Related Experiment Video
Updated: Dec 25, 2025
Digital Spatial Profiling for Characterization of the Microenvironment in Adult-Type Diffusely Infiltrating Glioma
Published on: September 13, 2022
Digital quantitative assessment of PD-L1 using digital spatial profiling
Swati Gupta1, Jon Zugazagoitia1, Sandra Martinez-Morilla1
1Department of Pathology, Yale University School of Medicine, New Haven, CT, USA.
Insights
Digital spatial profiling (DSP) offers a new, quantitative method for assessing programmed death 1 ligand 1 (PD-L1) expression. This technique shows high correlation with current methods and potential for companion diagnostics in immunotherapy.
Area of Science:
- Biomarker analysis
- Immunotherapy
- Digital pathology
Background:
- Programmed death 1 ligand 1 (PD-L1) expression measured by immunohistochemistry (IHC) is an FDA-approved predictive marker for anti-PD-1/PD-L1 immunotherapies.
- Existing PD-L1 IHC assays vary in antibodies and scoring methods, leading to inconsistent results.
- There is a need for standardized and accurate methods to assess PD-L1 expression.
Purpose of the Study:
- To investigate digital spatial profiling (DSP) as an alternative method for PD-L1 assessment.
- To compare the accuracy and reproducibility of DSP against FDA-approved IHC assays and other quantitative methods.
- To evaluate the potential of DSP for companion diagnostic testing in immunotherapy.
Main Methods:
- Utilized a standardization tissue microarray (TMA) with 10 isogenic cell lines expressing varying PD-L1 levels.
- Measured PD-L1 dynamic range using the GeoMx DSP assay on the nCounter platform.
- Compared DSP results with FDA-approved PD-L1 assays, an LDT assay, and quantitative fluorescence assays.
Main Results:
- DSP demonstrated a very high correlation with quantitative IHC scoring and quantitative fluorescence assays.
- High correlation of PD-L1 digital DSP counts was observed between different sections of the same Index TMA.
- DSP assay reproducibility was independent of slide storage time (up to three weeks) after antibody labeling.
Conclusions:
- Digital spatial profiling shows significant quantitative potential, comparable to quantitative IHC.
- DSP can accurately measure PD-L1 protein levels across a dynamic range.
- DSP technology holds promise as a reliable system for companion diagnostic testing in immune therapy selection.
Abstract:
The assessment of programmed death 1 ligand 1 (PD-L1) expression by Immunohistochemistry (IHC) is the US Food and Drug Administration (FDA)-approved predictive marker to select responders to checkpoint blockade anti-PD-1/PD-L1 axis immunotherapies. Different PD-L1 immunohistochemistry (IHC) assays use different antibodies and different scoring methods in tumor cells and immune cells. Multiple studies have compared the performance of these assays with variable results. Here, we investigate an alternative method for assessment of PD-L1 using a new technology known as digital spatial profiling. We use a previously described standardization tissue microarray (TMA) to assess the accuracy of the method and compare digital spatial profiler (DSP) to each FDA-approved PD-L1 assays, one LDT assay and three quantitative fluorescence assays. The standardized cell line Index tissue microarray contains 10 isogenic cells lines in triplicates expressing various ranges of PD-L1. The dynamic range of PD-L1 digital counts was measured in the ten cell lines on the Index TMA using the GeoMx DSP assay and read on the nCounter platform. The digital method shows very high correlation with immunohistochemistry scored with quantitative software and with quantitative fluorescence. High correlation of PD-L1 digital DSP counts were seen between rows on the same Index TMA. Finally, experiments from two Index TMAs showed reproducibility of DSP counts were independent of variable slide storage time over a three-week period after antibody labeling but before collection of cleaved tags. In summary, DSP appears to have quantitative potential comparable to quantitative immunohistochemistry. It is possible that this technology could be used as a PD-L1 protein measurement system for companion diagnostic testing for immune therapy.
