Epidermal growth factor receptor T790M mutation: A major culprit in the progression of epidermal growth factor receptor-driven non-small cell lung cancer and the role of repeat biopsy

Non-small cell lung cancer (NSCLC) accounts for the majority of primary lung cancer cases worldwide. The activating mutations of epidermal growth factor receptor (EGFR) have been demonstrated to associate with the development of NSCLC, with T790M mutation being the most common. Over the years, EGFR tyrosine kinase inhibitors (TKIs) were developed to target EGFR-related mutations. However, patients with activating EGFR mutations who are initially responsive to EGFR-TKIs eventually develop acquired resistance after a median progression-free survival of 10-16 months, followed by disease progression. Recently, the third-generation EGFR inhibitors have emerged as potential therapeutics to block the growth of EGFR T790M-positive tumors. This article reviews the emerging data regarding EGFR mutations and clinical evidence on third-generation agents against EGFR T790M mutation in the treatment of patients with advanced NSCLC. It also reviews the role of repeat biopsy in improving the success rates of treatment of EGFR T790M-derived drug-resistant NSCLC.

Navigating the "No Man's Land" of TKI-Failed EGFR-Mutated Non-Small Cell Lung Cancer (NSCLC): A Review

As the leading cause of cancer-related mortality, lung cancer is a worldwide health issue that is overwhelmingly caused by smoking. However, a substantial minority (~25%) of patients with non–small cell lung cancer (NSCLC) has never smoked. In these patients, activating mutations of the epidermal growth factor receptor (EGFR) are more likely, which render their tumors susceptible for a finite period to treatment with EGFR tyrosine kinase inhibitors (TKIs) and confer a better prognosis than EGFR wild-type NSCLC. On progression, due to the inevitable insurgence of resistance, TKIs are generally followed by second- or third-line salvage chemotherapy until treatment failure, after which no standard treatment options are available, resulting in a poor prognosis and a high risk of death. With the focus of clinical attention on treatment with TKIs, few studies on optimal salvage therapies, including cytotoxic chemotherapy, after failure of EGFR TKIs have been reported. Despite a paucity of available data, the aim of this review is to summarize the “no-man's land” of TKI-failed EGFR-mutated NSCLC and expand on alternative strategies as well as potential future directions.

Generations of Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors: Perils and Progress

OPINION STATEMENT

Epidermal growth factor receptor (EGFR) mutations have been detected in approximately 10 % of North American patients diagnosed with non-small cell lung cancer (NSCLC). Approximately 90 % of these mutations are exon 19 deletions or exon 21 L858R point mutations. First- and second-generation EGFR tyrosine kinase inhibitors (TKIs) are approved as first-line therapy based on clinical trials demonstrating superior response rates, progression free survival (PFS), and overall survival (OS) compared to chemotherapy in patients with EGFR mutation-positive NSCLC treated with an EGFR TKI prior to chemotherapy. However, the majority of patients treated with an EGFR TKI develop resistance to therapy within about 12 months, approximately 50 % of patients due to a second site mutation, the T790M mutation occurring within exon 20. At the time of progression, the EGFR TKI is most commonly discontinued and a different systemic therapy is initiated. However, oncogene addiction persists and recent exciting data with third-generation EGFR TKIs suggests that acquired resistance may be surmountable. The newest EGFR TKIs have shown activity against EGFR-mutant NSCLC after progression on first-generation TKIs, including those with T90M, while sparing wild-type EGFR and hence appear to be both well tolerated and efficacious. At this time, it appears that third-generation EGFR TKIs are effective following first-generation therapy, and determining the most appropriate sequence to maximize overall survival is a matter of ongoing investigation. As the arsenal of active agents in EGFR mutant NSCLC grows, future research into potential combinations, optimal timing, and resistance mechanisms of these new treatments, as well as their possible role in the adjuvant, post-chemoradiation, and neoadjuvant settings holds great promise for this group of patients.

Next-Generation Covalent Irreversible Kinase Inhibitors in NSCLC: Focus on Afatinib

First-generation, reversible epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), erlotinib and gefitinib, represented an important addition to the treatment armamentarium for non-small-cell lung cancer (NSCLC) patients with activating EGFR mutations. However, all patients inevitably develop acquired resistance to these agents, primarily due to secondary EGFR mutations, molecular aberrations affecting other signaling pathways, or transformation to small-cell histology. It was hypothesized that development of second-generation TKIs with broader inhibitory profiles could confer longer-lasting clinical activity and overcome acquired resistance to first-generation inhibitors. Here, we review the development of afatinib, an irreversible ErbB family blocker that potently inhibits signaling of all homodimers and heterodimers formed by the EGFR, human epidermal growth factor receptor (HER)-2, HER3, and HER4 receptors. In two phase III trials in patients with EGFR mutation-positive NSCLC, first-line afatinib significantly improved progression-free survival (PFS) and health-related quality of life versus standard-of-care chemotherapy. Moreover, in preplanned sub-analyses, afatinib significantly improved overall survival in patients harboring EGFR Del19 mutations. Afatinib has also demonstrated clinical activity in NSCLC patients who had progressed on erlotinib/gefitinib, particularly when combined with cetuximab, and offers ‘treatment beyond progression’ benefit when combined with paclitaxel versus chemotherapy alone. Furthermore, a recent phase III study demonstrated that PFS was significantly improved with afatinib versus erlotinib for the second-line treatment of patients with squamous cell carcinoma of the lung. The activity of afatinib in both first-line and relapsed/refractory settings may reflect its ability to irreversibly inhibit all ErbB family members. Afatinib has a well-defined safety profile with characteristic gastrointestinal (diarrhea, stomatitis) and cutaneous (rash/acne) adverse events.

Advances in molecular biology of lung disease: aiming for precision therapy in non-small cell lung cancer

Lung cancer is the principal cause of cancer-related mortality in the developed world, accounting for almost one-quarter of all cancer deaths. Traditional treatment algorithms have largely relied on histologic subtype and have comprised pragmatic chemotherapy regimens with limited efficacy. However, because our understanding of the molecular basis of disease in non-small cell lung cancer (NSCLC) has improved exponentially, it has become apparent that NSCLC can be radically subdivided, or molecularly characterized, based on recurrent driver mutations occurring in specific oncogenes. We know that the presence of such mutations leads to constitutive activation of aberrant signaling proteins that initiate, progress, and sustain tumorigenesis. This persistence of the malignant phenotype is referred to as "oncogene addiction." On this basis, a paradigm shift in treatment approach has occurred. Rational, targeted therapies have been developed, the first being tyrosine kinase inhibitors (TKIs), which entered the clinical arena > 10 years ago. These were tremendously successful, significantly affecting the natural history of NSCLC and improving patient outcomes. However, the benefits of these drugs are somewhat limited by the emergence of adaptive resistance mechanisms, and efforts to tackle this phenomenon are ongoing. A better understanding of all types of oncogene-driven NSCLC and the occurrence of TKI resistance will help us to further develop second- and third-generation small molecule inhibitors and will expand our range of precision therapies for this disease.

First-Line Pemetrexed plus Cisplatin followed by Gefitinib Maintenance Therapy versus Gefitinib Monotherapy in East Asian Never-Smoker Patients with Locally Advanced or Metastatic Nonsquamous Non-Small Cell Lung Cancer: Final Overall Survival Results from a Randomized Phase 3 Study

INTRODUCTION

The primary analysis of this open-label, randomized, multicenter phase 3 study revealed no significant difference in progression-free survival between pemetrexed plus cisplatin followed by maintenance gefitinib (PC/G) and gefitinib monotherapy (G) in patients with advanced nonsquamous non-small cell lung cancer (NSCLC) and unknown epidermal growth factor receptor gene (EGFR) mutation status; however, the hazard ratio favored PC/G. This report describes the final overall survival (OS) results.

METHODS

Chemonaive, East Asian light ex-smokers/never-smokers with advanced nonsquamous NSCLC and unknown EGFR mutation status were randomized (1:1) to PC/G (n = 118) or G (n = 118). EGFR mutation status was retrospectively determined for 76 patients, 52 (68.4%) of whom had EGFR-mutated tumors (exon 19 deletions in 26 and L858R point mutation in 24). OS was analyzed by the Kaplan-Meier method. The study was registered at ClinicalTrials.gov (NCT01017874).

RESULTS

Median OS was similar in the PC/G (26.9 months) and G (27.9 months) groups (hazard ratio = 0.94, 95% confidence interval: 0.68-1.31, p = 0.717). Median OS was longer with PC/G than with G in patients with EGFR wild-type tumors (28.4 versus 8.9 months) and longer with G than with PC/G in patients with EGFR-mutated tumors (45.7 versus 32.4 months), especially those with exon 19 deletions. Second-line postdiscontinuation therapy was common and included chemotherapy (PC/G, 41 of 118 [34.7%]; G, 73 of 118 [61.9%]) and rechallenge with an EGFR tyrosine kinase inhibitor (PC/G, 27 of 118 [22.9%]; G, 9 of 118 [7.6%]).

CONCLUSIONS

The progression-free survival and OS results from this study further demonstrate the importance of determining EGFR mutation status to select the most appropriate first-line treatment for patients with advanced NSCLC.

Subsequent treatment of epidermal growth factor receptor-tyrosine kinase inhibitor failure in patients with advanced lung adenocarcinoma

BACKGROUND

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) effectively treat advanced non-small cell lung cancer with EGFR-mutation. However, most patients develop acquired resistance without effective therapy subsequent to EGFR-TKI failure. We evaluated the efficacy of subsequent treatment strategies for EGFR-TKI resistance.

METHODS

We retrospectively analyzed 240 patients with advanced lung adenocarcinoma with EGFR-TKI failure and following subsequent treatment. According to the first subsequent strategies after EGFR-TKI failure, patients were divided into groups of EGFR-TKI continuation (21 cases), EGFR-TKI continuation with chemotherapy (23 cases), chemotherapy alone (143 cases), and best supportive care (BSC) (53 cases).

RESULTS

Except for 53 cases of BSC, the disease control rates (DCR) of the remaining 187 patients in the EGFR-TKI continuation, EGFR-TKI continuation with chemotherapy, and chemotherapy alone groups were 66.7%, 73.9%, and 44.8%, respectively. The median post-progression progression-free survival (PFS) for the three groups was 3.0, 3.3, and 2.0 months, respectively. The DCR for the EGFR-TKI continuation with chemotherapy group was significantly higher than the chemotherapy alone group (P = 0.006). The post-progression PFS of the EGFR-TKI continuation with chemotherapy group was significantly longer than the chemotherapy alone group (P = 0.037). The median overall survival in the EGFR-TKI continuation, EGFR-TKI continuation with chemotherapy, chemotherapy alone, and BSC groups were 6.9, 11.6, 8.8, and 0.9 months, respectively. Compared to the BSC group, all groups achieved a survival benefit (P < 0.001).

CONCLUSIONS

EGFR-TKI continuation with chemotherapy could provide benefits for patients with acquired resistance to EGFR-TKI.

Systemic Therapy for Stage IV Non-Small-Cell Lung Cancer: American Society of Clinical Oncology Clinical Practice Guideline Update

PURPOSE

To provide evidence-based recommendations to update the American Society of Clinical Oncology guideline on systemic therapy for stage IV non-small-cell lung cancer (NSCLC).

METHODS

An Update Committee of the American Society of Clinical Oncology NSCLC Expert Panel based recommendations on a systematic review of randomized controlled trials from January 2007 to February 2014.

RESULTS

This guideline update reflects changes in evidence since the previous guideline.

RECOMMENDATIONS

There is no cure for patients with stage IV NSCLC. For patients with performance status (PS) 0 to 1 (and appropriate patient cases with PS 2) and without an EGFR-sensitizing mutation or ALK gene rearrangement, combination cytotoxic chemotherapy is recommended, guided by histology, with early concurrent palliative care. Recommendations for patients in the first-line setting include platinum-doublet therapy for those with PS 0 to 1 (bevacizumab may be added to carboplatin plus paclitaxel if no contraindications); combination or single-agent chemotherapy or palliative care alone for those with PS 2; afatinib, erlotinib, or gefitinib for those with sensitizing EGFR mutations; crizotinib for those with ALK or ROS1 gene rearrangement; and following first-line recommendations or using platinum plus etoposide for those with large-cell neuroendocrine carcinoma. Maintenance therapy includes pemetrexed continuation for patients with stable disease or response to first-line pemetrexed-containing regimens, alternative chemotherapy, or a chemotherapy break. In the second-line setting, recommendations include docetaxel, erlotinib, gefitinib, or pemetrexed for patients with nonsquamous cell carcinoma; docetaxel, erlotinib, or gefitinib for those with squamous cell carcinoma; and chemotherapy or ceritinib for those with ALK rearrangement who experience progression after crizotinib. In the third-line setting, for patients who have not received erlotinib or gefitinib, treatment with erlotinib is recommended. There are insufficient data to recommend routine third-line cytotoxic therapy. Decisions regarding systemic therapy should not be made based on age alone. Additional information can be found at http://www.asco.org/guidelines/nsclc and http://www.asco.org/guidelineswiki.

The Evolution of Therapies in Non-Small Cell Lung Cancer

The landscape of advanced non-small lung cancer (NSCLC) therapies has rapidly been evolving beyond chemotherapy over the last few years. The discovery of oncogenic driver mutations has led to new ways in classifying NSCLC as well as offered novel therapeutic targets for anticancer therapy. Targets such as epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) gene rearrangements have successfully been targeted with appropriate tyrosine kinase inhibitors (TKIs). Other driver mutations such as ROS, MET, RET, BRAF have also been investigated with targeted agents with some success in the early phase clinical setting. Novel strategies in the field of immune-oncology have also led to the development of inhibitors of cytotoxic T lymphocyte antigen-4 (CTLA-4) and programmed death-1 receptor (PD-1), which are important pathways in allowing cancer cells to escape detection by the immune system. These inhibitors have been successfully tried in NSCLC and also now bring the exciting possibility of long term responses in advanced NSCLC. In this review recent data on novel targets and therapeutic strategies and their future prospects are discussed.

Overcoming resistance to targeted therapies in NSCLC: current approaches and clinical application

The discovery that a number of aberrant tumorigenic processes and signal transduction pathways are mediated by druggable protein kinases has led to a revolutionary change in nonsmall cell lung cancer (NSCLC) treatment. Epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK) are the targets of several tyrosine kinase inhibitors (TKIs), some of them approved for treatment and others currently in clinical development. First-generation agents offer, in target populations, a substantial improvement of outcomes compared with standard chemotherapy in the treatment of advanced NSCLC. Unfortunately, drug resistance develops after initial benefit through a variety of mechanisms. Novel generation EGFR and ALK inhibitors are currently in advanced clinical development and are producing encouraging results in patients with acquired resistance to previous generation agents. The search for new drugs or strategies to overcome the TKI resistance in patients with EGFR mutations or ALK rearrangements is to be considered a priority for the improvement of outcomes in the treatment of advanced NSCLC.

Afatinib: a second-generation EGF receptor and ErbB tyrosine kinase inhibitor for the treatment of advanced non-small-cell lung cancer

First-generation reversible EGF receptor (EGFR) tyrosine kinase inhibitors (TKIs) changed our understanding of advanced non-small-cell lung cancer biology and behavior. The presence of sensitizing EGFR mutations in advanced non-small-cell lung cancer defines a subset of patients with a better prognosis and sensitivity to EGFR-TKIs with a better response rate, progression-free survival, quality of life and symptom control than with chemotherapy in the first-line therapy setting. However, current EGFR-TKIs show minimal responses in EGFR wild-type patients or with acquired TKI resistance mediated through the EGFR T790M allele. Afatinib is an irreversible pan-ErbB-TKI, active against wild-type EGFR, sensitizing and T970M-mutant EGFR, ErbB2 and ErbB4 receptors, and represents a step change between reversible first-generation and future irreversible highly specific third-generation EGFR-TKIs. Here, we review the clinical development of afatinib through the LUX-Lung trials portfolio highlighting benefits and toxicities.

Prognostic factors in non-small cell lung cancer patients who are recommended to receive single-agent chemotherapy (docetaxel or pemetrexed) as a second- or third-line chemotherapy: in the era of oncogenic drivers and molecular-targeted agents

PURPOSE

Docetaxel or pemetrexed monotherapy is recommended either as a second-line treatment for non-small cell lung cancer (NSCLC) patients without EGFR mutation or ALK fusion genes or as a third-line treatment for patients with EGFR mutation or ALK fusion. However, efficacy and survival for these two settings have not been compared, leaving it unclear whether these two populations can be included in the same clinical trials. Moreover, prognostic factors for patients who are recommended to receive docetaxel/pemetrexed monotherapy are largely unknown.

METHODS

Docetaxel or pemetrexed was administered to 67 EGFR wild-type patients as a second-line treatment following one platinum-based combination chemotherapy and to 17 EGFR mutant patients as a third-line treatment following EGFR tyrosine kinase inhibitors and one platinum-based combination chemotherapy. Docetaxel and pemetrexed were administered at 60 and 500 mg/m(2), respectively, every 3 weeks until disease progression, intolerable toxicity, or patient refusal. Overall survivals (OSs) between the two groups were compared using the log-rank test, and prognostic factors were evaluated via Cox's proportional hazards models.

RESULTS

The median OS was 345.5 days in the EGFR wild-type second-line group and 616 days in the EGFR mutant third-line group. Multivariate analyses revealed that the stage before first-line treatment, performance status, and EGFR status were significant prognostic factors.

CONCLUSIONS

When planning clinical studies of NSCLC patients recommended to receive docetaxel or pemetrexed as single-agent chemotherapy, the EGFR status and stage before first-line treatment should be considered as stratification factors of randomized clinical studies.

Delay of treatment change after objective progression on first-line erlotinib in epidermal growth factor receptor-mutant lung cancer

BACKGROUND

Erlotinib is a highly active epidermal growth factor receptor (EGFR) kinase inhibitor that is approved for first-line use in lung cancers harboring EGFR mutations. Anecdotal experience suggests that this drug may provide continued disease control after patients develop objective progression of disease (PD), although this has not been systematically studied to date.

METHODS

Patients who had Response Evaluation Criteria In Solid Tumors-defined PD who were participating in 3 prospective trials of first-line erlotinib in advanced lung cancer were studied retrospectively, and the progression characteristics were compared between patients with and without EGFR-sensitizing mutations. Factors were studied that influenced the time until treatment change (TTC), defined as the time from PD to the start of a new systemic therapy or death. The rate of tumor progression was assessed by comparing tumor measurements between the computed tomography scan obtained at the time of PD and the preceding scan.

RESULTS

In total, 92 eligible patients were studied, including 42 with and 50 without an EGFR-sensitizing mutation. The EGFR-mutant cohort had a slower rate of progression (P = .003) and a longer TTC (P < .001). Among the patients with EGFR-mutant cancers, 28 (66%) continued single-agent erlotinib after PD, and 21 (50%) were able to delay a change in systemic therapy for >3 months; only 2 patients received local debulking therapy during that period. Multivariate analysis of the patients with EGFR-mutant tumors demonstrated that a longer time to progression, a slower rate of progression, and a lack of new extrathoracic metastases were associated with a longer TTC.

CONCLUSIONS

A change in systemic therapy commonly can be delayed in patients with EGFR-mutant lung cancer who objectively progress on first-line erlotinib, particularly in those with a longer time to progression, a slow rate of progression, and a lack of new extrathoracic metastases.

Strategies to overcome resistance to tyrosine kinase inhibitors in non-small-cell lung cancer

The use of molecularly targeted agents has dramatically improved the prognosis of defined subsets of patients with non-small-cell lung cancer harboring somatically activated oncogenes, such as mutant EGFR or rearranged ALK. However, after initial marked responses to EGFR or ALK tyrosine kinase inhibitors (TKIs), almost all patients inevitably progress due to development of acquired resistance. Multiple molecular mechanisms of resistance have been identified; the best characterized are secondary mutations in the tyrosine kinase domain of the oncogene, such as T790M in EGFR and L1196M in ALK, which prevent target inhibition by the corresponding TKI. Other mechanisms include copy number gain of the ALK fusion gene and the activation of bypass signaling pathways that can maintain downstream proliferation and survival signals despite inhibition of the original drug target. Here, the authors provide an overview of the known mechanisms of resistance to TKIs and outline the therapeutic strategies, including new investigational agents and targeted therapies combinations, that have been developed to overcome resistance.

Clinical approaches to treat patients with non-small cell lung cancer and epidermal growth factor receptor tyrosine kinase inhibitor acquired resistance

The discovery of epidermal growth factor receptor activating mutations (EGFR Mut+) has determined a paradigm shift in the treatment of non-small cell lung cancer (NSCLC). In several phase III studies, patients with NSCLC EGFR Mut+ achieved a significantly better progression-free survival when treated with a first- (gefitinib, erlotinib) or second-generation (afatinib) EGFR tyrosine kinase inhibitor (TKI) compared with standard chemotherapy. However, despite these impressive results, most patients with NSCLC EGFR Mut+ develop acquired resistance to TKIs. This review will discuss both the mechanisms of resistance to TKIs and the therapeutic strategies to overcome resistance, including emerging data on third-generation TKIs.

Tyrosine kinase inhibitors for epidermal growth factor receptor gene mutation-positive non-small cell lung cancers: an update for recent advances in therapeutics

The presence of activating gene mutations in the epidermal growth factor receptor of non-small cell lung cancer patients is predictive (improved progression-free survival and improved response rate) when treated with small molecule tyrosine kinase inhibitors such as gefitinib, erlotinib and afatinib. The two most common mutations that account for greater than 85% of all EGFR gene mutations are in-frame deletions in exon 19 (LREA deletions) and substitution in exon 21 (L858R). Exon 18 mutations occur much less frequently at about 4% of all EGFR gene mutations. Together, exon 19 deletion and exon 21 L858R gene substitution are present in about 10% of Caucasian patients and 20-40% of Asian patients with non-small cell lung cancer. T790M gene mutation at exon 20 is associated with acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitors. Early studies showed that activating EGFR gene mutations are most common in patients with adenocarcinoma histology, women, never smokers and those of Asian ethnicity. A recent multi-center phase III trial suggested that frontline epidermal growth factor receptor tyrosine kinase inhibitor therapy with afatinib is associated with improved progression-free survival compared to chemotherapy regardless of race. Moreover, guidelines now suggest EGFR gene mutation testing should be conducted in all patients with lung adenocarcinoma or mixed lung cancers with an adenocarcinoma component, regardless of characteristics such as smoking status, gender or race. The success of targeted therapies in non-small cell lung cancer patients has changed the treatment paradigm in metastatic non-small cell lung cancer. However, despite a durable response of greater than a year, resistance to epidermal growth factor receptor tyrosine kinase inhibitors inevitably occurs. This mini-review describes the clinically relevant EGFR gene mutations and the efficacy/toxicity of small molecule epidermal growth factor receptor tyrosine kinase inhibitors as targeted therapies for these gene mutations. Therapeutic strategies to overcome resistance, including emerging and novel therapies, are discussed.

Gefitinib: a review of its use in adults with advanced non-small cell lung cancer

Gefitinib (Iressa®) is a selective small-molecule epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (EGFR TKI) indicated for the treatment of adults with locally advanced or metastatic non-small cell lung cancer (NSCLC) with activating mutations of EGFR tyrosine kinase. Large phase III or IV clinical trials in patients with locally advanced or metastatic NSCLC showed that gefitinib as first- or subsequent-line treatment significantly prolonged progression-free survival (PFS) and improved objective response rates and/or health-related quality of life parameters in patients with activating EGFR mutations and in clinically selected patients (e.g., Asian patients or never-smokers) who are more likely to harbour these mutations. Overall survival did not increase significantly with gefitinib, although post-study treatments may have had a confounding effect on this outcome. Gefitinib was generally well tolerated in these studies, with mild or moderate skin reactions, gastrointestinal disturbances and elevations in liver enzymes among the most common adverse reactions in gefitinib recipients; interstitial lung disease has also been reported in <6 % of gefitinib recipients. Compared with chemotherapy, gefitinib as first- or subsequent-line therapy provided similar or greater PFS benefit and was generally associated with fewer haematological adverse events, neurotoxicity, asthenic disorders, as well as grade ≥3 adverse events. Although the position of gefitinib with respect to other EGFR TKIs is not definitively established, current evidence indicates that gefitinib monotherapy is an effective and generally well-tolerated first- or subsequent-line treatment option for patients with NSCLC and activating EGFR mutations who have not received an EGFR TKI previously.

Current and Future Approaches in the Management of Non-Small-Cell Lung Cancer Patients With Resistance to EGFR TKIs

Metastatic non-small-cell lung cancer carries a dismal prognosis. However, the recognition of the predictive value of activating epidermal growth factor receptor (EGFR) mutations and the availability of tyrosine kinase inhibitors has markedly improved the prognosis of these patients, because treatment with these inhibitors induces rapid and robust responses. Unfortunately, the responses are not durable and resistance inevitably occurs after a median of 9 to 14 months. Although the management of resistant patients who harbor EGFR mutations is rapidly evolving, there are no conclusive guidelines regarding this issue. However, palliative cytotoxic chemotherapy is considered the standard of care for these patients. The elucidation of the mechanisms of acquired resistance has led to efforts to personalize the treatment approach. Promising results from early clinical trials using the third-generation inhibitors that specifically target the most common mechanism of resistance, the gatekeeper T790M mutation, provide the basis to look to the future with cautious optimism. Moreover, it has been shown that in some cases of oligoprogressive disease, aggressively treating all metastatic sites while continuing the targeted treatment could improve outcomes. Herein, we review the treatment strategies being evaluated that will shape the future management of these patients.

EGFR Mutation Positive Stage IV Non-Small-Cell Lung Cancer: Treatment Beyond Progression

Non-small-cell lung cancer (NSCLC) is the leading cause of death from cancer for both men and women. Chemotherapy is the mainstay of treatment in advanced disease, but is only marginally effective. In about 30% of patients with advanced NSCLC in East Asia and in 10–15% in Western countries, epidermal growth factor receptor (EGFR) mutations are found. In this population, first-line treatment with the tyrosine kinase inhibitors (TKIs) erlotinib, gefitinib, or afatinib is recommended. The treatment beyond progression is less well-defined. In this paper, we present three patients, EGFR mutation positive, with local progression after an initial treatment with TKI. These patients were treated with local radiotherapy. TKI was temporarily stopped and restarted after radiotherapy. We give an overview of the literature and discuss the different treatment options in case of progression after TKI: TKI continuation with or without chemotherapy, TKI continuation with local therapy, alternative dosing or switch to next-generation TKI or combination therapy. There are different options for treatment beyond progression in EGFR mutation positive metastatic NSCLC, but the optimal strategy is still to be defined. Further research on this topic is ongoing.