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Non-small cell lung cancers (NSCLCs) harboring anaplastic lymphoma kinase (ALK) rearrangement are generally responsive to treatment with ALK tyrosine kinase inhibitors (TKIs). Crizotinib is the first-in-class TKI approved as front-line or salvage therapy in advanced ALK-rearranged NSCLC. Unfortunately, drug resistance develops after initial benefit, through a variety of mechanisms preserving or not the dominance of ALK signaling in the crizotinib-resistant state. The distinction between patients who preserve ALK dominance (secondary mutations alone or in combination with the number of copy ALK gain) compared to those that have decreased ALK dominance (separate or second oncogenic drivers, with or without concurrent persistence of the original ALK signal) is important in order to overcome resistance. Novel second-generation ALK inhibitors are currently in clinical development with promising results in ALK-rearranged NSCLC, as well as in crizotinib-resistant patients. Among these, ceritinib in the United States was granted by Food and Drug Administration accelerated approval for treatment of patients with ALK-rearranged, metastatic NSCLC with progression disease on or intolerance to crizotinib. Fully understanding of the different mechanisms of resistance to crizotinib will help us to continue to exploit personalized medicine approaches overcoming crizotinib resistance in these patients in the future. This review aims to discuss on strategy overcoming crizotinib-resistance starting from molecular mechanisms of resistance until novel ALK kinase inhibitors in ALK-rearranged NSCLC patients.

Lung cancer continues to be the leading cause of cancer death worldwide. Among lung cancers, 80% are classified as nonsmall- cell lung cancer (NSCLC) and are mostly diagnosed at an advanced stage (either locally advanced or metastatic disease). In the last years, the discovery of the pivotal role in tumorigenesis of the Epidermal Growth Factor Receptor (EGFR) has provided a new class of targeted therapeutic agents: the EGFR tyrosine kinase inhibitors (EGFR-TKIs). Since the first reports of an association between somatic mutations in EGFR exons 19 and 21 and response to EGFR-TKIs, treatment of advanced NSCLC has changed dramatically. Histologic profile, clinical characteristics, and mutational profile of lung carcinoma have all been reported as predictive factors of response to EGFR-TKIs and other targeted therapies. In advanced NSCLC patients harboring EGFR mutations, the use of EGFR TKIs in first-line treatment has provided an unusually large progression-free survival (PFS) benefit with a negligible toxicity when compared with cytotoxic chemotherapy in phase III randomized trials. Considering the findings regarding the excellent benefit and better safety profile of EGFR TKIs in EGFR mutation positive patients, these targeted therapeutic agents can be now considered as first-line treatment in this setting of patients. This review will discuss the new evidences in the role of EGFR-TKIs in the first-line treatment of advanced NSCLC and their implication in the current clinical decision-making.

Although substantial progress has been made in the therapeutic options currently available for patients with advanced non-small cell lung cancer (NSCLC), the overall survival profile remains poor for most patients. One of the strategies currently under investigation with the aim of prolonging survival in NSCLC patients is maintenance treatment with either a chemotherapeutic agent or a molecularly targeted agent after first-line chemotherapy. Moreover, this can consist of drugs included in the induction regimen or other noncrossresistant agents. With the currently available data, maintenance treatment with a different noncrossresistant agent (i.e., an early second-line treatment) is perhaps the most promising strategy. The drug chosen for the early second-line treatment should be a well-tolerated agent, considering that patients have just completed a particularly toxic platinum-based chemotherapy. Extending treatment with targeted agents rather than chemotherapy can provide longer progression-free and overall survival times without increasing toxicity. However, at the moment, only progression-free survival has been shown to be consistently superior with maintenance approaches; the evaluation of survival benefits is warranted before defining this strategy as a possible treatment option. Further studies are warranted to establish the role of maintenance chemotherapy in patients with advanced NSCLC.