Improving the Diagnostic Accuracy of the PD-L1 Test with Image Analysis and Multiplex Hybridization
Matthew P Humphries1, Victoria Bingham1, Fatima Abdullahi Sidi1
1Precision Medicine Centre of Excellence, The Patrick G Johnston Centre for Cancer Research, Queen's University, Belfast BT9 7BL, UK.
Abstract:
Targeting of the programmed cell death protein (PD-1)/programmed death-ligand 1 (PD-L1) axis with checkpoint inhibitors has changed clinical practice in non-small cell lung cancer (NSCLC). However, clinical assessment remains complex and ambiguous. We aim to assess whether digital image analysis (DIA) and multiplex immunofluorescence can improve the accuracy of PD-L1 diagnostic testing. A clinical cohort of routine NSCLC patients reflex tested for PD-L1 (SP263) immunohistochemistry (IHC), was assessed using DIA. Samples of varying assessment difficulty were assessed by multiplex immunofluorescence. Sensitivity, specificity, and concordance was evaluated between manual diagnostic evaluation and DIA for chromogenic and multiplex IHC. PD-L1 expression by DIA showed significant concordance (R² = 0.8248) to manual assessment. Sensitivity and specificity was 86.8% and 91.4%, respectively. Evaluation of DIA scores revealed 96.8% concordance to manual assessment. Multiplexing enabled PD-L1+/CD68+ macrophages to be readily identified within PD-L1+/cytokeratin+ or PD-L1-/cytokeratin+ tumor nests. Assessment of multiplex vs. chromogenic IHC had a sensitivity and specificity of 97.8% and 91.8%, respectively. Deployment of DIA for PD-L1 diagnostic assessment is an accurate process of case triage. Multiplex immunofluorescence provided higher confidence in PD-L1 assessment and could be offered for challenging cases by centers with appropriate expertise and specialist equipment.
Insights
Digital image analysis (DIA) and multiplex immunofluorescence enhance programmed cell death protein 1 (PD-1) ligand 1 (PD-L1) diagnostic accuracy in non-small cell lung cancer (NSCLC). These methods offer improved sensitivity and specificity for PD-L1 testing, aiding clinical decisions.
Area of Science:
- Oncology
- Immunotherapy
- Diagnostic Pathology
Background:
- Immune checkpoint inhibitors targeting the PD-1/PD-L1 axis have transformed non-small cell lung cancer (NSCLC) treatment.
- Accurate PD-L1 expression assessment is crucial for treatment selection but remains complex and subjective.
- Current diagnostic methods for PD-L1 require improvement in accuracy and reproducibility.
Purpose of the Study:
- To evaluate the efficacy of digital image analysis (DIA) in improving PD-L1 diagnostic testing accuracy for NSCLC.
- To assess the utility of multiplex immunofluorescence in complex PD-L1 assessment.
- To compare the diagnostic performance of DIA and multiplex immunofluorescence against manual evaluation.
Main Methods:
- A cohort of routine NSCLC patient samples, initially tested for PD-L1 (SP263) via immunohistochemistry (IHC), were analyzed using DIA.
- Samples with varying assessment difficulty were further evaluated using multiplex immunofluorescence.
- Sensitivity, specificity, and concordance rates were calculated for DIA and multiplex IHC compared to manual assessment.
Main Results:
- DIA demonstrated significant concordance (R² = 0.8248) with manual PD-L1 assessment, showing 86.8% sensitivity and 91.4% specificity.
- DIA scoring achieved 96.8% concordance with manual evaluation, indicating its reliability for case triage.
- Multiplex immunofluorescence identified PD-L1+/CD68+ macrophages within tumor nests and offered higher sensitivity (97.8%) and specificity (91.8%) compared to chromogenic IHC.
Conclusions:
- Digital image analysis is an accurate method for PD-L1 diagnostic assessment and efficient case triage in NSCLC.
- Multiplex immunofluorescence enhances confidence in PD-L1 evaluation, particularly for challenging cases.
- These advanced techniques can support clinical decision-making in NSCLC immunotherapy.
