Programmed Death Ligand 1 Immunohistochemistry Assays Research Articles

Real-world prevalence of PD-L1 expression in non-small cell lung cancer: an Australia-wide multi-centre retrospective observational study

An investigator-initiated, Australia-wide multi-centre retrospective observational study was undertaken to investigate the real-world prevalence of programmed death ligand-1 (PD-L1) expression in non-small cell lung carcinoma (NSCLC). Multiple centres around Australia performing PD-L1 immunohistochemistry (IHC) were invited to participate. Histologically confirmed NSCLC of any stage with a PD-L1 IHC test performed for persons aged ≥18 years between 1 January 2018 and 1 January 2020, and eligible for review, were identified at each centre, followed by data extraction and de-identification, after which data were submitted to a central site for collation and analysis. In total data from 6690 eligible PD-L1 IHC tests from histologically (75%) or cytologically (24%) confirmed NSCLC of any stage were reviewed from persons with a median age of 70 years, 43% of which were female. The majority (81%) of tests were performed using the PD-L1 IHC SP263 antibody with the Ventana BenchMark Ultra platform and 19% were performed using Dako PD-L1 IHC 22C3 pharmDx assay. Reported PD-L1 tumour proportion score (TPS) was ≥50% for 30% of all tests, with 62% and 38% scoring PD-L1 ≥1% and <1%, respectively. Relative prevalence of clinicopathological features with PD-L1 scores dichotomised to <50% and ≥50%, or to <1% and ≥1%, were examined. Females scored ≥1% slightly more often than males (64% vs 61%, respectively, p=0.013). However, there was no difference between sexes or age groups (<70 or ≥70 years) where PD-L1 scored ≥50%. Specimens from patients with higher stage (III/IV) scored ≥1% or ≥50% marginally more often compared to specimens from patients with lower stage (I/II) (p≤0.002). Proportions of primary and metastatic specimens did not differ where PD-L1 TPS was ≥1%, however more metastatic samples scored TPS ≥50% than primary samples (metastatic vs primary; 34% vs 27%, p<0.001). Cytology and biopsy specimens were equally reported, at 63% of specimens, to score TPS ≥1%, whereas cytology samples scored TPS ≥50% slightly more often than biopsy samples (34% vs 30%, respectively, p=0.004). Resection specimens (16% of samples tested) were reported to score TPS ≥50% or ≥1% less often than either biopsy or cytology samples (p<0.001). There was no difference in the proportion of tests with TPS ≥1% between PD-L1 IHC assays used, however the proportion of tests scored at TPS ≥50% was marginally higher for 22C3 compared to SP263 (34% vs 29%, respectively, p<0.001). These real-world Australian data are comparable to some previously published global real-world data, with some differences noted.

A comprehensive pan-cancer analysis of PD-L1 expression using clone E1L3N in Chinese patients with cancer.

2656 Background: Immune checkpoint inhibitors (ICIs) benefit patients with multiple cancer types, and the expression of programmed death ligand 1 (PD-L1) protein assessed by immunohistochemistry (IHC) has been correlated with response and survival benefit from anti-PD-1/PD-L1 ICI therapies in several cancer types. IHC assay with E1L3N clone is currently approved by the NMPA for PD-L1 detection in non-small cell lung cancer (NSCLC), but its performance in other cancer types needs to be further validated. Thus, we performed this study to examine the prevalence of PD-L1 expression in a wide variety of tumor types in Chinese pan-cancer patients using the E1L3N antibody clone. Methods: From 2019 to 2022, a total of 13,647 patient across multiple tumor types were analyzed. Tumor tissue samples were subjected to IHC. PD-L1 expression was tested using the E1L3N PD-L1 IHC assay (Amoy Diagnostics, Xiamen, China), and scored with the tumor proportion score (TPS) and combined positive score (CPS). PD-L1 expression status was identified as positive and negative according to TPS or CPS. For NSCLC: negative (TPS &lt; 1%), low expression (TPS 1-49%), and high expression (TPS ≥ 50%). For gastric/gastroesophageal junction carcinoma (GC/GJC): negative (CPS &lt; 1), low expression (CPS 1-5), and high expression (CPS ≥ 5). For other cancer: negative (CPS &lt; 1), low expression (CPS 1-10), and high expression (CPS ≥ 10). Results: In total, 14 cancer types were enrolled in the present study, including 68.2% NSCLC, 6.9% colorectal carcinoma (CRC), and 3.8% GC/GJC, and the remaining 21.1% include esophageal cancer (EC), breast cancer, cervical cancer (CC), biliary tract cancer (BTC), pancreatic cancer (PC), ovarian cancer, renal cancer, small cell lung cancer, urothelial carcinoma (UC), bladder cancer, head and neck squamous cell carcinoma (HNSCC), etc. PD-L1 positivity by TPS was observed in 52.5% NSCLC patients, similar to the frequency of PD-L1 expression in Chinese NSCLC patients detected using 22C3 clone. 76.0% and 36.7% of GC/GJC patients with PD-L1-positive tumors at a CPS cutoff of ≥ 1 and ≥ 5, respectively. PD-L1 positive expression frequency was higher than that in western GC/GJC patients detected using 22C3 and 28-8 clone (as reported from previous research: PD-L1 positivity with CPS ≥ 1 was 45.5% using the 22C3 assay and 49.1% using the 28-8 assay). 73.6% and 17.5% of CRC patients with PD-L1-positive tumors at a CPS cutoff of ≥ 1 and ≥ 10, respectively. In addition, 8 tumors (EC, CC, breast cancer, PC, BTC, UC, HNSCC, and bladder cancer) had the prevalence of PD-L1 CPS ≥ 1 greater than 50%. Conclusions: E1L3N can be used as a reliable alternative antibody clone to evaluate PD-L1 expression status not only in NSCLC patients but also in other cancer types.

Durable responders in advanced NSCLC with elevated TMB and treated with 1L immune checkpoint inhibitor: a real-world outcomes analysis

BackgroundFor patients with advanced non-small cell lung carcinoma (NSCLC), immune checkpoint inhibitor (ICPI) and chemotherapy (chemo) ICPI represent two distinct first-line standard-of-care regimens without clear and established biomarkers to inform...

Choice of PD-L1 immunohistochemistry assay influences clinical eligibility for gastric cancer immunotherapy

BackgroundImmune checkpoint inhibitors (ICI) are now standard-of-care treatment for patients with metastatic gastric cancer (GC). To guide patient selection for ICI therapy, programmed death ligand-1 (PD-L1) biomarker expression is routinely assessed via immunohistochemistry (IHC). However, with an increasing number of approved ICIs, each paired with a different PD-L1 antibody IHC assay used in their respective landmark trials, there is an unmet clinical and logistical need for harmonization. We investigated the interchangeability between the Dako 22C3, Dako 28–8 and Ventana SP-142 assays in GC PD-L1 IHC.MethodsIn this cross-sectional study, we scored 362 GC samples for PD-L1 combined positive score (CPS), tumor proportion score (TPS) and immune cells (IC) using a multiplex immunohistochemistry/immunofluorescence technique. Samples were obtained via biopsy or resection of gastric cancer.ResultsThe percentage of PD-L1-positive samples at clinically relevant CPS ≥ 1, ≥ 5 and ≥ 10 cut-offs for the 28–8 assay were approximately two-fold higher than that of the 22C3 (CPS ≥ 1: 70.3 vs 49.4%, p < 0.001; CPS ≥ 5: 29.1 vs 13.4%, p < 0.001; CPS ≥ 10: 13.7 vs 7.0%, p = 0.004). The mean CPS score on 28–8 assay was nearly double that of the 22C3 (6.39 ± 14.5 vs 3.46 ± 8.98, p < 0.001). At the clinically important CPS ≥ 5 cut-off, there was only moderate concordance between the 22C3 and 28–8 assays.ConclusionOur findings suggest that scoring PD-L1 CPS with the 28–8 assay may result in higher PD-L1 scores and higher proportion of PD-L1 positivity compared to 22C3 and other assays. Until stronger evidence of inter-assay concordance is found, we urge caution in treating the assays as equivalent.

The utilization of artificial intelligence to produce clinically relevant scores on PD-L1 immunostained non-small cell lung cancer biopsies.

e14576 Background: Immunotherapies targeting complex programmed death-ligand 1 (PD-L1) interactions have been groundbreaking in the treatment of non-small cell lung cancer (NSCLC), offering new strategies for patients who are likely to respond. PD-L1 binds to the checkpoint PD-1 to regulate T cells, which has an important role in boosting the immune response. Identifying patients who may benefit from PD-L1 focused care is dependent on the interpretation of the drug’s associated companion diagnostic (CDx) immunohistochemistry (IHC) assay. PD-L1 IHC assays stratify NSCLC patients using a Tumor Proportion Score (TPS), a manual scoring paradigm which must be applied by a clinical pathologist. Application of the score is complex as it requires the reader to visually exclude stromal and tumor-infiltrating immune cells across a full sample, retaining PD-L1 expression information for true tumor cells only. Methods: In this study, we utilized the PD-L1 [28-8] immunohistochemistry (IHC) assay to stain 10 NCSLC specimens. Stained slides were then imaged using the AT2 scanner (Leica Biosystems, Buffalo Grove, IL) scanner and analyzed using the Visiopharm Image Analysis platform. Results: The intricacy of TPS application is time consuming for the pathologist and introduces opportunity for inter- and intra-reader variability. Our novel image analysis approach utilizes artificial intelligence (AI) to automatically denote tumor nests and exclude tumor-infiltrating immune cells. The remaining true tumor cells may then be quantified for PD-L1 expression across the full biopsy, producing a TPS for each sample. Conclusions: This method allows for great accuracy and time-efficiency in providing a TPS than traditional methods, which may result in improved patient care.

Choice of PD-L1 immunohistochemistry assay influences clinical eligibility for gastric cancer immunotherapy.

4026 Background: Immune checkpoint inhibitors (ICI) are now standard-of-care treatment for patients with metastatic gastric cancer (GC). To guide patient selection for ICI therapy, programmed death ligand-1 (PD-L1) biomarker expression is routinely assessed via immunohistochemistry (IHC). Regulatory approval for ICIs is granted based on PD-L1 expression status, scored using metrics such as the combined positive score (CPS). However, with an increasing number of approved ICIs, each paired with a different PD-L1 antibody IHC assay used in their respective landmark trials, there is an unmet clinical and logistical need for harmonization. We thus investigated the interchangeability between the Dako 22C3, Dako 28-8 and Ventana SP-142 assays in GC PD-L1 IHC. Methods: In this cross-sectional study, samples were obtained via biopsy or resection of gastric cancer at the National University Hospital, Singapore. We scored 362 GC samples for PD-L1 CPS, tumor proportion score (TPS) and immune cells (IC) using a multiplex immunohistochemistry/immunofluorescence technique. 344 samples were developed into a tissue microarray (TMA), while 18 samples were used as whole slides for orthogonal validation. The samples selected for whole slide analysis were obtained from GC patients treated with ICI therapy. Results: The percentage of PD-L1 positive samples at clinically relevant CPS ≥1, ≥5 and ≥10 cut-offs (Table) for the 28-8 assay were approximately two-fold higher than that of the 22C3 (CPS≥1: 70.3% vs 49.4%, p&lt;0.001; CPS≥5: 29.1% vs 13.4%, p&lt;0.001; CPS≥10: 13.7% vs 7.0%, p=0.004). The mean CPS score on 28-8 assay was nearly double that of the 22C3 (6.39 ±14.5 vs 3.46±8.98, p&lt;0.001). At the clinically important CPS≥5 cut-off, there was only moderate concordance between the 22C3 and 28-8 assays. Conclusions: Our findings suggest that scoring PD-L1 CPS with the 28-8 assay may result in higher proportion of PD-L1 positivity and higher PD-L1 scores compared to assessment with the 22C3 and other assays. Clinically, this could lead to a larger number of patients eligible and approved for ICI therapy. If assays are viewed and used interchangeability, a substantial number of patients may be inaccurately denied or granted treatment with ICIs based on the assay chosen. As such, until stronger evidence of inter-assay concordance is found, we urge caution in treating the assays as equivalent.[Table: see text]

Abstract 435: A novel image analysis assay for determining programmed death-ligand 1 (22C3) in non-small cell lung cancer that accounts for tissue and alveolar macrophages

Abstract The Dako PD-L1 (22C3) antibody is used in immunohistochemistry (IHC) to measure tumor programmed death-ligand 1 (PD-L1) levels, serving as a common companion diagnostic to the check point inhibitor drug pembrolizumab in non-small cell lung cancer (NSCLC). Yet for the practicing pathologist, interpretation of the PD-L1 (22C3) IHC assay is cumbersome and time-consuming resulting in poor intra- and inter-pathologist precision. We have developed a clinically validated PD-L1 (22C3) image analysis (IA) assay that was previously shown to perform equivalently to manual pathologist scoring, require less labor, and produce standardized and reproducible results with greater precision than manual scoring across repeated assessment. However, there is growing literature on the significance of macrophage PD-L1 positivity for predicting treatment response, highlighting the need to differentiate PD-L1 positivity in tumor cells versus macrophages. This need is further underscored by the tendency of manual and digital reads to confuse alveolar macrophages as tumor cells. In this study, we have applied a novel machine learning solution for tissue and alveolar macrophage detection to our PD-L1 (22C3) IA assay to improve its digital scoring accuracy in NSCLC as well as generate additional complementary data on the presence and PD-L1 positivity status of tissue and alveolar macrophages. 24 whole tissue NSCLC samples were purchased and IHC stained for PD-L1. Stained slides were scanned at 20X magnification and analyzed using Flagship's IA solutions that separate tumor and stromal compartments, identify tissue and alveolar macrophages, and quantify PD-L1 expression. Resulting image markups of cell detection and PD-L1 expression were reviewed by an MD pathologist for acceptance. PD-L1 staining was evaluated by digital IA and manual pathology in the sample's tumor compartment for Tumor Proportion Score (TPS). Applying the tissue and alveolar macrophage solution to the PD-L1 (22C3) assay successfully removed macrophages from the digital TPS assessment and generated additional data on tissue and alveolar macrophages (% present, % PD-L1 positive) without significantly impacting the integrity of the IA assay (i.e., the correlation between the digital and manual TPS remained high). This preliminary data demonstrates the robust performance of the clinically validated PD-L1 (22C3) IA assay, even when accounting for tissue and alveolar macrophages. Ongoing experiments include testing the macrophage algorithm on a larger sample of NSCLC tissues to determine the correlation and treatment cut-off concordance between digital and manual scoring obtained by three pathologists. A follow-up clinical validation study of the sensitivity, specificity, accuracy, and precision of this updated PD-L1 (22C3) IA assay is also pending. Citation Format: Roberto Gianani, Will Paces, Elliott Ergon, Vitria Adisetiyo, Charles Caldwell. A novel image analysis assay for determining programmed death-ligand 1 (22C3) in non-small cell lung cancer that accounts for tissue and alveolar macrophages [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 435.

The clinical impact of three validated PD-L1 immunohistochemistry assays as a prognostic factor in small cell lung cancer.

BackgroundEvidence of the clinical impact of programmed death-ligand 1 (PD-L1) expression in small cell lung cancer (SCLC) is scarce and conflicting, even though atezolizumab became the first PD-L1 inhibitor approved by the US Food and Drug Administration (FDA) in recent years for the initial treatment of extensive-stage (ES)-SCLC.MethodsWe investigated PD-L1 expression in SCLC tumors using the three validated PD-L1 immunohistochemistry (IHC) assays (SP263, SP142, and 22C3) and assessed the correlation between PD-L1 expression and clinicopathological factors to determine the prognostic value of PD-L1 expression. The three PD-L1 IHC analyses were prospectively used to assess tumor samples of patients with SCLC at diagnosis.ResultsOf the total of 59 patients, 47 patients received the active treatment beyond platinum-based chemotherapy at our institution. PD-L1 expression was positive in 39.0% with SP263, 37.3% with SP142, and 22.0% with 22C3. In a univariate analysis, the positive result of at least one of the three PD-L1 assays and the positive result of the SP142 assay were associated with longer overall survival (OS). A multivariable analysis confirmed that performance status, stage, and the SP142 assay were independent predictors of OS. In subgroup analysis, these results revealed more significant prognostic factors in ES than in limited-stage (LS). In patients with SCLC, especially those with ES, the expression of the SP142 assay is a significant independent prognostic factor.ConclusionsAlthough these results need to be further validated in larger cohorts, this information will benefit clinicians and patients in determining the immunotherapy for patients with ES-SCLC.

Pan-cancer analysis of CD274 (PD-L1) mutations in 314,631 patient samples and subset correlation with PD-L1 protein expression

BackgroundThe effects of non-amplification short variant (SV) mutations in CD274 (programmed death-ligand 1 (PD-L1)) on PD-L1 protein expression and immune checkpoint inhibitors (ICPIs) therapy are unknown. Here, we present a...

Interpretation According to Clone-Specific PD-L1 Cutoffs Reveals Better Concordance in Muscle-Invasive Urothelial Carcinoma.

Because immune checkpoint inhibitors have been approved for treating advanced urothelial carcinoma (UC), programmed death-ligand 1 (PD-L1) immunohistochemistry (IHC) assays have been widely used as companion or complementary diagnostic tests for predicting treatment outcomes. Because different clones, scoring algorithms, and cutoffs have been used for interpretation, this study investigated the variation, correlation, and concordance of four validated PD-L1 clones (SP142, SP263, 22C3, and 28-8) and proposed a practical solution for the harmonization of PD-L1 IHC. A tissue microarray, including 46 muscle-invasive UCs, was constructed for PD-L1 testing with the four clones. Tumor cell (TC) and immune cell (IC) expression was analyzed. SP142 had significantly low TC expression, whereas SP263, 22C3, and 28-8 exhibited a moderate correlation (rho ≥ 0.6), with almost perfect concordance (intraclass correlation coefficient > 0.8) in TC expression. Fair to moderate correlation and concordance were observed in IC expression in most pairwise comparisons of clones. Substantial concordance (kappa > 0.6) was noted when high PD-L1 expression was defined by applying clone-specific cutoffs to each clone. Our findings imply that a universal cutoff value is not feasible for UC; we propose that PD-L1 IHC assays for UC should be interpreted according to a clone-specific scoring algorithm and cutoff value.

Predictive biomarkers for response to immune checkpoint inhibitors in lung cancer: PD-L1 and beyond

Immune checkpoint inhibitor (ICI) therapies, including the programmed cell death protein 1 (PD-1) axis blockade, are considered a major oncological breakthrough of the early twenty-first century and have led to remarkable response rates and survival in a subset of patients with non-small cell lung cancer (NSCLC). However, the available therapies work only for one in five unselected, advanced NSCLC patients; thus, patient selection needs to be performed with the use of efficient biomarkers. Although imperfect, programmed death-ligand 1 (PD-L1) expression by immunohistochemistry (IHC) on tumor cells and/or immune cells has been established as a predictive biomarker for response to the PD-1 axis blockade. There remain several pre-analytical, analytical, and post-analytical issues, however, before implementing a PD-L1 IHC assay(s) in the pathology laboratory. In addition, given the lack of robust sensitivity and specificity of PD-L1 IHC for predicting response to ICIs, other biomarkers including tumor mutation burden (TMB) are under investigation. In this review, issues associated with PD-L1 IHC and TMB estimations will be discussed, and other promising biomarkers for predicting response to ICIs will be briefly introduced.

Performance of Ventana SP263 PD-L1 assay in endobronchial ultrasound guided-fine-needle aspiration derived non-small-cell lung carcinoma samples.

Introduction of programmed death-ligand 1 (PD-L1) inhibitors has significantly changed the treatment landscape of non-small-cell lung carcinomas (NSCLC). Since endobronchial ultrasound guided fine-needle aspiration (EBUS FNA) has become the primary diagnostic and staging modality for NSCLC, this study was pursued to determine the adequacy of Ventana SP263 PD-L1 assay in cytology cell blocks. Fifty NSCLC cases with cytology and corresponding histology specimens obtained between 2014 and 2018 were identified. After assessing for adequacy (100 or more tumor cells), forty cases were selected for Ventana SP263 PD-L1 immunohistochemistry (IHC) assay and assessed for tumor proportion scores (TPS) and staining intensity scores (SIS) and analyzed for concordance. Of the 40 matched pairs 33 (82.5%) showed concordant PD-L1 expression. On cytology, 32 cases were positive (8 high-expressors and 24 low-expressors) of which 27 were concordant and 5 discordant with matched histology specimens. On histology, 29 cases were positive (7 high-expressor and 22 low-expressors) while 11 cases were negative for PD-L1 expression of which 6 had concordant negative cytology. The intraclass correlation coefficients (ICC) for TPS was 0.81 with 95% confidence interval (0.68, 0.9) and for the SIS, it was 0.78 with 95% CI (0.62, 0.88), both considered as having excellent agreement. With an overall concordance rate of 82.5% between cytology and histology specimen, this study demonstrates the feasibility of PD-L1 IHC with SP263 clone on cytology samples of NSCLC and adds to a growing body of evidence validating the use of cytology cell blocks for PD-L1 expression testing.

Implementation of PD-L1 22C3 IHC pharmDxTM in Cell Block Preparations of Lung Cancer: Concordance with Surgical Resections and Technical Validation of CytoLyt® Prefixation

Background: Programmed death ligand-1 (PD-L1) assessed by immunohistochemistry (IHC) is used as biomarker for pembrolizumab therapy in advanced stage lung cancer patients. However, data permitting direct performance comparison between cytology and surgical specimen types are limited since both specimens from a single tumor site are infrequently available. In addition, alcohol fixation used with cytology specimens requires technical validation of the PD-L1 IHC assay before clinical use. We here report our experience with implementation of the PD-L1 22C3 IHC pharmDx^TM assay for cytologic samples at a large tertiary cancer center. Study Design: Archival formalin-fixed (FF), paraffin-embedded cell blocks (CBs) and subsequent lung tumor resections (LTRs) from the same anatomical site were used for a direct comparison of PD-L1 tumor proportion scores (TPSs). TPS values were independently determined by one surgical lung pathologist and two cytopathologists blinded to the specimen pairs. An interim analysis was performed to facilitate the pooling of expertise among observers. After PD-L1 22C3 IHC pharmDx^TM implementation for FF cytology specimens, dual-processed samples were used for a prospective technical validation of CytoLyt® prefixation (CF). Digital image analysis was performed for a subset of dual-processed specimens. Results: Eighty-one CBs and LTRs were included for comparison of the specimen types. PD-L1 assessment in CBs had an accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of 88.9/72.8, 66.7/73.5, 95.2/72.3, 80.0/65.8, and 90.9/79.1% for the ≥50/≥1% cutoff, respectively. The intraclass correlation coefficient was 0.84 (95% confidence interval [CI]: 0.76, 0.90), and it improved after interim analysis (before: 0.79 and after: 0.92). The overall concordance between CF and FF for the categories defined by the ≥50/≥1% cutoff values was 90.4% (95% CI: 79.0, 96.8). Similar assay performance was confirmed by digital analysis. Conclusions: PD-L1 22C3 IHC pharmDx^TM shows good reliability if used with CB preparations. CF does not impact assay results significantly. Clinical validation with outcome data is needed, and digital methods of assessment should be further investigated.

Selected highlights of the 2019 Pulmonary Pathology Society Biennial Meeting: PD-L1 test harmonization studies.

Immune checkpoint inhibitors (ICI) including programmed death 1 (PD-1) inhibitors, such as nivolumab and pembrolizumab, or programmed death ligand 1 (PD-L1) inhibitors, such as atezolizumab and durvalumab, have recently emerged in advanced stage lung cancer as new standards of care. They are now indicated in first- line and second- or later-line treatment of metastatic or locally-advanced stage III non-small cell lung cancer (NSCLC), as well as for metastatic small cell lung cancer (SCLC), as single agent immunotherapy or in combination with chemotherapy. Four PD-L1 immunohistochemistry (IHC) assays have been established and validated in randomized trials, each for a specific ICI. They use different primary monoclonal antibodies, platforms and detection systems, as well as different scoring systems to assess PD-L1 expression either by tumor cells (TCs) and/or by infiltrating immune cells (ICs). Most studies have shown a close analytical performance of three of these clinically-validated standardized assays, but their use restricted to dedicated platforms, which are not all available in most laboratories, questions their applicability. In addition, the relative high costs of the assays have led to the development of in-house protocols in many pathology laboratories. Their use in clinical practice to assess the predictive value of PD-L1 expression for prescription of ICI raises the issue of their reliability and their validation as compared to standardized assays. This article discusses the main comparative studies available between LDT and assays, with clear evidence that LDT can reach a performance equivalent to the trial-validated assays. The requirements are an adequate validation as compared to an appropriate standard, and the participation to external quality assurance programs and training programs for PD-L1 IHC assessment for pathologists.

A comparative study of PD-L1 IHC assays using immune cell scoring and CPS in breast cancer.

e15262 Background: The clinical benefit of immune checkpoint inhibitors (ICIs) targeting the programmed death-1/programmed death ligand 1 (PD-L1) pathway has previously been demonstrated across a range of tumor types, including in PD-L1+ patients with metastatic triple-negative breast cancer (TNBC). Various PD-L1 immunohistochemistry (IHC) assays and scoring algorithms are being investigated to select patients with breast cancer (BC) most likely to respond to ICIs. Scoring algorithms include PD-L1 expression on tumor cells, immune cells (ICs), or both. We compared the analytical concordance of 3 PD-L1 IHC assays and evaluated PD-L1+ prevalence, using combined positive score (CPS) and % IC scoring algorithms in commercially procured TNBC and hormone receptor–positive, HER2-negative (HR+/HER2−) BC samples. Methods: PD-L1 expression was assessed by HistoGeneX (Naperville, IL) in 163 commercially procured, surgically resected, formalin-fixed, paraffin-embedded BC samples (mostly stage I–III) using the Ventana PD-L1 (SP142) and Dako PD-L1 IHC 28-8 and 22C3 pharmDx assays in conjunction with the CPS (28-8 and 22C3 assays) and % IC algorithms (SP142 and 28-8 assays). PD-L1+ prevalence with each assay and concordance between assays were calculated using CPS ≥ 1 and IC ≥ 1% cutoffs, with a single pathologist assigned to each scoring algorithm. Results: 93 HR+/HER2− BC and 70 TNBC samples were evaluable for PD-L1 expression across all assays and algorithms. Overall concordance was higher between the 28-8 and 22C3 assays (CPS cutoff of 1) than between the 28-8 and SP142 assays (IC cutoff of 1%). PD-L1+ prevalence was similar with the 28-8 and 22C3 assays (CPS ≥ 1) and higher with the 28-8 assay (IC ≥ 1%) than with the SP142 assay (IC ≥ 1%). PD-L1+ samples identified by the SP142 assay (IC ≥ 1%) were mostly included within PD-L1+ sample sets defined by the 28-8 assay (IC ≥ 1% and CPS ≥ 1). PD-L1+ prevalence was higher in TNBC vs HR+/HER2− BC for all assays (Table). No clear trend in PD-L1+ prevalence was observed across tumor grade and stage. Conclusions: High analytical concordance was observed between the 28-8 and 22C3 assays (CPS cutoff of 1) in both HR+/HER2− BC and TNBC samples. PD-L1+ prevalence varied according to IHC assay, scoring algorithm, and cutoff used. Further studies are needed to select the most appropriate PD-L1 assay and scoring algorithm for BC clinical trials. [Table: see text]

Digital pathology to evaluate PD-L1 IHC scoring as a predictor of outcome with second-line avelumab treatment in patients with non-small cell lung cancer (NSCLC).

e21539 Background: Assessment of programmed death ligand-1 (PD-L1) protein expression using immunohistochemistry (IHC)-based tests is currently the only approved biomarker guiding treatment of non-small cell lung cancer (NSCLC) with checkpoint inhibitors. Robust scoring guidelines and suitable cut-offs should be defined specifically for each PD-L1 IHC assay and are critical for appropriate treatment decisions. Methods: We retrospectively applied a novel digital pathology (DP) solution that mimics the conventional tumor proportion scoring (TPS) of PD-L1. The exploratory DP solution was developed and validated using samples from 340 patients enrolled in the first- and second-line (1L and 2L) NSCLC cohorts of the avelumab phase 1 JAVELIN Solid Tumor trial (NCT01772004) and 792 patients with NSCLC enrolled in the avelumab phase 3 JAVELIN Lung 200 trial (NCT02395172). Efficacy analyses were conducted for overall survival (OS) and progression-free survival (PFS) using the full analysis set with evaluable imaging data (n = 136 and n = 544, respectively). Results: Comparison of DP and conventional, semiquantitative pathologist scoring resulted in a high correlation overall (Spearman correlation coefficient, 0.86), with comparable performance for prediction of outcome to treatment with avelumab in 2L NSCLC. Consistent with conventional scoring, median OS and median PFS in avelumab-treated patients increased with higher PD-L1 expression cut-offs: in patients with ≥1%, ≥50%, and ≥80% PD-L1 expression on tumors cells, median OS was 10.0 months (95% CI: 8.6-14.3), 13.8 months (95% CI: 9.6-20.4) and 18.5 months (95% CI: 9.6-not estimable), respectively; median PFS, 3.1 months (95% CI: 2.7-4.9), 5.5 months (95% CI: 2.8-8.3) and 5.6 months (95% CI: 2.8-9.9). Conclusions: Our results demonstrate the technical feasibility, robustness, and utility of DP in scoring PD-L1 IHC in clinical trial samples, achieving comparable performance to conventional, semiquantitative pathologist scoring. Furthermore, our study supports the manual pathologist scoring algorithm (TPS scoring) in NSCLC and the selection of higher cut-offs for the PD-L1 IHC Ab clone 73-10.

PD-L1 Assay Concordance in Metastatic Renal Cell Carcinoma and Metastatic Urothelial Carcinoma

Immune checkpoint inhibitors are now standard of care for many patients with metastatic renal cell carcinoma (mRCC) and metastatic urothelial carcinoma (mUC). Given real-world limitations in programmed death-ligand 1 (PD-L1) testing, concordance studies between PD-L1 assays are needed. We undertook comparisons of Dako 28-8 and Ventana SP142 assays in mRCC and Dako 22C3 and Ventana SP263 assays in mUC. Thirty-two patients with mRCC and 18 patients with mUC who had received immune checkpoint inhibitor therapy were identified. Formalin-fixed paraffin-embedded tumor samples for patients with mRCC were evaluated with Dako 28-8 and Ventana SP142 PD-L1 immunohistochemistry assays. For patients with mUC, formalin-fixed paraffin-embedded tumor samples were evaluated with Dako 22C3 and Ventana SP263 PD-L1 immunohistochemistry assays. The majority (29/32; 91%) of mRCC cases were concordant between assays. The majority (17/18; 94%) of mUC cases were also concordant between assays. There was strong concordance between PD-L1 assays chosen for comparison in both mRCC and mUC, with similar performance characteristics. One limitation is the small number of cases in this study; larger comparison studies are needed for this biomarker in mRCC and mUC.

Characterization of tumor mutation burden, PD-L1 and DNA repair genes to assess relationship to immune checkpoint inhibitors response in metastatic renal cell carcinoma

BackgroundImmune checkpoint inhibitors (ICIs) have expanded treatment options for metastatic renal cell carcinoma (mRCC); however, there are limited predictive biomarkers for response to ICIs in this indication, with programmed death-ligand...

PD-L1 Testing for Lung Cancer in 2019: Perspective From the IASLC Pathology Committee.

The recent development of immune checkpoint inhibitors (ICIs) has led to promising advances in the treatment of patients with NSCLC and SCLC with advanced or metastatic disease. Most ICIs target programmed cell death protein 1 (PD-1) or programmed death ligand 1 (PD-L1) axis with the aim of restoring antitumor immunity. Multiple clinical trials for ICIs have evaluated a predictive value of PD-L1 protein expression in tumor cells and tumor-infiltrating immune cells (ICs) by immunohistochemistry (IHC), for which different assays with specific IHC platforms were applied. Of those, some PD-L1 IHC assays have been validated for the prescription of the corresponding agent for first- or second-line treatment. However, not all laboratories are equipped with the dedicated platforms, and many laboratories have set up in-house or laboratory-developed tests that are more affordable than the generally expensive clinical trial-validated assays. Although PD-L1 IHC test is now deployed in most pathology laboratories, its appropriate implementation and interpretation are critical as a predictive biomarker and can be challenging owing to the multiple antibody clones and platforms or assays available and given the typically small size of samples provided. Because many articles have been published since the issue of the IASLC Atlas of PD-L1 Immunohistochemistry Testing in Lung Cancer, this review by the IASLC Pathology Committee provides updates on the indications of ICIs for lung cancer in 2019 and discusses important considerations on preanalytical, analytical, and postanalytical aspects of PD-L1 IHC testing, including specimen type, validation of assays, external quality assurance, and training.

359P - Reproducibility and concordance of 4 clinically developed programmed death-ligand 1 (PD-L1) immunohistochemistry (IHC) assays in triple negative breast cancer (TNBC)

359P - Reproducibility and concordance of 4 clinically developed programmed death-ligand 1 (PD-L1) immunohistochemistry (IHC) assays in triple negative breast cancer (TNBC)