Provided are a compound represented by Formula I, a pharmaceutically acceptable salt thereof, or a solvate thereof; and a pharmaceutical composition for cancer treatment and a pharmaceutical composition for a radiation sensitizer for cancer treatment, each pharmaceutical composition including the compound of Formula I, the pharmaceutically acceptable salt thereof, or the solvate thereof: wherein, in Formula I, —R1 is a C1-C3 alkoxy, ═O, or —OH, and —R2 is a 5- or 6-membered heteroaryl including 1 to 2 hetero atoms selected from nitrogen and oxygen, wherein a carbon of the 5- or 6-memberedheteroaryl is optionally substituted with a C1-C3 alkyl a C1-C3 alkoxy, or hydroxy.