Chemotherapy outcomes by histologic subtypes of non-small-cell lung cancer: analysis of the southwest oncology group database for antimicrotubule-platinum therapy

OBJECTIVE

Histologic subtyping has been advocated to select chemotherapy for patients with advanced-stage non-small-cell lung cancer (NSCLC). To determine whether histologic subtype was associated with efficacy for the commonly used antimicrotubule (AMT) agents, paclitaxel, docetaxel, and vinorelbine plus a platinum compound, we examined the Southwest Oncology Group (SWOG) lung cancer database.

METHODS

Data from 4 randomized trials (S9308, S9509, S9806, and S0003) administering an AMT agent plus platinum in patients receiving first-line treatment for advanced-stage NSCLC were analyzed. Overall survival (OS) and progression-free survival (PFS) comparisons were performed using Cox proportional hazard regression, adjusting for sex. Median survival times were estimated by Kaplan-Meier.

RESULTS

Of 1146 patients included in this analysis, 640 had adenocarcinoma (56%), 220 had squamous cell carcinoma (19%), 121 had large cell carcinoma (11%), and 165 had NSCLC not otherwise specified (NOS) (14%). Median OS times by histologic subtypes were 8.5, 8.4, 8.2, and 9.6 months, respectively, and median PFS times were 4.2, 4.3, 4.3, and 4.6 months, respectively. No difference in OS or PFS was observed by histologic subtype and, specifically, between nonsquamous and squamous histologies.

CONCLUSIONS

This pooled analysis from 4 SWOG trials using an AMT-platinum regimen did not show a difference in survival outcomes by histologic subtype. Because the majority of patients with advanced NSCLC continue to receive chemotherapy, defining molecular-based predictive markers of responsiveness is warranted.

Differences in outcome and toxicity between Asian and caucasian patients with lung cancer treated with systemic therapy

It is increasingly recognized that differences in overall survival and toxicity exist between Asian and caucasian patients with small-cell and non-small-cell lung cancer, with a longer survival, higher response rates and greater toxicity to chemotherapy and targeted therapy reported in Asian patients. Two global studies are used to illustrate how the proportions of Asian patients can influence survival outcome. Ethnicity is an important and complex characteristic that should considered in the design and conduct of a global clinical study, as the safety, tolerability and response may vary between Asian and caucasian patients. Whether ethnic differences in lung cancer survival are attributed to genetic differences among races or are simply a surrogate marker of differences in access to healthcare because of socioeconomic differences is unclear. Carefully designed prospective studies investigating ethnic-specific determinants of sensitivity and toxicity to systemic therapy are warranted.

Inhibition of dUTPase induces synthetic lethality with thymidylate synthase-targeted therapies in non-small cell lung cancer

Chemotherapies that target thymidylate synthase (TS) continue to see considerable clinical expansion in non-small cell lung cancer (NSCLC). One drawback to TS-targeted therapies is drug resistance and subsequent treatment failure. Novel therapeutic and biomarker-driven strategies are urgently needed. The enzyme deoxyuridine triphosphate nucleotidohydrolase (dUTPase) is reported to protect tumor cells from aberrant misincorporation of uracil during TS inhibition. The goal of this study was to investigate the expression and significance of dUTPase in mediating response to TS-targeted agents in NSCLC. The expression of dUTPase in NSCLC cell lines and clinical specimens was measured by quantitative real-time reverse transcriptase PCR and immunohistochemistry. Using a validated RNA interference approach, dUTPase was effectively silenced in a panel of NSCLC cell lines and response to the fluoropyrimidine fluorodeoxyuridine (FUdR) and the antifolate pemetrexed was analyzed using growth inhibition and clonogenic assays. Apoptosis was analyzed by flow cytometry. Significant variation in the quantity and cellular expression of dUTPase was observed, including clear evidence of overexpression in NSCLC cell line models and tumor specimens at the mRNA and protein level. RNA interference-mediated silencing of dUTPase significantly sensitized NSCLC cells to growth inhibition induced by FUdR and pemetrexed. This sensitization was accompanied by a significant expansion of intracellular dUTP pools and significant decreases in NSCLC cell viability evaluated by clonogenicity and apoptotic analyses. Together, these results strongly suggest that uracil misincorporation is a potent determinant of cytotoxicity to TS inhibition in NSCLC and that inhibition of dUTPase is a mechanism-based therapeutic approach to significantly enhance the efficacy of TS-targeted chemotherapeutic agents.

How close are we to customizing chemotherapy in early non-small cell lung cancer?

Although surgery is the only potentially curative treatment for early-stage non-small cell lung cancer (NSCLC), 5-year survival rates range from 77% for stage IA tumors to 23% in stage IIIA disease. Adjuvant chemotherapy has recently been established as a standard of care for resected stage II-III NSCLC, on the basis of large-scale clinical trials employing third-generation platinum-based regimens. As the overall absolute 5-year survival benefit from this approach does not exceed 5% and potential long-term complications are an issue of concern, the aim of customized adjuvant systemic treatment is to optimize the toxicity/benefit ratio, so that low-risk individuals are spared from unnecessary intervention, while avoiding undertreatment of high-risk patients, including those with stage I disease. Therefore, the application of reliable prognostic and predictive biomarkers would enable to identify appropriate patients for the most effective treatment.This is an overview of the data available on the most promising clinicopathological and molecular biomarkers that could affect adjuvant and neoadjuvant chemotherapy decisions for operable NSCLC in routine practice. Among the numerous candidate molecular biomarkers, only few gene-expression profiling signatures provide clinically relevant information warranting further validation. On the other hand, real-time quantitative polymerase-chain reaction strategy involving relatively small number of genes offers a practical alternative, with high cross-platform performance. Although data extrapolation from the metastatic setting should be cautious, the concept of personalized, pharmacogenomics-guided chemotherapy for early NSCLC seems feasible, and is currently being evaluated in randomized phase 2 and 3 trials. The mRNA and/or protein expression levels of excision repair cross-complementation group 1, ribonucleotide reductase M1 and breast cancer susceptibility gene 1 are among the most potential biomarkers for early disease, with stage-independent prognostic and predictive values, the clinical utility of which is being validated prospectively. Inter-assay discordance in determining the biomarker status and association with clinical outcomes is noteworthing.

[What is the best sequence of treatment for patients with EGFR mutations?]

The arrival of tyrosine kinase inhibitors (TKI) in first line of treatment for advanced non-small cell lung cancer with EGFR mutations has changed the strategy of treatment of theses patients. Indeed, response rates in these cases reach around 60 to 70%, with a progression-free survival greatly prolonged, up to 10 months. It seems that these patients with mutated tumor benefit from TKI whatever the treatment line, with the same efficacy. So, the best sequence of treatment (TKI in first line then chemotherapy in second line, or the opposite) needs still to be defined in this sub-group of NSCLC. The choice has to take in account the data of efficacy of TKIs and chemotherapy in the EGFR mutated tumors, with an anticipation of subsequent lines from the first line. Besides, data of toxicity and quality of life have also to be considered.

Association of epidermal growth factor receptor activating mutations with low ERCC1 gene expression in non-small cell lung cancer

INTRODUCTION

Patients with non-small cell lung cancer (NSCLC) with cancers harboring activating mutations in the epidermal growth factor receptor (EGFR) show improved efficacy from EGFR tyrosine kinase inhibitors. Some clinical studies also suggest enhanced efficacy of platinum-based chemotherapy in patients with EGFR-mutant cancers. We investigated the relationship of EGFR mutation status and DNA repair capacity, as exemplified by excision repair cross-complementing 1 (ERCC1) gene expression, as a potential explanation for this observation.

METHODS

Microdissected formalin-fixed paraffin-embedded tumors from 1207 patients with NSCLC were analyzed by real-time polymerase chain reaction for mRNA expression levels of ERCC1 and for EGFR mutation status by an allele-specific polymerase chain reaction assay.

RESULTS

NSCLC subtype was adenocarcinoma (AC) in 712 patients, squamous in 175, and not otherwise specified or other in 320. EGFR activating mutations were detected in 183/1207 patients (15.2%). Median ERCC1 expression overall was 1.82 (range, 0.22-27.31) and was histology related: AC, median = 1.68 (0.22-11.33) and squamous, median = 2.42 (0.51-14.28) (p < 0.001). Using a previously defined reference level of <1.7, ERCC1 expression was categorized as low in 556 of 1207 patients (46.1%). The presence of EGFR mutations was highly associated with ERCC1 expression (p < 0.001). This association was retained when adjusting for AC histologic subtype (p = 0.001).

CONCLUSIONS

NSCLC specimens harboring EGFR activating mutations are more likely to express low ERCC1 mRNA levels. Whether these findings translate into enhanced clinical efficacy of EGFR-mutant cancers to platinum-based chemotherapy remains to be determined.

Summary of presentations from the 46th Annual Meeting of the American Society of Clinical Oncology: focus on non-small cell lung cancer (2010)

The promising results of crizotinib in molecularly selected patients with advanced non-small cell lung cancer (NSCLC) whose tumor cells had a novel fusion protein involving anaplastic lymphoma kinase presented at the 2010 American Society of Clinical Oncology reinforce once again the importance of understanding molecular heterogeneity of lung cancer and careful patient selection. Several other important issues were the subject of presentations related to lung cancer at the recently concluded American Society of Clinical Oncology annual meeting. The articles covered a wide variety of topics including optimal staging techniques to detect mediastinal nodal involvement, the role of platinum-based doublet chemotherapy in the management of elderly patients with advanced NSCLC, use of maintenance therapy with gemcitabine, and the impact of early introduction of organized palliative care in improving the quality of life of patients with advanced NSCLC. This report provides a brief overview of the presentations related to lung cancer that are relevant to clinical practice and future research.

Parameters for individualizing systemic therapy in non-small cell lung cancer

Rational drug design based on molecular targets is starting to revolutionize cancer care. To maximize its potential for patients, a concomitant leveraging of molecular knowledge for selection of patients to future and current therapeutic options is paramount. The terms "individualized", "personalized", or "precision therapy" are currently used to describe these efforts. Here, we summarize current knowledge for selection of systemic targeted and cytotoxic therapy for patients with non-small-cell lung cancer. Based on this knowledge, we present a potential decision algorithm to best select patients for currently available therapies, which include the treatment options single-agent erlotinib or gefitinib, the ALK inhibitor crizotinib, double agent gemcitabine and platinum, double agent platinum and pemetrexed, and as a default option a taxane combined with a non-platinum drug, for instance a vinca alkaloid. The addition of bevacizumab to double-agent chemotherapy is also discussed. Currently available data on predictive biomarkers are largely based on subgroup or companion biomarker analyses of patient cohorts or clinical trials. Current and emerging markers must be incorporated prospectively into the design of clinical trials that test novel and established agents to better understand their clinical utility and to refine selection parameters and marker interactions. Future development will lead to increasing complexity in clinical decision making with substantial anticipated benefits to patients including increased therapeutic efficacy, reduced toxicity, and better quality of life.