Results of Multivariate Regression Analyses.

From the multivariate regression analyses three variables were found to be independently associated with gefitinib sensitivity and are listed in descending order of importance. The response variable is the log10(IC50) values of gefitinib.After adjusting for the effects of EGFR and HER2 copy numbers, the EGFR mutation status is significantly associated with gefitinib sensitivity as indicated in the ��Estimate�� column of the Table. The association coefficient is ?1.5, which means after adjusting for EGFR and HER2 copy number effects, the IC50 for EGFR wild type cell lines is 32 fold higher that that of EGFR mutation cell lines.After adjusting for the effects of EGFR mutation and HER2 copy numbers, the EGFR copy number is significantly associated with gefitinib sensitivity. The association coefficient is ?0.07, which means after adjusting for EGFR mutation and HER2 copy number effects, the IC50 will decrease 0.85 fold when EGFR relative copy number increases 1 unit.After adjusting for the effects of EGFR mutation and EGFR copy numbers, the HER2 copy number is significantly associated with gefitinib sensitivity. The association coefficient is ?0.01, which means after adjusting for EGFR mutation and EGFR copy number effects, the IC50 will decrease 0.98 fold when HER2 relative copy number increases 1 unit.*to the base 10.