Automated image analysis of NSCLC biopsies to predict response to anti-PD-L1 therapy

Abstract

Background: Immune checkpoint therapies (ICTs) targeting the programmed cell death-1 (PD1)/programmed cell death ligand-1 (PD-L1) pathway have improved outcomes for patients with non-small cell lung cancer (NSCLC), particularly those with high PD-L1 expression. However, the predictive value of manual PD-L1 scoring is imperfect and alternative measures are needed. We report an automated image analysis solution to determine the predictive and prognostic values of the product of PD-L1+ cell and CD8+ tumor infiltrating lymphocyte (TIL) densities (CD8xPD-L1 signature) in baseline tumor biopsies.

Methods: Archival or fresh tumor biopsies were analyzed for PD-L1 and CD8 expression by immunohistochemistry. Samples were collected from 163 patients in Study 1108/NCT01693562, a Phase 1/2 trial to evaluate durvalumab across multiple tumor types, including NSCLC, and a separate cohort of 199 non-ICT- patients. Digital images were automatically scored for PD-L1+ and CD8+ cell densities using customized algorithms applied with Developer XD™ 2.7 software.

Results: For patients who received durvalumab, median overall survival (OS) was 21.0 months for CD8xPD-L1 signature-positive patients and 7.8 months for signature-negative patients (p = 0.00002). The CD8xPD-L1 signature provided greater stratification of OS than high densities of CD8+ cells, high densities of PD-L1+ cells, or manually assessed tumor cell PD-L1 expression ≥25%. The CD8xPD-L1 signature did not stratify OS in non-ICT patients, although a high density of CD8+ cells was associated with higher median OS (high: 67 months; low: 39.5 months, p = 0.0009) in this group.

Conclusions: An automated CD8xPD-L1 signature may help to identify NSCLC patients with improved response to durvalumab therapy. Our data also support the prognostic value of CD8+ TILS in NSCLC patients who do not receive ICT.

Trial registration: ClinicalTrials.gov identifier: NCT01693562 . Study code: CD-ON-MEDI4736-1108. Interventional study (ongoing but not currently recruiting). Actual study start date: August 29, 2012. Primary completion date: June 23, 2017 (final data collection date for primary outcome measure).

Keywords: Biomarker; CD8; Cancer immune checkpoint therapy; Image analysis; Immunohistochemistry; NSCLC; PD-L1.

Conflict of interest statement

Ethics approval and consent to participate

Clinical study NCT01693562, from which data in this report were obtained, was carried out in accordance with the Declaration of Helsinki and Good Clinical Practice guidelines. The study protocol, amendments, and participant informed consent document were approved by the appropriate institutional review boards.

Consent for publication

No individual data were used in this study.

Competing interests

SAH, MCR, KR, BWH, and KES are employees of AstraZeneca and own stock and/or stock options in AstraZeneca. THT, AS, LR, TW, TH, MW, and GS are employees of Definiens AG. SA at the time of this study was an employee of Definiens AG.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Figures

Fig. 1

Digital image analysis segmentation of CD8+ and programmed cell death ligand-1 (PD-L1) + cells in single immunohistochemistry labelled sections of non-small cell lung cancer. Serial tumor sections of durvalumab-treated patients enrolled in Study 1108 were labelled separately using brown chromogen for both CD8 (a) and PD-L1 (b). Image analysis segmentations of cells expressing each marker (c and d) are shown as red and quantifications of the corresponding expression levels are performed separately

Fig. 2

Predictive value of the CD8xPD-L1 signature compared to individual components. The comparative values are demonstrated by Kaplan-Meier analysis for overall survival of the durvalumab-treated patient test set for CD8xPD-L1 signature (a), CD8+ cell density (b), programmed cell death ligand-1 (PD-L1) + cell density (c), and manual pathologist scoring of PD-L1 tumor cell expression (d). Kaplan-Meier curves show survival probability, with shaded areas representing 95% confidence intervals. The cutoff values by which each measure was determined positive or negative were 1.54 × 105 cells2/mm4 for CD8xPD-L1 signature positivity; 297 cells/mm2 for CD8+ tumor infiltrating lymphocyte density; and 644 cells/mm2 for PD-L1+ cell density. The cutoff value for PD-L1 manual scoring, ≥25% tumor cells, was determined previously [39]

Fig. 3

Predictive versus prognostic values of the CD8xPD-L1 signature. These are demonstrated by Kaplan-Meier analysis of overall survival for the CD8xPD-L1 signature in the combined (training and test) set of patients treated with durvalumab (a) compared to the set of non-immune checkpoint therapy (ICT) patients (b). Kaplan-Meier curves show survival probability, with shaded areas representing 95% confidence intervals. The prevalence for the non-ICT patients was matched to that for patients treated with durvalumab. The resulting cutoffs for CD8xPD-L1 signature positivity for the durvalumab and non-ICT sets respectively were 1.54 × 105 and 2.85 × 104 cells2/mm4

Fig. 4

The prognostic values of CD8+ tumor infiltrating lymphocyte (TIL) densities and programmed cell death ligand-1 (PD-L1) measures. These are demonstrated by Kaplan-Meier analysis for overall survival by CD8+ (a) and PD-L1+ (b) cell densities and manual pathologist scoring of PD-L1 tumor cell expression (c) in patients who did not receive immune checkpoint therapy. Kaplan-Meier curves show survival probability, with shaded areas representing 95% confidence intervals. The cutoff values by which each measure was determined positive or negative were 297 cells/mm2 for CD8+ TIL density and 644 cells/mm2 for PD-L1+ cell density. The cutoff value for PD-L1 manual scoring, ≥25% tumor cells, was determined previously [39]