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A. Husain
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MINI 38 - Biology and Prognosis (ID 167)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Thymoma, Mesothelioma and Other Thoracic Malignancies
- Presentations: 2
- Moderators:R. Tsuchiya, M. Wynes
- Coordinates: 9/09/2015, 18:30 - 20:00, 702+704+706
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MINI38.11 - Tumor Volume and Epithelioid Differentiation Are Independent Predictors of Survival in Malignant Pleural Mesothelioma (ID 2428)
18:30 - 20:00 | Author(s): A. Husain
- Abstract
- Presentation
Background:
Maximal cyto-reductive surgery with adjuvant therapy provides survival advantage in selected patients with malignant pleural mesothelioma (MPM). Extended pleurectomy and decortication (EPD), a lung sparing procedure, provides an opportunity to measure the tumor volume. We hypothesized that tumor volume is a better predictor of survival than the T and N, because it represents tumor burden more accurately. Currently the significance of epithelioid differentiation in the biphasic histology also remains poorly understood. We report our experience with patients undergoing EPD and the implication of tumor volume and epithelioid differentiation in overall survival.
Methods:
We evaluated 116 patients who underwent EPD for MPM. The following variables were assessed: age, gender, histology, tumor volume and pathological T and N stage. The tumor volume of resected specimens was measured using a water displacement method. All histological examinations were performed by a single pathologist, and the percent epithelioid histology was estimated in all patients. A Cox regression model was used to identify significant predictors of survival. Kaplan-Meier was used to summarize overall and subgroup survival.
Results:
There were 95 males and 21 females with a median age of 68 years (range 43-88 years). Epithelioid differentiation was 100% in 60 patients, 50-95% in 35 patients, and less than 50% in 21 patients (no patient with pure sarcomatoid histology was included in this report). Mean tumor volume was 642+/- 400ml. Tumor volume was between 100-299cc in 20 patients, between 300-599cc in 37 patients, and >600cc in 54 patients. In 5 patients the volume was not estimated. Six patients (5%) died within 30 days. Two-year survival from EPD was 28%. Median survival was 15.7 months. Percent epithelioid differentiation (p=0.0004) and tumor volume (p=0.001) were significant predictors of survival. T (p=0.05) stage, but not N stage, was a significant predictor of survival. Tumor volume was a predictor of T stage (p=0.05). No relationship between N stage and either tumor volume or histology was observed.
Conclusion:
Percent epithelioid differentiation and tumor volume are independent predictors of survival in MPM patients undergoing EPD.
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MINI38.12 - Multiplex Immunofluorescence Identifies Differences in Immune Microenvironment & Prognostic Biomarkers between Mesothelioma Subtypes (ID 3217)
18:30 - 20:00 | Author(s): A. Husain
- Abstract
- Presentation
Background:
Malignant mesothelioma (MM) is a universally lethal disease, which develops in the pleura, peritoneum, pericardium, and tunica vaginalis. MM is commonly associated with a prominent inflammatory reaction, including extensive macrophage infiltration. Early reports indicate presence of tumor infiltrating lymphocytes (TILs), PD-L1 expression (Kindler et al ASCO 2014), and activity of anti-PD-1 therapy (Alley et al AACR 2015). However, quantitative evaluation of multiple immune markers in a large mesothelioma cohort and evaluation of prognostic and biologic implications has not been reported.
Methods:
We performed multiplex immunofluorescence (IF) staining and automated, quantitative density assessments in a clinically annotated cohort of 109 malignant mesotheliomas (58 epithelioid, 43 biphasic, 8 sarcomatoid). Staining for PD-1, PD-L1 (immune checkpoint), FOXP3 (T-regulatory cells), and CD8 (TILs) was performed using a quantitative, multiplex IF system (TissueFax), and a multi-tumor-validated, quantitative StrataQuest analysis algorithm in order to identify specific immune cells and respective densities. Gene expression data (TCGA) was analyzed to confirm individual correlations. Staining for CD206 (macrophages) is ongoing.
Results:
PD-L1 density correlated with more aggressive histology, and was highest in sarcomatoid (median density score of 3016), and biphasic (2720) tumors compared with epithelioid tumors (1740). Using a cutoff of 5% PD-L1 density by area 19% of epithelioid, 38% of sarcomatoid, and 44% of biphasic tumors were deemed PD-L1 positive. PD-L1 expression exhibited a bimodal distribution (peaks at both high and low PD-L1 densities). Also with the biphasic tumor cohort expression of PD-L1 correlated with worse outcome (P=0.02), while PD-1 and CD8 did not have prognostic implications (and could not distinguish histologic subtypes). By contrast in epithelioid MM CD8 infiltration density showed a trend towards improved prognosis (P=0.06) (and correlated with PD-1 expression), while PD-L1 expression was not prognostic. Interestingly, PD-1/CD8 and PD-L1 expression did not correlate regardless of histology (R=0.02-0.08), suggesting macrophage-driven PD-L1 expression. Gene expression data supported this hypothesis and staining for M2-related macrophage markers is ongoing. In epithelioid tumors FOXP3 T-regulatory cell density showed a trend towards worse prognosis (P=0.07). In biphasic and sarcomatoid tumors prognosis was poor regardless of FOXP3 expression. Data on stromal versus tumor expression patterns is being processed.
Conclusion:
In mesothelioma CD8, PD-1, PD-L1 and FOXP3 are widely expressed, with 19% of epithelioid, and 38-44% of sarcomatoid and biphasic tumors showing elevated PD-L1 density. PD-L1 expression correlates with a worse prognosis by subtype and in the biphasic tumor population. In epithelioid tumors PD-1 may indicate better outcome. PD-1 and PD-L1 expression do not correlate with each other in malignant mesothelioma, which relates to pro-tumorigenic macrophages leading to potentially interferon gamma independent PD-L1 expression.
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P1.04 - Poster Session/ Biology, Pathology, and Molecular Testing (ID 233)
- Event: WCLC 2015
- Type: Poster
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 2
- Moderators:
- Coordinates: 9/07/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P1.04-001 - MET/RON Inhibition in KRAS Mutated Non Small Cell Lung Cancer (ID 2174)
09:30 - 17:00 | Author(s): A. Husain
- Abstract
Background:
Molecular genetics have allowed us to categorize non-small cell lung cancer (NSCLC) based on their genetic profile. KRAS mutations occur in 25-30% of NSCLCs. KRAS regulates cellular function in response to growth factors and their receptors. When mutated, KRAS is constitutively active and is responsible for driving tumor oncogenesis. Direct inhibition of KRAS has not been a successful clinical strategy. The strategy of synthetic lethality (targeting a non-lethal defect in cancer cells combined with a second defect, that together make the cancer cell more susceptible to treatment) has gained traction in recent years. Several synthetic lethal targets have been identified with KRAS. We have previously shown that MET plays an important role in the oncogenic addiction observed in KRAS mutated NSCLC and contributes to both tumor growth and metastasis. However, the development of resistance in MET targeting due to upregulation of RON, a related receptor tyrosine kinase, is also evident. Our hypothesis is that dual targeting of MET and RON may be synthetic lethal to KRAS mutated NSCLC and studies to investigate this as a potential therapeutic strategy are warranted.
Methods:
MET- and RON-specific siRNAs (small molecule inhibitors), crizotinib, and the ligand for MET (hepatocyte growth factor), were used in in vitro assays. Immunoblotting, cell viability, and cell migration assays were carried out in a panel of KRAS mutated as well as KRAS wild type NSCLC cells. In addition, human bronchial epithelial cells (HBECs) that were rendered tumorigenic with sequential mutations in CDk4, hTERT, p53, and KRAS genes were also used.
Results:
Our analysis of a panel of NSCLC cells showed that most KRAS mutant cell lines express both MET and RON, and stimulation with HGF activated KRAS effector pathways such as MAPK, AKT and S6RP. When we silenced MET expression with siRNA, it led to upregulation of RON, indicating the interaction between MET and RON. Cell viability assays using crizotinib showed that KRAS mutant cell lines (A549 and H460) are three-fold more sensitive than KRAS wild type cells (H1975 and H1437), and cells with MET amplification (H1993) showed the highest response. Preliminary data with the KRAS-transformed HBECs also showed that they are more sensitive to crizotinib inhibition than the non-transformed control HBECs. Wound healing assays with these same cells showed a similar trend in MET specific inhibition of cell migration in KRAS-mutated cells compared to wild type cells.
Conclusion:
These data highlight the potential therapeutic benefit of targeting MET and RON simultaneously in a subpopulation of KRAS mutated NSCLC patients who may have MET overexpression or amplification. Based on KRAS oncogenic addiction to MET, we propose that NSCLC cells that are MET amplified and KRAS mutated are potentially synthetic lethal and will benefit from dual MET/RON treatment
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P1.04-012 - Using Computed Tomography Scans to Assess the Histology of Malignant Pleural Mesothelioma (ID 3003)
09:30 - 17:00 | Author(s): A. Husain
- Abstract
Background:
The purpose of this study is to assess the histology of malignant pleural mesothelioma using computed tomography (CT) based imaging.
Methods:
28 patients with malignant pleural mesothelioma were used (histologies: 17 epithelioid, 11 biphasic). A CT scan was acquired for each patient prior to surgical resection of the tumor. A radiologist identified and outlined the tumor boundary on each CT section that demonstrated tumor. These outlines were analyzed to determine the total volume of disease present, the mean volume of disease per outlined section, and the distribution of Hounsfield Unit (HU) values throughout the outlined tumor. These parameters were used to differentiate tumors of epithelioid and biphasic histologies. For each parameter, cutoffs were determined to maximize the extraction of biphasic cases from the entire cohort, while minimizing the extraction of epithelioid cases.
Results:
Discernable differences were extracted from the images of the two different histologies of the disease. Figure 1 shows the mean HU value, the standard deviation and skew in the distribution in the HU values, and the volume of tumor represented on each CT section demonstrating disease. With regard to HU distribution, the biphasic cases generally had a higher mean HU value. For example, 73% of the biphasic cases had a mean value greater than 30, compared to only 29% of the epithelioid cases. Biphasic cases also tend to have a more negative skew in their HU distribution; 73% of biphasic cases had a skew value less than -1, compared to 35% of epithelioid cases. It was also seen that biphasic cases also tended to have a higher volume of tumor present throughout their disease presenting CT sections. There were promising results from extracting the biphasic cases by using optimized cutoffs from gathered data. The criteria used were as follows: Cases that exhibited more than 9 mL of tumor per outlined CT section, or exhibited a mean HU value greater than 10 as well as a skew in HU values less than -1 were extracted from the cohort and identified as biphasic. Of the cases that match these criteria, 10 were actually biphasic while 6 were actually epithelioid. These results are 91% specific, missing only one biphasic case, and 65% specific, correctly excluding 11 of the 17 epithelioid cases. Figure 1 Figure 1 – Comparison of Epithlioid and Biphasic cell types.
Conclusion:
This study demonstrates that CT-based imaging may be a useful tool for the assessment of tumor histology through image analysis.
