This retrospective study further validates ERCC1 and RRM1 genes as reliable candidates for customized chemotherapy and shows a higher impact on the survival of NSCLC patients treated with cisplatin/gemcitabine for ERCC1. Prospective pharmacogenomic studies represent a research priority in early and advanced NSCLC.

BACKGROUND.In patients with cancer, one of the main mechanism of resistance to antimetabolite drugs is related to higher levels of thymidylate synthase (TS) activity.METHODS.To investigate the association between TS expression and histopathologic data, 56 resection specimens from patients with nonsmall cell lung carcinoma (NSCLC) were collected consecutively. TS messenger RNA (mRNA) was evaluated in tumor specimens by using real‐time polymerase chain reaction (PCR) analysis; protein expression was evaluated by using immunohistochemistry (IHC) in formalin‐fixed, paraffin‐embedded (FFPE) specimens; and the analysis of TS transcriptional regulation activity was performed by using real‐time PCR analysis in snap‐frozen normal and tumor specimens.RESULTS.The amplification of the TS gene from FFPE tissues was obtained from all samples, with a median level (unit‐less ratio) of 1.45 (range, 0.34–5.24); whereas positive TS status at IHC (>10% positive cells) was detected in 56% of samples. It is noteworthy that TS expression was significantly higher in squamous cell carcinoma compared with adenocarcinoma when both mRNA levels (2.17 vs. 1.16; P < .0001) and protein levels (P = .0269) were considered in FFPE specimens, and a strong association was observed between mRNA and protein expression (P = .00017). Moreover, higher TS levels were observed in high‐grade tumors (P = .0389 and P = .0068 for mRNA and protein quantification, respectively). The analysis in snap‐frozen samples revealed that the TS gene was up‐regulated strongly in tumors (P = 3.8 × 10−12), and an 8‐fold increase (as a cut‐off value) in the TS mRNA ratio between tumor and corresponding normal tissue was detected in 32 of 56 patients (57%) bearing preferentially squamous cell tumors (P = .0022) and high‐grade tumors (P < .001).CONCLUSIONS.Data from the current study consistently indicated higher TS expression levels in squamous cell and in high‐grade carcinomas. This information may be useful in selecting which patients with NSCLC should receive treatment with TS‐inhibiting agents. Cancer 2006. © 2006 American Cancer Society.

Purpose: The effect of translesion DNA synthesis system in conferring cellular tolerance to DNA-damaging agents has been recently described. DNA polymerase D (Pol D) is part of this machinery and in vitro models showed that it can overcome DNA damages caused by cisplatin and UV rays. The aim of the present study was to investigate the role of Pol D mRNA expression levels in non^small cell lung cancer (NSCLC). Experimental Design: Pol D mRNA expression levels were evaluated by real-time PCR in (a) formalin-fixed paraffin-embedded biopsies of 72 NSCLC patients treated with platinum-based chemotherapy, (b) fresh snap-frozen surgical specimens of tumor and corresponding normal lung tissue from 50 consecutive patients not treated with perioperative or postoperative chemotherapy, and (c) five NSCLC cell lines. Results: High Pol D expression levels were strongly associated with shorter survival at both univariate (6.9 versus 21.1months; P = 0.003) and multivariate (hazard ratio, 3.18; 95% confidence interval, 1.73-5.84; P = 0.008) analysis in the group of platinum-treated patients. By contrast, Pol D expression was not significantly correlated with the prognosis in surgically resected patients (P = 0.54) and mRNA levels did not significantly differ in tumor versus normal lung (P = 0.82). Moreover, endogenous Pol D mRNA expression was found to be inducible by cisplatin in three of five cell lines and significantly associated with in vitro sensitivity (P = 0.01). Conclusions: Taken together, these data indicate Pol D as a predictive rather than prognostic marker worth of further investigation in NSCLC patients candidate to platinum-based chemotherapy.

Purpose: In non-small cell lung cancer, higher thymidylate synthase (TS) levels have been reported in squamous cell carcinoma (SCC) compared with adenocarcinoma (ADC). Data on TS expression in large-cell carcinoma (LCC) are scanty. Experimental Design: TS mRNA and protein levels were analyzed in 42 surgical cases of pulmonary LCC, including 8 large-cell neuroendocrine carcinomas, and were compared with controls represented by ADC (n = 41), SCC (n = 30), and small-cell lung carcinoma (SCLC; n = 33). TS levels were also correlated with the expression of Ki67 and E2F1. Moreover, the reliability of TS expression analysis was assessed in 22 matched cytologic and surgical specimens of non-small cell lung cancer. Results: TS mRNA levels of LCC were comparable with those of control SCC, but significantly higher than those of ADC (P < 0.001) and lower than SCLC (P < 0.001). A correlation between TS mRNA and protein levels was observed in control ADC and SCC, but not in LCC. Large-cell neuroendocrine carcinomas had the highest TS expression, whereas in non-neuroendocrine LCCs, TS protein levels were significantly higher (P = 0.02) in LCC immunoreactive for p63 and desmocollin3 (markers of squamous differentiation) than those expressing TTF-1 (a marker of ADC). Both E2F1 and Ki67 levels were not correlated with TS in LCCs. Finally, a linear correlation in TS protein levels was observed between matched cytologic and surgical specimens. Under the commonly used term of non-small cell lung cancer (NSCLC), there are three major histologic types according to the current WHO classification for lung tumors: (a) adenocarcinoma (ADC), characterized by glandular differentiation and mucin production; (b) squamous cell carcinoma (SCC), characterized by keratinization and/or intracellular bridges; and (c) large-cell carcinoma (LCC), which accounts for <10% of lung cancers and is represented by poorly differentiated tumors lacking the cytologic and architectural features of the two above histotypes, including variants of neuroendocrine and nonneuroendocrine types (1).Although histology has not consistently been associated with clinical outcomes in advanced NSCLC (2), it has recently emerged as a potential predictive factor of response to or survival with pemetrexed. In phase III studies on NSCLC, pemetrexed, alone or in combination with cisplatin, showed a statistically superior activity in nonsquamous histotypes (3-5), which was also supported by additional retrospective analyses from phase II data (6, 7). Preliminary molecular evidence indicated that this differential activity may be related to a lower baseline expression of thymidylate synthase (TS), the main molecular target of pemetrexed, in ADC compared with squamous cell (8) and small-cell (9) lung carcinoma. In different tumors (9-12), preclinical data support the hypothesis that overexpression of TS correlates with reduced sensitivity to pemetrexed (13), and high TS expression levels were associated with poor outcome of patients treated with antifolate drugs.In one of t...

Genes involved in DNA repair and replication have been recently investigated as predictive markers of response to chemotherapy in non-small cell lung cancer (NSCLC). However, few data on the expression of these genes in tumor compared with corresponding normal lung are available. The aim of this study was to evaluate differential mRNA levels of 22 DNA repair genes of five different DNA repair pathways: direct, base excision, nucleotide excision (NER), double-strand break (DSBR), and postreplicative repair. In addition, six genes involved in DNA replication (REP) and three telomere maintenance genes were investigated. Total RNAs extracted from fresh-frozen tumors and corresponding normal tissues of 50 consecutive chemo-naïve resected NSCLC patients were analyzed. Transcript levels were quantified by real-time PCR. A significant overexpression was detected in 20 of 30 (67%) genes, mostly belonging to DSBR pathways, whereas others (XPA, XPC, and UBE2N; 10%) were significantly underexpressed. For 7 of 30 (23%) genes, mostly belonging to NER pathway, no significant difference between paired tumor and normal samples was observed. Transcript overexpression of DSBR and REP genes was significantly higher in poorly differentiated carcinomas and DSBR levels were higher in men compared with women. The transcriptional overexpression of four genes (XRCC5, TOP3B, TYMS, and UNG) showed significant correlation with a shorter patients' outcome at the univariate, whereas only stage of disease appeared as an independent factor affecting prognosis, as assessed by multivariate analysis. In conclusion, genes belonging to DNA repair/replication pathways are overexpressed in NSCLC and are associated with a more aggressive phenotype. [Cancer Res 2009;69(8):3390-6]