The present invention provides an in vitro method for selecting a patient affected with a tumor for a treatment with an antitumor compound, wherein the method comprises a step of measuring the expression level of CDA (Cytidine Deaminase) in a cancer sample from said patient. When the CDA expression level of a cancer sample is lower than the reference expression level, it is indicative that the patient is suitable for a treatment with an antitumor compound selected from the group consisting of the compounds of table 4, in particular aminoflavone. Alternatively, when the CDA expression level of a cancer sample is higher than the reference expression level, it is indicative that the patient is suitable for a treatment with an antitumor compound selected from the group consisting of the compounds of table 3, in particular dasatinib.