Abstract 4468: In vitro evaluation of multi-targeted kinase inhibitors in scirrhous gastric cancer cell lines by tyrosine kinase activity profiling

Abstract

Abstract Scirrhous-type gastric cancer, which accounts for about 10% of all gastric cancers, interacts with stromal cells with involvement of multiple growth factors. Although a fluoropyrimidine and platinum-containing regimen has been established as the standard chemotherapy, its efficacy is not satisfactory. Multi-targeted kinase inhibitors (MTKIs) such as sunitinib, sorafenib and pazopanib are active in renal cell carcinoma and are under clinical evaluation for other types of solid tumors. Here we examined the efficacy of the MTKIs in scirrhous gastric cancer cell lines and conducted an exploratory predictive biomarker study by tyrosine kinase activity profiling with PamChip® peptide micro-arrays. For 11 scirrhous and 8 non-scirrhous gastric cancer cell lines, the growth-inhibitory effect of the MTKIs sunitinib, sorafenib and pazopanib was evaluated by the MTT assay. For assessment of protein tyrosine kinase activity, cells were grown until semi-confluent, lysed, aliquoted and stored at -80°C until use. The tyrosine kinase activity of the lysates was measured in the absence and presence of the MTKIs on PamChip® peptide micro-arrays, containing 144 peptides derived from known human phosphorylation sites. Data analysis was carried out on inhibition profiles calculated for each MTKI by taking the log-ratio of peptide phosphorylation measured in the absence and presence of the MTKIs. Peptides with a low basal signal were excluded from the analysis. In the MTT assay, cell lines HSC-39, HSC-40A, KATO-III, HSC-43 (scirrhous) and SNU-16 (non-scirrhous) were sensitive to all three MTKIs with IC50 values < 1 μmol/L. The other 14 cell lines were classified as insensitive, except that three cell lines showed intermediate sensitivity to sunitinib with IC50 values < 3 μmol/L. Per peptide analysis showed a clear correlation between sensitivity to the MTKIs and in vitro inhibition of tyrosine kinase activity, with stronger response associated with more inhibition for a larger number of peptides (out of 100 peptides 48, 46, and 30 with p < 0.05 for sunitinib, sorafenib and pazopanib, respectively). Principal component analysis of the inhibition profiles revealed a clustering of sensitive vs. insensitive cell lines. Partial least squares-discriminant analysis was used to correlate the in vitro inhibition on the PamChip® micro-arrays to the sensitivity to the MTKIs. Good predictive performance with a misclassification rate < 20% was obtained with leave-one-out-cross-validation for all 3 inhibitors. MTKIs seem to be efficacious in a subset of scirrhous-type gastric cancer. Sunitinib showed the most potent growth-inhibitory effect, suggesting that it should be considered for further evaluation in scirrhous-type gastric cancer. Sensitivity to the MTKIs in the MTT assay could be correlated to the in vitro inhibition of kinase activity on the PamChip® peptide micro-array. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4468. doi:10.1158/1538-7445.AM2011-4468