Angiogenesis and non-small cell lung cancer

Lung cancer is the commonest cause of cancer death in the western world. Recent evidence suggests that angiogenesis is related to poor prognosis in many solid tumours including non-small cell lung cancer. Angiogenesis is controlled by a complex interaction between growth and apoptotic factors, proteases and adhesion molecules. The angiogenic process may prove a target for novel therapies such as matrix metalloproteinase inhibitors, growth factor antisense RNA, growth factor receptor antagonists and naturally occurring antiangiogenic peptides. These agents may be used alone or in combination with traditional chemotherapy, radiotherapy and surgery. (C) 2000 Elsevier Science Ireland Ltd.

Herceptest: HER2 expression and gene amplification in non-small cell lung cancer

HER2 is an erbB/HER type I tyrosine kinase receptor that is frequently over-expressed in malignant epithelial tumours. Herceptin, a humanised mouse monoclonal antibody to HER2, is proven therapeutically in the management of metastatic breast cancer, significantly prolonging survival when combined with cytotoxic chemotherapeutic agents. Immunohistochemical studies suggest that non-small-cell lung cancer (NSCLC) tumours may over-express HER2. Our aim was to evaluate HER2 gene amplification and semi-quantitative immuno-expression in NSCLC. A total of 344 NSCLC cases were immunostained for HER2 expression in 2 centres using the HercepTest. Fluorescence in situ hybridisation (FISH) analysis for HER2 gene amplification was performed on most positive cases and a subset of negative cases. Fifteen cases (4.3%) demonstrated 2+ or 3+ membranous HER2 immuno-expression. There was no correlation between immuno-expression and tumour histology or grade. Tumours from higher-stage disease were more often HercepTest-positive (p < 0.001). All 4 HercepTest 3 + cases demonstrated gene amplification. One of the 5 2+ cases tested for gene amplification showed areas of borderline amplification and areas of polyploidy. None of the 19 HercepTest-negative cases demonstrated gene amplification or polyploidy (p < 0.001). Gene amplification was demonstrated in all HercepTest 3+ scoring NSCLC cases. Unlike breast cancer, gene amplification and HER2 protein over-expression assessed by the HercepTest appeared to be uncommon in NSCLC. Herceptin may therefore target only a small proportion of NSCLC tumours and be of limited clinical value in this disease, particularly in the adjuvant setting. © 2001 Wiley-Liss, Inc.

Prognostic significance of platelet and microvessel counts in operable non-small cell lung cancer

Background: Microvessel density, an indirect measure of angiogenesis, has been shown to be an independent prognostic marker in many solid tumours including non-small cell lung cancer (NSCLC). Platelets transport and release angiogenic growth factors. Platelets are increasingly likely to adhere to tumour microvessels due to raised expression of platelet-binding proteins and stasis in blood-flow. Increased vascular permeability in tumour microvessels facilitates platelet extravasation into the extracellular matrix. Adherence and extravasation both lead to platelet activation and release of growth factors capable of instigating the angiogenic process. Methods: A total of 181 patients were identified who underwent resection of stage I-IIIa NSCLC with a post-operative survival >60 days. Patients were followed-up for a minimum of 24 months. Sections from the tumour periphery were stained for the endothelial marker CD34 (Novocastra NCL-END) using standard ABC immunohistochemistry. Chalkley counting was used to assess microvessel density. Results: A pre-operative platelet count greater than the median and above the normal range (>400) was associated with a poor outcome (P = 0.01 and P = 0.04, respectively). Tumours with an above median and high Chalkley count (upper tertile) had a worse prognosis (P = 0.007 and P = 0.0006, respectively). There was no association between platelet count and Chalkley count. Conclusions: Platelet and microvessel counts are both potential prognostic markers for NSCLC. The role of platelets in the angiogenic process needs to be further investigated. (C) 2000 Elsevier Science Ireland Ltd.

First-cycle rash and survival in patients with advanced non-small-cell lung cancer receiving cetuximab in combination with first-line chemotherapy : a subgroup analysis of data from the FLEX phase 3 study

Background: The randomised phase 3 First-Line Erbitux in Lung Cancer (FLEX) study showed that the addition of cetuximab to cisplatin and vinorelbine significantly improved overall survival compared with chemotherapy alone in the first-line treatment of advanced non-small-cell lung cancer (NSCLC). The main cetuximab-related side-effect was acne-like rash. Here, we assessed the association of this acne-like rash with clinical benefit. Methods: We did a subgroup analysis of patients in the FLEX study, which enrolled patients with advanced NSCLC whose tumours expressed epidermal growth factor receptor. Our landmark analysis assessed if the development of acne-like rash in the first 21 days of treatment (first-cycle rash) was associated with clinical outcome, on the basis of patients in the intention-to-treat population alive on day 21. The FLEX study is registered with ClinicalTrials.gov, number NCT00148798. Findings: 518 patients in the chemotherapy plus cetuximab group-290 of whom had first-cycle rash-and 540 patients in the chemotherapy alone group were alive on day 21. Patients in the chemotherapy plus cetuximab group with first-cycle rash had significantly prolonged overall survival compared with patients in the same treatment group without first-cycle rash (median 15·0 months [95% CI 12·8-16·4] vs 8·8 months [7·6-11·1]; hazard ratio [HR] 0·631 [0·515-0·774]; p<0·0001). Corresponding significant associations were also noted for progression-free survival (median 5·4 months [5·2-5·7] vs 4·3 months [4·1-5·3]; HR 0·741 [0·607-0·905]; p=0·0031) and response (rate 44·8% [39·0-50·8] vs 32·0% [26·0-38·5]; odds ratio 1·703 [1·186-2·448]; p=0·0039). Overall survival for patients without first-cycle rash was similar to that of patients that received chemotherapy alone (median 8·8 months [7·6-11·1] vs 10·3 months [9·6-11·3]; HR 1·085 [0·910-1·293]; p=0·36). The significant overall survival benefit for patients with first-cycle rash versus without was seen in all histology subgroups: adenocarcinoma (median 16·9 months, [14·1-20·6] vs 9·3 months [7·7-13·2]; HR 0·614 [0·453-0·832]; p=0·0015), squamous-cell carcinoma (median 13·2 months [10·6-16·0] vs 8·1 months [6·7-12·6]; HR 0·659 [0·472-0·921]; p=0·014), and carcinomas of other histology (median 12·6 months [9·2-16·4] vs 6·9 months [5·2-11·0]; HR 0·616 [0·392-0·966]; p=0·033). Interpretation: First-cycle rash was associated with a better outcome in patients with advanced NSCLC who received cisplatin and vinorelbine plus cetuximab as a first-line treatment. First-cycle rash might be a surrogate clinical marker that could be used to tailor cetuximab treatment for advanced NSCLC to those patients who would be most likely to derive a significant benefit. Funding: Merck KGaA. © 2011 Elsevier Ltd.

Prognostic value of angiogenesis in operable non-small cell lung cancer

Tumour angiogenesis is an important factor for tumour growth and metastasis. Although some recent reports suggest that microvessel counts in non-small cell lung cancer are related to a poor disease outcome, the results were not conclusive and were not compared with other molecular prognostic markers. In the present study, the vascular grade was assessed in 107 (T1,2-N0,1) operable non-small cell lung carcinomas, using the JC70 monoclonal antibody to CD31. Three vascular grades were defined with appraisal by eye and by Chalkley counting: high (Chalkley score 7-12), medium (5-6), and low (2-4). There was a significant correlation between eye appraisal and Chalkley counting (P < 0.0001). Vascular grade was not related to histology, grade, proliferation index (Ki67), or EGFR or p53 expression. Tumours from younger patients had a higher grade of angiogenesis (P = 0.05). Apart from the vascular grade, none of the other factors examined was statistically related to lymph node metastasis (P < 0.0001). A univariate analysis of survival showed that vascular grade was the most significant prognostic factor (P = 0.0004), followed by N-stage (P = 0.001). In a multivariate analysis, N-stage and vascular grade were not found to be independent prognostic factors, since they were strongly related to each other. Excluding N-stage, vascular grade was the only independent prognostic factor (P = 0.007). Kaplan-Meier survival curves showed a statistically significant worse prognosis for patients with high vascular grade, but no difference was observed between low and medium vascular grade. These data suggest that angiogenesis in operable non-small cell lung cancer is a major prognostic factor for survival and, among the parameters tested, is the only factor related to cancer cell migration to lymph nodes. The integration of vascular grading in clinical trials on adjuvant chemotherapy and/or radiotherapy could substantially contribute in defining groups of operable patients who might benefit from cytotoxic treatment.

Invading edge vs. inner (edvin) patterns of vascularization : an interplay between angiogenic and vascular survival factors defines the clinical behaviour of non-small cell lung cancer

Neo-angiogenesis during neoplastic growth involves endothelial mitogenic and migration stimuli produced by cancer or tumour stromal cells. Although this active angiogenesis takes place in the tumour periphery, the process of vessel growth and survival in inner areas and its clinical role remain largely unexplored. The present study compared the microvessel score (MS) as well as the single endothelial cell score (ECS) in the invading edge and in inner areas of non-small cell lung carcinomas (NSCLCs). Three different patterns of vascular growth were distinguished: the edvin (edge vs. inner) type 1, where a low MS was observed in both peripheral and inner tumour areas; the edvin type 2, where a high MS was noted in the invading front but a low MS in inner areas; and the edvin type 3, where both peripheral and inner tumour areas had a high MS. The ECS was high in the invading edge in edvin type 2 and 3 cases and was sharply decreased in both types in inner areas, suggesting that endothelial cell migration is unlikely to contribute to the angiogenic process in areas away from the tumour front. Expression of the vascular endothelial growth factor (VEGF) and of thymidine phosphorylase (TP) was associated with a high MS in the invading edge. VEGF was associated with a high MS in inner areas (edvin 3), while TP expression was associated with edvin type 2, showing that VEGF (and not TP) contributes to the preservation of the inner vasculature. Both edvin type 2 and 3 cases showed an increased incidence of node metastasis, but edvin type 3 cases had a poorer prognosis, even in the N1-stage group. The present study suggests that tumour factors regulating angiogenesis and vascular survival are not identical. A possible method is reported to quantify these two parameters by comparing the MS in the invading edge and inner areas (edvin types). This observation may contribute to the evaluation of the effectiveness of different therapeutic approaches, namely vascular targeting vs. anti-angiogenesis. Copyright (C) 2000 John Wiley and Sons, Ltd.

Regulation of EP receptors in non-small cell lung cancer by epigenetic modifications

Background: Cyclooxygenase (COX)-2 is frequently overexpressed in non-small cell lung cancer (NSCLC) and results in increased levels of prostaglandin E2 (PGE 2), an important signalling molecule implicated in tumourigenesis. PGE 2 exerts its effects through the E prostanoid (EP) receptors (EPs1-4). Methods: The expression and epigenetic regulation of the EPs were evaluated in a series of resected fresh frozen NSCLC tumours and cell lines. Results: EP expression was dysregulated in NSCLC being up and downregulated compared to matched control samples. For EPs1, 3 and 4 no discernible pattern emerged. EP2 mRNA however was frequently downregulated, with low levels being observed in 13/20 samples as compared to upregulation in 5/20 samples examined. In NSCLC cell lines DNA CpG methylation was found to be important for the regulation of EP3 expression, the demethylating agent decitabine upregulating expression. Histone acetylation was also found to be a critical regulator of EP expression, with the histone deacteylase inhibitors trichostatin A, phenylbutyrate and suberoylanilide hydroxamic acid inducing increased expression of EPs2-4. Direct chromatin remodelling was demonstrated at the promoters for EPs2-4. Conclusions: These results indicate that EP expression is variably altered from tumour to tumour in NSCLC. EP2 expression appears to be predominantly downregulated and may have an important role in the pathogenesis of the disease. Epigenetic regulation of the EPs may be central to the precise role COX-2 may play in the evolution of individual tumours. © 2009 Elsevier Ltd. All rights reserved.

Transcriptional regulation of IRS5/DOK4 expression in non-small-cell lung cancer cells

The insulin-receptor substrate family plays important roles in cellular growth, signaling, and survival. Two new members of this family have recently been isolated: IRS5/Dok4 and IRS6/Dok5. This study examines the expression of IRS5/DOK4 in a panel of lung cancer cell lines and tumor specimens. The results demonstrate that expression of IRS5/DOK4 is frequently altered with both elevated and decreased expression in non-small-cell lung cancer (NSCLC) tumor specimens. The altered expression of IRS5/DOK4 observed in tumor samples is not due to aberrant methylation. In vitro cell culture studies demonstrate that treatment of NSCLC cell lines with the histone deacetylase inhibitor trichostatin A (TSA) upregulates IRS5/DOK4. This finding indicates that expression is regulated epigenetically at the level of chromatin remodeling. Chromatin immunoprecipitation experiments confirm that the IRS5/DOK4 promoter has enhanced histone hyperacetylation following treatments with TSA. Finally, hypoxia was demonstrated to downregulate IRS5/DOK4 expression. This expression was restored by TSA. The clinical relevance of altered IRS5/DOK4 expression in NSCLC requires fur ther evaluation.

bcl-2 and c-erbB-2 proteins are involved in the regulation of VEGF and of thymidine phosphorylase angiogenic activity in non-small-cell lung cancer

Tumour angiogenesis has been recently recognised as one of the most important prognostic factors in lung cancer. Although a variety of angiogenic factors have been identified, the angiogenesis process remains poorly understood. Bcl-2, c-erbB-2 and p53 are well-known oncogenes involved in non- small-cell lung cancer pathogenesis. A direct correlation of thymidine phosphorylase (TP) and of vascular endothelial growth factor (VEGF) with intratumoural angiogenesis has been reported. In the present study we investigated the possible regulatory role if bcl-2, c-erB-2 proteins in angiogenesis and in VEGF and TP expression in non-small-cell lung cancer. Two hundred sixteen specimens from T1,2-NO, 1 staged patients treated with surgery alone were immunohistochemically examined. Bcl-2 and c-erbB-2 were significantly inversely related to each other (P = 0.04) and both were inversely associated with microvessel density (P < 0.02). High TP and VEGF reactivity was statistically related to loss of bcl-2 expression (P < 0.01). A significant co-expression of c-erbB-2 with TP was noted (P = 0.01). However, TP expression was related to high angiogenesis only in cases with absence of c-erB-2 expression (P < 0.0001). c-erbB-2 expression in poorly vascularised tumours was linked with poor outcome (P = 0.03). The present study provides strong evidence that the bcl-2 gene has a suppressive function over genes involved in both angiogenesis (VEGF and TP) and cell migration (c- erbB-2) in NSCLC. TP and c-erbB-2 proteins are significantly, and often simultaneously, expressed in bcl-2 negative cases. However, expression of the c-erbB-2 abolishes the TP-related angiogenic activity. Whether this is a result of a direct activity of the c-erbB-2 protein or a consequence of a c- erbB-2-related immune response remains to be further investigated.

Potential role of bcl-2 as a suppressor of tumour angiogenesis in non- small-cell lung cancer

It has been reported that genes regulating apoptosis may play a role in tumoral angiogenesis. This study examined the relationship between tumour vascularization, a measure of tumour angiogenesis, and bcl-2 and p53 expression in operable non-small-cell lung cancer (NSCLC). The relationship between bcl-2, p53 and tumour vascularization and epidermal-growth-factor- receptor(EGFR) and c-erbB-2 expression was also studied. Tissue sections from resected tumour specimens of 107 NSCLC patients were evaluated immunohistochemically for vascular grade and bcl-2, p53, EGFR and c-erbB-2 expression. bcl-2 expression was found in 20/107 (19%) cases and was associated with squamous-cell histology (p = 0.03). A strong inverse relationship was found between bcl-2 expression and vascular grade (p = 0.005). All c-erbB-2-positive cases were negative for bcl-2 expression (p = 0.01). Overall no association was found between c-erbB-2 expression and vascular grade. However, in bcl-2-negative cases positive c-erbB-2 expression correlated with low angiogenesis (p = 0.05). No relationship was found between p53 and EGFR expression and bcl-2, c-erbB-2 or vascular grade. The improved prognosis reported in bcl-2-positive NSCLC may be related to low tumour vascularization. The results suggest that the anti-apoptotic gene bcl- 2 plays a role in regulating tumour angiogenesis. Since normal lung epithelium expresses bcl-2, a sequence of tumour progression involving loss of bcl-2, then activation of c-erbB-2 or increase in tumour vascularization is proposed.

Phase III trial comparing paclitaxel poliglumex (CT-2103, PPX) in combination with carboplatin versus standard paclitaxel and carboplatin in the treatment of PS 2 patients with chemotherapy-naïve advanced non-small cell lung cancer

INTRODUCTION: Performance status (PS) 2 patients with non-small cell lung cancer (NSCLC) experience more toxicity, lower response rates, and shorter survival times than healthier patients treated with standard chemotherapy. Paclitaxel poliglumex (PPX), a macromolecule drug conjugate of paclitaxel and polyglutamic acid, reduces systemic exposure to peak concentrations of free paclitaxel and may lead to increased concentrations in tumors due to enhanced vascular permeability. METHODS: Chemotherapy-naive PS 2 patients with advanced NSCLC were randomized to receive carboplatin (area under the curve = 6) and either PPX (210 mg/m/10 min without routine steroid premedication) or paclitaxel (225 mg/m/3 h with standard premedication) every 3 weeks. The primary end point was overall survival. RESULTS: A total of 400 patients were enrolled. Alopecia, arthralgias/myalgias, and cardiac events were significantly less frequent with PPX/carboplatin, whereas grade ≥3 neutropenia and grade 3 neuropathy showed a trend of worsening. There was no significant difference in the incidence of hypersensitivity reactions despite the absence of routine premedication in the PPX arm. Overall survival was similar between treatment arms (hazard ratio, 0.97; log rank p = 0.769). Median and 1-year survival rates were 7.9 months and 31%, for PPX versus 8 months and 31% for paclitaxel. Disease control rates were 64% and 69% for PPX and paclitaxel, respectively. Time to progression was similar: 3.9 months for PPX/carboplatin versus 4.6 months for paclitaxel/carboplatin (p = 0.210). CONCLUSION: PPX/carboplatin failed to provide superior survival compared with paclitaxel/carboplatin in the first-line treatment of PS 2 patients with NSCLC, but the results with respect to progression-free survival and overall survival were comparable and the PPX regimen was more convenient. © 2008International Association for the Study of Lung Cancer.

An evaluation of tumor oxygenation and gene expression in patients with early stage non-small cell lung cancers

Background: To directly assess tumor oxygenation in resectable non - small cell lung cancers (NSCLC) and to correlate tumor pO2 and the selected gene and protein expression to treatment outcomes. Methods: Twenty patients with resectable NSCLC were enrolled. Intraoperative measurements of normal lung and tumor pO2 were done with the Eppendorf polarographic electrode. All patients had plasma osteopontin measurements by ELISA. Carbonic anhydrase-IX (CA IX) staining of tumor sections was done in the majority of patients (n = 16), as was gene expression profiling (n = 12) using cDNA microarrays. Tumor pO2 was correlated with CA IX staining, osteopontin levels, and treatment outcomes. Results: The median tumor pO2 ranged from 0.7 to 46 mm Hg (median, 16.6) and was lower than normal lung pO2 in all but one patient. Because both variables were affected by the completeness of lung deflation during measurement, we used the ratio of tumor/normal lung (T/L) pO2 as a reflection of tumor oxygenation. The median T/L pO 2 was 0.13. T/L pO2 correlated significantly with plasma osteopontin levels (r = 0.53, P = 0.02) and CA IX expression (P = 0.006). Gene expression profiling showed that high CD44 expression was a predictor for relapse, which was confirmed by tissue staining of CD44 variant 6 protein. Other variables associated with the risk of relapse were T stage (P = 0.02), T/L pO2 (P = 0.04), and osteopontin levels (P = 0.001). Conclusions: Tumor hypoxia exists in resectable NSCLC and is associated with elevated expression of osteopontin and CA IX. Tumor hypoxia and elevated osteopontin levels and CD44 expression correlated with poor prognosis. A larger study is needed to confirm the prognostic significance of these factors. © 2006 American Association for Cancer Research.

Single-agent versus combination chemotherapy in patients with advanced non-small cell lung cancer and a performance status of 2 : prognostic factors and treatment selection based on two large randomized clinical trials

Purpose: Data from two randomized phase III trials were analyzed to evaluate prognostic factors and treatment selection in the first-line management of advanced non-small cell lung cancer patients with performance status (PS) 2. Patients and Methods: Patients randomized to combination chemotherapy (carboplatin and paclitaxel) in one trial and single-agent therapy (gemcitabine or vinorelbine) in the second were included in these analyses. Both studies had identical eligibility criteria and were conducted simultaneously. Comparison of efficacy and safety was performed between the two cohorts. A regression analysis identified prognostic factors and subgroups of patients that may benefit from combination or single-agent therapy. Results: Two hundred one patients were treated with combination and 190 with single-agent therapy. Objective responses were 37 and 15%, respectively. Median time to progression was 4.6 months in the combination arm and 3.5 months in the single-agent arm (p < 0.001). Median survival imes were 8.0 and 6.6 months, and 1-year survival rates were 31 and 26%, respectively. Albumin <3.5 g, extrathoracic metastases, lactate dehydrogenase ≥200 IU, and 2 comorbid conditions predicted outcome. Patients with 0-2 risk factors had similar outcomes independent of treatment, whereas patients with 3-4 factors had a nonsignificant improvement in median survival with combination chemotherapy. Conclusion: Our results show that PS2 non-small cell lung cancer patients are a heterogeneous group who have significantly different outcomes. Patients treated with first-line combination chemotherapy had a higher response and longer time to progression, whereas overall survival did not appear significantly different. A prognostic model may be helpful in selecting PS 2 patients for either treatment strategy. © 2009 by the International Association for the Study of Lung Cancer.

The beneficial effects of specialist thoracic surgery on the resection rate for non-small-cell lung cancer

We aimed to evaluate the effect of the appointment of a dedicated specialist thoracic surgeon on surgical practice for lung cancer previously served by cardio-thoracic surgeons. Outcomes were compared for the 240 patients undergoing surgical resection for lung cancer in two distinct 3-year periods: Group A: 65 patients, 1994-1996 (pre-specialist); Group B: 175 patients, 1997-1999 (post-specialist). The changes implemented resulted in a significant increase in resection rate (from 12.2 to 23.4%, P<0.001), operations in the elderly (over 75 years) and extended resections. There were no significant differences in stage distribution, in-hospital mortality or stage-specific survival after surgery. Lung cancer surgery provided by specialists within a multidisciplinary team resulted in increased surgical resection rates without compromising outcome. Our results strengthen the case for disease-specific specialists in the treatment of lung cancer. © 2004 Published by Elsevier Ireland Ltd.

Thymidylate synthase expression and outcome of patients receiving pemetrexed for advanced nonsquamous non-small-cell lung cancer in a prospective blinded assessment phase II clinical trial

INTRODUCTION In retrospective analyses of patients with nonsquamous non-small-cell lung cancer treated with pemetrexed, low thymidylate synthase (TS) expression is associated with better clinical outcomes. This phase II study explored this association prospectively at the protein and mRNA-expression level. METHODS Treatment-naive patients with nonsquamous non-small-cell lung cancer (stage IIIB/IV) had four cycles of first-line chemotherapy with pemetrexed/cisplatin. Nonprogressing patients continued on pemetrexed maintenance until progression or maximum tolerability. TS expression (nucleus/cytoplasm/total) was assessed in diagnostic tissue samples by immunohistochemistry (IHC; H-scores), and quantitative reverse-transcriptase polymerase chain reaction. Cox regression was used to assess the association between H-scores and progression-free/overall survival (PFS/OS) distribution estimated by the Kaplan-Meier method. Maximal χ analysis identified optimal cutpoints between low TS- and high TS-expression groups, yielding maximal associations with PFS/OS. RESULTS The study enrolled 70 patients; of these 43 (61.4%) started maintenance treatment. In 60 patients with valid H-scores, median (m) PFS was 5.5 (95% confidence interval [CI], 3.9-6.9) months, mOS was 9.6 (95% CI, 7.3-15.7) months. Higher nuclear TS expression was significantly associated with shorter PFS and OS (primary analysis IHC, PFS: p < 0.0001; hazard ratio per 1-unit increase: 1.015; 95%CI, 1.008-1.021). At the optimal cutpoint of nuclear H-score (70), mPFS in the low TS- versus high TS-expression groups was 7.1 (5.7-8.3) versus 2.6 (1.3-4.1) months (p = 0.0015; hazard ratio = 0.28; 95%CI, 0.16-0.52; n = 40/20). Trends were similar for cytoplasm H-scores, quantitative reverse-transcriptase polymerase chain reaction and other clinical endpoints (OS, response, and disease control). CONCLUSIONS The primary endpoint was met; low TS expression was associated with longer PFS. Further randomized studies are needed to explore nuclear TS IHC expression as a potential biomarker of clinical outcomes for pemetrexed treatment in larger patient cohorts. © 2013 by the International Association for the Study of Lung Cancer.