[Personalized targeted therapy for lung cancer]

由于每一肺癌患者在临床特征、预后、治疗反应和耐受性方面的进展都是独特的，所以肺癌被认为是异质性疾病。个体化用药是指运用标志物来预测哪些患者更易获益于某种治疗。对于肺癌而言，日趋完善的表皮生长因子受体(epidermal growth factor receptor, EGFR)和新发现的棘皮动物微管相关蛋白样4-间变淋巴瘤激酶(echinoderm microtubule associated protein like 4-anaplastic lymphoma kinase, EML4-ALK)是重要的治疗靶标。本综述包括EGFR和EML4-ALK活化的机制、预测性生物标记物、耐药的机理和已有的靶向性酪氨酸激酶抑制剂。本文将通过总结基于生物标记物筛选患者而进行的前瞻性临床试验来探讨EGFR和ALK靶向治疗的疗效。此外，由于革命性的测序和系统生物学技术会为癌症的分子特征提供一个全面的理解，有助于为更适宜靶向治疗的患者提供更精确的区分从而提供更有前景的个体化治疗，本综述也将包括这些技术。同时，非亚裔人群中EGFR和ALK相对较低的突变发生率和突变患者反应的缺乏限制了靶向于EGFR或ALK的治疗的应用。测序和系统生物学策略则可能为这些患者提供新的解决方案。

Personalized targeted therapy for lung cancer

Lung cancer has long been recognized as an extremely heterogeneous disease, since its development is unique in every patient in terms of clinical characterizations, prognosis, response and tolerance to treatment. Personalized medicine refers to the use of markers to predict which patient will most likely benefit from a treatment. In lung cancer, the well-developed epidermal growth factor receptor (EGFR) and the newly emerging EML4-anaplastic lymphoma kinase (ALK) are important therapeutic targets. This review covers the basic mechanism of EGFR and EML4-ALK activation, the predictive biomarkers, the mechanism of resistance, and the current targeted tyrosine kinase inhibitors. The efficacy of EGFR and ALK targeted therapies will be discussed in this review by summarizing the prospective clinical trials, which were performed in biomarker-based selected patients. In addition, the revolutionary sequencing and systems strategies will also be included in this review since these technologies will provide a comprehensive understanding in the molecular characterization of cancer, allow better stratification of patients for the most appropriate targeted therapies, eventually resulting in a more promising personalized treatment. The relatively low incidence of EGFR and ALK in non-Asian patients and the lack of response in mutant patients limit the application of the therapies targeting EGFR or ALK. Nevertheless, it is foreseeable that the sequencing and systems strategies may offer a solution for those patients.

Impact on disease-free survival of adjuvant erlotinib or gefitinib in patients with resected lung adenocarcinomas that harbor EGFR mutations

BACKGROUND

Patients with stage IV lung adenocarcinoma and epidermal growth factor receptor (EGFR) mutation derive clinical benefit from treatment with EGFR tyrosine kinase inhibitors (TKIs). Whether treatment with TKI improves outcomes in patients with resected lung adenocarcinoma and EGFR mutation is unknown.

METHODS

Data were analyzed from a surgical database of patients with resected lung adenocarcinoma harboring EGFR exon 19 or 21 mutations. In a multivariate analysis, we evaluated the impact of treatment with adjuvant TKI.

RESULTS

The cohort consists of 167 patients with completely resected stages I to III lung adenocarcinoma. Ninety-three patients (56%) had exon 19 del, 74 patients (44%) had exon 21 mutations, and 56 patients (33%) received perioperative TKI. In a multivariate analysis controlling for sex, stage, type of surgery, and adjuvant platinum chemotherapy, the 2-year disease-free survival (DFS) was 89% for patients treated with adjuvant TKI compared with 72% in control group (hazard ratio = 0.53; 95% confidence interval: 0.28-1.03; p = 0.06). The 2-year overall survival was 96% with adjuvant EGFR TKI and 90% in the group that did not receive TKI (hazard ratio: 0.62; 95% confidence interval: 0.26-1.51; p = 0.296).

CONCLUSIONS

Compared with patients who did not receive adjuvant TKI, we observed a trend toward improvement in DFS among individuals with resected stages I to III lung adenocarcinomas harboring mutations in EGFR exon 19 or 21 who received these agents as adjuvant therapy. Based on these data, 320 patients are needed for a randomized trial to prospectively validate this DFS benefit.

Update on epidermal growth factor receptor mutations in non-small cell lung cancer

In 2004, several investigators reported that somatic mutations in the epidermal growth factor receptor gene were associated with clinical responses to erlotinib and gefitinib in patients with non-small cell lung cancer. Since then, multiple groups have examined the biological properties that such mutations confer as well as the clinical relevance of these mutations in patients with non-small cell lung cancer. Although a tremendous amount of knowledge has been gained in the past 2 years, there remain a number of important epidemiologic, biological, and clinical questions.

Epidermal growth factor receptor inhibition and non-small cell lung cancer

The majority of non-small cell (NSC) lung cancers express epidermal growth factor receptor (EGFR). Many studies have evaluated the clinical effect from targeted therapy achieved by blocking EGFR in patients with NSC lung cancer. Treatment of biologically unselected patients with NSC lung cancer with two reversible quinazole EGFR inhibitors, gefitinib and erlotinib, gave negative results in all controlled trials but one. Ten percent to 20% of patients with NSC lung cancers have somatic mutations in EGFR, and these patients have a significantly higher response rate (73%) to treatment with EGFR inhibitors than patients with wild-type EGFR (10%). Patients with Asian background, women, non-smokers, and patients with adenocarcinoma had higher response rates than other patients, and the differences may be due to an association between the clinical characteristics and EGFR mutations. Further studies are needed to fully evaluate the effect of EGFR inhibitor-treatment for subgroups of patients with NSC lung cancer with favorable biological and clinical characteristics.