The first such marker is RRM1, which can predict resistance to gemcitabine.8 The overexpression of ERCC1 can lead to resistance to platinum drugs.9,10 The expression of TS can predict resistance to 5FU.7,11,12 Based on the tumor biomarker profile, the algorithm outlined in Figure 1 was used to assign patients to one of seven possible “doublet” chemotherapy combinations. The gene discussed is TYMS; the disease is neoplasm.