Published in:
01-08-2019 | NSCLC | Original Article
18F-FDG PET metabolic-to-morphological volume ratio predicts PD-L1 tumour expression and response to PD-1 blockade in non-small-cell lung cancer
Authors:
Mario Jreige, Igor Letovanec, Kariman Chaba, Stephanie Renaud, Sylvie Rusakiewicz, Valerie Cristina, Solange Peters, Thorsten Krueger, Laurence de Leval, Lana E. Kandalaft, Marie Nicod-Lalonde, Pedro Romero, John O. Prior, George Coukos, Niklaus Schaefer
Published in:
European Journal of Nuclear Medicine and Molecular Imaging
|
Issue 9/2019
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Abstract
Purpose
Anti-PD-1/PD-L1 blockade can restore tumour-specific T-cell immunity and is an emerging therapy in non-small-cell lung cancer (NSCLC). We investigated the correlation between 18F-FDG PET/CT-based markers and tumour tissue expression of PD-L1, necrosis and clinical outcome in patients receiving checkpoint inhibitor treatment.
Methods
PD-Li expression in biopsy or resection specimens from 49 patients with confirmed NSCLC was investigated by immunohistochemistry. Maximum standardized uptake value (SUVmax), mean SUV (SUVmean), metabolic tumour volume (MTV) and total lesion glycolysis (TLG) were obtained from 18F-FDG PET/CT images. The ratio of metabolic to morphological lesion volumes (MMVR) and its association with PD-L1 expression in each lesion were calculated. The associations between histologically reported necrosis and 18F-FDG PET imaging patterns and radiological outcome (evaluated by iRECIST) following anti-PD-1/PD-L1 therapy were also analysed. In 14 patients, the association between necrosis and MMVR and tumour immune contexture were analysed by multiple immunofluorescent (IF) staining for CD8, PD-1, granzyme B (GrzB) and NFATC2.
Results
In total, 25 adenocarcinomas and 24 squamous cell carcinomas were analysed. All tumours showed metabolic 18F-FDG PET uptake. MMVR was correlated inversely with PD-L1 expression in tumour cells. Furthermore, PD-L1 expression and low MMVR were significantly correlated with clinical benefit. Necrosis was correlated negatively with MMVR. Multiplex IF staining showed a greater frequency of activated CD8+ cells in necrotic tumours than in nonnecrotic tumours in both stromal and epithelial tumour compartments.
Conclusion
This study introduces MMVR as a new imaging biomarker and its ability to noninvasively capture increased PD-L1 tumour expression and predict clinical benefit from checkpoint blockade in NSCLC should be further evaluated.