Abstract 1161P
Background
Anti-PD-(L)1 agents play an important role in the management of NSCLC. PD-L1 analysis by immunohistochemistry is an important biomarker but displays temporospatial heterogeneity. In advanced NSCLC, metabolic parameters tumoural maximum standardised uptake value (SUVmax) and total lesion glycolysis (TLG) of 18F-FDG-PET/CT have been shown to correlate with PD-L1 expression. However, advanced status itself has been associated with high SUVmax and the relationship in early-stage disease has yet to be determined.
Methods
This retrospective study included NSCLC patients who underwent primary resection at a UK cancer centre. PD-L1 tumour proportion score (TPS) was assessed using the 22C3 pharmDx DAKO assay. Pre-surgical 18F-FDG-PET/CT scans were assessed for metabolic parameters: SUVmax; SUVmean; SUVpeak; SULpeak (lean body mass corrected), metabolic tumour volume (MTV), TLG and SUV-based heterogeneity index (HISUV). 40 cases were assessed by 2 observers to determine interobserver reliability. To determine correlation between metabolic parameters and PD-L1 TPS, unpaired t-test, one-way ANOVA or Kruskall-Wallis tests were applied. Interobserver reliability was determined using intraclass correlation coefficient (ICC).
Results
Patients (n=100) were grouped by primary tumour PD-L1 TPS of <1% (n=45), 1-49% (n=37) and ≥50% (n=18). There was no statistical difference between PD-L1 TPS groups for primary tumour SUVmax with mean SUVmax of 12.0 (95% CI 10.0-14.0) in PD-L1 <1% group, 14.0 (11.9-16.0) in PD-L1 1-49%, and 12.9 (10.2-15.7) in PD-L1 ≥50% (p=0.38). There was a non-significant trend in correlation with MTV with a mean MTV of 29.86 (19.2-40.6) in PD-L1 <1% group, 24.2 (14.3-34.2) in PD-L1 1-49%, and 15.5 (1.3-29.6) in PD-L1 ≥50% group (p=0.06). There was no significance between PD-L1 subgroups for SUVmean (p=0.48), SUVpeak (p=0.91), SULpeak (p=0.88), TLG (p=0.21) and HISUV (p=0.07). The ICCs between observers for all parameters were excellent (>0.9).
Conclusions
There was no correlation between primary resected NSCLC 18F-FDG-PET/CT metabolic parameters and PD-L1 TPS. A trend toward significant correlation for MTV and HISUV warrants further investigation. Importantly, we determined that interobserver reliability was excellent.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
MSD.
Disclosure
All authors have declared no conflicts of interest.