Ventana Programmed Death Ligand 1 Research Articles

Concordance of PD-L1 combined positive score (CPS) analysis between primary gastric cancer and matched peritoneal metastasis.

e16068 Background: Peritoneum represents one of the most common metastatic sites of gastroesophageal adenocarcinoma (GEA) and is associated with poor prognosis. Programmed death-ligand 1 (PD-L1) expression is a recognized predictive biomarker of response to immune checkpoint inhibitors (ICIs) in the first-line setting. However, data from pivotal trials showed poorer clinical efficacy of ICIs in the sub-set of patients with peritoneal involvement, regardless of PD-L1 score magnitude. Here, we investigated the temporal and spatial heterogeneity of PD-L1 expression between primary tumor and matched peritoneal metastasis. Methods: PD-L1 expression according to CPS was determined by immunohistochemistry using VENTANA PD-L1 (SP263) assays on formalin-fixed paraffin-embedded (FFPE) tumor tissues derived from 22 patients treated at our institution for advanced GEA from September 2015 to August 2023. Concordance rate of PD-L1 expression between primary tumor and matched peritoneal metastasis using PD-L1 CPS cut-off of 1 and 5 was reported (spatial heterogeneity); additionally, concordance between PD-L1 value before and after the administration of systemic treatments was analyzed (temporal heterogeneity). Results: 12(54.5%)/5(22.7%) primary tumor samples and 12(54.5%)/1(4.5%) peritoneal metastases showed PD-L1 CPS ≥ 1/ ≥ 5, respectively. Concordance of PD-L1 CPS between primary and peritoneal specimens was 54.5% and 72.7% according to CPS cuts-off of 1 and 5, respectively, highlighting marked spatial heterogeneity. High concordance rate (94%) was reported between negative PD-L1 CPS primary tumor samples and matched peritoneal metastases, against the cut-off of CPS ≥ 5; in contrast, none of the positive primary tumor samples retained PD-L1 expression in the peritoneum. Evident temporal heterogeneity of PD-L1 expression was also observed, with 56% concordance against CPS ≥ 5 in the pre- versus post-treatment comparison. Conclusions: PD-L1 expression in GEA is characterized by spatial and temporal heterogeneity which is more prominent for lower CPS cut-offs values. This evidence could hamper its role as predictive biomarker for ICIs. The high intra-patient discordance rate of PD-L1 CPS expression between positive primary tumor samples and matched peritoneal metastases suggests that peritoneal specimens should not be recommended as the preferred source for PD-L1 assessment.

Concordance among three programmed death-ligand 1 (PD-L1) scoring methods and their association with clinical outcomes of tislelizumab (TIS) monotherapy in esophageal squamous cell carcinoma (ESCC).

390 Background: Multiple scoring methods and cutoffs have been developed to evaluate tumor PD-L1 expression status in patients with ESCC, and PD-L1 expression level has been associated with the degree of response to anti-programmed cell death protein 1 (PD-1)/PD-L1 therapy. Here, we retrospectively investigated concordance between three PD-L1 scoring methods and their association with clinical outcomes in RATIONALE-302, a phase 3 study of the anti-PD-1 antibody TIS vs investigator-chosen chemotherapy (ICC) as second-line treatment for advanced unresectable/metastatic ESCC (NCT03430843). Methods: Patients enrolled in RATIONALE-302 with evaluable PD-L1 expression by the tumor area positivity (TAP) score (based on visual estimation of positive tumor cells [TCs] and tumor-associated immune cells [ICs]) using the VENTANA PD-L1 (SP263) assay were categorized at a 10% cutoff. Stained slides from those patients were rescored post hoc using both combined positive score (CPS; based on counting positive TCs and ICs) at cutoff 10 and TC (based on counting positive TCs only) score at a 1% cutoff, thresholds currently used in ESCC for anti-PD-(L)1 therapy. Concordance at these thresholds was investigated. Clinical efficacy (overall survival [OS]) for PD-L1 subgroups was assessed. Results: Of 512 pts enrolled, 364 had evaluable TAP scores (TIS, n=180; ICC, n=184), of whom 355 had evaluable post-hoc CPS and TC scores (TIS, n=175; ICC, n=180). TAP score and CPS showed high concordance in terms of overall percentage agreement (OPA; 90% [95% confidence interval (CI): 86, 93]) and Cohen’s Kappa (0.79 [95% CI: 0.72, 0.85]), while TAP and TC scores had lower concordance (OPA: 78% [95% CI: 73, 82]; Cohen’s Kappa: 0.56 [95% CI: 0.47, 0.64]). OS benefit with TIS vs ICC in PD-L1 subgroups defined by TAP, CPS, and TC score cutoffs were generally similar (Table). Conclusions: OS subgroup analysis showed comparable treatment effect by TAP score at 10% cutoff, CPS at cutoff 10, and TC score at 1% cutoff based on SP263 staining. TAP score and CPS at these cutoffs exhibited substantial concordance. The results indicate that the less time-consuming, visually estimated TAP score and CPS may be interchangeable for clinical measurement of PD-L1 expression in patients with ESCC. Clinical trial information: NCT03430843 . [Table: see text]

Biomarker Analysis of Zanubrutinib and Tislelizumab Combination Therapy in Patients with Relapsed/Refractory B-Cell Malignancies

Background/Introduction: Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin lymphoma world-wide. Although frontline therapies have yielded positive outcomes in most patients with DLBCL, about one-third of patients are refractory to or relapse after standard therapy (Sehn et al. J Clin Oncol 2005;23(22):5027-33). The antitumor efficacy of zanubrutinib and tislelizumab combination therapy has been demonstrated in patients with B-cell malignancies (Tam et al. Blood 2019;134:1594). Herein, we performed a comprehensive analysis to examine biomarkers associated with response or resistance to zanubrutinib and tislelizumab combination therapy in patients with B-cell malignancies. Methods: Biomarker analysis was performed in 24 patients with published response data determined by the investigator using Lugano 2014 criteria (Cheson et al. J Clin Oncol 2014;32(27):3059-68). Programmed death-ligand 1 (PD-L1) gene amplification was assessed in the baseline tumor of 11 patients with non-germinal center B-cell (GCB) subtype of DLBCL by fluorescence in situ hybridization (Empire Genomics). PD-L1 protein expression was examined in the baseline tumor (8 DLBCL) by immunohistochemistry (IHC) (Ventana PD-L1 [SP263] assay; Roche). DLBCL subtype and gene expression were examined in the baseline tumor (14 DLBCL) by HTG EdgeSeq DLBCL cell of origin assay (HTG Molecular Diagnostics). Gene mutation was examined in the baseline tumor (17 DLBCL) by DNA-seq (CGI NGS 220-Gene Panel assay; Cancer Genetic Inc.). PD-L1 and CD8 protein expression were examined in paired biopsy samples (1 DLBCL, 3 transformed follicular lymphoma [tFL], 1 follicular lymphoma [FL], 1 mantle cell lymphoma) before and 8 days after zanubrutinib treatment by IHC (Ventana SP263, CONFIRM CD8 SP57). Gene expression profiles were examined in paired biopsy samples (3 tFL, 1 FL, 1 chronic lymphocytic leukemia) by RNA-seq (RNA Access assay; Illumina). Results:PD-L1 gene alteration was observed in 2 of 11 patients with non-GCB DLBCL, including 1 with gene amplification and 1 with chromosome 9 polysomy. A higher overall response rate (ORR; 2/2 [100%] vs 3/9 [33.3%]) and complete response (CR) rate (2/2 [100%] vs 2/9 [22.2%]) was observed in patients with PD-L1 gene alteration than in patients without. Two of 8 [25%] evaluable patients with DLBCL harbored PD-L1+ tumor cells (defined using a PD-L1 protein expression cut-off ≥1%). A higher ORR (1/2 [50%] vs 2/6 [33%]) and CR rate (1/2 [50%] vs 1/6 [16.7%]) was observed in patients with PD-L1+ tumor cells than in those without. High mRNA levels of CD3D (P < 0.05), HLA-DRA (P < 0.07), and LAG3 (P < 0.05) were enriched in responders, suggesting an inflamed tumor microenvironment (TME). In contrast, non-responders harbored high mRNA levels of the NF-kB pathway-related gene REL (P < 0.05). High mRNA levels of REL were associated with an inferior clinical outcome to zanubrutinib and tislelizumab combination therapy (P < 0.05). Mutations in the tumor suppressor gene TP53 (5/10 [50%] vs 0/7 [0%]) were enriched in non-responders. Non-responders harbored higher frequency of mutations in genesinvolved in immune evasion (3/10 [30%] vs 1/7 [14.3%]), epigenetic modifications (2/10 [20%] vs 1/7 [14.3%]), and cell survival (2/10 [20%] vs 0/7 [0%]) than responders, suggesting that non-responders may have complex resistance mechanisms. Results from paired tumor biopsies from 5 patients before and after zanubrutinib treatment revealed that zanubrutinib treatment downregulated B-cell and MYC target-related gene sets and upregulated the NK cell-related gene set NK-2. Zanubrutinib treatment seemed to have no effect on the frequency of PD-L1+ cells and CD8+ T cells (using a CD8 expression cutoff of ≥1%) in the TME, although the sample size was too small to draw a definitive conclusion. Conclusion: Patients with PD-L1 gene amplification, PD-L1+ tumor cells, and high mRNA levels of CD3D, HLA-DRA, and LAG3 in baseline tumor tissue may be more responsive to zanubrutinib and tislelizumab combination therapy. A high mRNA level of REL or mutations in TP53 may contribute to resistance of zanubrutinib and tislelizumab combination therapy. Due to the limited number of samples, results must be interpreted with caution.

1775P Prevalence of PD-L1 high expression in advanced urothelial carcinoma (aUC): Results from the PREVAIL prospective cohort study

Programmed death-ligand 1 (PD-L1) expression in aUC has been studied extensively in clinical trials. In the DANUBE trial, 60% of patients (pts) with aUC had high tumor PD-L1 expression using the Ventana PD-L1 (SP263) Assay. As the first-line (1L) aUC therapy landscape keeps evolving, discovery and validation of biomarkers with the clinical utility to enable patient selection is important. In that context, there is a need to better understand testing practices and the prevalence of PD-L1 for patients with aUC in the real-world setting.

Malignant pleural effusion cell blocks are reliable resources for PD-L1 analysis in advanced lung adenocarcinomas: a concordance study with matched histologic samples.

In lung cancer patients presenting with malignant pleural effusion (MPE), cytology might represent the only source of tumor tissue for diagnosis and predictive biomarker testing. Programmed death ligand 1 (PD-L1) expression in tumor cells is a predictive biomarker for immunotherapy in non-small cell lung carcinomas and is tested using immunohistochemistry. However, knowledge of the validity of PD-L1 testing on MPE samples is limited. We evaluated the feasibility of immunocytochemistry (ICC) for PD-L1 in MPE cell blocks (CBs) and assessed the concordance in expression with patient-matched histologic samples. ICC for PD-L1 was performed on formalin-fixed paraffin-embedded CBs of MPE and patient-matched histologic samples, if available, using the automated Ventana PD-L1 SP263 assay. The tumor proportion score (TPS), based on partial or complete membranous tumor cell staining, was categorized as negative (&lt;1%), low (≥1% to &lt;50%), and high (≥50%). In CBs with any degree of PD-L1 expression, ICC for CD163 highlighting macrophages was performed to exclude nonspecific PD-L1 expression in macrophages. The CB PD-L1 TPS was compared with the TPS obtained from the patient-matched histologic samples. Of 43 MPE CBs available, 25 were positive for PD-L1 (25 of 42; 59%), and 1 sample was inadequate. Of the 11 patient-matched histologic samples tested, the PD-L1 TPS categories were concordant for 10 of the 11 (91% concordance) cases. PD-L1 expression in MPE CBs showed good concordance with expression in histologic samples and is feasible as a source for PD-L1 testing. The concurrent use of CD163 immunostains will aid in the manual assessment of PD-L1 TPS.

Artificial intelligence-assisted system for precision diagnosis of PD-L1 expression in non-small cell lung cancer

Standardized programmed death-ligand 1 (PD-L1) assessment in non-small cell lung cancer (NSCLC) is challenging, owing to inter-observer variability among pathologists and the use of different antibodies. There is a strong demand for the development of an artificial intelligence (AI) system to obtain high-precision scores of PD-L1 expression in clinical diagnostic scenarios. We developed an AI system using whole slide images (WSIs) of the 22c3 assay to automatically assess the tumor proportion score (TPS) of PD-L1 expression based on a deep learning (DL) model of tumor detection. Tests were performed to show the diagnostic ability of the AI system in the 22c3 assay to assist pathologists and the reliability of the application in the SP263 assay. A robust high-performance DL model for automated tumor detection was devised with an accuracy and specificity of 0.9326 and 0.9641, respectively, and a concrete TPS value was obtained after tumor cell segmentation. The TPS comparison test in the 22c3 assay showed strong consistency between the TPS calculated with the AI system and trained pathologists (R = 0.9429–0.9458). AI-assisted diagnosis test confirmed that the repeatability and efficiency of untrained pathologists could be improved using the AI system. The Ventana PD-L1 (SP263) assay showed high consistency in TPS calculations between the AI system and pathologists (R = 0.9787). In conclusion, a high-precision AI system is proposed for the automated TPS assessment of PD-L1 expression in the 22c3 and SP263 assays in NSCLC. Our study also indicates the benefits of using an AI-assisted system to improve diagnostic repeatability and efficiency for pathologists.

Determining PD-L1 Status in Patients With Triple-Negative Breast Cancer: Lessons Learned From IMpassion130.

Triple-negative breast cancer (TNBC) accounts for approximately 12% to 17% of all breast cancers and has an aggressive clinical behavior. Increased tumor-infiltrating lymphocyte counts are prognostic for survival in TNBC, making this disease a potential target for cancer immunotherapy. Research on immunophenotyping of tumor-infiltrating lymphocytes is revealing molecular and structural organization in the tumor microenvironment that may predict patient prognosis. The anti-programmed death-ligand 1 (PD-L1) antibody atezolizumab plus nab-paclitaxel was the first cancer immunotherapy combination to demonstrate progression-free survival benefit and clinically meaningful overall survival benefit in the first-line treatment of metastatic TNBC (mTNBC) in patients with PD-L1-expressing tumor-infiltrating immune cells in 1% or more of the tumor area. This led to its United States and European Union approval for mTNBC and US approval of the VENTANA PD-L1 (SP142) assay as a companion diagnostic immunohistochemistry assay. Subsequently, the anti-programmed death-1 (PD-1 ) antibody pembrolizumab plus chemotherapy was approved by the US Food and Drug Administration for mTNBC based on progression-free survival benefit in patients with a combined positive score of at least 10 by its concurrently approved 22C3 companion diagnostic assay. Treatment guidelines now recommend PD-L1 testing for patients with mTNBC, and the testing landscape will likely become increasingly complex as new anti-PD-L1 and anti-PD-1 agents and diagnostics are approved for TNBC. Integrating PD-L1 testing into current diagnostic workflows for mTNBC may provide more treatment options for these patients. Therefore, it is critical for medical oncologists and pathologists to understand the available assays and their relevance to therapeutic options to develop an appropriate workflow for immunohistochemistry testing.

The Use of Atezolizumab + Nab-Paclitaxel for Women with PD- L1 Positive Advanced Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an uncommon subtype of breast cancer that constitutes 15-20% of cases which has a poorer prognosis and lower survival rates (approximately 18 months or less with available treatments) compared to other types of breast cancer. As the name suggests, TNBC is immunohistologically marked by the lack of expression of factors namely estrogen receptors (ER), progesterone receptors (PR), and lack of overexpression and/or amplification of the human epidermal growth factor receptor 2 (HER2)/NEU gene. TNBC is characterized by high grades of Tumor-Infiltrating lymphocytes (TILs), programmed-death ligand 1 (PD-L1) expression, and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) as observed in other cancers too. Hence, metastatic TNBC (mTNBC) therapy focuses on the advancement of immune checkpoint inhibitors which block the above immune checkpoint proteins. The use of Atezolizumab (anti-PD-L1) in combination with nab-paclitaxel (chemotherapy agent) has been marked as a relevant advance in the treatment of metastatic, PD-L1-positive TNBC. It is better to consider advanced and approved diagnostic (VENTANA PD-L1 SP142 assay) in patients who get benefit from treatment with Atezolizumab plus nab-paclitaxel. Keywords: Triple Negative Breast Cancer (TNBC), Atezolizumab, Nab-paclitaxel, Chemotherapy.

Primary results from IMpassion131, a double-blind, placebo-controlled, randomised phase III trial of first-line paclitaxel with or without atezolizumab for unresectable locally advanced/metastatic triple-negative breast cancer

In the phase III IMpassion130 trial, combining atezolizumab with first-line nanoparticle albumin-bound-paclitaxel for advanced triple-negative breast cancer (aTNBC) showed a statistically significant progression-free survival (PFS) benefit in the intention-to-treat (ITT) and programmed death-ligand 1 (PD-L1)-positive populations, and a clinically meaningful overall survival (OS) effect in PD-L1-positive aTNBC. The phase III KEYNOTE-355 trial adding pembrolizumab to chemotherapy for aTNBC showed similar PFS effects. IMpassion131 evaluated first-line atezolizumab-paclitaxel in aTNBC. Eligible patients [no prior systemic therapy or ≥12 months since (neo)adjuvant chemotherapy] were randomised 2:1 to atezolizumab 840 mg or placebo (days 1, 15), both with paclitaxel 90 mg/m2 (days 1, 8, 15), every 28 days until disease progression or unacceptable toxicity. Stratification factors were tumour PD-L1 status, prior taxane, liver metastases and geographical region. The primary endpoint was investigator-assessed PFS, tested hierarchically first in the PD-L1-positive [immune cell expression ≥1%, VENTANA PD-L1 (SP142) assay] population, and then in the ITT population. OS was a secondary endpoint. Of 651 randomised patients, 45% had PD-L1-positive aTNBC. At the primary PFS analysis, adding atezolizumab to paclitaxel did not improve investigator-assessed PFS in the PD-L1-positive population [hazard ratio (HR) 0.82, 95% confidence interval (CI) 0.60-1.12; P= 0.20; median PFS 6.0 months with atezolizumab-paclitaxel versus 5.7months with placebo-paclitaxel]. In the PD-L1-positive population, atezolizumab-paclitaxel was associated with more favourable unconfirmed best overall response rate (63% versus 55% with placebo-paclitaxel) and median duration of response (7.2 versus 5.5 months, respectively). Final OS results showed no difference between arms (HR 1.11, 95% CI 0.76-1.64; median 22.1 months with atezolizumab-paclitaxel versus 28.3 months with placebo-paclitaxel in the PD-L1-positive population). Results in the ITT population were consistent with the PD-L1-positive population. The safety profile was consistent with known effects of each study drug. Combining atezolizumab with paclitaxel did not improve PFS or OS versus paclitaxel alone. CLINICALTRIALS.GOV: NCT03125902.

Circulating tumor cell proportion scoring (CTPS) based PD-L1 assessment and clinical application of circulating tumor cells (CTCs) on stage IV non-small cell lung cancer (NSCLC) through liquid biopsy.

e15031 Background: Stage IV lung cancer is the most advanced lung cancer state accompanied by metastasized to the area around the lungs or distant major organs. The most common type of lung cancer is non-small cell lung cancer, which is more aggressive and may spread quickly due to organ-specific complex networks such as lymph and major blood vessels. Thus, only precise diagnostic strategy approaches will determine the effectiveness of the actual and successful clinical treatment. Until a recent date, Immunohistochemistry (IHC) for programmed death-ligand 1(PD-L1) test is the only available biomarker test that purpose diagnostics (CDx) and guide the treatment with immune checkpoint inhibitors in NSCLC. Methods: Given that CDx strategy, tissue biopsy has inevitable limitations, including patient risk, repetitive examination, sample preparation, sensitivity, and accuracy. For this reason, our research team contrived the best strategy for biomarker, PD-L1-specific CTCs in stage IV NSCLC group (N = 30) compared to pulmonary inflammatory patient groups (N = 30) CytoGen Smart biopsy platform. Herein, we removed false-positive cells for the first strategy of distinguishing between lymphoid/myeloid cells and the enriched-CTCs. And the second strategic approach is to calculate the pure CTCs (without false-positive cells) and then CTPS) as measured by the PD-L1 expression among pure-CTCs. That application is the percentage of viable CTCs showing partial or complete stained cells at the deducted cut-off value in each fluorescence, respectively. Results: Consequently, we demonstrated over 80% of the concordance rate between VENTANA PD-L1(SP263) and DAKO PD-L1(SP263) assay tested by the PD-L1 expression on stage IV NSCLC in tissue and pure-CTCs based CTPS from the blood. In contrast, pure-CTCs based CTPS in the pulmonary inflammatory group were all negative (recorded as zero). Conclusions: Conclusively, this study implicates that pure-CTCs based CTPS could be deployed for innovative diagnosis strategies as alternatives for tissue biopsy. Our clinical study's data suggested that the possibility for prompt decision for diagnosis and gain powerful insights to guide the personalized treatment in NSCLCs. Clinical trial information: 2020-0553.

RATIONALE 302: Randomized, phase 3 study of tislelizumab versus chemotherapy as second-line treatment for advanced unresectable/metastatic esophageal squamous cell carcinoma.

4012 Background: Tislelizumab (tisle) monotherapy or plus chemotherapy demonstrated antitumor activity in patients (pts) with solid tumors, including esophageal squamous cell carcinoma (ESCC) (NCT03469557 and CTR20160872). Methods: In this global phase 3 study (NCT03430843), adults with histologically confirmed advanced/unresectable or metastatic ESCC whose disease progressed following prior systemic therapy with ≥1 evaluable lesion per RECIST v1.1 and an Eastern Cooperative Oncology Group performance score (ECOG PS) of ≤1 were included. Pts were randomized (1:1) to receive tisle 200 mg intravenously every 3 weeks or investigator-chosen standard chemotherapy ([ICC]; paclitaxel, docetaxel, or irinotecan) and treated until disease progression, unacceptable toxicity, or withdrawal. Stratification factors included ICC option, region, and ECOG PS. The primary endpoint was overall survival (OS) in the intent-to-treat (ITT) population. The key secondary endpoint was OS in the programmed death-ligand 1 (PD-L1)+ population (visually-estimated combined positive score [vCPS] ≥10%, by VENTANA PD-L1 SP263 assay). Other secondary endpoints included (by RECIST v1.1) progression-free survival, overall response rate (ORR), duration of response (DoR), and safety. Results: Overall, 512 pts (median age: 62 years; range 35-86 years) from 132 sites in 10 countries in Asia (404 pts [79%]), Europe, and North America (108 pts [21%]) were randomized to tisle (n=256) or ICC (n=256) (ITT population). Of these, 157 pts (tisle [n=89], ICC [n=68]) had vCPS ≥10% (PD-L1+ population). On 1 Dec 2020 (data cut-off), median follow-up was 8.5 months (m) with tisle and 5.8 m with ICC. The study met its primary endpoint: tisle clinically and significantly improved OS vs ICC in the ITT population (median OS: 8.6 vs 6.3 m; HR 0.70, 95% CI 0.57-0.85, p=0.0001). Tisle also demonstrated significant improvement in OS vs ICC in the PD-L1+ population (median OS: 10.3 vs 6.8 m; HR 0.54, 95% CI: 0.36-0.79, p=0.0006). Survival benefit was consistently observed across pre-defined subgroups, including baseline PD-L1 status and region. Treatment with tisle was also associated with a higher ORR (20.3% vs 9.8%) and more durable response (median DoR: 7.1 vs 4.0 m; HR 0.42, 95% CI 0.23-0.75) than ICC in the ITT population. Fewer pts had ≥Grade 3 (46% vs 68%) treatment-emergent adverse events with tisle vs ICC. Of these, fewer ≥Grade 3 AEs were treatment-related (TR) with tisle vs ICC (19% vs 56%). Fewer pts discontinued tisle vs ICC (7% vs 14%) due to a TRAE. Conclusion: Tisle demonstrated statistically significant and clinically meaningful improvement in OS vs ICC in pts with advanced or metastatic ESCC who had disease progression during or after first-line systemic therapy. Tisle showed a higher and longer response vs ICC. The safety profile of tisle was more favorable than ICC. Clinical trial information: NCT03430843.

PD-L1 expression in urothelial bladder cancer varies more among specimen types than between companion assays

Urothelial bladder cancer (UBC) patients ineligible to platinum-based chemotherapy can be treated with immune-checkpoint inhibitors (ICI) in Programmed Death Ligand 1 (PD-L1) positive cases. Although concordance exists between different PD-L1 assays, little is known on PD-L1 expression variability in matched UBC samples. We compared PD-L1 expression in whole slides of matched transurethral resections (TURBT), radical cystectomies (RC), and lymph node metastasis (LN). Immunohistochemistry using the VENTANA PD-L1 (SP263) assay was performed on 115 patients and scored positive if expression occurred in ≥25% immune cells (IC), ≥25% tumour cells (TC), or both. PD-L1 was positive in 42.7% TURBT, 39.8% RC, and 27.3% LN specimens. Concordance was moderate (κ=0.52; P<0.001) between TURBT and RC, and fair between LN and TURBT (κ=0.31; P=0.048) or RC (κ=0.25; P=0.075). Comparison with the VENTANA PD-L1 (SP142) assay which had been performed previously on the same cohort showed moderate to substantial inter-assay agreement (κ=0.42–0.66). Although TC staining is not part of the SP142 scoring algorithm, discordant PD-L1 assay outcome could be attributed to SP263 TC≥25% staining in only 41% of cases. These results show that PD-L1 expression variability between matched specimens is higher than that between individual assays. Optimal specimen determination for PD-L1 testing needs to be addressed in future studies.

Interobserver Variation of PD-L1 SP142 Immunohistochemistry Interpretation in Breast Carcinoma: A Study of 79 Cases Using Whole Slide Imaging.

The Ventana programmed death ligand-1 (PD-L1) SP142 immunohistochemical assay (IHC) is approved by the US Food and Drug Administration as the companion diagnostic assay to identify patients with locally advanced or metastatic triple-negative breast cancer for immunotherapy with atezolizumab, a monoclonal antibody targeting PD-L1. To determine interobserver variability in PD-L1 SP142 IHC interpretation in invasive breast carcinoma. The pathology database was interrogated for all patients diagnosed with primary invasive, locally recurrent, or metastatic breast carcinoma on which PD-L1 SP142 IHC was performed from November 2018 to June 2019 at our institution. A subset of cases was selected using a computerized random-number generator. PD-L1 IHC was evaluated in stromal tumor-infiltrating immune cells using the IMpassion130 trial criteria, with positive cases defined as immunoreactivity in immune cells in 1% or more of the tumor area. IHC was interpreted on whole slide images by staff pathologists with breast pathology expertise. Interobserver variability was calculated using unweighted κ. A total of 79 cases were assessed by 8 pathologists. Interobserver agreement was substantial (κ = 0.727). There was complete agreement among all 8 pathologists in 62% (49 of 79) of cases, 7 pathologists or more in 84% (66 of 79) of cases, and 6 pathologists or more in 92% (73 of 79) of cases. In 4% (3 of 79) of cases, all of which were small biopsies, pathologists' interpretations were evenly split between scores of positive and negative. The findings show substantial agreement in PD-L1 SP142 IHC assessment of breast carcinoma cases among 8 pathologists at a single institution. Further study is warranted to define the basis for discrepant results.

Tumor Mutational Burden and PD-L1 Expression in Hematologic Malignancies

Introduction: The activity of immune checkpoint blockade including anti-cytotoxic T-lymphocyte associated protein-4 and anti-programmed cell death protein-1 monoclonal antibodies in hematologic malignancies is limited outside of classical Hodgkin lymphoma and primary mediastinal B-cell lymphoma. Tumor mutational burden (TMB), programmed death ligand-1 (PD-L1) expression, and microsatellite instability-high (MSI-H) are well-established biomarkers predicting response to checkpoint blockade in solid malignancies. In addition, tumors with high TMB, defined as ≥10 mutations/megabase (mut/Mb), and/or MSI-H are Food and Drug Administration (FDA) approved tissue agnostic biomarkers for treatment with pembrolizumab. The frequencies of high TMB, MSI-H, and expression pattern of PD-L1 across specific hematologic malignancies are undefined. Methods: Patients with hematologic malignancies who had next generation sequencing (NGS) performed by Foundation One Heme were identified. TMB and MSI were measured by NGS. TMB was classified as high if ≥10 mut/Mb and low if &amp;lt;10 mut/Mb. When available, PD-L1 expression on tumor cells by immunohistochemistry (IHC) was also collected. PD-L1 IHC was performed with either Ventana (SP142) PD-L1 antibody or Dako (22C3) PD-L1 antibody. Scores were classified as high (≥ 50%), low (1-49%), and negative (&amp;lt;1%) based on the percent of tumor cells staining positive for PD-L1. Pathology reports were retrospectively re-reviewed to determine the diagnosis. Results: A total of 390 patients with hematologic malignancies with NGS were identified. Forty eight of the 390 samples (12%) had a high TMB (Table 1). Twenty five of 45 (56%) patients with DLBCL had a high TMB (Table 2). The TMB was low in all myeloid malignancies tested. None of the 302 samples tested were MSI-H. PD-L1 IHC was performed on 86 samples. Eleven (13%) had high expression, 26 (30%) had low expression, and 49 (57%) had no expression of PD-L1 on the tumor cells (Table 1). The majority of samples with PD-L1 expression were mature lymphomas (81%). TMB and PD-L1 score had a significant linear relationship (R = 0.22,p= 0.04, 95% CI 0.01 - 0.41) (Figure 1). Conclusion: This study provides detailed characteristics of TMB, MSI status, and PD-L1 expression for hematologic malignancies. Notably, a subset of lymphomas had high TMB and/or PD-L1 expression. Biomarker driven studies of checkpoint blockade in hematologic malignancies with high TMB and/or PD-L1 expression are warranted. Disclosures Sokol: Foundation Medicine:Current Employment;Roche:Current equity holder in publicly-traded company.Kurzrock:Medimmune:Research Funding;Foundation Medicine:Research Funding;Konica Minolta:Research Funding;IDbyDNA:Current equity holder in private company;Pfizer:Consultancy, Research Funding;Sequenom:Research Funding;Bicara Therapeutics, Inc.:Consultancy;Incyte:Research Funding;Takeda:Research Funding;TopAlliance:Research Funding;Boehringer Ingelheim:Research Funding;CureMatch Inc:Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees;Grifols:Research Funding;Guardant:Research Funding;X Biotech:Consultancy;Neomed:Consultancy;Actuate Therapeutics:Consultancy;Roche:Consultancy;Merck Serono:Research Funding;Genentech:Research Funding;Debiopharm:Research Funding;CureMetrix:Membership on an entity's Board of Directors or advisory committees;OmniSeq:Research Funding;TD2/Volastra:Consultancy;Turning Point Therapeutics:Consultancy.Goodman:EUSA Pharma:Consultancy;Seattle Genetics:Consultancy.

Clinical Significance of Program Death Ligand-1 and Indoleamine-2,3-Dioxygenase Expression in Colorectal Carcinoma.

Colorectal cancer is a heterogenous disease with striking biological diversity. Colorectal carcinoma (CRC) is one of the most common malignancies, accounting for over 9% of all cancers worldwide. To put it in perspective, 5% of people will develop CRC in their lifetime. Biomarkers specific to a particular cancer type can assist in the evaluation of survival probability and help clinicians assess treatment modalities, an example being programmed death ligand-1 (PD-L1). With regards to PD-L1, this is the first study to evaluate the SP-142 antibody clone in CRC. The Ventana PD-L1 (SP-142) assay for PD-L1 expression identifies patients who may benefit from treatment with atezolizumab. SP-142 was chosen as large stage 3 clinical trials are being undertaken with atezolizumab in CRC. Indoleamine 2,3-dioxygenase (IDO-1) was also chosen as there are several ongoing trials for Epacadostat, the best-in-class oral IDO-1 enzyme inhibitor, in many solid tumors. For solid tumors, IDO-1-based immune escape has the potential to inhibit monotherapeutic efficacy of PD-L1-based therapeutics. In this study, a total of 223 cases of CRC were retrospectively reviewed and clinicopathologic data were analyzed in relation to PD-L1 and IDO-1 protein expression. Moreover, tumor-infiltrating lymphocytes, mismatch repair deficiency, high mitotic index, and worse survival outcomes were found in cohorts with significant PD-L1 and IDO-1 expression. Both PD-L1 and IDO-1 are actionable biomarkers, with potential therapeutic implications in CRC. Our findings support the theoretical foundation for targeting PD-L1 and IDO-1 in CRC, which now needs verification in well-designed robust clinical trials.

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]

505P - PD-L1 expression in ALK rearranged NSCLC: All questions answered?

BackgroundTreatment of non-small cell lung cancer (NSCLC) has undergone a paradigm shift in the last decade with the advent of targeted therapy and immunotherapy. Anaplastic Lymphoma Kinase (ALK) rearrangement and Programmed Death-Ligand 1 (PD-L1) expression are important predictive biomarkers for response to targeted therapy and immunotherapy respectively. How these two biomarkers interplay with each other is yet to be determined. Various studies have tried to establish a relationship between PD-L1 expression in tumors and treatment outcomes in ALK rearranged NSCLC, with conflicting results. There is a paucity of data regarding this relationship from the Indian subcontinent. MethodsPD-L1 expression was assessed in tissue samples of 58 patients with advanced ALK rearranged NSCLC treated between 2015 and 2018. PD-L1 expression was measured by immunohistochemistry using VENTANA PD-L1 (SP263) antibody on formalin-fixed paraffin-embedded specimens. The epidemiological profile of patients and the relationship between progression free survival (PFS) on small molecule ALK inhibitor and PD-L1 expression were noted. ResultsThe median age was 47 years (range 25-72 years) and there were 25 males (50%). Most of the patients were never smokers (88%). Thirty-seven (63.7%) of tumors expressed PD-L1 (≥1%) and 13 (22.4%) tumors had a PD-L1 expression of ≥ 50%. All of the patients received crizotinib as first line ALK inhibitor. Of the 44 patients evaluable for treatment response there was no significant difference in PFS between PDL1 negative cohort (median PFS - 13.8 months, CI 6.2-21.3 months) and PDL1 positive cohort (median PFS 10.9 months, CI 6.5-15.2 months, P-0.81). No association was seen between PD-L1 expression and PFS when PD-L1 expression levels were stratified by median or quartiles. In the subgroup analysis, PFS was not significantly different between different patterns of PDL1 expression or intensity of staining. ConclusionsIn contrast to previous studies, we found a higher incidence of PD-L1 expression in patients with ALK rearranged advanced NSCLC. PFS on ALK inhibitors did not differ based on PD-L1 expression. However, this was a retrospective study in a limited number of patients. More prospective studies are needed to confirm our findings. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.

PD-L1 assessment in urothelial carcinoma: a practical approach.

Five programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) inhibitors are currently approved for treatment of locally advanced or metastatic urothelial carcinoma of the bladder and the upper urinary tract. Due to restrictions by the FDA and EMA first-line treatment with Atezolizumab and Pembrolizumab in platinum-ineligible patients requires immunohistochemical PD-L1 testing. In the second-line setting all drugs are approved without PD-L1 testing. Used PD-L1 assays in clinical trials include the 28-8 pharmDx (Nivolumab), the 22C3 pharmDx (Pembrolizumab), Ventana SP142 (Atezolizumab), and the Ventana PD-L1 SP263 assays (Durvalumab). Differences in antibodies, needed platforms and testing algorithms have raised questions about interchangeability and comparability among these assays and their diagnostic use. We provide a practical review about the current recommendations, used assays and algorithms of PD-L1 testing in urothelial carcinoma to help oncologists, urologists and pathologists to understand analytical features, differences in antibody assays, differences in scoring algorithms and comparability of various PD-L1 assays. We reviewed and summarized published studies from the last four years (2016-2019) on PD-L1 testing in bladder cancer and present a condensed practical guideline including pre-analytical, analytical and test-specific issues.

Abstract 3993A: Real-world utilization of PD-L1 IHC testing and results across multiple tumor types

Abstract Background: A number of programmed death ligand 1 (PD-L1) immunohistochemistry (IHC) diagnostic (Dx) tests have been approved by the FDA to guide treatment (Tx) with programmed death-1/PD-L1 inhibitors. Here, we evaluate the utilization of the Dako PD-L1 IHC 28-8 and 22C3 pharmDx and Ventana PD-L1 (SP142) assays on real-world samples across multiple tumor types, characterize PD-L1 testing practices among physicians who order a PD-L1 test, and investigate how PD-L1 test results impact physicians’ Tx decision-making and use of immuno-oncology (I-O) Tx. Methods: 55,652 samples with clinical characteristics were provided by Symphony Health Solutions. NeoGenomics Laboratories, Inc assessed PD-L1 expression between October 2015–April 2018, according to manufacturers’ protocols at time of study. Clinical characteristics were matched to PD-L1 test results using unique identifiers for the 4714 patients (pts) whose diagnoses and treatment could be determined. Results: Across tumor types, 56% of pts received a test prior to first-line (1L) Tx. Most lung cancer (57%) or melanoma (MEL; 65%) pts had a PD-L1 test prior to 1L Tx, while most squamous cell carcinoma of the head and neck (70%) or urothelial carcinoma (73%) pts had a PD-L1 test after Tx initiation, in line with drug and complementary Dx approvals for these tumor types during the testing period. The percentage of lung cancer pts whose PD-L1 expression was tested prior to 1L Tx rose from 32% during Q4 2015–Q3 2016 to 63% during Q4 2016–Q1 2018, in line with FDA approval of a companion PD-L1 IHC Dx for non-small cell lung cancer. Regardless of PD-L1 test used, most lung cancer (73%) or MEL (93%) pts received I-O Tx, defined as nivolumab (NIVO; + ipilimumab [IPI] for MEL only), pembrolizumab (pembro) ± chemotherapy, atezolizumab, or IPI alone. Moreover, the majority of lung cancer pts who had ≥1% PD-L1 expression or MEL regardless of PD-L1 expression received 1L I-O Tx irrespective of the PD-L1 test used. Analysis of PD-L1 expression, Dx test used, and Tx received showed that, for MEL pts tested with 22C3, 28%, 17%, and 0% of pts received NIVO or IPI, while 28%, 43%, and 43% received NIVO+IPI, at the expression cutoffs of 0%, 1–49%, and ≥50%, respectively. Lung cancer pts with 1–49% PD-L1 expression, as determined by a 22C3 test, received NIVO or pembro monotherapy at similar rates (12–18%). Of those who had ≥50% PD-L1 expression, as determined by the 28-8 test only, 52% received pembro monotherapy vs other Tx. Conclusions: Since FDA approval of the first PD-L1 IHC Dx in 2015, analyses of PD-L1 testing practices and physicians’ Tx decision behavior at a US national reference laboratory have shown that physicians’ adoption of PD-L1 testing is responsive to FDA approvals and that most testing for lung cancer and MEL occurs before 1L Tx initiation. In lung cancer or MEL pts who had a PD-L1 test result available, Tx decisions do not appear to be tied to the specific intended use of the PD-L1 assay that was ordered. Citation Format: Gabriel S. Krigsfeld, Emily Prince, Kim Zerba, Vladislav Chizhevsky, Josette William Ragheb, James White. Real-world utilization of PD-L1 IHC testing and results across multiple tumor types [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3993A.

Programmed death ligand 1 (PD-L1) expression in parathyroid tumors.

IntroductionPD-L1 is associated with prognosis and immunotherapeutic response in patients with malignancies. In previous studies, PD-L1 expression was detected in many endocrine tumors. However, the PD-L1 expression status in parathyroid tumors is unknown.MethodsWe included 26 parathyroid carcinoma and 37 adenoma samples, as well as the corresponding patient information. PD-L1 was stained using the FDA-approved PD-L1 IHC 22C3 pharmDx and Ventana PD-L1 (SP263) assays, and staining was assessed by the estimated percentages of positive tumor cells and immune cells, respectively.ResultsWe classified the PD-L1 expression in the parathyroid tumors into four groups: (0) <1%, (1) 1–4%, (2) 5–9% and (3) ≥10% positive. With the SP263 clone, 37 (carcinoma:adenoma = 18:19) samples scored 0, 13 (carcinoma:adenoma = 4:9) scored 1, 7 (carcinoma:adenoma = 1:6) scored 2 and 6 (carcinoma:adenoma = 3:3) scored 3. However, in the series of cases using the 22C3 clone, 45 (carcinoma:adenoma = 20:25) samples scored 0, 10 (carcinoma: adenoma = 3:7) scored 1, 5 (carcinoma:adenoma = 1:4) scored 2, and 3 (carcinoma:adenoma = 2:1) scored 3. Concerning tumor-infiltrating immune cells, 57 samples were negative and six were positive with SP263, and 59 were negative and four were positive with 22C3. Moreover, PD-L1 expression was negatively correlated with the Ki-67 index and mitotic rate in parathyroid tumors depending on the different clones. However, the results indicated only moderate consistency between the SP263 and 22C3 clones in parathyroid tumors.ConclusionWe found deficient PD-L1 expression in the majority of parathyroid tumors. However, the PD-L1 expression score in parathyroid tumors depended greatly on the antibody clone used.