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The prognosis of patients with metastatic colorectal cancer (mCRC) remain poor despite the impressive improvement of treatments observed over the last 20 years that led to an increase in median overall survival from 6 mo, with the only best supportive care, to approximately 30 mo with the introduction of active chemotherapy drugs and targeted agents. The monoclonal antibodies (moAbs) cetuximab and panitumumab, directed against the epidermal growth factor receptor (EGFR), undoubtedly represent a major step forward in the treatment of mCRC, given the relevant efficacy in terms of progression-free survival, overall survival, response rate, and quality of life observed in several phase III clinical trials among different lines of treatment. However, the anti-EGFR moAbs were shown only to be effective in a subset of patients. For instance, KRAS and NRAS mutations have been identified as biomarkers of resistance to these drugs, improving the selection of patients who might derive a benefit from these treatments. Nevertheless, several other alterations might affect the response to these drugs, and unfortunately, even the responders eventually become resistant by developing secondary (or acquired) resistance in approximately 13-18 mo. Several studies highlighted that the landscape of responsible alterations of both primary and acquired resistance to anti-EGFR drugs biochemically converge into MEK-ERK and PIK3CA-AKT pathways. In this review, we describe the currently known mechanisms of primary and acquired resistance to anti-EGFR moAbs together with the various strategies evaluated to prevent, overcame or revert them.

Treatment of unselected patients with advanced non-small cell lung cancer (NSCLC) receiving third-generation platinum-based chemotherapy has reached a plateau of effectiveness. Histology and molecular analyses are the cornerstone in the initial diagnosis of NSCLC and are key determinants to address the appropriate strategy of treatment. In non-squamous histology the combination of cisplatin plus pemetrexed or carboplatin plus paclitaxel plus bevacizumab are considered today the best regimens yielding better activity and efficacy. Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), such as gefitinib, erlotinib or afatinib are the standard-of-care for patients with advanced NSCLC harbouring activating EGFR mutations. The identification of anaplastic lymphoma kinase (ALK) rearrangements in 2-5% of NSCLC patients led to the rapid clinical development of its oral TKI, crizotinib, also targeting the proto-oncogene MET and ROS1. The results reported from the first phase III trial showed superiority of crizotinib compared with standard chemotherapy in second-line treatment of ALK-positive NSCLC, which was recently approved in several countries in this setting. Unfortunately, after initial activity of crizotinib, patients will ultimately develop acquired resistances within 1 or 2 years of therapy. A second generation of ALK inhibitors, such as LDK378, alectinib and AP26113 may represent a promising treatment approach: they are under investigation with very promising early results. This review discusses ALK rearrangements, the clinical development and use of crizotinib, and other ALK-TKIs in advanced NSCLC.

Platinum-based doublets are the standard first-line therapy for patients with advanced non-small-cell lung cancer, with approximately a third of patients obtaining an objective response with first-line chemotherapy and another 20-30% achieving temporary disease stabilization. However, all patients inevitably experience disease progression. Three agents are approved for treating patients who progress after one prior regimen: docetaxel, pemetrexed and erlotinib. Erlotinib is the only agent approved for use in the third-line setting. Although these agents have yielded similar outcomes in terms of anti-tumor activity and efficacy, they have different toxicity profiles, and some factors that can help in the choice among them have begun to emerge, such as smoking history and histotype. Several new molecularly targeted agents have shown activity in Phase II trials and may be integrated into second-line therapy as single agents or in combination with current agents in the future. In particular, the most encouraging data in this clinical setting have been reported with the antiangiogenetic drugs bevacizumab (already approved for use in the first-line setting), vandetanib and sunitinib. Phase III trials with these agents are ongoing.

Small-cell lung cancer (SCLC) accounts for almost 15% of lung carcinomas. Chemotherapy is the cornerstone of treatment of patients with SCLC. In limited disease, median survival is about 12-20 months, with no more than 6%-12% of patients surviving beyond 5 years. In extensive disease, median survival is 7-12 months, with < 5% of patients living beyond 2 years and a 5-year survival rate of just 2%. Several therapeutic approaches have been used in an attempt to improve the outcome of SCLC. Among these, a better understanding of tumor biology and the subsequent development of novel therapeutic strategies have been identified as a possible approach for increasing the survival rate of patients with SCLC. Several targeted agents have been introduced into clinical trials in SCLC, and a few phase III studies, including matrix metalloproteinase inhibitors, thalidomide, and vaccines, have already produced definitive results. Currently, negative results are more commonly reported than positive ones. However, this first generation of clinical trials represents only the beginning of clinical research in this field. To date, no targeted therapy has been approved for use in the treatment of patients with SCLC. Nevertheless, clinical research in this field is still in progress considering that several new targeted agents, such as antiangiogenic agents and mammalian target of rapamycin inhibitors, offer a promise of improved outcomes. This review will focus on the reported results and the future development of the main novel biologic agents for the treatment of patients with SCLC.