Targetable "driver" mutations in non small cell lung cancer

Lung cancer remains the leading cause of cancer-related mortality in the world despite advances in the field of cancer therapeutics. Traditional treatment with empirically chosen cytotoxic chemotherapeutic agents, have given small, but real survival benefits. Recent advances and insights into molecular pathogenesis of lung cancers have provided some novel molecular targets, offering newer strategies and agents that are tumor specific. Studies have identified mutations in specific genes that are involved in driving the development of lung cancer and so it is important to subsequently target them with specific drugs thus changing paradigms of management of this type of cancer. Recently, Lung Cancer Mutation Consortium (LCMC) has identified at least one of the many recognized "driver mutations" in nearly two thirds of the patients with advanced cancer. This study suggests that identification of driver mutations can help in molecular targeted therapeutics and in addition supplant tumor histology in guiding treatment decisions, identifying subset of patients who may benefit therapy. This review focuses on these mutations identified in specific genes serving as "drivers" of lung tumorigenesis and suggests that clear promise for the future of lung cancer treatment is indeed personalized therapy with drugs chosen according to the patient mutation profile. Most clinically relevant translational advances made in genes involved in lung tumorigenesis namely EML4-ALK fusions, HER2, PIK3CA, AKT, BRAF, MAP2K1, MET mutations and amplifications along with the well established EGFR and KRAS mutations are discussed in the context of NSCLCs. These studies emphasize the need for treatment management based on mutation profile along with routine histology based classification of these tumors in future for a directed therapy and thus a better therapeutic outcome.

Phase I study of continuous afatinib (BIBW 2992) in patients with advanced non-small cell lung cancer after prior chemotherapy/erlotinib/gefitinib (LUX-Lung 4)

PURPOSE

This Phase I study determined the maximum-tolerated dose (MTD) of afatinib (Afatinib is an investigational compound and its safety and efficacy have not yet been established) (BIBW 2992; trade name not yet approved by FDA), an irreversible inhibitor of epidermal growth factor receptor (EGFR)/human epidermal growth factor receptor (HER)1 and 2, up to a dose of 50 mg/day in advanced non-small cell lung cancer (NSCLC), to establish the recommended dose for Phase II.

METHODS

Patients with advanced NSCLC who had received prior platinum-doublet chemotherapy and/or erlotinib/gefitinib therapy, or who were ineligible for, or not amenable to, treatment with established therapies, received oral afatinib once daily. The MTD was determined based on dose-limiting toxicities (DLTs); other assessments included safety, pharmacokinetic profile, antitumour activity according to response evaluation criteria in solid tumours and EGFR/HER1 mutation analysis where possible.

RESULTS

Twelve evaluable patients were treated at doses of 20-50 mg/day. One DLT was observed at 50 mg/day in Course 1 (Grade 3 mucositis). The most frequent drug-related adverse events were diarrhoea, dry skin, stomatitis, rash, paronychia and anorexia; most were Grade 1 or 2. Six out of 12 patients had tumour size reductions; durable stable disease was achieved in three patients including one with EGFR/HER1 exon 19 and T790 M mutations. Peak plasma concentrations of afatinib were reached 3-4 h after administration and declined with a half-life of 30-40 h. Afatinib 50 mg/day was well tolerated with an acceptable safety profile during Phase I.

CONCLUSION

Recommended dose for Phase II was defined as 50 mg/day for Japanese patients; the same as for non-Japanese patients.

The role of irreversible HER family inhibition in the treatment of patients with non-small cell lung cancer

Small-molecule tyrosine kinase inhibitors (TKIs) of the human epidermal growth factor receptor (HER) include the reversible epidermal growth factor receptor (EGFR/HER-1) inhibitors gefitinib and erlotinib. EGFR TKIs have demonstrated activity in the treatment of patients with non-small cell lung cancer (NSCLC) harboring activating EGFR mutations; however, multiple mechanisms of resistance limit the benefit of these drugs. Although resistance to EGFR TKIs can be intrinsic and correlated with molecular lesions such as in Kirsten rat sarcoma viral oncogene homolog (KRAS; generally observed in a wild-type EGFR background), acquired resistance to EGFR TKIs can evolve in the setting of activating EGFR mutations, such as in the case of EGFR T790M mutations. Several irreversible inhibitors that target multiple members of the HER family simultaneously are currently in clinical development for NSCLC and may have a role in the treatment of TKI-sensitive and TKI-resistant disease. These include PF00299804, an inhibitor of EGFR/HER-1, HER-2, and HER-4, and afatinib (BIBW 2992), an inhibitor of EGFR/HER-1, HER-2, and HER-4. Results of large, randomized trials of these agents may help to determine their potential for the treatment of NSCLC.

Outcome of advanced NSCLC patients harboring sensitizing EGFR mutations randomized to EGFR tyrosine kinase inhibitors or chemotherapy as first-line treatment: a meta-analysis

BACKGROUND

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) are effective as first-line treatment of advanced non-small-cell lung cancer patients with EGFR mutations (EGFR-M+).

PATIENTS AND METHODS

We conducted a literature-based meta-analysis to quantify the magnitude of benefit with upfront EGFR TKI in EGFR-M+ patients. Meta-regression and sensitivity analyses were also carried out to identify additional predictors of outcome and to assess the influence of trial design.

RESULTS

Five trials (805 patients) were identified (three trials prospectively enrolling EGFR-M+ patients and two retrospective analyses of EGFR-M+ patients). TKI significantly increased progression-free survival (PFS) [hazard ratio (HR) 0.45, 95% confidence interval (CI) 0.36-0.58, P < 0.0001] and overall response rate (ORR) (HR 2.08, 95% CI 1.75-2.46, P < 0.0001)] over chemotherapy, while significantly decreasing neutropenia. No significant difference was observed in overall survival. The rate of exon-19 mutations, female gender, and nonsmoking status were identified as additional predictors of outcome at meta-regression analysis. A significant interaction with trial design was found for both PFS (P = 0.028) and ORR (P = 0.008), suggesting a larger advantage for patients treated within prospective trials.

CONCLUSIONS

In EGFR-M+ patients, first-line TKI increase both PFS and ORR by ~25%, while significantly decreasing toxicity. The role of additional predictive factors and the influence of trial design on the magnitude of the observed benefit warrant further investigation.

EGFR-mutated lung cancer: a paradigm of molecular oncology

The development of EGFR tyrosine kinase inhibitors for clinical use in non-small cell lung cancer and the subsequent discovery of activating EGFR mutations have led to an explosion of knowledge in the fields of EGFR biology, targeted therapeutics and lung cancer research. EGFR-mutated adenocarcinoma of the lung has clearly emerged as a unique clinical entity necessitating the routine introduction of molecular diagnostics into our current diagnostic algorithms and leading to the evidence-based preferential usage of EGFR-targeted agents for patients with EGFR-mutant lung cancers. This review will summarize our current understanding of the functional role of activating mutations, key downstream signaling pathways and regulatory mechanisms, pivotal primary and acquired resistance mechanisms, structure-function relationships and ultimately the incorporation of molecular diagnostics and small molecule EGFR tyrosine kinase inhibitors into our current treatment paradigms.

Personalized medicine for non-small-cell lung cancer

Non-small-cell lung cancer (NSCLC) is a heterogeneous illness associated with a high mortality rate. Personalized therapy may improve treatment outcomes by identification of a specific genotypic anomaly and target-specific therapy. The most significant development in recent years was the discovery of activated EGF receptor (EGFR) mutations at exons 19 and 21. Patients with EGFR mutations respond dramatically to EGFR tyrosine kinase inhibitors such as gefitinib or erlotinib, resulting in longer progression-free survival. Multiple randomized studies, including the Iressa Pan-Asia Study and WJTOG3405, have confirmed the role of EGFR tyrosine kinase inhibitors as standard first-line therapy for patients with the EGFR mutation. In this article, we summarize the current nonpersonalized therapies and examine the available and investigational personalized therapies for patients with resectable early-stage, unresectable locally advanced, or metastatic disease.

Mutations in the epidermal growth factor receptor gene in non-small cell lung cancer: Impact on treatment beyond gefitinib and erlotinib

Epidermal growth factor receptor (EGFR)-activating mutations in non-small cell lung cancer (NSCLC) are molecular targets for treatment with gefitinib and erlotinib, often resulting in improved response and prolonged progression-free survival. Resistance to these drugs, which develops during treatment, is a problem of paramount importance. Several mechanisms of "acquired resistance" have been discovered and treatments for this specific entity are on the horizon.

EGFR mutant lung cancer

Thoracic oncologists traditionally have made treatment decisions based upon tumor histology, distinguishing non-small cell lung cancer (NSCLC) from small cell lung cancer (SCLC). However, recent data has revealed that at least one histological subtype of NSCLC, lung adenocarcinoma comprises multiple molecularly distinct diseases. Lung adenocarcinoma subsets now can be defined by specific 'driver' mutations in genes encoding components of the EGFR signaling pathway. Importantly, these mutations have implications regarding targeted therapy. Here, we focus on EGFR mutant NSCLC-a prime example of a clinically relevant molecular subset of lung cancer, with defined mechanisms of drug sensitivity, primary drug resistance, and acquired resistance to EGFR tyrosine kinase inhibitors. Efforts are now being made to overcome mechanisms of acquired resistance. These findings illustrate how knowledge about the genetic drivers of tumors can lead to rational targeted therapy for individual patients.

Epidermal growth factor receptor inhibition in lung cancer: the evolving role of individualized therapy

Non-small cell lung cancer (NSCLC) is the major cause of cancer-related deaths in the USA and worldwide. Most patients present with advanced disease, and treatment options for these patients are generally limited to platinum-based chemotherapy and a few targeted therapies. Targeted agents currently in use for NSCLC inhibit oncogenic receptor tyrosine kinase pathways, such as the epidermal growth factor receptor (EGFR) pathway. While current EGFR-targeted agents, including erlotinib and gefitinib, may result in dramatic responses, they demonstrate efficacy in only a fraction of patients, and resistance to these agents frequently develops. In order to select patients most likely to benefit from blockade of EGFR pathways, investigators have focused on identifying molecular correlates of response to anti-EGFR therapy. New strategies to minimize the risk of resistance to EGFR inhibition have been employed in the development of next-generation EGFR tyrosine kinase inhibitors, such as PF00299804 and BIBW 2992; these include irreversibility of target binding, inhibition of multiple EGFR family receptors, and/or simultaneous inhibition of EGFR and other oncogenic pathways.