Assessment Of PD-L1 Expression Research Articles

The optimal threshold of PD-L1 combined positive score to predict the benefit of PD-1 antibody plus chemotherapy for patients with HER2-negative gastric adenocarcinoma: a meta-analysis

BackgroundImmune checkpoint inhibitors (ICIs) combined with chemotherapy have become the first-line treatment of metastatic gastric and gastroesophageal adenocarcinomas (GEACs). This study aims to figure out the optimal combined positive score (CPS) cutoff value.MethodsWe searched for randomized phase III trials to investigate the efficacy of ICIs plus chemotherapy for metastatic GEACs compared with chemotherapy alone. Pooled analyses of hazard ratios (HRs) based on PD-L1 expression were performed.ResultsA total of six trials (KEYNOTE-062, KEYNOTE-590, KEYNOTE-859, ATTRACTION-04, CheckMate 649, and ORIENT-16) were included, comprising 5,242 patients. ICIs plus chemotherapy significantly improved OS (HR: 0.79, 95% CI 0.72–0.86 in global patients; HR: 0.75, 95% CI 0.57–0.98 in Asian patients) and PFS (HR: 0.74, 95% CI 0.68–0.82 in global patients; HR: 0.64, 95% CI 0.56–0.73 in Asian patients) compared with chemotherapy alone. The differences in OS (ratio of HR: 1.05, 95% CI 0.79–1.40; predictive value: − 5.1%) and PFS (ratio of HR: 1.16, 95% CI 0.98–1.36; predictive value: − 13.5%) were not statistically significant between the global and Asian patients. Subgroup analyses indicated that the optimal CPS threshold was at ≥ 5 for OS and ≥ 10 for PFS with the highest predictive values.ConclusionsThe benefit derived from ICIs plus chemotherapy is similar between Asian and global GEAC patients. However, those with a PD-L1 CPS < 5 or CPS < 10 may not have significant benefits from ICIs therapy. Therefore, it is advisable to routinely assess PD-L1 expression in GEAC patients considered for ICIs treatment.

Abstract PO5-07-02: AI-assisted interpretation of PD-L1 CPS improves the precision medicine in Triple-negative breast cancer

Abstract Objective: The IMpassion 031 and KEYNOTE-355 clinical trial demonstrated the advantages of atezolizumab and pembrolizumab in the treatment of Triple-negative breast cancer (TNBC). However, the application of CPS in assessing PD-L1 expression is challenging. Pathologists have great variability in interpretation of PD-L1 CPS, the daily diagnostic workload is too heavy and their diagnostic efficiency is low, and they still have deficiencies in terms of accurate enumeration. It is of necessity to establish an objective and effective method which is highly repeatable. Methods: In this study, we established a deep learning-based artificial intelligence-assisted (AI-assisted) model which using cell detection and region segmentation algorithm. Three rounds of ring studies (RSs) were conducted. 12 pathologists of different level evaluate the CPS of PD-L1 (DAKO 22C3) in TNBC patients by visual assessment and AI-assisted model. Compare the difference, consistency and accuracy of the interpretation. Our research evaluated PD-L1 CPS expression with continuous score. Shapiro-Wilk (S-W) method performs normality test, difference analysis using Friedman M and Bonferroni calibration tests, consistency analysis is studied by intraclass correlation coefficient (ICC) and heat maps and box plots. Results: In the visual assessment, the interpretation results of PD-L1 (DAKO 22C3) CPS in different level pathologists have significant differences (P &amp;lt; 0.05), and the consistency of all the pathologists interpretation results was weak. Due to this strong inconsistency, it may result in a number of patients losing the opportunity to use ICIs for treatment. Moreover, the internal consistency of all pathologists in the visual assessment is moderate, in which the repeatability of junior pathologists is the worst, the ICC value is 0.664 (95%CI: 0.564-0.762). Through AI-assisted interpretation, there is no significant difference between all pathologists (P = 0.425), and the ICC value increased to 0.883 (95%CI:0.836-0.922) which improved the consistency of the interpretation results. In addition, through AI-assisted interpretation, the repeatability and accuracy of the interpretation results has been further upgraded. At the same time, the acceptance of AI results by junior pathologists are high, and 80% of the AI results are accepted. Conclusions: With the help of the AI-assisted diagnostic model, different levels of all the pathologists have achieved excellent consistency and repeatability in the interpretation of PD-L1 (DAKO 22C3) CPS. Moreover, the level of interpretation has been sought the rapid enhancement. It can be seen that AI-assisted diagnostic model provides a good approach to strengthen the consistency and repeatability in clinical practice. Our research also shows that PD-L1 CPS can receive precise interpretation from pathologists, so more patients have the opportunity to use ICIs. Therefore, these patients can benefit from treatment and achieve better survival. The interpretation results and system diagram of PD-L1 CPS by AI-assisted model. The consistency and repeatability of the interpretation results. (A)-(C) The consistency of the PD-L1 CPS interpretation among the different level of pathologists in three ring studies. (D)The repeatability of the interpretation results between 12 pathologists in RS1 and RS2. Accuracies and acceptance rates of different experienced pathologists. (A) Boxplots of scoring accuracies for pathologists in different levels. (B) Acceptance rates of all pathologists in total 50 slides. (C) Percent stacked column chart of different levels of pathologists with AI score acceptance. Citation Format: Jinze Li, Xinran Wang, Yueping Liu. AI-assisted interpretation of PD-L1 CPS improves the precision medicine in Triple-negative breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-07-02.

PD-L1 Expression in Nonbacterial Chronic Cystitis and Bladder Cancer.

The objective was to assess PD-L1 expression in nonbacterial chronic cystitis (NCC) and bladder cancer (BC). The present study included 20 NCC and 20 BC patients. The degree of inflammation of the bladder wall was assessed on slides stained with H&E. Viral pathogens (herpes simplex virus, Epstein-Barr virus, cytomegalovirus, and high-risk HPVs) were detected using real-time polymerase chain reaction analyses of the bladder specimens. Immunohistochemistry was performed to assess the PD-L1 expression in bladder tissue. Expression of PD-L1 was detected in 40% of NCC patients and 85% of BC patients. Viral pathogens were found in 50% of NCC patients and 60% of BC patients, with EBV being the most common. In NCC patients the immune cell score correlated strongly with the degree of inflammatory infiltration of the bladder wall (r = 0.867, p < 0.001), the presence of lymphoid aggregates in the submucosa (r = 0.804, p < 0.001), koilocytosis (r = 0.620, p = 0.004), and the presence of viral pathogens (r = 0.784, p < 0.001). In BC patients the immune cell score correlated with the degree of inflammatory infiltration of the bladder wall (r = 0.534, p = 0.015) and the presence of viral pathogens (r = 0.626, p = 0.003), but not with the presence of lymphoid aggregates in the submucosa (r = 0.083, p = 0.729), and koilocytosis (r = 0.366, p = 0.112). Expression of PD-L1 was detected in a cohort of NCC patients, although the PD-L1 positivity rate was lower than that in BC. Our results demonstrate that the degree of PD-L1 expression in bladder tissue is associated with the presence of viral infections and with the degree of inflammatory infiltration of the bladder wall in both NCC and BC.

Artificial intelligence-based assessment of PD-L1 expression in diffuse large B cell lymphoma

Diffuse large B cell lymphoma (DLBCL) is an aggressive blood cancer known for its rapid progression and high incidence. The growing use of immunohistochemistry (IHC) has significantly contributed to the detailed cell characterization, thereby playing a crucial role in guiding treatment strategies for DLBCL. In this study, we developed an AI-based image analysis approach for assessing PD-L1 expression in DLBCL patients. PD-L1 expression represents as a major biomarker for screening patients who can benefit from targeted immunotherapy interventions. In particular, we performed large-scale cell annotations in IHC slides, encompassing over 5101 tissue regions and 146,439 live cells. Extensive experiments in primary and validation cohorts demonstrated the defined quantitative rule helped overcome the difficulty of identifying specific cell types. In assessing data obtained from fine needle biopsies, experiments revealed that there was a higher level of agreement in the quantitative results between Artificial Intelligence (AI) algorithms and pathologists, as well as among pathologists themselves, in comparison to the data obtained from surgical specimens. We highlight that the AI-enabled analytics enhance the objectivity and interpretability of PD-L1 quantification to improve the targeted immunotherapy development in DLBCL patients.

Abstract 7617: Quantitative continuous scoring of PD-L1 for superior patient selection for anti-PD-L1 treatment of locally advanced or unresectable NSCLC

Abstract Background: Immune checkpoint inhibitors (ICIs) targeting PD-(L)1 following concurrent chemoradiotherapy (cCRT) have shown clinical activity in locally advanced, unresectable NSCLC, e.g. with the PACIFIC regimen [1]. PD-L1 expression is typically assessed by pathologist scoring of immunohistochemically (IHC) stained tissue using the tumor cell (TC) score. In this work, we present PD-L1 Quantitative Continuous Scoring (PD-L1 QCS) to digitally assess PD-L1 expression (Ventana SP263 assay), and analyze its utility for identification of patient subgroups with higher likelihood of treatment response. Method: 368 digitized whole slide images (WSI) of fresh biopsy and archival samples were obtained from the PACIFIC trial (NCT02125461), including 126 patients who received placebo and 242 patients who received Durvalumab post-cCRT [1]. WSI analysis included two deep learning models for epithelial TC segmentation followed by optical density (OD) quantification of membrane expression [2]. Initially, PD-L1 QCS was calibrated to compute the TC score at 1% cutoff by determining an optimal OD cell positivity threshold. Next, other scoring approaches were investigated, which included various OD thresholds and biomarker cutoffs. Results: PD-L1 QCS-based TC scoring was able to maintain median overall survival (mOS) of 57.4 months in the biomarker positive (BM+) ICI cohort, while increasing prevalence to 191 out of 242 patients (78.9%) compared to 177 (73.1%) with manual TC score at 1% cutoff. Extending the scoring paradigm to the PD-L1+ TC density &amp;gt;= 542.5 cells/mm² lead to a more pronounced increase of prevalence to 200 patients (82.6%) in the ICI population, while mOS was not reached and additionally showed comparable hazard ratios (HR) when evaluating against the BM+ placebo cohort (HR=0.54 [0.39, 0.76] resp. HR=0.52 [0.37, 0.74]). Results further demonstrated that PD-L1 QCS density scoring of the ICI treated population allowed for a clearer separation of patients with less treatment benefit (34.2m mOS, N=42, log rank p=0.0067) compared to manual scoring (47.4m mOS, N=65, log rank p=0.2). Conclusion: We investigated a computational pathology approach for selecting patients for treatment with the PACIFIC regimen and compared it against established manual pathology scoring. Results indicate that PD-L1 QCS TC proportion scoring can increase prevalence, while PD-L1 QCS TC density scoring has the potential to identify an even larger patient subgroup with increased survival benefit.

Chronic Lymphocytic Thyroiditis with Oncocytic Metaplasia Influences PD-L1 Expression in Papillary Thyroid Carcinoma.

Despite the increasing recognition of PD-L1 as predictor of immunotherapeutic response in various malignancies, its role and prognostic significance in thyroid cancer remain underexplored and subject to debate. This study begins to address this gap by comprehensively analyzing PD-L1 expression in papillary thyroid carcinoma (PTC) and investigating its correlation with key clinicopathological variables. We conducted immunohistochemistry (IHC) to assess PD-L1 expression in whole-tissue sections from 121 primary papillary thyroid carcinoma (PTC) cases. We then analyzed the correlations between PD-L1 expression and various clinicopathological variables. PD-L1 expression was detected in 33.1% of papillary thyroid carcinomas (PTCs), predominantly exhibiting weak to moderate intensity. Notably, this study found no significant correlation between PD-L1 expression and various clinicopathological variables. The lack of association with traditional factors such as age, sex, histological subtype, and tumor size suggests the complex and multifaceted nature of PD-L1 regulation in PTC. Multivariate logistic regression analysis identified chronic lymphocytic thyroiditis with oncocytic metaplasia as the sole independent predictor of PD-L1 expression (P = 0.014), underlining the potential influence of the tumor microenvironment on immune checkpoint expression in PTC. Our study underscores the intricate interplay between chronic lymphocytic thyroiditis with oncocytic metaplasia and PD-L1 expression in papillary thyroid carcinoma. The observed link suggests a potential avenue for therapeutic intervention using anti-PD-1/PD-L1 therapies in surgery-refractory PTC. Understanding the dynamics of immune checkpoint regulation in the context of the tumor microenvironment is crucial for devising effective treatment strategies. Future research endeavors should delve deeper into the molecular mechanisms underlying this interaction and explore its implications for patient outcomes. As the field of immunotherapy continues to evolve, our findings contribute valuable insights into the complex immunological landscape of thyroid cancer.

Development and In Vivo Evaluation of Small-Molecule Ligands for Positron Emission Tomography of Immune Checkpoint Modulation Targeting Programmed Cell Death 1 Ligand 1.

A substantial portion of patients do not benefit from programmed cell death protein 1/programmed cell death 1 ligand 1 (PD-1/PD-L1) checkpoint inhibition therapies, necessitating a deeper understanding of predictive biomarkers. Immunohistochemistry (IHC) has played a pivotal role in assessing PD-L1 expression, but small-molecule positron emission tomography (PET) tracers could offer a promising avenue to address IHC-associated limitations, i.e., invasiveness and PD-L1 expression heterogeneity. PET tracers would allow for improved quantification of PD-L1 through noninvasive whole-body imaging, thereby enhancing patient stratification. Here, a large series of PD-L1 targeting small molecules were synthesized, leveraging advantageous substructures to achieve exceptionally low nanomolar affinities. Compound 5c emerged as a promising candidate (IC50 = 10.2 nM) and underwent successful carbon-11 radiolabeling. However, a lack of in vivo tracer uptake in xenografts and notable accumulation in excretory organs was observed, underscoring the challenges encountered in small-molecule PD-L1 PET tracer development. The findings, including structure-activity relationships and in vivo biodistribution data, stand to illuminate the path forward for refining small-molecule PD-L1 PET tracers.

The prognostic significance of programmed cell death protein 1 and its ligand on lymphoma cells and tumor-immune cells in diffuse large B-cell lymphoma, not otherwise specified.

Diffuse large B-cell lymphoma, not otherwise specified (DLBCL, NOS) is the most common type non-Hodgkin's lymphoma, where the treatment of relapsed/refractory cases is the major challenge. Programmed cell death protein 1 (PD-1) and its ligand PD-L1 play a crucial role in the negative regulation of the immune response against the disease. The aim of the study was to analyze the expression of PD-1 and PD-L1 on lymphoma cells (LCs) and tumor-immune cells (TICs) and to investigate their correlation with outcome. Samples from 283 patients diagnosed with DLBCL, NOS (both germinal center B cell like [GCB] and non-GCB subtypes) were included in the study. Expression of PD-1 and PD-L1 was determined using double immunohistochemical staining (D-IHC) for PD-1/PAX5 and PD-L1/PAX5 on tissue microarrays. LCs were highlighted by D-IHC to obtain more accurate results. Clinical data and histologic diagnoses were obtained from electronic data records. We correlated clinical characteristics, and PD-1 and PD-L1 expression on LCs and TICs with progression-free survival (PFS) and overall survival (OS). Expression of PD-1 on TICs was observed in 38.4% and on LCs in 8.8% of cases, while PD-L1 was expressed on TICs in 46.8% and on LCs in 6.5% of cases. PD-L1 expression on LCs was more frequent in non-GCB subtype (p = 0.047). In addition, patients with PD-L1 expression on LCs had significantly shorter PFS (p = 0.015), and the expression retained significant in the multivariate model (p = 0.034). PD-L1 was more frequently expressed in LCs of the non-GCB subtype. Additionally, PD-L1 in LCs may predict shorter PFS time. D-IHC staining for PD-L1/PAX5 is a feasible method to assess PD-L1 expression on LCs of DLBCL, NOS patients and can be used to identify patients who may benefit from targeted immunotherapy with checkpoint inhibitors.

Development of small-molecular-based radiotracers for PET imaging of PD-L1 expression and guiding the PD-L1 therapeutics.

Programmed cell death protein ligand 1 (PD-L1) is a crucial biomarker for immunotherapy. However, nearly 70% of patients do not respond to PD-L1 immune checkpoint therapy. Accurate monitoring of PD-L1 expression and quantification of target binding during treatment are essential. In this study, a series of small-molecule radiotracers were developed to assess PD-L1 expression and direct immunotherapy. Radiotracers of[68Ga]Ga-D-PMED, [68Ga]Ga-D-PEG-PMED, and [68Ga]Ga-D-pep-PMEDwere designed based on a 2-methyl-3-biphenyl methanol scaffold and successfully synthesized. Cellular experiments and molecular docking assays were performed to determine their specificity for PD-L1. PD-L1 status was investigated via positron emission tomography (PET) imaging in MC38 tumor models. PET imaging of [68Ga]Ga-D-pep-PMED was performed to noninvasively quantify PD-L1 blocking using an anti-mouse PD-L1 antibody (PD-L1 mAb). The radiosyntheses of [68Ga]Ga-D-PMED, [68Ga]Ga-D-PEG-PMED, and [68Ga]Ga-D-pep-PMED were achieved with radiochemical yields of 87 ± 6%, 82 ± 4%, and 79 ± 9%, respectively. In vitro competition assays demonstrated their high affinities (the IC50 values of [68Ga]Ga-D-PMED, [68Ga]Ga-D-PEG-PMED, and [68Ga]Ga-D-pep-PMED were 90.66 ± 1.24, 160.8 ± 1.35, and 51.6 ± 1.32nM, respectively). At 120min postinjection (p.i.) of the radiotracers, MC38 tumors displayed optimized tumor-to-muscle ratios for all radioligands. Owing to its hydrophilic modification, [68Ga]Ga-D-pep-PMED had the highest target-to-nontarget (T/NT) ratio of approximately 6.2 ± 1.2. Interestingly, the tumor/liver ratio was hardly affected by different concentrations of the inhibitor BMS202. We then evaluated the impacts of dose and time on accessible PD-L1 levels in the tumor during anti-mouse PD-L1 antibody treatment. The tumor uptake of [68Ga]Ga-D-pep-PMED significantly decreased with increasing PD-L1 mAb dose. Moreover, after 8days of treatment with a single antibody, the uptake of [68Ga]Ga-D-pep-PMED in the tumor significantly increased but remained lower than that in the saline group. PET imaging with[68Ga]Ga-D-pep-PMED, a small-molecule radiotracer, is a promising tool for evaluating PD-L1 expression and quantifying the target blockade of PD-L1 to assist in the development of effective therapeutic regimens.

Impact of PD-L1 expression on survival in patients with unresectable/recurrent gastric cancer receiving first-line chemotherapy without immune checkpoint inhibitors.

391 Background: Although high PD-L1 expression predicts a favorable response of advanced solid tumors to immune checkpoint inhibitors (ICIs), its impact on survival in patients with unresectable/recurrent gastric cancer (GC) has remained unclear. We investigated the prognostic value of PD-L1 expression for survival in unresectable/recurrent GC patients receiving first-line chemotherapy without ICIs. Methods: JCOG1013, a phase 3 randomized trial, demonstrated the addition of docetaxel to cisplatin and S-1 as first-line chemotherapy was of no benefit to patients with unresectable/recurrent GC (N=741) either for overall survival (OS) or progression-free survival (PFS). Tumor specimens prior to chemotherapy were collected for assessing PD-L1 expression for this ancillary study. PD-L1 expression was determined using immunohistochemistry (Dako, 28-8 pharmDx) and used to derive the PD-L1 combined positive score (CPS) and PD-L1 tumor proportion score (TPS). As with the CheckMate 649 study, the cutoff values for PD-L1 CPS and PD-L1 TPS were set at 5 and 1%, respectively. Multivariable analyses were performed using Cox proportional hazard models to evaluate the prognostic significance of PD-L1 CPS and PD-L1 TPS as predictors of OS and PFS. All p values were 2-sided; values &lt;0.05 were considered statistically significant. Results: We analyzed 427 patients with unresectable/recurrent GC. The prevalence of PD-L1 CPS≥5, and PD-L1 TPS≥1% was 33% and 24%, respectively. There was no significant difference in OS and PFS between the PD-L1 CPS ≥5 group and the PD-L1 CPS &lt;5 group (Table). The PD-L1 TPS ≥1% group had superior OS and PFS compared to the PD-L1 TPS &lt;1% group (Table). In multivariable analyses for OS, PD-L1 TPS ≥1% was a significant favorable prognostic factor (hazard ratio (HR) = 0.64 [95% CI: 0.50–0.83], p&lt;0.001), but PD-L1 CPS≥5 was not (HR = 0.82 [95% CI: 0.65–1.02], p = 0.073). In multivariable analyses for PFS, PD-L1 TPS ≥1% was a significant favorable prognostic factor (HR = 0.67 [95% CI: 0.52–0.84], p&lt;0.001), but PD-L1 CPS≥5 was not (HR = 0.83 [95% CI: 0.67–1.03], p = 0.090). Conclusions: PD-L1 TPS≥1% is significantly correlated with longer OS and PFS in patients with unresectable/recurrent GC receiving first-line chemotherapy without ICIs. PD-L1 TPS should be considered as a stratification factor in randomized clinical trials for unresectable/recurrent GC. Clinical trial information: UMIN000007652 . [Table: see text]

Self-assembly circular multi-DNA mediated rolling circle amplification for sensitive detection of PD-L1+ circulating tumor cells in the peripheral blood of cancer patients

It has been found that evaluating the status of programmed cell death ligand (PD-L1) in the circulating tumor cells (CTCs) was associated with improved efficacy to anti-PD-L1 inhibitors. However, high-quality detection of PD-L1 positive (PD-L1+) CTCs remains a huge challenge. In this study, we propose a short time, high efficiency and applicability method that fabricated by self-assembly circular multi-DNA (CMD) mediating rolling circle amplification (RCA) for highly sensitive and rapid analysis of PD-L1+ cells. Firstly, a short single-stranded circular DNA which could bind specifically with PD-L1 protein was designed. In addition, CMD were designed as self-assembly which could serve as a template in RCA process. Next, the exponential amplification of DNA was achieved by the rolling circle amplification and the fluorescence signal was detected by using the molecular beacons. The unique CMD mediated rolling circle amplification facilitated quantitative detection of PD-L1+ CTCs in the blood of different cancer patients. To visualize the results of CMD on the target cells, we used confocal microscope to assess PD-L1 expression in MCF-7 (breast cancer), OE33 (esophaguscancer) and HCC827 (lung cancer) cells. The results indicated that the CMD mediating RCA can perfectly combine with different kinds of cells, amplify the signal and the recovery rate was over 99 %. What’s more, we performed clinical tests in the blood of the corresponding patient (14 cases of breast cancer, 15 esophageal cancer and 11 lung cancer). We further quantified the number of CTCs in patient blood through establishing the standard curve and the limit of detection (LOD) was calculated to be 1 cell/mL. Moreover, the ring structure was designed to have replaceable sequence and to realize combining different CTCs surface markers (such as Her-2). This method has the advantages of high sensitivity, good expansibility, low cost and can be completed in a short time as well. Therefore, it is expected to develop a new CTCs typing detection kit and might thus provide reliable diagnostic results to provide individualized treatment strategies.

Programmed Cell Death Ligand 1 Immunoexpression in Head and Neck Squamous Cell Carcinoma: A Narrative Review of Considerations for the Histopathologist

Head and Neck Squamous Cell Carcinoma (HNSCC) is one of the most common malignancies worldwide with most of the patients presenting in advanced stage. The associated high mortality and poor prognosis of the tumour has rendered the search for better therapeutic options than the traditional modalities of surgery, radiotherapy and chemotherapy. Immunotherapy targeting Programmed Cell Death Protein 1 / Programmed Cell Death Ligand 1 (PD-1/PD-L1) has been approved in recurrent/ metastatic HNSCC cases. PD-L1 expressing HNSCCs are likely to respond to immunotherapy. PD-L1 expression has been studied in peripheral blood utilising Circulating Tumour Cells (CTC) and soluble exosomes. Despite these non invasive techniques, PD-L1 expression has been most frequently assessed by immunohistochemistry (IHC) application on the Formalin Fixed Paraffin Embedded (FFPE) tissue of the tumour. Currently, many antibody clones and various IHC platforms are available for PD-L1, but only 22c3 has been approved by the Food and Drug Administration (FDA). Although, the availability of multiple options has made PD-L1 assessment possible and affordable at many centres worldwide, but various procedural, pre-analytical, and analytic issues have to be considered prior to the interpretation of immunoexpression of PD-L1. In this review, the authors aim to highlight the problem areas, and to understand the implications of PD-L1 expression in HNSCC. The authors propose recommendations for the optimal assessment of PD-L1 expression in HNSCC on IHC.

Development, Characterization, and Radiation Dosimetry Studies of 18F-BMS-986229, a 18F-Labeled PD-L1 Macrocyclic Peptide PET Tracer

PurposeIn cancer immunotherapy, the blockade of the interaction between programmed death-1 and its ligand (PD-1:PD-L1) has proven to be one of the most promising strategies. However, as mechanisms of resistance to PD-1/PD-L1 inhibition include variability in tumor cell PD-L1 expression in addition to standard tumor biopsy PD-L1 immunohistochemistry (IHC), a comprehensive and quantitative approach for measuring PD-L1 expression is required. Herein, we report the development and characterization of an 18F-PD-L1-binding macrocyclic peptide as a PET tracer for the comprehensive evaluation of tumor PD-L1 expression in cancer patients.Procedures18F-BMS-986229 was characterized for PD-L1 expression assessment by autoradiography or PET imaging. 18F-BMS-986229 was utilized to evaluate tumor PD-L1 target engagement in competition with a macrocyclic peptide inhibitor of PD-L1 (BMS-986189) over a range of doses using PET imaging. A whole-body radiation dosimetry study of 18F-BMS-986229 in healthy non-human primates (NHPs) was performed.ResultsIn vitro autoradiography showed an 8:1 binding ratio in L2987(PD-L1 +) vs. HT-29 (PD-L1-) tumors, more than 90% of which could be blocked with 1 nM of BMS-986189. Ex vivo autoradiography showed that 18F-BMS-986229 detection was penetrant over a series of sections spanning the entire L2987 tumor. In vivo PET imaging in mice demonstrated a 5:1 tracer uptake ratio (at 90–100 min after tracer administration) in L2987 vs. HT-29 tumors and demonstrated 83%-93% specific binding of BMS-986189 within those dose ranges. In a healthy NHP dosimetry study, the resultant whole-body effective dose was 0.025 mSv/MBq.Conclusion18F-BMS-986229 has been preclinically characterized and exhibits high target specificity, low background uptake, and a short blood half-life supportive of same day imaging in the clinic. As the PET tracer, 18F-BMS-986229 shows promise in the quantification of PD-L1 expression, and its use in monitoring longitudinal changes in patients may provide insights into PD-1:PD-L1 immuno-therapy treatment outcomes.

The discovery and evaluation of [18F]BMS-986229, a novel macrocyclic peptide PET radioligand for the measurement of PD-L1 expression and in-vivo PD-L1 target engagement.

A same-day PET imaging agent capable of measuring PD-L1 status in tumors is an important tool for optimizing PD-1 and PD-L1 treatments. Herein we describe the discovery and evaluation of a novel, fluorine-18 labeled macrocyclic peptide-based PET ligand for imaging PD-L1. [18F]BMS-986229 was synthesized via copper mediated click-chemistry to yield a PD-L1 PET ligand with picomolar affinity and was tested as an in-vivo tool for assessing PD-L1 expression. Autoradiography showed an 8:1 binding ratio in L2987 (PD-L1 (+)) vs. HT-29 (PD-L1 (-)) tumor tissues, with >90% specific binding. Specific radioligand binding (>90%) was observed in human non-small-cell lung cancer (NSCLC) and cynomolgus monkey spleen tissues. Images of PD-L1 (+) tissues in primates were characterized by high signal-to-noise, with low background signal in non-expressing tissues. PET imaging enabled clear visualization of PD-L1 expression in a murine model in vivo, with 5-fold higher uptake in L2987 (PD-L1 (+)) than in control HT-29 (PD-L1 (-)) tumors. Moreover, this imaging agent was used to measure target engagement of PD-L1 inhibitors (peptide or mAb), in PD-L1 (+) tumors as high as 97%. A novel 18F-labeled macrocyclic peptide radioligand was developed for PET imaging of PD-L1 expressing tissues that demonstrated several advantages within a nonhuman primate model when compared directly to adnectin- or mAb-based ligands. Clinical studies are currently evaluating [18F]BMS-986229 to measure PD-L1 expression in tumors.

The Role of Digital Pathology in The Assessment of PD-L1 Expression in HER2-neu Positive Breast Cancer

The Role of Digital Pathology in The Assessment of PD-L1 Expression in HER2-neu Positive Breast Cancer

PD-L1 Expression Spatial Heterogeneity in Colorectal Adenocarcinoma

Abstract Introduction/Objective PD-L1 expression on colon cancer cells is associated with a worse prognosis[CGTLUMB(1] and may be an important selection marker in colon cancer patients for developing or combination immunotherapies in the future. A patient is eligible for targeted therapy if they demonstrate PD-L1 expression on a representative section, with different positivity threshold percentages used in different indications. However, little is known about the spatial heterogeneity of PD-L1 expression within tumors or how sampling bias may impact patient care. Here we report the results of a single institution retrospective study of PD-L1 heterogeneity in colorectal cancer to test the hypothesis that PD-L1 staining is homogenous throughout the tumor microenvironment. Methods/Case Report Long-term tissue storage at a single tertiary care center was queried for all cases of resectable (stage I-IV) colonic adenocarcinoma between 1 Jan 2014 and 1 Oct 2020. Cases with at least 4 formalin- fixed paraffin embedded blocks with tumor were selected; exclusion criteria included neoadjuvant therapy and absence of residual tumor on resection. 8 patients were identified meeting inclusion criteria (mean age 68 17 years, 5:3 M:F). PD-L1 (5H1 monoclonal antibody) immunohistochemistry was performed on corresponding tissue. Percent tumor cells expressing PD-L1 in a representative 1mm2 area at invasive margin and central tumor was quantified for each section on digital slide images acquired on an Aperio CS2 Digital Slide Scanner (Leica Biosystems, Wetzlar, Germany) using QuPath (Version: 0.4.3). Results (if a Case Study enter NA) The mean ± SD of PD-L1 staining was 2.7±4.4% at invasive margin and 0.2±0.25% within central tumor; no statistically significant difference between regions was identified (paired t-test, p=0.15). Notably, 2 of the 8 cases demonstrated ranges at the invasive margin (0-36% and 1.3-35%) that span the cutoff for several commercially available anti-PD-1/PD-L1 agents. Conclusion These findings demonstrate that PD-L1 quantification can vary significantly within the same tumor depending on where counts are performed. This has significant clinical implications as PD-L1 positivity and patient eligibility for targeted therapy is most often assessed in a single location. Our current clinical methods of assessing PD-L1 expression do not account for the spatial complexities of the tumor microenvironment and could contribute to inaccuracy of small volume biopsies.

Assessing PD-L1 Expression in Head and Neck Squamous Cell Carcinoma: Trials and Tribulations.

Immune checkpoint inhibitors have improved the outcome of patients diagnosed with inoperable recurrent or metastatic head and neck squamous cell carcinoma. However, as only a subset of head and neck cancer patients benefit from this treatment, biomarkers predicting treatment response help guide physicians in their clinical decision-making. PD-L1 expression assessed by immunohistochemistry is the single most clinically relevant biomarker predicting response to PD-1-blocking antibodies. Here, we discuss in which clinical context assessment of PD-L1 expression is instrumental for the choice of therapy, how pathologists score it, and how it affects the approval of anti-PD-1 antibodies. Furthermore, we discuss the heterogeneity of PD-L1 expression and review technical aspects of determining this prominent biomarker-knowledge that might influence clinical decision-making.

Assessment of PD-L 1 expression in a tumor improves the accuracy of predicting the risk of regional breast cancer metastases

Background: Improving the accuracy of axillary lymph node (ALN) status assessment and the search for new markers associated with the risk of breast cancer (BC) metastasis continues to be an urgent problem. Aim: To establish the prognostic significance of the expression of PD-L1 in a tumor for assessing the risk of BC metastasis in ALNs. Materials and methods: A retrospective, case‒control cohort study included 158 patients aged 30 to 85 years with newly diagnosed BC. The material for the study was tumor samples obtained by trephine biopsy. The expression of PD-L1 in the tumor was studied on the invasive component of puncture biopsy specimens by immunohistochemistry using PD-L1 polyclonal antibodies. Statistical analysis was performed using Statistica 12.0 software. Receiver operating characteristic (ROC) curves for PD-L1 and Ki67 were constructed to discriminate cases with and without metastases in the ALNs. Univariate and multivariate analyses were performed to establish independent predictors associated with the risk of BC metastasis. A value of p &lt; 0.05 was considered statistically significant. Results: According to the results, independent predictors of a high risk of BC regional metastasis were T2 (OR = 5.81, 95% CI = 1.75–19.35, p = 0.004) and T3-4 (OR = 43.07, 95% CI = 9.31–199.2, p &lt; 0.0001) stages of BC, absence of an intraductal component (OR = 3.68, 95% CI = 1.32–10.33, p = 0.013), presence of lymphovascular invasion (OR = 3.32, 95% CI = 1.34–8.22, p = 0.009), luminal B HER2-positive (OR = 6.82, 95% CI = 1.13–42.26, p = 0.036) and triple negative (OR = 8.52, 95% CI = 1.12–64.89, p = 0.038) molecular biological subtypes of BC, and PD-L1 expression coefficient greater than 1.65 (OR = 6.39, 95% CI = 2.54–16.09, p = 0.0001). Based on the data obtained, an original noninvasive method for assessing a high risk of BC regional metastasis was developed, the sensitivity of which was 80.9%, the specificity - 82.6%, and the accuracy - 85.7%. The area under the curve (AUC) was 0.876 (95% CI = 0.818–0.924, р &lt; 0.0001). Conclusion: The results of the study indicate that the assessment of PD-L1 expression in a tumor can improve the accuracy of predicting the risk of regional BC metastasis.

Exploring Hydrophilic PD-L1 Radiotracers Utilizing Phosphonic Acids: Insights into Unforeseen Pharmacokinetics.

Immune checkpoint inhibitor therapy targeting the PD-1/PD-L1 axis in cancer patients, is a promising oncological treatment. However, the number of non-responders remains high, causing a burden for the patient and the healthcare system. Consequently, a diagnostic tool to predict treatment outcomes would help with patient stratification. Molecular imaging provides said diagnostic tool by offering a whole-body quantitative assessment of PD-L1 expression, hence supporting therapy decisions. Four PD-L1 radioligand candidates containing a linker-chelator system for radiometalation, along with three hydrophilizing units-one sulfonic and two phosphonic acids-were synthesized. After labeling with 64Cu, log D7.4 values of less than -3.03 were determined and proteolytic stability confirmed over 94% intact compound after 48 h. Binding affinity was determined using two different assays, revealing high affinities up to 13 nM. µPET/CT imaging was performed in tumor-bearing mice to investigate PD-L1-specific tumor uptake and the pharmacokinetic profile of radioligands. These results yielded an unexpected in vivo distribution, such as low tumor uptake in PD-L1 positive tumors, high liver uptake, and accumulation in bone/bone marrow and potentially synovial spaces. These effects are likely caused by Ca2+-affinity and/or binding to macrophages. Despite phosphonic acids providing high water solubility, their incorporation must be carefully considered to avoid compromising the pharmacokinetic behavior of radioligands.

246. SPATIAL HETEROGENEITY OF PD-L1 EXPRESSION INFLUENCE ITS ASSESSMENT IN ESOPHAGEAL SQUAMOUS CARCINOMA (ESCC)

Abstract Background Anti-PD-1/PD-L1 immunotherapy is a promising treatment for ESCC. High PD-L1 expression is a theoretical predictive biomarker, but the poor response is also observed in some patients with high PD-L1 expression. Biopsies assessment of PD-L1 expression always focuses on a single region which may be influenced by spatial heterogeneity of tumor microenvironment. This study investigates whether the PD-L1 expression by biopsy assessment in the different spatial regions is related to its paradoxical predictive value. Methods We prospectively included 30 consecutive patients with treatment-naïve, stage II-III ESCC who underwent upfront esophagectomy. Multi-region sampling was taken with endoscopic biopsy forceps (Fig. A) from four regions (A/B/C/D) from the proximal, distal, midpoint of tumor surface, and internal center, respectively. Each region was spaced ≥1 cm apart and avoided areas of severe necrosis. We compared the PD-L1 expression at different endoscopic-biopsy regions and the overall surgical-resected tumor specimen. PD-L1 expression was evaluated by immunohistochemistry using combined positive score (CPS). PD-L1 expression positive and negative is defined as CPS ≥ 1 and CPS &amp;lt; 1, respectively. Results Based on surgical-resected tumor, PD-L1 positive and high were 66.7% and 10% of 30 patients, respectively. PD-L1 positive/negative discordance rate of four sampling regions was 66.7% with poor concordance (kappa = 0.206) (Fig. B). Correlations between four biopsy regions of PD-L1 expression (Fig. C) revealed high in B and D (r = 0.77) but relatively low in others. Combining multi-region sampling for evaluation improved the correlation consistency of PD-L1 expression assessment (Fig. D). Comparing PD-L1 expression based on the endoscopic-biopsy region with the gold standard surgical-resected specimen, the sensitivity was increased by 12.5% for multi-region versus single-region assessment. Conclusion PD-L1 expression was spatially heterogeneous in ESCC, and a single region cannot reflect the PD-L1 status of the tumor, consistent with the observation of suboptimal prediction of PD-L1 expression for ESCC immunotherapy. Multi-region biopsy could help improve the assessment bias of PD-L1 expression related to spatial heterogeneity, and may help to improve the identification of the candidate for immunotherapy.