A method of treating acute myeloid leukemia, acute lymphoblastic leukemia, high risk myelodysplastic syndrome, and/or HR-MDS/AML in a mammal by administering a solid dispersion comprising an amorphous thienotriazolodiazepine compound of the Formula (1) wherein R1 is alkyl having a carbon number of 1-4, R2 is a hydrogen atom； a halogen atom； or alkyl having a carbon number of 1-4 optionally substituted by a halogen atom or a hydroxyl group, R3 is a halogen atom； phenyl optionally substituted by a halogen atom, alkyl having a carbon number of 1-4, alkoxy having a carbon number of 1-4 or cyano； -NR 5 -(CH 2)m R6 wherein R5 is a hydrogen atom or alkyl having a carbon number of 1-4, m is an integer of 0-4, and R6 is phenyl or pyridyl optionally substituted by a halogen atom.
