1283P - Predicting PD-L1 expression using [18F]FDG PET/CT in early stage non-small cell lung cancer (NSCLC)

Background

Advances in the management of early stage NSCLC include the introduction of PD-1/PD-L1 checkpoint inhibitors. PD-L1 is an important biomarker but its role in early NSCLC remains unclear. PD-L1 is also closely associated to glucose transporter 1 (GLUT1) expression and the correlation of metabolic parameters measured using [18F] FDG-PET/CT has been demonstrated in advanced disease. Our aim was to investigate the association of [18F] FDG-PET/CT metabolic parameters with PD-L1 expression in a cohort of patients with resected early stage NSCLC.

Methods

We conducted a retrospective analysis of 210 patients with node-positive early stage resected NSCLC. DAKO 22C3 PD-L1 immunohistochemistry was performed on primary tumour and positive nodes and scored according to tumour proportion score (TPS) of <1, 1-49, or ≥50%. [18F]FDG PET/CT was analysed using semiautomated techniques for max, mean and peak standardised uptake values (SUV), metabolic tumour volume (MTV), total lesion glycolysis (TLG) and SUV heterogeneity index (HISUV).

Results

Patients were predominantly male (57%), median age 70 years, a majority had non-squamous NSCLC (68%), and were current smokers (89%). Stage T2(a-b) disease was common (48%) and most had negative primary PD-L1 expression (TPS <1%; 53%). Mean SUVmax scores of the primary tumour (n = 210; p = 0.02) and nodes (n = 50; p = 0.03) increased according to PD-L1 TPS. There were similar trends for mean SUVmean and SUVpeak values in the primary and nodes across all TPS groups. SUVmax, mean and peak scores were all significantly (p<0.05) associated with PD-L1 positivity using a

Conclusions

This study demonstrated the association of standard [18F]FDG PET/CT metabolic parameters of SUVmax, SUVmean and SUVpeak with PD-L1 expression in early NSCLC. However, the sensitivity/specificity of these measurements for predicting PD-L1 positivity using the < or >1% threshold was poor. Future prospective studies are warranted to determine the association, predictive role, and clinical utility of these metabolic measurements.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Merck Sharp & Dohme.

Disclosure

All authors have declared no conflicts of interest.