Quinazoline derivative having FLT3 inhibitory activity, and use thereof

A compound of the following Chemical Formula 7 or a pharmaceutically acceptable salt thereof:

• wherein, in Chemical Formula 7,
• R1 is
• R2 is selected from the group consisting of indazolyl, naphthalenyl, dihydrobenzofuranyl, pyridinyl, acetyl piperidine, phenyl which is unsubstituted or substituted with one or more non-hydrogen substituents, pyrazolyl which is unsubstituted or substituted with one or more non-hydrogen substituents, dihydroisoxazole which is unsubstituted or substituted with one or more non-hydrogen substituents,
• or a C3-C7 cycloalkyl, the non-hydrogen substituent in R2 is selected from the group consisting of
• phenyl, hydroxy, a C1-C6 alkyl, a C1-C6 halogenated alkyl, or a halogen atom,
• R3 is a hydrogen atom, hydroxy, a C1-C6 alkyl or a C1-C6 halogenated alkyl,
• R4 is a hydrogen atom, hydroxy or a C1-C6 alkyl, or is absent, here, X is a nitrogen or oxygen atom, and Y is a halogen or oxygen atom,
• R5 is a hydrogen atom, hydroxy, a halogen atom or a C1-C6 halogenated alkyl,
• R6 is a hydrogen atom, hydroxy or a C1-C6 alkyl, and
• a connecting line expressed as a double line () of a solid line and a dotted line represents a single carbon-carbon bond or a double carbon-carbon bond.