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Efficacy of afatinib, an irreversible ErbB family blocker, in the treatment of intracerebral metastases of non-small cell lung cancer in mice.

ABSTRACT: Few effective therapeutic options are currently available for the treatment of non-small cell lung cancer (NSCLC) with brain metastases (BM). Recent evidence shows that NSCLC patients with BMs respond well to afatinib, but little is known about the underlying mechanisms. In this study, we evaluated the efficacy of afatinib in treatment of BMs in mice and investigated whether afatinib could actively penetrate the brain-blood barrier and bind to its target. NSCLC BM model was established in nude mice by intracerebral injection of PC-9.luc cells. The tumors were measured weekly using in vivo quantitative bioluminescence. The mice are administrated afatinib (15, 30 mg·kg-1·d-1, ig) for 14 d. The antitumor efficacy of afatinib was determined by tumor growth inhibition (TGI), which was calculated as [1-(change of tumor volume in treatment group/control group)×100]. Pharmacokinetic characteristics were measure in mice receiving a single dose of afatinib (30 mg/kg, ig). Pharmacodynamics of afatinib was also assessed by detecting the expression of pEGFR (Tyr1068) in brain tumor foci using immunohistochemistry. Administration of afatinib (15, 30 mg·kg-1·d-1) dose-dependently inhibited PC-9 tumor growth in the brain with a TGI of 90.2% and 105%, respectively, on d 14. After administration of afatinib (30 mg/kg), the plasma concentration of afatinib was 91.4±31.2 nmol/L at 0.5 h, reached a peak (417.1±119.9 nmol/L) at 1 h, and was still detected after 24 h. The cerebrospinal fluid (CSF) concentrations followed a similar pattern. The T1/2 values of afatinib in plasma and CSF were 5.0 and 3.7 h, respectively. The AUC(0-24 h) values for plasma and CSF were 2375.5 and 29.1 nmol/h, respectively. The plasma and CSF concentrations were correlated (r=0.844, P<0.01). Pharmacodynamics study showed that the expression levels of pEGFR were reduced by 90% 1 h after afatinib administration. The Emax was 86.5%, and the EC50 was 0.26 nmol/L. A positive correlation between CSF concentrations and pEGFR modulation was revealed. Afatinib penetrates the BBB in NSCLC BM mice and contributes to the brain tumor response. The CSF exposure level is correlated with the plasma level, which in turn is correlated with the modulation of pEGFR in the tumor tissues. The results support for the potential application of afatinib in NSCLC patients with BMs.

SUBMITTER: Zhang SR

PROVIDER: S-EPMC5309749 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature

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Efficacy of afatinib, an irreversible ErbB family blocker, in the treatment of intracerebral metastases of non-small cell lung cancer in mice.

Zhang Shi-Rong SR Zhu Lu-Cheng LC Jiang Yan-Ping YP Zhang Jing J Xu Ru-Jun RJ Xu Ya-Si YS Xia Bing B Ma Sheng-Lin SL

Acta pharmacologica Sinica 20161114 2

Few effective therapeutic options are currently available for the treatment of non-small cell lung cancer (NSCLC) with brain metastases (BM). Recent evidence shows that NSCLC patients with BMs respond well to afatinib, but little is known about the underlying mechanisms. In this study, we evaluated the efficacy of afatinib in treatment of BMs in mice and investigated whether afatinib could actively penetrate the brain-blood barrier and bind to its target. NSCLC BM model was established in nude m ...[more]

PMID: 27840411

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Project description:IntroductionEpidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are associated with favorable response in EGFR mutant lung cancer. Acquired resistance to reversible EGFR TKIs remains a significant barrier, and acquired EGFR T790M-mutation is the major mechanism. Second-generation irreversible EGFR TKI, afatinib, had also been approved for treating EGFR mutant lung cancer patients, but the mechanism of acquired resistance to afatinib has not been well studied.ResultsForty-two patients had tissue specimens taken after acquiring resistance to afatinib. The sensitizing EGFR mutation were all consistent between pre- and post-afatinib tissues. Twenty patients (47.6%) had acquired T790M mutation. T790M rate was not different between first-generation EGFR TKI-naïve patients (50%) and first-generation EGFR TKI-treated patients (46.4%) (p = 0.827). No clinical characteristics or EGFR mutation types were associated with the development of acquired T790M. No other second-site EGFR mutations were detected. There were no small cell or squamous cell lung cancer transformation. Other genetic mutations were not identified in PIK3CA, BRAF, HER2, KRAS, NRAS, MEK1, AKT2, LKB1 and JAK2.MethodsAfatinib-prescription record of our department of pharmacy from January 2007 and December 2014 was retrieved. We investigated patients with tissue specimens available after acquiring resistance to afatinib. Enrolled patients should have partial response or durable stable disease of treatment response to afatinib. Various mechanisms of acquired resistance to first-generation EGFR TKIs were evaluated. Histology and cytology were reviewed. EGFR, PIK3CA, BRAF, HER2, KRAS, NRAS, MEK1, AKT2, LKB1 and JAK2 genetic alterations were evaluated by sequencing. Statistical analysis was performed using Chi-square test and Kaplan-Meier method.ConclusionsT790M was detected in half of the lung adenocarcinoma after acquiring resistance to afatinib. T790M is still the major acquired resistance mechanism. First-generation EGFR TKI exposure did not influence the prevalence of T790M in lung cancer acquired resistance to afatinib.

Dataset Information

Efficacy of afatinib, an irreversible ErbB family blocker, in the treatment of intracerebral metastases of non-small cell lung cancer in mice.

Publications

Efficacy of afatinib, an irreversible ErbB family blocker, in the treatment of intracerebral metastases of non-small cell lung cancer in mice.

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