Mutations in the tyrosine kinase domain of the EGFR gene associated with gefitinib response in non-small-cell lung cancer.

The potential relevance of epidermal growth factor receptor (EGFR) mutations to non-small-cell lung cancer treatment has recently been identified. We have examined the presence of EGFR mutations in Japanese and Spanish gefitinib-treated non-small-cell lung cancer patients. A total of 34 gefitinib-treated patients were screened, 18 from Japan and 16 from Spain. Laser capture microdissection was performed for the accurate procurement of tumor cells. EGFR exons 18, 19 and 21 were amplified from genomic DNA by means of PCR, and the samples were then subjected to bi-directional automatic sequencing. EGFR somatic mutations in the tyrosine kinase domain were found in 8 of 34 patients (23.5%). Gefitinib response was observed in 7 of 8 patients (87.5%) with EGFR mutations and in 3 of 24 (12.5%) with wild-type EGFR (P=0.0003). Five deletion mutations were clustered in the region spanning codons 746 to 750 (ELREA) within exon 19. Three additional tumors had amino acid substitutions within exon 18, at codons 718 and 719. Logistic regression analysis showed that response was primarily linked to the presence of EGFR mutations and secondarily linked to female gender, non-smoker status and a greater number of prior chemotherapy regimens. The presence of EGFR mutations is a major determinant of gefitinib response, and EGFR tyrosine kinase inhibitors should be tested in clinical trials of first-line treatment of lung adenocarcinomas harboring EGFR mutations.

Effect of the methylenetetrahydrofolate reductase C677T polymorphism on patients with cisplatin/gemcitabine-treated stage IV non-small-cell lung cancer.

Single nucleotide polymorphisms (SNPs) in the metabolic pathways of S-adenosylmethionine have been related to global hypomethylation and a lower number of hypermethylated CpG islands of tumor suppressor genes. Hypermethylation of checkpoint and DNA repair genes has been shown to be indicative of chemosensitivity. In the present study, we have examined the SNP of methylenetetrahydrofolate reductase (MTHFR) C677T, which affects DNA methylation patterns and is linked to elevated plasma homocysteine levels in 208 patients with gemcitabine/cisplatin-treated stage IV non-small-cell lung cancer (NSCLC). No differences in response rate were observed according to the MTHFR genotype. However, time to progression was 7.4 months for 68 patients with CC genotype, 5.5 months for 108 patients with heterozygous CT genotype, and 5.2 months for 28 patients with TT genotype. These findings can lead us to distinguish different outcome patterns among patients with stage IV NSCLC whose similar clinical prognostic factors would otherwise indicate similar outcomes. Carriers of the MTHFR 677T allele could benefit from supplementation with folic acid and vitamin B12. The Spanish Lung Cancer Group has undertaken a phase III randomized trial to elucidate this concept.

Nucleotide excision repair pathways involved in Cisplatin resistance in non-small-cell lung cancer.

BACKGROUND: In spite of the growing list of genetic abnormalities identified as being involved in DNA repair pathways that alter chemosensitivity in non-small-cell lung cancer (NSCLC) patients, translational assays have not yet been developed for use in individualized chemotherapy. METHODS: In metastatic NSCLC, no single cisplatin-based chemotherapy regimen has been shown to be superior to any other. Although these studies show a small survival tail at 3 years, the majority of patients had a median survival of 8 to 10 months. We review the principal mechanisms of cisplatin resistance, particularly those involved in the nucleotide excision repair (NER) pathways (transcription-coupled repair and global genomic repair). RESULTS: ERCC1 is a single-stranded DNA endonuclease that forms a tight heterodimer with xeroderma pigmentosum complementation group F. It incises DNA on the 5' side of a lesion such as cisplatin-DNA adduct. Therefore, overexpression of ERCC1 and other NER enzymes during ovarian cancer chemotherapy with cisplatin appears to be implicated in the formation of cellular and clinical drug resistance. Recently, baseline ERCC1 mRNA overexpression has been related to poor response and survival in cisplatin-treated NSCLC patients. CONCLUSIONS: The level of evidence for many assays is limited, and only ERCC1 mRNA levels have been analyzed extensively. The impact of ERCC1 should be fully validated in prospective clinical trials.

Methylation patterns and K-ras mutations in tumor and paired serum of resected non-small-cell lung cancer patients.

Gene methylation and K-ras mutations were examined in tumor and paired serum DNA of 50 resected non-small-cell lung cancer patients. RASSF1A, death associated protein kinase and target of methylation-induced silencing were methylated in 17/50 (34%), 23/50 (45%) and 18/50 (35%) tumors, respectively, and in 17/50 (34%), 20/50 (40%) and 17/50 (34%) sera, respectively. Methylation in tumor and serum were closely correlated (P=0.001), but no correlation was found with survival. Twelve K-ras mutations (cysteine) were found in serum and nine mutations were found in tumor (five cysteine, one alanine, one aspartic, one arginine, and one valine). K-ras mutations in serum correlated significantly with survival (P=0.01).

O6-methyl-guanine-DNA methyltransferase methylation in serum and tumor DNA predicts response to 1,3-bis(2-chloroethyl)-1-nitrosourea but not to temozolamide plus cisplatin in glioblastoma multiforme.

PURPOSE: In glioblastoma multiforme (GBM), the cytotoxic effect of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and temozolamide is dependent on O(6) alkylation, which correlates inversely with expression of the DNA repair enzyme O(6)-methyl-guanine-DNA methyltransferase (MGMT). Thus, MGMT assessment can be useful in predicting response in GBM, but the scarcity of neoplastic cells limits the practicality of MGMT assessment in these tumors. Although GBM grows within the skull, we investigated the concordance of methylation in glioma tissue, and paired serum DNA and the potential correlation with response and time to progression. EXPERIMENTAL DESIGN: Using MSP assay, we assessed the methylation of MGMT, p16, DAPK, and RASSF1A in tumor and serum DNA from 28 GBM patients treated with BCNU or with temozolamide plus cisplatin. RESULTS: The concordance between methylation in tumor and serum was highly significant. Overall, response plus stable disease was noted in 10 of 11 (90.9%) patients with MGMT methylation and in 5 of 14 (35.7%) patients without (P = 0.01). In the 16 patients treated with temozolamide plus cisplatin, no significant correlation between MGMT methylation status and response was observed, whereas in BCNU-treated patients, a significant difference was observed in favor of those with methylated MGMT. Time to progression was 29.9 weeks in 12 patients with MGMT methylation and 15.7 weeks in 10 patients without (P = 0.006). No correlation was observed between response or time to progression and p16, DAPK, or RASSF1A methylation. CONCLUSIONS: Methylated MGMT, p16, DAPK, and RASSF1A were found in serum DNA of GBM patients, with a good correlation between serum and primary tumor tissue. Serum MGMT methylation predicted response and time to progression in BCNU-treated GBM patients. The methylation-specific PCR assay in serum DNA could be a good predictive tool for selecting GBM patients to be treated with BCNU or alternatively with the combination of temozolamide plus cisplatin.

Pharmacogenomic strategies for developing customized chemotherapy in non-small cell lung cancer.

In this review, we deal with six groups of cytotoxic drugs commonly used in the treatment of non-small cell lung cancer (NSCLC). Although there are many reviews of thymidylate synthase (TS) and antifolate inhibitors, in this article, we have tried to highlight aspects that are more important for medical oncologists to consider when treating NSCLC patients. There is compelling evidence that TS gene transcripts and TS polymorphisms could be used to decide which patients can best benefit from adjuvant chemotherapy approaches, especially in colorectal cancer, and not less importantly, to tailor chemotherapy in metastatic NSCLC when using drugs akin to fluorouracil, such as pemetrexed. Secondly, cisplatin is central to chemotherapy combinations and evidence indicates that DNA repair capacity influences response to cisplatin-based regimens. ERCC1 gene transcript stands out as a predictive marker of cisplatin sensitivity. Thirdly, preliminary studies indicate that upregulation of beta-tubulin III correlates with response to paclitaxel and vinorelbine. Fourthly, overexpression of ribonucleotide reductase can influence response to gemcitabine. Fifthly, we describe mechanisms of resistance to topoisomerase I inhibitors, although this subject has not yet been completely elucidated. Finally, to understand the mechanisms of resistance to EGF-R inhibitors, which have been shown to be useful in many different types of cancer, the Src-STAT signaling pathways are described here in detail. Hopefully, the assessment of Src and of STAT-3 can be implemented as predictive markers.