Biomarkers and IHC
tumor
TUMOR
Following an initial 1 week of DS‐1205c monotherapy, plasma levels of soluble AXL increased from the baseline level by approximately 1.5‐fold. Although most patients showed increases in soluble AXL plasma levels, increases were not dose dependent and no additional increases were observed during combination therapy with gefitinib. Due to small patient numbers, a correlation between an increase in soluble AXL plasma levels and efficacy was not clear. No significant changes of either IL‐8 or osteopontin from baseline levels in plasma were observed in response to DS‐1205c.At baseline, immunohistochemical analysis showed that 16 of 17 evaluated tumor cell samples were negative for AXL, and 1 showed AXL‐positive staining in around 60% of tumor cells. In contrast, in the portion of stromal nontumor cells in those samples, AXL‐positive staining was observed in fibroblasts (