. Together, these data demonstrate that PD-L1 microSPECT/CT is a sensitive technique to detect variations in tumor PD-L1 expression, and in the future, this technique may enable patient selection for PD-1/PD-L1-targeted therapy.
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