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Background: Non-small cell lung cancer (NSCLC) harboring common epidermal growth factor receptor (EGFR) gene mutations (exon 19 deletion or exon 21 L858R) respond to EGFR tyrosine kinase inhibitors (EGFR-TKIs). The secondary T790 M mutation in exon 20 of the EGFR gene is the most common type of acquired resistance mutation. Several reports have also shown that other secondary mutations (L747S, D761Y and T854A), while uncommon, can induce acquired resistance to first-generation EGFR-TKIs. However, little is known about the anticancer activities of second- or third-generation EGFR-TKIs. Methods: Uncommon secondary mutations were introduced into Ba/F3 cells along with the sensitive EGFR L858R mutation (Ba/F3-L858R/L747S, Ba/F3-L858R/D761Y, and Ba/F3-L858R/T854A), and the sensitivities to various EGFR-TKIs were then investigated. Results: Both the Ba/F3-L858R/L747S and Ba/F3-L858R/D761Y cell lines exhibited weak resistances to first-generation reversible EGFR-TKIs, while the Ba/F3-L858R/T854A cell line exhibited a strong resistance. In contrast, irreversible EGFR-TKIs, especially third-generation EGFR-TKIs, were capable of overcoming these resistances. Western blot analyses demonstrated that gefitinib (first-generation) inhibited the phosphorylation of EGFR to a lesser extent in cells with these secondary mutations than in cells with the sensitive L858R mutation alone. In contrast, afatinib and osimertinib (second- and thirdgeneration) inhibited the phosphorylation of EGFR in cells with these secondary mutations to a similar extent as that seen in cells with the sensitive L858R mutation alone. Conclusions: Our experimental findings suggest that irreversible EGFR-TKIs, especially third-generation EGFR-TKIs, can be effective against uncommon secondary mutations and that switching to third-generation EGFR-TKIs could be a promising treatment strategy for patients with acquired resistance because of these uncommon secondary mutations. [ABSTRACT FROM AUTHOR]

Abstract: The most serious adverse reaction associated with treatment with epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) is drug-induced interstitial lung disease (ILD). Because EGFR-TKIs are key drugs for patients with non-small cell lung cancer who have somatic activating mutations of the epidermal growth factor receptor gene (EGFR mutations), several cases of retreatment with EGFR-TKIs after ILD induced by these drugs have been reported. Here, we present a 68-year-old man with lung adenocarcinoma and leptomeningeal metastases having an EGFR mutation who was retreated with erlotinib after erlotinib-induced ILD. He suffered no ILD recurrence and his leptomeningeal metastases dramatically improved. In addition to the present case, reports of nine patients who were retreated with EGFR-TKIs after ILD were found in the literature. Only one patient had recurrence of ILD (although seven were retreated at a reduced dose of EGFR-TKIs, including the patient with recurrence). In contrast, three patients had no recurrence of ILD even without dose-reduction. These reports suggest that dose-reduction plays a limited role in preventing recurrence. Many patients received corticosteroids during retreatment, but not the one with recurrence of ILD. This may suggest that corticosteroids can prevent recurrence due to their antiinflammatory properties. [Copyright &y& Elsevier]

Abstract: Purpose: The maximum tolerated dose (MTD) of erlotinib (150mg) is the approved daily dose. In contrast, the approved daily dose of gefitinib (250mg) is only one-third of its MTD. Significantly different adverse events have been associated with gefitinib and erlotinib. Experimental design: A retrospective investigation examining the adverse events and tolerances of 250mg daily gefitinib and 150mg daily erlotinib in Japanese patients with non-small cell lung cancer (NSCLC) was performed. Adverse events were assessed according to Common Terminology Criteria for Adverse Events version 3.0. To determine tolerance for each agent, failure was defined as dose reduction or discontinuation of the drug due to adverse events, and early failure as dose reduction or discontinuation due to adverse events before the first evaluation of response. Results: More adverse events including skin disorders, diarrhea, oral mucositis, asthenic conditions, anorexia, nausea, vomiting, and gastrointestinal bleeding were observed in the erlotinib group. Liver function test abnormalities and pneumonitis did not differ between the two groups. Based on multivariate analysis, failure, early failure, and discontinuation due to adverse events were independently associated with erlotinib use. Conclusion: Our data show that 150mg daily erlotinib was associated with more toxicity and less tolerability than 250mg daily gefitinib. [Copyright &y& Elsevier]

Purpose: We examined patients with advanced nonsquamous, non-small cell lung cancer (NSCLC) to evaluate epidermal growth factor receptor (EGFR) mutation status and serum C-reactive protein (CRP) for their associations with response to gefitinib therapy and for prognostic impacts. Methods: Serum levels of CRP from 79 Japanese patients with advanced nonsquamous NSCLC were measured before the start of gefitinib. We used the peptic nucleic acid-locked nucleic acid clamp method to determine their EGFR somatic mutation status. We evaluated the relationship between each independent clinicopathological variable and the response to gefitinib therapy and the risk factors associated with prognosis. Results: Having CRP-positive serum and having wild-type EGFR were both independent negative predictive factors for the response to gefitinib treatment by multivariate logistic regression model analysis. Having CRP-positive serum and having wild-type EGFR were significant independent negative prognostic factors for survival based on multivariate analysis. Conclusions: Having CRP-positive serum predicted a lack of response to gefitinib therapy independent of EGFR mutational status. Both CRP-positive serum and wild-type EGFR were independent poor prognostic factors in patients with nonsquamous NSCLC who received gefitinib therapy. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]