The identification of [11C]AZD3759 also provides an alternative to ABCB1/ABCG2-substrate radiolabeled EGFR inhibitors for peripheral tumor imaging and could be used to validate the hypothesis that ABCB1/ABCG2 interaction has been the key determinant in the failure of [11C]gefitinib and [18F]gefitinib for peripheral tumor imaging in preclinical models. The gene discussed is EGFR; the disease is neoplasm.