The results showed that siRNA/PEI–ALA NPs successfully allowed the silencing of the BCR–ABL gene and BCR–ABL protein, thereby decreasing the growth on CML K562 cells in vitro and arresting the growth of localized tumors in a CML mouse model [84]. The gene discussed is ABL1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.