Efficacy and safety of icotinib in patients with brain metastases from lung adenocarcinoma

lnc-REG3G-3-1/miR-215-3p Promotes Brain Metastasis of Lung Adenocarcinoma by Regulating Leptin and SLC2A5

This study aims to explore the role and mechanism of specific lncRNA in brain metastasis (BM) from lung adenocarcinoma (LADC), providing an effective biomarker for early diagnosis and targeted therapy of BM from LADC. Based on the gene expression profiles of lncRNA and mRNA in LADC and BM tissues detected by Gene Chip, lnc-REG3G-3-1 was selected, and the related genes, including miR-215-3p, leptin, and SLC2A5, were identified by data analysis. Human LADC cell lines A549 and H1299 were cultured. Dual-luciferase and endogenous validation experiments were used to confirm the regulation between these genes. Real-time quantitative reverse transcription-polymerase chain reaction and Western blotting were used to detect gene expression. The tumor metastasis-related gene function of lnc-REG3G-3-1 and miR-215-3p in H1299 cells was verified by Transwell invasion, migration assays, and scratch testing. Nude mice xenograft tumors constructed with decreased lnc-REG3G-3-1 confirmed the influences on gene expression in vivo. lnc-REG3G-3-1 was highly expressed in BM tissues that originated from LADC compared with that in primary cancer tissues. lnc-REG3G-3-1 reduced miR-215-3p expression, thereby regulating the target genes leptin and SLC2A5 and the signaling pathways, taking part in the lnc-REG3G-3-1/miR-215-3p axis in the process of BM from LADC. lnc-REG3G-3-1, leptin, and SLC2A5 through regulating signaling pathways may be jointly involved in the regulation of the biological process of BM in patients with LADC.

Tyrosine kinase inhibitors show different anti-brain metastases efficacy in NSCLC: A direct comparative analysis of icotinib, gefitinib, and erlotinib in a nude mouse model

Brain metastasis is an increasing problem in non-small cell lung cancer (NSCLC) patients. Tyrosine kinase inhibitors (TKIs), including gefitinib, erlotinib, and icotinib, are reported to be effective in patients with brain metastases. However, direct comparative studies of the pharmacokinetics and efficacy of these three drugs in treating brain metastases are lacking. In the present investigation, we found that gefitinib penetrated the blood-tumor barrier and was distributed to brain metastases more effectively than erlotinib or icotinib in a nude mouse model. The 1-h ratio of brain metastases to plasma concentration for gefitinib, erlotinib, and icotinib was 9.82±1.03%, 4.83±0.25%, and 2.62±0.21%, respectively. The 2-h ratio of brain metastases to plasma concentration for gefitinib, erlotinib, and icotinib was 15.11±2.00%, 5.73±1.31%, and 2.69±0.31%, respectively. Gefitinib exhibited the strongest antitumor activity (p_{gefitinib vs. erlotinib}=0.005; p_{gefitinib vs. icotinib}=0.002). Notably, erlotinib exhibited a better treatment efficacy than icotinib (p=0.037). Consistently, immunohistochemical data showed that TKIs differentially inhibit the proliferation of metastatical tumor cells. Gefitinib and erlotinib markedly inhibited the proliferation of tumor cells, while there were more ki-67-positive tumor cells in the icotinib group. Additionally, gefitinib inhibited the phosphorylation of EGFR better than the other drugs, whereas pEGFR expression levels in erlotinib groups were lower than levels in the icotinib group (p_{gefitinib vs. erlotinib}=0.995; p_{gefitinib vs. icotinib}=0.028; p_{erlotinib vs. icotinib}=0.042).Altogether, our findings suggest that gefitinib and erlotinib can inhibit the growth of PC-9-luc brain tumors. Gefitinib demonstrated better antitumor activity and penetration rate in brain metastases than erlotinib or icotinib.

Role of epidermal growth factor receptor in lung cancer and targeted therapies

Lung cancer is the foremost cause of cancer-related deaths world-wide. Both, the major forms of lung cancer, Non-small cell lung cancer (NSCLC) and Small cell lung cancers (SCLC), have responded effectively to chemo-, radiation and adjuvant-therapies. Tumor removal through surgery also appeared as a good therapeutic strategy. However, these therapies demonstrated unfavourable side-effects, and hence novel drugs targeting lung cancer emerged essential. Activation of epidermal growth factor receptor (EGFR)-tyrosine kinases is a key reason for lung cancer progression. Two important strategies that have attenuated lung cancers were through treatments with EGFR-tyrosine kinase-inhibitors, erlotinib and gefitinib, or EGFR-neutralizing antibodies, cetuximab and bevacizumab. A major advantage with erlotinib and gefitinib was their role in second and third-line treatments following chemotherapies. Phase II/III clinical trials showed that combinatorial treatment of tyrosine kinase (TK)-inhibitors with chemotherapeutics, such as docetaxel and pemetrexed, caused significant improvements in progression-free survival and overall survival.Phase I and II clinical studies also revealed that combination of tyrosine kinase-inhibitors with the EGFR-targeted antibodies was an effective approach for treating lung cancer. However, patients having T790M-mutations within EGFR gene were resistant to erlotinib and gefitinib. Alternatively, another second-generation EGFR-tyrosine kinase-inhibitor, afatinib, that could circumvent the problem of drug resistance has been developed as lung cancer therapy. The current review focuses on the role of EGFR in lung cancer progression and apprises about the EGFR-targeted therapies. The review also informs on the adverse side-effects of these therapies and enlightens the need for safer therapeutic regimens to eradicate this dreaded disease.