Prevalence Of PD-L1 Expression Research Articles

EP06.02-01 Prevalence of PD-L1 Expression in Non-Small Cell Lung Cancer: a Real-World Australian Perspective

EP06.02-01 Prevalence of PD-L1 Expression in Non-Small Cell Lung Cancer: a Real-World Australian Perspective

Abstract 6658: Prevalence of PD-L1 expression and its correlation with tumor biomarkers in the Chinese muscle invasive urothelial bladder carcinoma patients

Abstract The association of programmed cell death-ligand 1 (PD-L1) expression with the activity of immune checkpoint inhibitor therapy setting has encouraged us to study the prevalence of PD-L1 in muscle invasive urothelial bladder cancer (MIUBC) patients. Since, the prevalence of PD-L1 expression and its prognostic role in MIUBC is unclear in China, we conducted a multi-center, prospective, epidemiological study to investigate prevalence of high PD-L1 expression and its correlation with other exploratory biomarkers including CD8+ T cells and tumor mutation burden (TMB) in Chinese MIUBC patients (NCT03433924). The study enrolled newly diagnosed, untreated MIUBC patients from 17 hospitals in China. High PD-L1 expression by Ventana PD-L1 [SP263] assay was defined as 1) ≥25% tumor cell (TC) + or 2) tumor associated immune cell (IC) area >1%: ≥25% IC+; 3) IC area=1%: 100% IC+. The primary outcome was prevalence of high PD-L1 expression; secondary outcome was PD-L1 expression profile in TC or IC in patients. An exploratory study was conducted to investigate the percentage of patients with high infiltration of CD8+ T cells and elevated TMB using immunohistochemistry and next generation sequencing, respectively. High CD8+ and TMB status was considered if it refers to ˃ median value (3%) and ˃10 mut/Mb, respectively. Association of PD-L1 expression with demographic and baseline characteristics was evaluated by logistic regression model while PD-L1 with tumor biomarkers were evaluated by spearman’s rank correlation coefficient. Overall, 248 MIUBC patients were enrolled and 229 patients with PD-L1 data were included. High PD-L1 expression was observed in 52.4% patients. High PD-L1 expression was positive in 59 (25.8%) patients of TC and 82 (35.8%) patients of IC. CD8+ T cell and TMB showed high expression in 44.5% and 54.1% patients, respectively, with mean TMB of 14.14 mut/Mb. The exploratory analysis showed no significant association of PD-L1 expression with age, gender, primary tumor site, metastatic disease, regional lymph node, tobacco use or AJCC stage. Further a weak and positive correlation was observed between percentage of TC with membrane PD-L1 positivity and CD8+ T cells (0.34, 95%Cl, 0.22 - 0.45, p˂0.001), IC with membrane PD-L1 positivity and CD8+ T cells (0.44, 95%Cl, 0.33 - 0.54, p˂0.001), TC with membrane PD-L1 positivity and TMB (0.05, 95%Cl, -0.08 - 0.19, p=0.441), IC with membrane PD-L1 positivity and TMB (0.16, 95%Cl, 0.02 - 0.29, p=0.020). In conclusion, our study showed high prevalence of PD-L1 expression in patients with MIUBC along with their weak, positive correlation with CD8+ T cells and TMB. These findings are consistent with other studies that show that PD-L1 and TMB stand as the most robust predictive biomarkers, but may be uncorrelated. With subsequent follow-up time, the effect of biomarkers on survival will be assessed in future study. Citation Format: Yu Fan, Tao Dai, Dahong Zhang, Hongqian Guo, Fangjian Zhou, Benkang Shi, Shaogang Wang, Zhigang Ji, Chunxi Wang, Xudong Yao, Qiang Wei, Nanhui Chen, Jinchun Xing, Jinjian Yang, Chuize Kong, Jian Huang, Dingwei Ye, Liqun Zhou. Prevalence of PD-L1 expression and its correlation with tumor biomarkers in the Chinese muscle invasive urothelial bladder carcinoma patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6658.

Discordance of PD-L1 expression in primary and metastatic ovarian high-grade serous carcinoma and its correlation with CD8 + tumor-infiltrating lymphocytes and patient prognosis.

Differential expression of programmed death-1 ligand (PD-L1) and its clinical significance in primary and metastatic ovarian high-grade serous carcinoma (HGSC) have not been defined. Thus, we investigated the PD-L1 expression of paired ovarian primary and omental metastatic HGSC and its correlation with CD8 + tumor-infiltrating lymphocyte (TILs) and patient survival. A total of 212 cases of ovarian HGSCs with matched primary ovarian and metastatic omental tumors accessioned between 2003 and 2018 were selected for further analysis. Using immunohistochemistry, we evaluated the density of CD8 + TILs and expression of PD-L1 on whole tissue sections. Applying tumor proportion score (TPS, cutoff 1%) and combined positive score (CPS, cutoff 1), the prevalence of PD-L1 expression was similar but with significant discordance in ovarian and omental tumor. Using TPS, patients with PD-L1-positive tumors demonstrated significantly worse recurrence free survival (RFS) and overall survival (OS) than patients with PD-L1-negative tumors. Using CPS, patients with PD-L1-positive ovarian tumors demonstrated significantly worse OS while no significant difference in RFS was found. Patients with PD-L1-positive omental tumors demonstrated significantly worse RFS and OS. Patients with omental PD-L1-positive tumors (TPS) were associated with poorer RFS and OS, while patients with ovarian PD-L1-positive tumors (TPS) were associated with OS not RFS, in COX multivariant analysis. Nonetheless, ovarian and omental high CD8 TILs density was not associated with worse OS in univariant and COX multivariant analysis. PD-L1 expression in ovarian and omental tumor associated with an increased CD8 + TILs density. PD-L1 expression by TPS was better correlated with survival than by CPS, and PD-L1 expression in omental tumors was a stronger prognostic indicator than that in ovarian tumors.

Capicua (CIC) mutations in gliomas in association with MAPK activation for exposing a potential therapeutic target.

2056 Background: Capicua (CIC) Gene is a tumor suppressor, transcriptional repressor, and a member of the high mobility (HMG)-box protein family. CIC is a negative regulator of MAPK and RTK pathways; inactivating CIC mutations (mut) occur in approximately 40% of oligodendrogliomas (OLIG) and less frequently in other gliomas putatively activating downstream signaling. With a goal to identify potential novel treatment options for various gliomas, we explored key signaling pathways associated with CIC mut. Methods: Consecutive glioma tumors were analyzed using Next-Gen DNA sequencing (NextSeq, 592 genes or NovaSeq, whole-exome), RNA sequencing (NovaSeq, WTS ) and IHC (Caris Life Sciences, Phoenix, AZ). Immune cell fraction was calculated by QuantiSeq; MAPK activation score (MPAS) was evaluated using RNAseq data. A comparison was made using Chi2 or Fisher’s-exact test with correction for multiple-comparison (q) using Benjamini-Hochberg. Results: A total of 196 (3.7%) tumors with CIC mut were seen in 5266 gliomas tumors analyzed, with the highest prevalence seen in OLIG (143 of 285, 50.2%). There was no difference between grade 3 (73 of 142, 51.4%) and grade 2 OLIG (70 of 143, 49%). CIC mut were infrequent in astrocytomas (16 of 829, 1.9%; grade 3, 12/510 or 2.4%; grade 2, 4/261 or 1.5%; grade 1, 0/58). CIC mut were present in glioblastomas (24/2753 or 0.6%), gliosarcomas (1/128 or 0.8%), and other mixed subtypes (12/185 or 6.5%). CIC mut were associated with higher prevalence of IDH1/2 mut (92% in CIC-mut vs. 17% in wild type), MGMT promoter methylation (97% vs. 47%), FUBP1 mut (32% vs. 1%) but lower PTEN mut (1% vs. 25%) and TP53 mut (12% vs. 39%) (all q < 0.05). Significant mutual exclusivity for CIC mut and MAPK pathway drivers observed: EGFR amplification (1.5% vs. 27%) , EGFR mut (0.5% vs. 12.6%), NF1 mut (4% vs. 18%) (all q < 0.05). BRAF mut rate was similar in CIC-mut or wild-type (1% vs. 3%, p = ns). Although associated with a higher tumor mutation burden (cutoff > = 10 mut/MB, 13% vs. 3%), a lower prevalence of PDL1 expression (1% vs. 16%) and lower M1 macrophage infiltration were seen (all q < 0.05). Similar effects were seen when stratifying by oligodendroglial and astrocytic histology. CIC mut were associated with increased MPAS score in OLIG (p = 0.01), particularly when compared to tumors lacking additional MAPK drivers (p = 0.001). This effect was not seen in astrocytic tumors, although EGFR alterations (including CNA, EGFRvIII, EGFR fusion and mut) were independently associated with increased MPAS scores (p < 0.001). Conclusions: CIC mut were frequent in oligodendrogliomas but occurred rarely in other glioma tumors and are associated with favorable prognostic markers. RNA expression analysis suggests CIC mut is associated with MAPK activation in OLIG, as are EGFR alterations in astrocytomas. Targeted inhibition of this pathway in selected gliomas may be a promising therapeutic avenue and should be explored further.

PD-L1 Expression in Papillary Thyroid Cancer

Abstract There is limited data on prevalence of PD-L1 expression in papillary thyroid cancer (PTC). Anti- PD-L1 therapy is now being trialled for head and neck cancers including thyroid cancer. Whether presence of PD-L1 staining in PTC might result in a better response to anti-PD-L1 therapy is uncertain. We evaluated the frequency of tumoral PD-L1 expression using standard antibody (SP263) and clinicopathologic factors including mutation status - BRAF, NRAS, KRAS using OncoFocus Mass Array System in an Australian PTC cohort with low or high risk of recurrence /treatment response as per 2015 ATA guidelines. The cohort had 128 patients; 66% were females; 40% had both multifocal and bilateral PTC; 47% had low recurrence risk, of whom 92% had excellent treatment response; 34% had high recurrence risk, of whom 37% had structural incomplete treatment response. There was nil (0%) PD-L1 staining in 59%, 1% staining in 20%, 5-10% staining in 11%, >10% staining in rest of the cohort; 30%, 40% and 70% staining was seen in 2% each. PD-L1 in immune cells was positive in 62%. There was no significant association between PD-L1 tumour status and age, gender, size of tumour, multifocality, bilaterality, both multifocality and bilaterality, lymphovascular invasion, perineural invasion, extrathyroidal extension (ETE), histological variants, risk stratification, treatment response, metastases or mutation status. Among PD-L1 negative vs positive patients, BRAFV600E was present in 64.9% vs 67.5%, NRAS in 8.8% vs 0% and nil mutation in 26 % vs 33 % p=0.15. The staining thresholds were chosen according to existing literature. When analysed according to the percentage of PD-L1 staining (0%, 1-10% and >=10% thresholds), there was no significant association between PD-L1 staining category and other features, except for ETE (35% vs 65% vs 27%; p=0.007), a relationship that remained significant in a multivariable-adjusted model (OR 9.9, p=0.04). PD-L1 staining thresholds of <5% and >=5% were significantly associated with the size of tumour (24.7±15.4 vs 33.3±21.8; p=0.02) and histological variants (57 % vs 61% for classic variants and 27% vs 11% for follicular variants, p=0.03). This is the first study to our knowledge that analysed PD-L1 staining based on the risk stratification categories. The majority of PTC showed negative or low staining intensity for PD-L1 expression. There was no significant association between PD-L1 staining, clinicopathologic characteristics and mutation status of the PTC. Relatively less ETE was seen in the group that showed >=10% and also >=5% PD-L1 staining as compared to the group that showed 1% <10% and 1% to <5% staining which is an interesting observation and needs further investigation. The significant variation in reported PD-L1 staining in current literature reiterates that the method is yet to be optimised. Moreover the relationship between PD-L1 staining and PTC remains to be further investigated.

P33.18 The Prevalence of PDL-1 Expression in Lung Cancer: Real-World Experience from a Tertiary Care Oncology Centre

P33.18 The Prevalence of PDL-1 Expression in Lung Cancer: Real-World Experience from a Tertiary Care Oncology Centre

Abstract PS4-18: Real-world PD-L1 test utilization and analytical concordance of the PD-L1 IHC 28-8 and 22C3 assays in patients with breast cancer

Abstract Background: Programmed death-1/programmed death ligand 1 (PD-[L]1) inhibitors are approved for use in a range of cancers. PD-L1 expression in the tumor microenvironment, assessed with an FDA-approved PD-L1 immunohistochemistry (IHC) diagnostic assay such as the Dako PD-L1 IHC 28-8 and 22C3 pharmDx or Ventana PD-L1 SP142 and SP263 assays, is associated with improved PD-(L)1 inhibitor treatment outcomes in some tumor types, including breast cancer (BC). In March 2019, the FDA approved atezolizumab + nab-paclitaxel for the treatment of patients with advanced triple-negative BC and immune cell (IC) PD-L1 expression ≥ 1% using the SP142 assay. Here, we investigated test utilization, test turnaround time (TAT), PD-L1 expression prevalence by assay and biopsy location, and analytical concordance between assays in real-world BC samples. Design: The study included samples from patients with BC that were tested for PD-L1 expression between Oct 2015 and Sep 2019 at NeoGenomics Laboratories, a US national reference laboratory. Patient characteristics from Symphony Healthcare Solutions were matched to PD-L1 test results using unique identifiers. Test volume and TAT were assessed for the 28-8, 22C3, SP142, and SP263 assays. PD-L1 expression was determined by trained pathologists using the 28-8, 22C3, or SP142 assays. Results for the 28-8 assay for the entire study period and for the 22C3 assay until Dec 2018 were reported as the percentage of tumor cells (% TC) with PD-L1 expression. From Jan 2019 onwards, 22C3 assay results were reported as a combined positive score (CPS). All SP142 assay results were reported as the percentage of ICs (% IC) with PD-L1 expression. Analytical concordance between assays was assessed in patients with matched samples (biopsies from the same site and collected on the same date). BioStat Solutions performed statistical analyses. Results: 2955 PD-L1 tests were performed on samples from 2508 patients with BC. The volume of PD-L1 tests on BC samples increased > 100-fold over the study period. Mean TAT was < 5 days for all 4 assays pooled. Table 1 shows PD-L1 expression prevalence in patients with a 28-8, 22C3, or SP142 test result. Median PD-L1 expression did not differ between primary tumors and metastatic sites. In matched samples, overall percentage agreement (OPA) between the 28-8 (TC ≥ 1%) and 22C3 (CPS ≥ 1) assays was 94%, and OPA between the 22C3 (CPS ≥ 1) and SP142 (IC ≥ 1%) assays was 64% (Table 2). Analytical concordance between the 28-8 and 22C3 assays for % TC scoring in matched samples from 27 patients was high (Kendall’s tau = 0.997 [95% CI, 0.883-1.000]). Conclusion: Mean PD-L1 test TAT for BC samples remained < 5 days across all tests despite a large increase in test volume over the study period. Prevalence of PD-L1 expression ≥ 1(%) was higher with the CPS and % IC algorithms than the % TC algorithm, although differences could be due to multiple confounding factors. Despite a small sample size, analytical concordance between the 28-8 and 22C3 assays in matched samples was high. These data provide real-world context for the PD-L1 testing landscape in BC. Table 1. Prevalence of PD-L1 expression in patients with BCPD-L1 expressiona28-8 and 22C3b22C3cSP142% TC, n (%)CPS, n (%)% IC, n (%)(N = 608)(N = 609)(N = 1080)<1(%)390 (64)253 (42)367 (34)≥1(%)218 (36)356 (58)713 (66)All patients had a single test result or ≥ 2 identical results. aThe CPS algorithm is reported on a scale of 0-100, not as a percentage; bSamples tested with the 22C3 assay between Q4 2015 and Q4 2018 were scored using the % TC algorithm; cSamples tested with the 22C3 assay between Q1 2019 and Q4 2019 were scored using the CPS algorithm. Table 2. Agreement between assays on matched samples from patients with BCAgreement between 28-8 (TC ≥ 1%) and 22C3 (CPS ≥ 1) (N = 18)a28-8 as reference22C3 as referenceOPA (n/N)94 (17/18)PPA (n/N)100 (6/6)86 (6/7)NPA (n/N)92 (11/12)100 (11/11)Agreement between 22C3 (CPS ≥ 1) and SP142 (IC ≥ 1%) (N = 33)b22C3 as referenceSP142 as referenceOPA (n/N)64 (21/33)PPA (n/N)86 (12/14)55 (12/22)NPA (n/N)47 (9/19)82 (9/11)aData are presented for 28-8 and 22C3 tests on matched samples with 22C3 tests performed between Q1 2019 and Q4 2019; bData are presented for 22C3 and SP142 tests on matched samples with 22C3 tests performed between Q1 2019 and Q4 2019. N, total number of samples; n, number of samples with the same results with the 2 tests; NPA, negative percentage agreement; PPA, positive percentage agreement. Citation Format: Shreya Mitra, Emily A. Prince, James Pratt, James Novotny, Jr, Vladislav Chizhevsky, Josette William Ragheb, David Huron. Real-world PD-L1 test utilization and analytical concordance of the PD-L1 IHC 28-8 and 22C3 assays in patients with breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS4-18.

Tumour PD-L1 Expression in Small-Cell Lung Cancer: A Systematic Review and Meta-Analysis.

Antibodies against programmed death-1 (PD-1), and its ligand, (PD-L1) have been approved recently for the treatment of small-cell lung cancer (SCLC). Although there are previous reports that addressed PD-L1 detection on tumour cells in SCLC, there is no comprehensive meta-analysis on the prevalence of PD-L1 expression in SCLC. We performed a systematic search of the PubMed, Cochrane Library and EMBASE databases to assess reports on the prevalence of PD-L1 expression and the association between PD-L1 expression and overall survival (OS). This meta-analysis included 27 studies enrolling a total of 2792 patients. The pooled estimate of PD-L1 expression was 26.0% (95% CI 17.0–37.0), (22.0% after removing outlying studies). The effect size was significantly heterogeneous (I2 = 97.4, 95% CI: 95.5–98.5, p < 0.0001).Positive PD-L1 expression was a favourable prognostic factor for SCLC but not statistically significant (HR = 0.86 (95% CI (0.49–1.50), p = 0.5880; I2 = 88.7%, p < 0.0001). Begg’s funnel plots and Egger’s tests indicated no publication bias across included studies (p > 0.05). Overall, there is heterogeneity in the prevalence of PD-L1 expression in SCLC tumour cells across studies. This is significantly moderated by factors such as immunohistochemistry (IHC) evaluation cut-off values, and assessment of PD-L1 staining patterns as membranous and/or cytoplasmic. There is the need for large size, prospective and multicentre studies with well-defined protocols and endpoints to advance the clinical value of PD-L1 expression in SCLC.

PD-L1 Expression and CD8+ Tumor-infiltrating Lymphocytes in Different Types of Tubo-ovarian Carcinoma and Their Prognostic Value in High-grade Serous Carcinoma.

The prevalence and significance of programmed death-1 ligand (PD-L1) expression in different types of tubo-ovarian carcinoma have not been well defined. We evaluated PD-L1 expression and CD8 tumor-infiltrating lymphocyte (TIL) density in whole tissue sections of 189 cases of tubo-ovarian carcinoma, including high-grade serous carcinoma (HGSC, n=100), clear cell carcinoma (CCC, n=24), endometrioid carcinoma (EmC, n=40), and mucinous carcinomas (MC, n=25). Using the tumor proportion score (TPS) with a 1% cutoff, PD-L1 expression was present in 21% of HGSC, 16.7% of CCC, 2.5% of EmC, and 4% of MC. Using the combined positive score (CPS) with a cutoff of 1, PD-L1 expression was present in 48% of HGSC, 25% of CCC, 20% of EmC, and 24% of MC. HGSC demonstrated significantly higher CD8 TIL density than CCC (P=0.013238), EmC (P=0.01341), or MC (P=0.004556). In HGSC, CD8 TIL density was directly correlated with PD-L1 positivity using either TPS (P=0.0008) or CPS (P=0.00011). Survival analysis of patients with high stage (stage III to IV) HGSC revealed PD-L1 positivity by TPS to be associated with improved progression-free survival (adjusted hazard ratio: 0.4912 vs. 2.036, P=0.0378). Although not statistically significant, a similar trend was observed in overall survival (adjusted hazard ratio: 0.3387 vs. 2.953, P=0.0548). In contrast, with CPS, no significant difference was identified between PD-L1-positive and negative groups in either progression-free survival (P=0.5086) or overall survival (P=0.7823). Neoadjuvant chemotherapy was associated with higher PD-L1 expression by TPS (P=0.00407) but not CPS. No significant difference in PD-L1 expression was detected in tumors from patients with germline BRCA1/2 mutations compared with germline mutation-negative tumors by either TPS or CPS. In conclusion, the prevalence of PD-L1 expression is variable in different types of tubo-ovarian carcinoma and is highest in HGSC. In high-stage HGSC, PD-L1 positivity in tumor cells is associated with an increased immune response and improved survival.

Prevalence of PD-L1 expression is associated with EMAST, density of peritumoral T-cells and recurrence-free survival in operable non-metastatic colorectal cancer

IntroductionMicrosatellite instability (MSI) predict response to anti-PD1 immunotherapy in colorectal cancer (CRC). CRCs with MSI have higher infiltration of immune cells related to a better survival. Elevated Microsatellite Alterations at Tetranucleotides (EMAST) is a form of MSI but its association with PD-L1 expression and immune-cell infiltration is not known.MethodsA consecutive, observational cohort of patients undergoing surgery for CRC. EMAST and clinicopathological characteristics were investigated against PD-L1, as well as CD3 and CD8 expression in the invasive margin or tumour centre (Immunoscore). Difference in survival between groups was assessed by log rank test.ResultsA total of 149 stage I–III CRCs patients, with a median follow up of 60.1 months. Patients with PD-L1+ tumours (7%) were older (median 79 vs 71 years, p = 0.045) and had EMAST+ cancers (OR 10.7, 95% CI 2.2–51.4, p = 0.001). Recurrence-free survival was longer in cancers with PD-L1+ immune cells (HR 0.35, 95% CI 0.16–0.76, p = 0.008, independent of EMAST) and high Immunoscore (HR 0.10, 95% CI 0.01–0.72, p = 0.022). Patients expressing PD-L1 in immune cells had longer disease-specific survival (HR 0.28, 95% CI 0.10–0.77, p = 0.014).ConclusionsHigher Immunoscore (CD3/CD8 cells) and expression of tumour PD-L1 is found in CRCs with EMAST. Lymphocytic infiltrate and peritumoral PD-L1 expression have prognostic value in CRC.

Correlation of tumor mutational burden, tumor microenvironment and alterations of driver genes in patients with NSCLC: A retrospective analysis.

e20019 Background: To investigate the correlation of tumor mutational burden, tumor microenvironment and alterations of driver genes in tumor tissue of patients with NSCLC. Methods: 79 patients with confirmed NSCLC admitted from January 2018 to January 2019 were included. Tumor DNA was isolated from FFPE samples or fresh tissue samples. Mutation profiles were obtained by targeted deep sequencing of 620 selected genes. Tumor mutational burden (TMB) was defined as the number of non-synonymous mutations per 1Mbp and divided into tertiles. PD-L1 expression, CD8+ T cell and tumor infiltrating lymphocyte density were evaluated by immunohistochemical analysis. The correlation coefficient of TMB, tumor microenvironment and alterations of driver genes was calculated by chi-square test. Results: Median TMB of these patients is 6.915 Muts/Mbp (4.22-9.44 Muts/Mbp). Prevalence of PD-L1 expression is 28.0% (n = 7/25) at a tumor proportion score cutoff of at least 5% evaluated by Dako 28-8 PharmDx Assay kit and prevalence of CD8+ T cell density is 95.8% (n = 23/24). TP53 mutations are the most common alteration (n = 49/79, 62.0%), followed by EGFR alterations (n = 31/79, 39.2%), CDKN2A alterations (n = 11/79, 13.9%), KRAS mutations (n = 10/79, 12.7%), STK11 mutations (n = 5/79, 6.3%), ALK fusions (n = 4/79, 5.1%) and POLE mutations (n = 4/79, 5.1%). According to results of chi-square test, squamous cell carcinoma has higher TMB (p= 0.023) than adenocarcinoma. Metastatic NSCLC has higher PD-L1 expression (p= 0.049) than non-metastatic NSCLC. Furthermore, EGFR alterations are associated with lower TMB (p=0.020) and POLE mutations are associated with higher TMB (p= 0.015). There are no correlations among CD8+ T cell density, tumor infiltrating lymphocyte density and other variants. Conclusions: Our study highlights the correlation of tumor mutational burden, tumor microenvironment and alterations of driver genes in patients with NSCLC. This result may be the reference of anti-PD-1 therapy.

PD-L1 expression in soft tissue sarcomas and its prognostic implication.

e14261 Background: The expression rate of PD-L1 in human malignant tumors paid a lot of attention and has been reported to vary from 19% to 92%, and the expression of PD-L1 was associated with poor prognosis of various human and may predicted the response to immune checkpoint inhibitors. The purpose of this study to investigate the expression of PD-L1 and its clinic-pathological feature in soft tissue sarcomas (STS). Methods: We collected Paraffin embedded tissue of 50 Patients with STS retrospectively from the archives of Pathology and oncology Department, Ain Shams University Hospitals from 2011-2017.then we correlated between PD-L1 expression and the clinico-pathological features. For PD-L1 expression we followed the Cologne 6-step proportional scoring system, using the rabbit monoclonal antibody (E1L3N 13684) and Tumors with &gt; /10% membranous stained cells were considered to be positive for expression. The differences among variables were calculated by chi-square test. Results: PD-L1 expression was found in 12 (24%) of cases. Of all sarcoma subtypes , desmoid tumors had the highest prevalence of PD-L1 expression noted in 2/3 (66%) of samples followed by GIST 2/4(50%), then liposarcoma 3/11(27%). In addition, there were 2 rhabdomyosarcoma cases with tumor positivity for PD-L1 expression. We found that STS patients with PD-L1 expression have shorter survival with a median OS 11 vs 19 months (p-value = 0.1) as well as a mean PFS 6 vs 11 months (p-value = 0.1) in PD-L1 positive and negative respectively; this finding considered as clinically significant, but not reached to statistical significant . Conclusions: We report here that PD-L1 expression is as prognostic factor for poorer outcome. This finding may be clinically significant but does not reach the statistically significant levels due to small number of samples included. Its role beyond that of a prognostic biomarker remains to be established in the context of larger clinical trials. Clinical trial information: 31/2017.

Prevalence of PD-L1 expression in first-line (1L) locally advanced/unresectable or metastatic urothelial carcinoma (UC).

TPS67 Background: Treatments for 1L advanced/metastatic UC include platinum-based chemotherapy, an immune checkpoint inhibitor (ICI) or clinical trial enrollment. Not all patients benefit from, or are eligible for, specific therapies due to comorbidities and performance status. There is an urgent need for biomarker-directed strategies to enable patient selection and improve outcomes. Currently the only clinically used molecular biomarker is PD-L1 protein expression in tumor tissue. Although inconsistent and variable among assays, higher PD-L1 expression generally correlates with increased ICI response rate. Improved understanding of the prevalence and potential prognostic and/or predictive role of PD-L1 can further enhance its clinical utility and guide novel clinical trial designs. Methods: This observational study will enroll 250 patients with advanced UC prior to starting or during 1L therapy, as initiated at the discretion of participating clinicians, from 60 US community sites. The primary endpoint is prevalence of PD-L1 expression by VENTANA SP263 Assay (exact [Clopper-Pearson] 95% CI) on pre-treatment tumor tissue. Secondary endpoints include the association of pre-treatment PD-L1 expression with pre-treatment tumor tissue mutational burden (tTMB), descriptions of treatment response and outcomes (ORR based on RECIST 1.1, PFS, OS) and assessment of their correlations with PD-L1 expression. Exploratory endpoints include the association of pre-treatment tumor tissue PD-L1 with pre-treatment blood-based tumor mutational burden (bTMB), changes in circulating tumor DNA (ctDNA) levels at various timepoints, the correlation between tTMB and bTMB values, and the association of those biomarkers for outcomes of PFS and OS. Enrollment will take place over 24 months with follow-up to 30 months from study enrollment. With 250 patients, the 95% CI for 30%, 45%, and 60% observed prevalence of PD-L1 high are (24.4%, 36.1%), (38.9%, 51.2%), and (53.6%, 66.1%), respectively; the various secondary and exploratory analyses will be descriptive.

467P - Correlation between PD-L1 expression and clinicopathological characterization in NSCLC

Background: Inhibition of the PD-1/PD-L1 pathway may induce anticancer immune responses in non-small cell lung cancer (NSCLC). Here, we analyzed the correlation between PD-L1 expression and clinicopathological characteristics, stromal tumor-infiltrating lymphocyts (sTILs), pulmonary major driver gene alteration in NSCLC. Methods: PD-L1 expression characterizations by immunohistochemistry using the clone 22C3 antibody were performed on 1156 NSCLC (329 archived and 827 recently acquired tumor) and 198 small biopsy. Results: PD-L1 high expression was observed in 9.7%, 6.5%, and 27.4% in recently acquired NSCLC, adenocarcinoma (ADC), and squamous cell carcinoma (SqCC) cohort, respectively, which showed higher than in archive cohorts previously reported in our group (4.9%, 0.5%, and 13.9% in NSCLC, ADC, and SqCC, respectively). In subgroup analysis, PD-L1 high expression was significantly associated with male sex (p = 0.002), larger tumor size (p < 0.001), pleural invasion (p = 0.001), venous and lymphatic invasion (p < 0.001), smoking history (p < 0.001), solid predominant histology (p < 0.001), and advanced pathological stage (p < 0.001) in ADC cohort. It tended to be more common in poorer differentiation (p = 0.011) and absence pleural invasion (p = 0.001) in SqCC. In the small biopsy specimens, PD-L1 high expression was found in 29.3% cases in NSCLC. PD-L1 high expression was significantly associated with high sTILs (p = 0.029). Both PD-L1 high and low expressions were more frequent in EGFR-wild type than in mutated type (p < 0.001). Conclusions: PD-L1 high expression was significantly associated with poor differentiation and ≥50% sTILs. It was more frequently observed in EGFR-wild tumors. The prevalence of PD-L1 expression in recently acquired sample was higher than in archived sample, which suggests that PD-L1 expression should be evaluated as soon as possible after operation, otherwise will be reduced. Legal entity responsible for the study: The author. Funding: Has not received any funding. Disclosure: The author has declared no conflicts of interest.

Abstract 4517: Characterization of a standardized immunohistochemical assay for detecting PD-L1 expression in non-small cell lung cancer using anti-PD-L1 clone 73-10

Abstract Background: Recent data have demonstrated the clinical efficacy of anti-PD-1/PD-L1 checkpoint inhibitors in non-small cell lung cancer (NSCLC), and approvals by regulatory authorities in first-line and second-line settings have followed. In selected treatment scenarios, expression of PD-L1 by immunohistochemistry (IHC) is considered predictive of patient outcome. A recent comparative study using the rabbit anti-PD-L1 monoclonal antibody clone 73-10 and other commercialized IHC assays demonstrated strong intra-assay reliability in NSCLC tumor cell scoring and inter-assay differences in the number of tumor cells detected by each assay (Blueprint 2 data presented at IASLC 2017). Here we report precision around a ≥ 1% tumor cell cutoff and PD-L1 expression in 428 procured NSCLC tissues using an immunohistochemical assay developed with this antibody clone. Methods: PD-L1 expression was assessed using a standardized PD-L1 IHC assay. Scoring of tumor specimens was performed on a 0 - 3+ intensity scale, with membrane staining in ≥ 1% of tumor cells at ≥ 1+ intensity defining PD-L1 positivity. Assay precision around this cutoff was assessed in 28 specimens. PD-L1 expression was evaluated in 428 Stage IIIA, IIIB, and IV procured NSCLC tissues. Assay specificity was examined in 30 normal tissues. Results: The PD-L1 IHC 73-10 assay showed &amp;gt; 95% negative, positive, and overall agreement in inter-day, inter-operator, intra-run, inter-instrument, and inter-lot conditions around the ≥ 1% tumor cell cutoff. The lower bound of the 95% confidence interval was &amp;gt; 90% for all agreement types and precision conditions. PD-L1 protein localization in normal tissues was consistent with known patterns. The 428 procured NSCLC samples had primarily squamous cell (39.5%), adenocarcinoma (43.7%) and a mixture of other less common (16.8%) histologic subtypes; 397 (92.8%) of samples were from primary and 31 (7.2%) were from metastatic tumors. Crisp membrane staining was observed in tumor cells. Other labeled cell types included macrophages, lymphocytes, endothelial cells, and fibroblasts that exhibited membrane and/or cytoplasmic staining. Of the 428 procured specimens, 270 (63.0%) were PD-L1-positive based on the ≥ 1% cutoff. Tissues of each NSCLC stage expressed PD-L1 in the full dynamic range from 0% - 100% positive. Conclusions: These data provide insight into the prevalence of PD-L1 expression in procured NSCLC specimens when stained with PD-L1 IHC 73-10, and demonstrate that this assay is precise around a ≥ 1% tumor cell cutoff while exhibiting expected antigen specificity. PD-L1 positivity in the tumor stages examined using this assay is greater than in the literature, where prevalence using different antibodies has been reported at less than 50% in various stages. Citation Format: Darlene Krohn, Mai Nguyen, Marko Srdanov, Christina Samathanam, Peng Duan, Monika Vilardo, Alexander Prenta, Sharika Vasudevan, Landry Nicholson-Legg, Debra Hanks, Aaron R. Ellison. Characterization of a standardized immunohistochemical assay for detecting PD-L1 expression in non-small cell lung cancer using anti-PD-L1 clone 73-10 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4517.

Lower prevalence of PD-L1 expression in advanced non-small lung cancer in Brazil.

e21140Background: Immune checkpoint inhibitors improved outcomes of patients with advanced non-small cell lung cancer (NSCLC). KEYNOTE-024 trial demonstrated that immunotherapy was superior to plat...

Comparing programmed death ligand-1 expression on tumor cells before and after acquiring resistance to tyrosine kinase inhibitor in EGFR harbouring non-small cell lung cancer.

11617 Background: Although anti-PD1/PD-L1-targeting immunotherapy has been successful in the treatment of non-small cell lung cancer (NSCLC) patients, the benefit is unclear in EGFR mutation(mEGFR) NSCLC. To date, there are several clones of anti-PD-L1 antibody which provide different predictive values and the level of expression also dynamically changed after treatment. The study examined changes of PD-L1 expression in mEGFR harbouring NSCLC tissues, comparing between before and after treatment with tyrosine kinase inhibitors(TKIs) using an FDA-approved PD-L1 assay. Methods: We retrospectively reviewed tumor specimen from 24 patients with mEGFR NSCLC who had been treated with gefitinib, erlotinib, afatinib and received second tissue biopsy after acquiring resistance to TKIs. The collected FFPE specimens were stained with commercial anti-PD-L1 22C3 assay monoclonal antibody. Tumor proportion score(TPS) and H-score were measured before and after TKIs. Results: Of the study patients,54.2% patients were exon 19 deletion(n = 13), 41.7% were exon 21 point mutation(L858R) (n = 10), and 1 case was L858R/S761I. After TKIs resistance 10/13 (76.9%) of exon 19del and 8/10 (80%) of L858R revealed presence of +T790M. Pretreatment PD-L1 expression was positive(TPS≥1%) in 6 cases (25%). Mean TPS of positive cases was 34.0% and H-score was 78.2, All except 2 of 6 positive cases had adequate specimens from second biopsy(n = 22). Among 4 positive cases,PD-L1 expression tended to be higher after TKIs; mean TPS changed from 23.9 to 40.9 (p = 0.171) and H-score were from 49.3 to 91.1 (p = 0.172). 18/24 patients with TPS and H-score zero at the beginning remained zero after progression. Median TTP were similar in patients with positive PD-L1 expression and negative,13.8 m vs 14.5 m (n = 24,p = 0.644) with TKIs and 3.9 m vs 2.5 m (n = 14, p = 0.560) with chemotherapy. Conclusions: Prevalence of PD-L1 expression in mEGFR NSCLC was low. PD-L1 expression tended to be higher after TKIs for this with positive cases which may guide the sequences of treatment. Nevertheless no changes of PD-L1 expression for those with negative, hence re-biopsy may not be necessary.

Preliminary correlative analysis of PD-L1 expression from the SUNRISE study.

11603 Background: SUNRISE, a global, double-bind, Phase III trial of docetaxel (D) plus bavituximab (B) or D plus placebo (P) in previously treated non-squamous non-small cell lung cancer, demonstrated similar overall survival (OS) in both treatment arms. Biomarkers including pre-treatment PD-L1 expression are being retrospectively assessed in on-going exploratory analyses. Methods: Archival tissue obtained at the time of diagnosis was requested but not required in the SUNRISE trial. FFPE slides were stained with a panel of lymphoid cell markers: CD3+, CD8+, FoxP3+, PD-L1+, CD163+, CK+ and DAPI using a 6-plex quantitative immunohistochemistry (IHC) assay (OPAL, PerkinElmer, Hopkinton, MA, USA). Baseline PD-L1 expression was retrospectively scored on tumor cells (TC) as a percentage of PD-L1 expressing tumor cells: TC3≥50%, TC2≥5% and &lt; 50%, TC1≥1% and &lt; 5%, and TC0 &lt; 1%. Cox regression models for PD-L1 IHC subgroup populations were used for correlation with OS. Results: In the subset of patients with available diagnostic biopsies (110 out of 597 randomized patients), the prevalence of PD-L1 expression was 5% for TC3, 18% for TC2/3, 35% for TC1/2/3, 65% for TC0. Median OS (mOS) of the D+B arm is 11.5 months (TC0, &lt; 1%) and 6.0 months (TC1/2/3, ≥1%) with HR 0.38 (95% CI, 0.19-0.76); p-value = 0.004. mOS of the D+P arm is 11.1 months (TC0, &lt; 1%) and 10.4 months (TC1/2/3, ≥1%) with HR 0.93 (95% CI, 0.47-1.87); p value = 0.844. Conclusions: Baseline PD-L1 expression in a subset of SUNRISE patients demonstrated that PD-L1 expression (TC0) was associated with a significantly prolonged OS compared to positive PD-L1 expression (TC1/2/3) in patients receiving D+B. No difference in OS was observed in the D+P group by PD-L1 expression. These observations are consistent with the hypothesis that bavituximab may demonstrate more effect in PD-L1 negative or low expressing “immune cold” tumors. Clinical trial information: NCT01999673.

PUB063 PD-L1 Expression Level Could Predict the Survival of Patients with Resectable Small Cell Lung Cancer

Several studies indicated PD-L1 expression on tumor cells is the potential predictive biomarker. However, the prevalence of PD-L1 expression in small cell lung cancer (SCLC) is unclear. This retrospective study aims to detect PD-L1 expression in patients with resectable SCLC and investigate the correlation between PD-L1 expression and the survival of patients. Formalin-fixed, paraffin-embedded samples were stained with PD-L1 antibody by immunohistochemical (IHC) analysis (M4424 antibody). IHC score was calculated according to staining intensity and the percentages of staining tumor cells. Kaplan-Meier method and Cox proportional hazards model analyses were used to evaluate the role of PD-L1 expression on the prognosis of patients with SCLC. From 2011 - 2013, totally 61 patients (43 males/18 females) who underwent complete resection were collected with median age 56 years (range, 30-74) at the time of diagnosis. For the whole group, 32.8% (20/61), 27.9% (17/61) and 39.3% (24/61) patients were diagnosed as pathological stage I, II and III. Until the end of follow-up, 60.7% (37/61) patients are alive. For entire group, the median survival time (MST) was not reached (NR) (range, 6-133.2+ months); 3- and 5-year survival rates were 57.3% and 54.2%, respectively. For the whole cohort, 57.4% (35/61), 37.7% (23/61) and 21.3% (13/61) patients expressed PD-L1 ≥ 1%, 5% and 10%, respectively; and 3-year survival rate was 60.0%, 72.3% and 74.0%, respectively. When the positivity threshold of PD-L1 expression was defined as PD-L1 expression ≥ 5%, the MST in patients with PD-L1 (+) tumors was significantly longer than that with PD-L1 (-) tumors (NR vs. 34 months, p = 0.0321). No significantly survival differences were observed when PD-L1 positivity threshold was defined as 1% or 10%. For patients with stage I SCLC, the MST in patients with PD-L1 expression ≥ 5%, was significantly longer than that in patients with PD-L1 expression < 5% (NR vs. 56 moths, p = 0.03). Regardless of the positivity threshold of PD-L1 expression with 1%, 5% or 10%, for patients with stage II or III SCLC, no significant survival differences were observed. Multivariate analysis indicated postoperative chemotherapy (hazard ratio [HR] = 0.322, p = 0.023), PCI (HR = 0.105, p = 0.029) and PD-L1 expression (HR = 0.253, p = 0.008) were independent prognostic factors for OS. PD-L1 highly expressed in patients with resectable SCLC. The level of PD-L1 expression could predict the survival of patients in this setting.

1060P - Prevalence of PD-L1 expression in patients with non-small cell lung cancer screened for enrollment in KEYNOTE-001, -010, and -024

1060P - Prevalence of PD-L1 expression in patients with non-small cell lung cancer screened for enrollment in KEYNOTE-001, -010, and -024