The present invention relates to a pharmaceutical composition for the prevention or treatment of malignant tumors comprising an agent capable of inhibiting the expression of HMGCLL1 IS3, a pharmaceutical composition for the prevention or treatment of malignant tumors showing resistance to tyrosine kinase inhibitors, a method for determining drug resistance in a subject having a malignant tumor using the expression level of HMGCLL1 IS3, a composition and a kit for diagnosing drug resistance used for the method, a method for determining the probability of developing a malignant tumor using the expression level of HMGCLL1 IS3, a method for screening malignant tumor therapeutic agents using the expression level of HMGCLL1 IS3, a method for predicting prognosis of malignant tumors using the expression level of HMGCLL1 IS3, a composition and a kit for predicting the prognosis of malignant tumors including an agent capable of measuring the expression level of HMGCLL1 IS3, a method for determining drug resistance in a subject having a malignant tumor using SNP, a composition and a kit for diagnosing drug resistance used for the method, a method for determining the probability of developing a malignant tumor using SNP, a method for predicting the prognosis of malignant tumors using SNP, and a composition and a kit for predicting the prognosis of malignant tumors used for the method. The method of the present invention can effectively predict or diagnose drug tolerance of a patient with chronic myeloid leukemia or a malignant tumor, and can further be used for efficient drug therapy and drug development research.
