 Many patients who receive EGFR inhibitors develop an acneiform rash and the severity of the rash is associated with good outcomes from treatment. Several of these studies have demonstrated no correlation between the intensity or percentage of tumor cells staining for EFUR expression and response to therapy. However, a Phase II study, at the University of Colorado, of cetuximab added to standard first-line treatment of NSCLC revealed 610 responders developed the rash within 2 weeks of initiating treatment Personal Communication, Dugan, et al. BMS. Therefore, early development of rash may be a clinically useful marker of subsequent response and novel approaches to the identification of biological markers for this phenotype prior to initiation of therapy may be helpful in subsequent determination of which patients will most likely benefit from EGFR inhibitor therapy. 