Percentage Of Viable Tumor Cells Research Articles

Comparison of SP263 and 22C3 immunohistochemistry PD-L1 assays for clinical efficacy of adjuvant atezolizumab in non-small cell lung cancer: results from the randomized phase III IMpower010 trial

BackgroundTumor samples from the phase III IMpower010 study were used to compare two programmed death-ligand 1 (PD-L1) immunohistochemistry assays (VENTANA SP263 and Dako 22C3) for identification of PD-L1 patient subgroups...

Histological response to radiotherapy is an early event in myxoid liposarcoma

Compared to other sarcomas, myxoid liposarcoma (MLS) is exceptionally sensitive to radiation therapy, but the underlying mechanism remains unknown. The objective was to assess the tissue-based changes in MLS during and after neoadjuvant radiotherapy in 26 patients of the DOREMY trial. Morphological assessment was performed on biopsies pre-treatment, after 8 fractions, 16 factions, and after surgical resection and included percentage of viable tumor cells, hyalinization, necrosis, and fatty maturation. Furthermore, immunohistochemistry was performed for apoptosis (cleaved caspase-3), anti-apoptosis (Bcl-2), activity of mTOR signaling (phospho-S6), hypoxia (CAIX), proliferation (Ki67), inflammation (CD45 and CD68), and microvessel density (CD34 Chalkley count). A pronounced reduction in vital tumor cells was observed early with a drop to 32.5% (median) tumor cells (IQR 10–93.8%) after 8 fractions. This decreased further to 10% (IQR 5–30%) after 16 fractions and 7.5% (IQR 5–15%) in the surgical specimen. All but one patient had an excellent response with < 50% remaining tumor cells. Inversely, treatment response was mainly observed as hyalinization and less often as fatty maturation. Additionally, a decrease of inflammatory cells was noticed especially during the first eight fractions. Microvessel density remained stable over time. Immunohistochemical markers for apoptosis, anti-apoptosis, activity of mTOR signaling, proliferation, and hypoxia did not show any marked changes within the remaining tumor cells during and after radiotherapy. As a modest dose of neoadjuvant radiotherapy induces profound tissue changes in MLS, mainly during the first 8 fractions, current findings might suggest that in a carefully selected patient population further deintensification of radiotherapy might be explored.

Prevalência e valor prognóstico da expressão do ligante de morte celular programada 1 (PD-L1) em amostras tumorais de pacientes com câncer do colo do útero

OBJECTIVES: This study aimed to investigate the programmed cell death-ligand 1 (PD-L1) expression in a cohort of cervical cancer (CC) patients evaluating its prognostic significance. METHODS: All patients diagnosed at Brazilian National Cancer Institute (INCA), in 2011, with invasive CC, squamous cell carcinoma (SCC) or adenocarcinoma (ADC) were retrospectively included. Clinical and treatment data were collected and PD-L1 expression was evaluated according to the percentage of viable tumor cells showing staining. The survival analysis was performed using the Kaplan Meier method. RESULTS: In total, 152 patients (105 SSC and 47 ADC) were included and the mean age was 52.4 years (±14.4). According to the International Federation of Gynecology and Obstetrics (FIGO) 2009, 84.2% had locally advanced disease (IB2-IVA). PD-L1 expression was considered positive (=1%) in 53.3% of the cases. After adjustment, the multivariable analysis confirmed that SCC (p=0.026) and tumor size >4cm (p=0.023) were independently associated with PD-L1 expression. There were no significant differences in disease-free survival (DFS), disease-specific survival (DSS) and overall survival (OS) comparing the subgroups with distinct PD-L1 expression. CONCLUSION: In this cohort, PD-L1 expression was not associated with DFS, DSS and OS.

Intra-Tumoral Pharmacokinetics of Pazopanib in Combination with Radiotherapy in Patients with Non-Metastatic Soft-Tissue Sarcoma.

Simple SummaryPazopanib plasma levels have been associated with treatment efficacy. Since pazopanib targets receptors present on cells in the vicinity of the tumor and on tumor cells themselves, measurement of pazopanib concentrations in tumor tissue might be an even better prognostic biomarker than plasma levels. The aim of our study was to quantify pazopanib concentrations in tumor tissue, correlate this with plasma concentrations, and assess whether this is a better biomarker for efficacy. A modest correlation was found between pazopanib tumor concentrations and plasma concentrations. Additionally, no correlation was found between pazopanib tumor concentrations and efficacy. We provide recommendations for future studies in which pazopanib concentrations are measured.There is a lack of understanding whether plasma levels of anticancer drugs (such as pazopanib) correlate with intra-tumoral levels and whether the plasma compartment is the best surrogate for pharmacokinetic and pharmacodynamic evaluation. Therefore, we aimed to quantify pazopanib concentrations in tumor tissue, to assess the correlation between tumor concentrations and plasma concentrations and between tumor concentrations and efficacy. In this clinical trial, non-metastatic STS patients were treated with neo-adjuvant concurrent radiotherapy and pazopanib. Plasma samples and tumor biopsies were collected, and pazopanib concentrations were measured using liquid chromatography-tandem mass spectrometry. Twenty-four evaluable patients were included. The median pazopanib tumor concentration was 19.2 µg/g (range 0.149–200 µg/g). A modest correlation was found between tumor concentrations and plasma levels of pazopanib (ρ = 0.41, p = 0.049). No correlation was found between tumor concentrations and percentage of viable tumor cells (p > 0.05); however, a trend towards less viable tumor cells in patients with high pazopanib concentrations in tumor tissue was observed in a categorical analysis. Possible explanations for the lack of correlation might be heterogeneity of the tumors and timing of the biopsy procedure.

Clinical impact of primary tumour 123ImIBG response to induction chemotherapy in children with high-risk neuroblastoma.

More than 50% children with high-risk neuroblastoma (HR-NBL) experience disease progression, which we hypothesise is due to non-response of primary tumour to treatment. Current imaging techniques are unable to characterise response in primary tumour (necrotic versus viable tissue) at diagnosis or follow-up. Compare clinico-histological characteristics between primary 123ImIBG-avid tumours that became entirely 123ImIBG-non-avid (responders) after induction chemotherapy (IC) versus primary 123ImIBG-avid tumour that remained 123ImIBG-avid (non-responders). Retrospective review of clinico-radiological data of children diagnosed with 123ImIBG-avid HR-NBL at our centre (2005-2016). Patients received Rapid COJEC IC and two additional courses of TVD if metastatic response was inadequate. Primary tumour 123ImIBG response was assessed qualitatively as positive, negative or intermediate at diagnosis and after IC. Post-surgical histopathology slices were marked considering percentage of viable tissue. Sixteen of 61 patients showed complete primary tumour 123ImIBG response, 20 partial response, while 25 no response. There was no statistically significant difference between clinical demographics of complete responders and group of non- or partial responders. Mean percentage of viable tumour cells was higher in non-responders than in complete responders (44.6% vs 20.6%; p = 0.05). Five-year EFS was significantly higher in complete responders than non-responders (43 ± 15% vs 7 ± 6%; p < 0.005). 123ImIBG response in primary HR-NBL correlates with amount of necrotic tissue, skeletal metastatic 123ImIBG response and outcome. An entirely 123ImIBG non-avid tumour can still harbour viable tumour cells. Therefore, our findings do not support utility of primary tumour 123ImIBG response in decision making regarding residual tumour surgery. Combining both, primary and metastatic 123ImIBG response will improve interpretability of clinical trial results.

Hot or not: defining trophoblast PD-L1 expression and lymphohistiocytic density in gestational trophoblastic neoplasia

<h3>Objectives:</h3> PD-L1 is an important axis of immunotolerance in normal pregnancy and this may be perpetuated as a mechanism of immune evasion in the pathobiologic development of gestational trophoblastic neoplasia (GTN). There are early efficacy signals for anti-PD-1 immunotherapy in chemoresistant GTN, however response rates are variable. The characteristics of predictive biomarkers used for triaging anti-PD-1 immunotherapy are not well-known in GTN. The aim of this study was to quantify trophoblast PD-L1 expression in GTN using the FDA approved PD-L1 22C3 immunohistochemical (IHC) companion assay and to profile GTN-infiltrating immune cells. <h3>Methods:</h3> Choriocarcinoma (CC), epithelioid trophoblastic tumor (ETT) and placental site trophoblastic tumor (PSTT) cases with available tissue blocks in the Johns Hopkins GTN library were used for this investigation. IHC staining for PD-L1 and each immune marker (CD68, CD8, CD4, FOXP3) was performed on paired, fresh cut 4 micrometer tissue sections. Tumor proportion scores (TPS, percentage of viable tumor cells with any PD-L1 membrane staining) were assigned by 2 independent gynecologic pathologists. Discrepancies in scoring were adjudicated by a third gynecologic pathologist. Digital image analyses using QuPath v0.2.3 to average CD68, CD8, CD4 and FOXP3 immune cell density in three 40x hotspots per case was performed. Hotspots were targeted to the tumor-immune cell interface. Descriptive statistics and the Wilcoxon Rank Sum Test were performed for analysis. <h3>Results:</h3> A large proportion of PSTT (n=6/8,75%) and CC (n=22/32, 69%) and approximately half of ETT (n=9/19, 47%) cases have highpositive PD-L1 expression defined as the clinically relevant TPS cutoff of >50%. These exceed the rates of high PD-L1 positivity observed in all other solid tumor sites, which ranges from 2-31%. PSTT and CC have significantly higher trophoblast PD-L1 expression than ETT; the median TPS for PSTT and CC is 90% and 85%, compared to 35% for ETT (p=0.02). CD68 monocytes were more abundant in CC and PSTT compared to ETT. However, CD8 cytotoxic T (p<0.01) and CD4 T (p=0.04) regulatory cell densities are significantly higher in ETT. ETT has a wider spectrum of tumor PD-L1 expression than PSTT and CC. ETT cases with low/negative trophoblast PD-L1 (TPS <5%) have fewer immune infiltrating lymphocytes than ETT cases with TPS >5% (Table). <h3>Conclusions:</h3> PD-L1 expression in GTN is heterogeneous, yet disproportionately high compared to other primary tumor sites. Of the 3 GTN subtypes, ETT has the lowest and broadest range of PD-L1 expression; this is associated with lower CD68 monocyte infiltration and correlates with degree of lymphocytic infiltration. How these expression patterns predict response to anti-PD-L1/PD-1 agents in GTN will be need to be explored. In a tumor type with such lineage inherent PD-L1 expression, characterization of tumor cell PD-L1 expression in conjunction with the tumor immune-microenvironment may provide a unique opportunity to study mechanisms of immune escape.Funding was provided by the Bruce Patsner Research Grant for Innovative Research and Technology through the Foundation for Women's Cancer.

Diffuse Large B Cell Lymphoma and Programmed Death-Ligand 1 Expression. a Clinical and Pathological Study of Patients Seen in Tawam Hospital UAE

Introduction: Diffuse Large B Cell Lymphoma (DLBL) is the most common type of Non-Hodgkin's Lymphoma (NHL) seen in Tawam hospital UAE. DLBL is a heterogenous disease arising either from a Germinal center (GC) or non- GCB cells. Molecular signature has identified 3 different groups of DLBL with significantly different prognosis (Primary mediastinal, Germinal center and Activated B Cell type). The therapy for DLBL has been without innovation since introduction of Rituximab more than 20 years ago and using R-CHOP. Attempts at improving the outcome has been uniformly unsatisfactory either by adding additional drugs, increasing the dose of drugs or deceasing the frequency of each cycle. New biomarkers and or targets are needed to improve the prognosis of patients with DLBL. Programmed Death-Ligand 1 (PDL1) has been shown to protect tumor cells by inducing T cell apoptosis (Dong et al., 2002). PDL1 targeting agents have been approved for many different types of malignancies including Hodgkin's Lymphoma. The role of PDL1 in DLBL is still under intense study. We report our findings of PDL1 expression in DLBL patients in UAE. Methods: Patients diagnosed with DLBL between December 1, 2019 till July 15th 2020. Patient records were reviewed in this study. Data was collected regarding patient demographics, clinical stage, International prognostic index (IPI), pathology and cell of origin {using immunohistochemistry (IHC) and Han's criteria}. PDL1 testing was performed by using FDA approved PharmaDx Dako Ab 22C3 kit for IHC on the gold standard Link 48 Dako platform. PDL1 expression was reported as Tumor proportion score (TPS). TPS in this assay was the percentage of viable tumor cells showing any perceptible partial or complete linear membranous (or membranous &amp; cytoplasmic) staining, in the large lymphoma cells. The specimen was considered PDL1 positive if the TPS was greater than or equal to 30%(Xu-Monette et al Blood 2018). All scores were reported by single pathologist Results Twenty-six patients were diagnosed with DLBL in the study period. The median age was 44 years (range 18-90 years). Majority of patients (75%) were less than sixty years of age. Advanced stage disease was seen in preponderance (66%) as compared to early stage (34%) while the LDH was elevated in 65 % patients (institutional normal &amp;lt; 225 IU per liter). Majority of patients (60%) were poor risk with IPI 3 or higher. Pathology review showed a uniformly elevated Ki 67 with the majority of specimens showing greater than 80 %. Molecular classification showed GCB type 50 % (n=13) as compared to non-GCB 42 % (n=11), data was not available for 2 patients. Epstein-Barr virus encoded small RNA (EBER) CISH was positive in only 3 patients (data was not available for 8 patients). PDL1 expression was tested in eighteen (GCB n=8, ABC n=10) patients. PDL1 expression was elevated in ABC type (90%) as compared GCB type (50 %) Fig 1. Conclusion The median age (44 years) is at least 2 decades less than the reported western cohort. Majority of the patients had high risk disease with advanced stage and IPI. Ki 67 was uniformly elevated (&amp;gt;80 % in 90 % of patients). There was a slight preponderance of GCB type (50 % vs 42%). PDL1 expression in ABC type DLBL was higher as compared to GCB. This observation needs to be validated in a larger cohort. Recent literature makes it very clear that ABC type DLBL has a poor outcome as compared to GCB type. PDL1 may offer an attractive target for treatment evaluation in ABC type DLBL. Figure Disclosures Alam: Pfizer:Honoraria;Roche:Honoraria.McCarthy:Karyopharm:Consultancy, Honoraria;Magenta:Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board;Janssen:Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board;Takeda:Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board;Juno Therapeutics, a Bristol-Myers Squibb Company:Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board , Research Funding is to Roswell Park, Research Funding;AbbVie:Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board;Genentech:Consultancy, Honoraria;Starton:Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board.

Diagnostic performance of the FDG-PET/CT in patients with resected mucinous colorectal liver metastases

Backgroundand purpose: FDG-PET/CT has gained acceptance for tumours staging. Few and conflicting data exist on the sensitivity of FDG-PET/CT in identifying colorectal mucinous liver metastases (mucCRLM). The aim of this study was to evaluate the diagnostic performance of the FDG-PET/CT in patients with mucCRLM who underwent liver surgery. MethodsAll patients affected by mucCRLM scheduled for liver resection who had undergone preoperative FDG-PET/CT between 2005 and 2018 were analyzed. Diagnostic performance of FDG-PET/CT was assessed in organ and lesion-based analysis. Results58 patients out of 131 (44.2%) affected by mucCRLM fulfilled the inclusion criteria. 118 mucCRLM were detected. FDG-PET/CT confirmed 71 (60.2%) CRLM in 51 patients. The sensitivity and specificity of FDG-PET/CT were 89.4% and 100% in the organ-based analysis and 60.7% and 100% in lesion-based analysis. Absence of micro-vascular invasion (100% vs. 23%, p < 0.001) and median percentage of viable tumour cells were associated with FDG-PET/CT false negative (15% vs. 60%, p = 0.007). At ROC analysis viable tumour cells percentage >25% was associated with low risk of false negative (AUC 0.848; p = 0.006). ConclusionsFDG-PET/CT had a significant rate of false negative results in patients with mucinous colorectal liver metastases. Negative FDG-PET/CT in patients with low percentage of viable tumour cells after chemotherapy should be considered with caution.

1654P Analysis of predictive biomarkers for immune checkpoint inhibitor therapy in several subtypes of sarcomas

The significance of predictive biomarkers when using immune checkpoint inhibitors (ICI) is becoming increasingly prominent. Clinical trials of ICI have been performed in sarcomas, such as (SARC028). However, most results have been negative for the reason that few have taken biomarkers into account. We analysed and evaluated data for immunotherapy biomarkers in several sarcomas subtypes. 172 samples from patients with sarcomas have been collected in China since February 2018. Tumour mutation burden was detected and measured by next generation sequencing (NGS). MSI status was evaluated by NGS covering 500 MSI loci. Expression of PD-L1 was detected using Dako PD-L1 IHC 22C3 pharmDx. PD-L1 expression was determined using the percentage of viable tumour cells stained, termed as Tumor Proportion Score (TPS). TPS score was defined as: strong positive ≥50%, moderate positive ≥5% and <50%, weak positive ≥1% and <5%, and negative <1%. Among these patients, 59% (101/172) male and 41% (71/172) female had 18 fibrosarcomas, 50 liposarcomas, 25 rhabdomyosarcomas, 18 synovial sarcomas, 28 osteosarcomas, 21 soft tissue sarcomas (STS) and 12 Ewing sarcomas. All these patients had microsatellite-stable tumours, and all had low TMB level (median 3.2 mutants/Mb, average 3.5 Mutants/Mb). PD-L1 expression in fibrosarcoma was 66.7% negative, 16.7% weak positive, 5.6% moderate positive, and 11.1 strong positive. In Liposarcoma it was 85.7% negative, 8.6% weak positive, 2.7% moderate positive, 2.7% strong positive. In Rhabdomyosarcoma it was 96.0% negative, 4% moderate positive. In synovial sarcoma tumours were 100% negative for PD-L1 expression. In Osteosarcoma levels were 78.6% negative, 7.4% weak positive, 10.1% moderate positive, 3.6% strong positive. In STS it was 80.9% negative, and 19.0% weak positive. In Ewing sarcoma it was 91.7% negative, 8.3% weak positive. Biomarkers for ICI therapy, such as TMB level, MSS/MSI status, and PD-L1 expression, were present in a low proportion of sarcomas, suggesting other predictive biomarkers need to be explored and applied to stratify and select patients suitable for ICI therapy in this tumour type.

Histologic Response Following Pre-Operative Radiotherapy for Soft Tissue Sarcoma (STS) in a French Reference Center and Review

Background and Purpose: Limb sparing surgery and radiotherapy is the main treatment of patients harboring soft tissue sarcoma of the extremity. There is limited data regarding the prognostic impact of histologic response after pre-operative radiotherapy. Patients and Methods: Between 2010 and 2018, 123 patients were treated with a pre-operative radiotherapy for soft tissue sarcoma at Leon Berard Centre (Lyon, France) and were retrospectively reviewed. All patients received a dose of 50 Gy in 25 fractions. The histologic response has been analysed by considering the following factors: necrosis ≥ 90%, percentage of viable tumor cells ≤ 10% and fibrosis ≥ 10%. Overall survival (OS), local recurrence-free survival (LRFS), distant recurrence-free survival (DRFS) and event-free survival (EFS) were evaluated. Results: Median follow up was 33.2 months (range 2.3-128.1 months). Local recurrence occurred in 9 patients (7.5%) and 40 patients (33%) presented a distant recurrence. The 2 and 5-year OS was 84% and 63%. Histologic response factors (necrosis ≥ 90%, viable tumor cells ≤ 10% and fibrosis ≥ 10%) were not predictive in DRFS and EFS. In multivariate analysis, grade was the only significant prognostic factor for EFS P=0.0087. Among the 14 patients with ≤ 10% viable cells after irradiation 13 presented a metastatic evolution within 6 months. Conclusion: This study showed that current histological response evaluation based on necrosis, fibrosis and viable cells could not predict clinical outcomes after radiotherapy for extremity soft tissue sarcoma. A significant proportion of patients with a good response after pre-operative radiotherapy present a metastatic recurrence.

Digital Pathology and PD-L1 Testing in Non Small Cell Lung Cancer: A Workshop Record.

A meeting among expert pathologists was held in 2019 in Rome to verify the results of the previous harmonization efforts on the PD-L1 immunohistochemical testing by scoring a representative series of non-small cell lung cancer (NSCLC) digital slides. The current paper shows the results of this digital experimental meeting and the expertise achieved by the community of Italian pathologists. PD-L1 protein expression was determined using tumor proportion score (TPS), i.e., the percentage of viable tumor cells showing partial or complete membrane staining at any intensity. The gold standard was defined as the final PD-L1 score formulated by a panel of seven lung committed pathologists. PD-L1 status was clustered in three categories, namely negative (TPS < 1), low (TPS 1–49%), and high (TPS ≥ 50%). In 23 cases (71.9%) PD-L1 staining was performed using the companion diagnostic 22C3 pharmDx kit on Dako Autostainer, while in nine (28.1%) cases it was performed using the SP263 Ventana kit on BenchMark platform. A complete PD-L1 scoring agreement between the panel of experts and the participants was reached in 57.1% of cases, whereas a minor disagreement in 16.1% of cases was recorded. Italian pathologists performed best in strong positive cases (i.e., tumor proportion score TPS > 50%), whereas only 10.8% of disagreement with the gold standard was observed, and 55.6% regarded a single challenging case. The worst performance was achieved in the negative cases, with 32.0% disagreement. A significant difference resulted from the analysis of the data separated by the different clones used: 22.3% and 38.1% disagreement (p = 0.01) was found in the group of cases analyzed by 22C3 and SP263 antibody clones, respectively. In conclusion, this workshop record proposed the application of a digital pathology platform to share controversial cases in educational meetings as an alternative possibility for improving the interpretation and reporting of specific histological tools. Due to the crucial role of PD-L1 TPS for the selection of patients for immunotherapy, the identification of unconventional approaches as virtual slides to focus experiences and give more detailed practical verifications of the standard quality reached may be a considerable option.

Expression level of PD-L1 is involved in ALDH1A1-mediated poor prognosis in patients with head and neck squamous cell carcinoma

ObjectiveTo evaluate the expression levels of ALDH1A1, PDL1, and PDL2 in head and neck squamous cell carcinoma (HNSCC) patients, and explore their clinical relevance in prognosis of patients with HNSCC. MethodsImmunohistochemistry of ALDH1A1 and PD-L1/PD-L2 in 85 primary HNSCC patients was carried out. The expression level of PD-L2 was assessed with the modified Moratin’s immune response scoring (IRS) system. tumor proportion score (TPS) was defined as the percentage of viable tumor cells showing partial or complete membrane staining at any intensity. The chi-square test and Fisher’s exact test were used to analyze the associations between ALDH1A1 expression and clinicopathological features. The Spearman’s correlation was applied to analyze the correlation of ALDH1A1 expression with PD-L1/PD-L2 expression. Resultskaplan-Meier analysis showed that the expression levels of ALDH1A1 and PD-L1/PD-L2 were inversely associated with recurrence-free survival (RFS; P = 0.001, 0.014, and 0.023, respectively). Moreover, expression levels of ALDH1A1 and PD-L1 were correlated with poor overall survival (OS; P = 0.002 and 0.039, respectively). Furthermore, multivariate logistics regression analyses demonstrated that expression level of ALDH1A1 was independently associated with shorter RFS (P = 0.013) and poorer OS (P = 0.014) in HNSCC patients, and the expression level of PD-L2 was only negatively associated with RFS (P = 0.041), rather than PD-L1. Spearman’s correlation analysis unveiled that expression levels of PD-L1 and PD-L2 were positively correlated with ALDH1A1 expression in HNSCC patients (P = 0.000 and 0.015, respectively). Especially, the patients with expression levels of ALDH1A1 and PD-L1 had the worst prognosis. ConclusionsOur results indicated that ALDH1A1 is an independent prognostic factor in patients with HNSCC, and the expression level of PDL-1 may be involved in ALDH1A1-mediated poor prognosis in patients with HNSCC.

Impact of tumor regression grade on recurrence after preoperative chemoradiation and gastrectomy for gastric cancer.

It is unknown whether the degree of response to preoperative therapy correlates with locoregional recurrence (LR) or distant recurrence (DR) after resection of gastric cancer. Patients who underwent resection of gastric adenocarcinoma following chemotherapy and chemoradiation (1995-2015) were reviewed. The tumor regression grade (TRG) was defined by the percentage of viable tumor cells in the specimen (TRG0 = 0%; TRG1 = 1%-2%; TRG2 = 3%-50%; TRG3 ≥ 50%). The relationships among TRG, recurrence-free survival (RFS), LR, and DR were examined. Two hundred forty-seven patients met the inclusion criteria (TRG0, 52 [21%]; TRG1, 49 [20%]; TRG2, 98 [40%]; TRG3, 48 [19%]). LR and DR occurred in 6.1% and 32.0% of patients, respectively. No patient with TRG0 experienced LR. R1 resection (6%-15%) and LR (6%-8%) rates were similar among TRG1-3 patients. R1 resection was associated with LR (hazard ratio [HR], 17.85; P < .001). ypN status (HR, 2.44; P = .004) and linitis plastica (HR, 2.90; P < .001) were associated with DR. TRG was not independently associated with RFS, LR, or DR. TRG0 imparted excellent local control. However, TRG1-3 patients had similar R1 resection rates and therefore similar LR. DR is associated with ypN status and linitis plastica, not TRG.

PD-L1 expression landscape and its relationship with tumor mutation burden in Chinese cancer patients.

e15267 Background: Little is known about the pan-cancer PD-L1 expression landscape in Chinese patients although PD-L1 expression has been approved by FDA as a diagnosis for anti-PD-(L)1 therapy in several types of cancer. We did a cross-sectional analysis to assess the PD-L1 expression landscape in Chinese patients and its relationship with Tumor mutation burden (TMB). Methods: Tissue samples were collected from more than 8,000 consecutive cases in China between January, 2017, and August, 2019 and were analyzed by 3D Medicines, a College of American Pathologists (CAP)-accredited and Clinical Laboratory Improvement Amendments (CLIA)-certified laboratory. The method for NGS sequencing and tumor mutational burden (TMB) measurement were described previously. Clinical data and PD-L1 expression profiles were obtained from 8,063 patients whose tissue samples assed quality control. IHC staining for PD-L1 expression was performed using PD-L1 IHC 22C3 pharmDx assay (Dako North America, Carpentaria, CA, U.S.) or Ventana PD-L1 SP263 assay (Ventana Medical Systems, Tucson, AZ, U.S.). PD-L1 expression was determined using Tumor Proportion Score (TPS), the percentage of viable tumor cells stained. Results: PD-L1 expression was examined for 8,063 tissue samples collected from more than 18 different types of solid tumors. There were 4,866 (60%) male and 3,197 (40%) female patients. Their median age was 59 (IQR range, 50-66) years. Given the significance of different cut-points of PD-L1 expression in predicting clinical outcomes, expression levels of PD-L1 were arranged into the following intervals: &lt; 1%, 1%-5%, 5%-50% and ≥50% for each cancer type. Small cell lung cancer (SCLC) had the lowest and Squamous Carcinoma of Head and Neck (HNSC) had the highest levels of PD-L1 expression. Spearman correlation analysis indicated no correlation between PD-L1 and tumor mutational burden (TMB) for Chinese cancer patients (R = 0.1, P &lt; 0.01), which is in line with the previous reports that PD-L1 and TMB were two independent predictors in immunotherapy. Conclusions: The landscape of PD-L1 expression among Chinese cancer population in this study will further assist the utilization of PD-L1 as a predictive biomarker in clinical practice.

MS17.02 Major Pathological Evaluation in Neoadjuvant Immunotherapy

The pathologists play different roles in the care of cancer patients. The main part of this activity is to make the diagnosis of the tumor type, followed by the support to the clinicians in the staging of the patient. In the group of patients that receive Chemotherapy (CT) and / or Radiotherapy (RT) before surgery, the pathologist has to evaluate the results of these treatments by evaluating the tumor bed and the response of the lung. There is a lot of experience in the literature referred to the different types of pathological response to lung cancer treatment after the use of either CT or RT. There are guidelines for the pathologists in order to give an objective evaluation of the treatment results (1). All of them ask the pathologists to evaluate the percentage of viable tumor cells, necrosis and stromal reaction. We can also find different attempts to find molecular markers useful for predicting survival after these traditional treatments (2). In order to have an objective evaluation of the lung cancer patients after CT in 2014 emerged the concept of Major Pathological Response (MPR) as a possible predictor of overall survival (3). This term was applied to describe those patients with a viability of 10% of the tumor cells after neoadjuvant CT. In this report, they propose the MPR as a surrogate endpoint. Since that, the concept of MPR has been used in different reports and assays, becoming a usual parameter for patients with lung resections after receiving chemotherapy. The percentage of viable cells became an important data that has to be evaluated with accuracy in order to avoid subjective results. One of the best ways is to use any of the commercial systems to make measurements on the slides. In our department, we use digital slides to get objective and reproducible data for this type of evaluation. The recent implementation of immunotherapy (IT) for NSCLC that is being applied to an increasing number of patients all over the world makes it necessary to study deeply its morphological effects over de tumor in lung specimens. As most of the patients will never go to the operating room, it becomes important to be aware of the limited knowledge that we have so far. There are some reports comparing the effects of the traditional chemotherapy with immunotherapy. One of these studies shows that the pathologist should look for the same features that are routinely evaluated in the cases after CT (4). The pathologist might evaluate the classic features (viable cells, necrosis and stromal reaction) and other characteristics such as macrophages, cholesterol clefts, lymphoid aggregates, giant cells and neovascularization. In this review, they did not find important differences between the type of morphological changes in both types of treatment, so they propose to use the same parameters in CT and in IT A recent report proposes the concept of Immuno related Pathological Response Criteria (irPRC) (5). They pay attention to the Immune activation with dense lymphoid infiltrate, macrophages and tertiary lymphoid structures as the main characteristics. They also evaluate the massive tumor cell death with destructive features such as cholesterol clefts and those indicative of tissue repair with neovascularization and fibrosis. Last year a review collected different assays done with neoadjuvant IT in patients with resectable lung cancer (6). There is no enough experience in these special groups of patients, as today the IT is given only to advanced lung carcinoma patients. Conclusions: At the present time there are no guidelines for the evaluation of lung tissues after IT. The pathologists have to be aware of the effects of these new biological treatments for lung cancer patients, in order to give as much information as possible in the short number of cases that are seen in the real clinical situation. The previous experience in resected lungs after neoadjuvant therapy is not enough to evaluate the cases after IT. The data obtained from these lung specimens have to give more information in order to improve the knowledge of the effects of these new therapies.

Abstract 3419: Genomic characterization of mutation hotspots related to chemotherapy responses in esophageal squamous-cell carcinoma with archived formalin-fixed paraffin-embedded tissues

Abstract Introduction: Currently neoadjuvant chemoradiation therapy (CRT) prior to surgery is the most common treatment for Esophageal Squamous-cell Carcinoma (ESCC) patients. Given the fact that traditional TNM staging of the patients before treatment could not reflect their overall survival, a recent study conducted in Hong Kong demonstrated that the percentage of viable tumor cells remaining in the primary tumor after the CRT therapy was a prognostic marker for overall survival. Clinicians defined patients with no viable tumor cells (0%) as good responders, while the others having greater than 50% tumor cells remaining (50-100%) were considered poor responders. They observed that good responders show significantly better five-year survival rate. However, little is known about the mutation profiles between good and poor responders stratified in this way. Methods: Taking advantage of archived formalin-fixed paraffin-embedded (FFPE) tissues with comprehensive clinical outcomes, I apply a novel approach to systematically screen for possible somatic mutations that are associated with patients' responses to CRT in ESCC. I obtained 100 archived FFPE blocks from Queen Mary Hospital, Hong Kong, 50 each representing either good responders or poor responders. DNA libraries were constructed to target 131 cancer-related genes with TOMA Os-seq, which adopted single-stranded ligation to minimize the loss of input FFPE DNA. Then, libraries were sequenced on Illumina HiSeq X Ten. The final list of somatic mutations was filtered with in-house pipeline, excluding both germline variants from public databases and in-house Hong Kong database. Copy number variations (CNVs) were also identified with a pre-designed control sample in the same sequencing batch. Results: One test run on samples with good quality DNA showed high sensitivity and specificity up to 100% for pre-designed mutations. For CNV, the sensitivity was 87.5% and the specificity was 97.5%. Trials of sequencing with several ESCC FFPE samples revealed deleterious mutations from genes including TP53, BRCA2, and those mutations were successfully validated by Sanger sequencing. Groups of critical protein-altered mutations and CNVs that distinguish good and poor responders of ESCC will be presented in detail. Conclusion: In all, FFPE blocks are valuable sources to uncover the biomarkers for CRT response in ESCC. I expect those biomarkers can aid future evaluation of newly diagnostic patients to avoid unnecessary efforts in treating patients that are unsuitable for the traditional therapy and thus facilitate effective treatments. Acknowledgements: Theme-based Research Scheme grant provided by the Hong Kong Research Grants Council (T12-701/17-R to MLL). Citation Format: Chen Guo, Josephine Ko, Wei Dai, Lihua Tao, Simon Law, Anthony Wing Ip Lo, Maria Li Lung. Genomic characterization of mutation hotspots related to chemotherapy responses in esophageal squamous-cell carcinoma with archived formalin-fixed paraffin-embedded tissues [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 3419.

Investigation of PD-L1 expression and response to pembrolizumab (pembro) in gastric cancer (GC) and cervical cancer (CC) using combined positive score (CPS) and tumor proportion score (TPS).

4065Background: TPS, the percentage of viable tumor cells with partial or complete membrane staining at any intensity, has been invaluable for assessing PD-L1 expression in non–small cell lung canc...

48P Clinical characteristics of Korean lung cancer patients with programmed death-ligand 1 expression

Background: Programmed death-ligand 1 (PD-L1) is a transmembrane protein binds to the programmed death-1 (PD-1) receptor and anti-PD-1 therapy enables the immune response against tumors. The aim of this study was to assess the clinical and pathologic characteristics of PD-L1 positive lung cancer patients in Korea. Methods: We retrospectively reviewed the clinical data of pathologically proven lung cancer patients, and collected 267 cases of formalin-fixed, paraffin-embedded tissue sample from single institution. PD-L1 expression was detected by immunohistochemical assay using Monoclonal Mouse Anti-PD-L1, Clone 22C3. PD-L1 protein expression is determined by using Tumor Proportion Score (TPS), the percentage of viable tumor cells showing partial or complete membrane staining. The specimen should be considered PD-L1 positive as TPS ≥ 50% of tumor cells. We categorized according to the percentage of TPS; more than 1% or 50%. Results: A total of 267 patients were enrolled and major histologic types were adenocarcinoma (ADC)(69.3%). The majority was smoker (67.4%) and clinical stage IV (60.7%). 31 (11.6%) cases of EGFR mutation and 17 (6.4%) cases of ALK FISH positive were included. The patients who showed TPS ≥ 1% and 50% were 116 (42%) and 58 (21%), respectively. More than 1% of TPS group was older than below (64.83 ± 9.38 vs. 61.73 ± 10.78, p = 0.014). More than 1% of TPS group was consisted of ADC (67.8%) and squamous cell carcinoma (SqC) (29.6%) histology. And more than 50% of TPS group was composed of ADC (72.4%), SqC (22.4%). More than 1% of TPS group was significantly older than less (64.83 ± 9.38 years vs. 61.73 ± 10.78 years, p = 0.014). The rate of poorly differentiated pathology was significantly higher in TPS ≥ 1% group (42(40.8%) vs. 32(25.8%)) and TPS ≥ 50% group (25(53.2%) vs. 49 (27.2%)). There was no difference in smoking, EGFR mutation, ALK rearrangement status or biopsy site. Conclusions: In Korean lung cancer patients, PD-L1 positive group defined as TPS ≥ 1% was older than negative group. And major histology was poorly differentiated non-small cell lung cancer in both TPS ≥ 1% and 50% groups. Legal entity responsible for the study: Chonnam National University Hospital, Hwasun Funding: Has not received any funding Disclosure: The author has declared no conflicts of interest.

Checkpoint inhibitors assessment in oropharynx carcinoma (CIAO).

TPS118 Background: Oropharyngeal squamous cell carcinoma (OPSCC) is classified by HPV status. Patients with HPV negative OPSCC have worse prognosis when compared to HPV positive. The epidemic of HPV associated OPSCC emphasizes the need to improve outcomes and reduce treatment related toxicities in this patient population. Taken together, there is an unmet need for novel treatment approaches to improve survival and/or quality of life in patients with OPSCC. Checkpoint inhibitors, particularly anti-PD-1/PD-L1, have shown encouraging activity in metastatic head and neck SCC. Targeting both PD-1 and CTLA-4 pathways may have additive or synergistic activity. Durvalumab and tremelimumab are immune checkpoint inhibitors that target, respectively, PD-L1 and CTLA-4. The optimal integration of novel therapeutics into clinical practice requires a thorough understanding of the molecular effects of treatment that is best evaluated by longitudinal tumor sampling. Minimally invasive transoral robotic surgery (TORS) provides opportunities to leverage standard-of-care surgery to interrogate the tumor microenvironment after neoadjuvant treatment. Methods: This is a randomized, window of opportunity trial evaluating durvalumab single agent or combined with tremelimumab in OPSCC patients amenable to curative intent surgery. The primary objective is to quantify differences in CD8+ TILs between pre- and post-treatment surgical specimens in patients treated with durvalumab vs. durvalumab plus tremelimumab. Secondary objectives include assessing the safety and toxicity of durvalumab plus or minus tremelimumab in the preoperative setting; objective response rate by RECIST at 8 weeks; percentage of patients undergoing surgery at 8 weeks; percentage of viable tumor cells in the surgical specimen; and patient-reported outcomes. Pre- and post- treatment tumor and blood based immune biomarkers will be evaluated and correlated with HPV status, outcomes, and toxicity. Eligible patients must be ≥ 18 years old, have surgically resectable stage II-IVA newly diagnosed OPSCC or loco-regional recurrence from an OPSCC primary ≥ 6 months after completion of curative intent treatment, and have a performance status ECOG 0-1. Enrollment is ongoing. Clinical trial information: NCT03144778.

Abstract 4719: MYC expression correlates with PD-L1 expression and related poor clinical outcome in non-small cell lung cancer

Abstract Background: Programmed death-ligand 1 (PD-L1) is widely used biomarker for the response prediction of immune checkpoint inhibitors, but its usefulness has been challenged. MYC, a transcriptional factor which is overexpressed in various cancers, plays critical roles in preventing immune cells from attacking tumor cells by inducing PD-L1 expression. We evaluated that MYC expression is positively related that of PD-L1 in non-small cell lung cancer (NSCLC) clinical specimens and that it has potential as a predictor of response to immune checkpoint inhibitors in NSCLC. Methods: Eighty-four cases who were diagnosed as NSCLC and underwent surgical resection were evaluated by immunohistochemistry (IHC). PD-L1 expression was evaluated by FDA-approved PD-L1, 22C3 PharmDxTM protocol using the Dako Automated Link 48 platform at Clarient Diagnostic Services, Inc (Aliso Viejo, CA, USA). Its expression was determined by using Tumor Proportion Score (TPS), which is the percentage of viable tumor cells showing partial or complete membrane staining. If TPS &amp;gt;= 50% of the viable tumor cells exhibit membrane staining at any intensity, it was considered positive. IHC of MYC was performed using anti-c-MYC antibody [Y69] (ab32072, Abcam, USA) and its expression was evaluated by scoring system using product of nuclear staining intensity and percentage of positive cells. Results: When MYC cDNA was transfected into KRAS-dependent lung cancer cell lines that did not express both MYC and PD-L1, the protein expression and mRNA of PD-L1 were induced in a dose-dependent manner. On the other hands, knockdown of MYC with siRNA inhibited protein expression and mRNA indicating MYC regulates PD-L1 at transcriptional level. Of 84 NSCLC tumor tissues, PD-L1 was expressed in 14 (16.7%) and MYC in 30 (35.7%) cases. Dual positive patients were 9 (10.7%) and dual negative patients were 49 (58.3%). When the relationship between PD-L1 and MYC expression was evaluated, significant positive correlation was observed between PD-L1 and MYC expression (γ=0.267, P=0.014). Dual positive patients showed significantly shorter disease free survival (16.1 vs. 62.5 months, P=0.004) and overall survival (24.9 vs. 70.9 months, P=0.002) than dual negative patients. Conclusion: MYC expression correlates with PD-L1 expression in the NSCLC and the patients with overexpression of both MYC and PD-L1 showed significantly poor survival. This suggest that it is worth of investigation of MYC expression as a surrogate predictive marker for treatment of immune checkpoint inhibitors in NSCLC. Citation Format: Eun Young Kim, Arum Kim, Se Kyu Kim, Yoon Soo Chang. MYC expression correlates with PD-L1 expression and related poor clinical outcome in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4719. doi:10.1158/1538-7445.AM2017-4719