t. To determine whether chronic dietary exposure of AG 1478 suppresses EGFR activity, we examined total and phosphorylated protein levels of EGFR and ERK1/2 in liver lysates from wild type B6 mice fed either control or AG 1478 containing diets for 90 days. Liver samples from mice on AG 1478 injected with 5 g/g body weight EGF prior to sacrifice CAY10505 PI3K inhibitor to enhance phospho EGFR levels had reduced phospho EGFR and phospho ERK1/2 protein levels compared to controls, although total EGFR protein levels were similar. Previous reports demonstrated that dietary exposure to irreversible EGFR small molecule inhibitors like EKB 569 dramatically inhibit intestinal polyp formation in the ApcMin/ mouse model of familial colorectal cancer.
Therefore, to biologically and quantitatively test oral delivery of AG 1478, B6 ApcMin/ littermates of both sexes were weaned PD-183805 HER2 inhibitor onto chow containing AG 1478 or control chow with ad libitum feeding until 90 days of age after which their intestinal tracts were removed and the number of intestinal tumors counted. AG 1478 reduced polyp number by 45% compared to controls, almost identical to that reported for another reversible EGFR inhibitor EKI 785 under similar experimental conditions, but less than the 87% reduction in tumor number reported for EKB 569. This establishes the anti tumor efficacy of AG 1478 in ApcMin/ mice and demonstrates that oral delivery in the diet is an effective route. Chronic exposure to EGFR inhibitors results in mild physiological changes Female wild type B6 mice chronically exposed to small molecule EGFR inhibitors exhibited depressed weight gain over the course of exposure compared to controls.
After 90 days of treatment, EKB 569 treated mice had lost almost 6% of their starting body weight while their respective controls gained approximately 14% over baseline body weights. Although AG 1478 treated mice and their respective control groups gained weight over the course of the experiment, drug treatment greatly retarded weight gain. Alterations in body weight suggested that EGFR inhibitors may have affected feeding behaviors or energy expenditure, or caused mild toxicity at the drug concentrations used, however, there were no signs of dehydration, lethargy or ataxia in any treatment groups. Barrick et al. Page 5 Toxicol Appl Pharmacol. Author manuscript, available in PMC 2009 May 18.
NIH PA Author Manuscript NIH PA Author Manuscript NIH PA Author Manuscript There were no significant differences in wet heart, liver or kidney weight by treatment group.. However, EKB 569 treated female mice had increased wet lung weights, which remained significant when normalized for body weight. Since interstitial lung disease has been reported in a subset of patients treated with the EGFR small molecule inhibitor gefitinib, we used Masson,s Trichrome stain for collagen production and found that EKB 569 treated female mice were indistinguishable from the control group. Similarly, there was no difference in lung inflammation. However, the lungs from EGFR inhibitor treated mice did have a slightly higher level of proteinosis than that observed in the lungs from control mice. EGFR inhibition results in altered cardiovascular function due to increased LV apoptosis Chronic dietary exposure to EGFR small molecule inhibitors led to significantly altered cardiac function as assessed by TTE only in female mice, although the severity