Imatinib, a tyrosine kinase inhibitor, is primarily used to treat chronic myeloid leukemia,40 whereas toremifene, a selective non-steroidal estrogen receptor modulator, is administered to treat breast cancer.41 Clozapine is an anti-psychotic drug used in the treatment of severely ill patients with schizophrenia. Here, ESR1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.