Regression analysis showing the positive correlation between number of months since the prior chemotherapy regimen (X axis) and the difference between initial and final CEA-specific T-cell responses in HLA-A2 positive patients (Y axis). Regression analysis showing the positive correlation between number of months since the prior chemotherapy regimen (X axis) and the difference between initial and final CEA-specific T-cell responses in HLA-A2 positive patients (Y axis). Margaret von Mehren et al. Clin Cancer Res 2001;7:1181-1191 ©2001 by American Association for Cancer Research