When comparing the ratios of overall tumor exposure (area under the curve, AUC07d) of all three analytes between high-HER2 and low-HER2 tumors (Figure 2C), it was observed that there was ~12-fold higher exposure of total trastuzumab, ~1.6-fold higher exposure of unconjugated MMAE, and ~1.8-fold higher exposure of total MMAE in N87 tumors compared to the GFP-MCF7 tumors. The gene discussed is ERBB2; the disease is neoplasm.