Pyrimidoheterocyclic compounds and application thereof

A method of treating KRAS-related diseases in a subject in need thereof, comprising administering to the subject a compound of represented by formula (III) or a pharmaceutically acceptable salt thereof,

• wherein
• T1 is selected from O and N;
• R1 is selected from C6-10 aryl and 5- to 10-membered heteroaryl, wherein the C6-10 aryl and 5- to 10-membered heteroaryl are optionally substituted with 1, 2, 3, 4 or 5 Ra;
• when T1 is O, R2 is not present;
• when T1 is N, R2 is selected from H, C1-3 alkyl, —C(═O)—C1-3 alkyl and —S(═O)2—C1-3 alkyl, wherein the C1-3 alkyl, —C(═O)—C1-3 alkyl and —S(═O)2—C1-3 alkyl are optionally substituted with 1, 2 or 3 Rb;
• R3 is C1-3 alkyl, wherein the C1-3 alkyl is optionally substituted with 1, 2 or 3 Rc;
• R4 is selected from H and C1-3 alkyl, wherein the C1-3 alkyl is optionally substituted with 1, 2 or 3 Rd;
• R5, R6 and R7 are each independently selected from H, F, Cl, Br, I, and C1-3 alkyl, wherein the C1-3 alkyl is optionally substituted with 1, 2 or 3 F;
• R8 is selected from H and CH3;
• Ra is each independently selected from F, Cl, Br, I, OH, NH2, CN, C1-3 alkyl, C1-3 alkoxy, C2-3 alkynyl and C2-3 alkenyl, wherein the C1-3 alkyl, C1-3 alkoxy, C2-3 alkynyl and C2-3 alkenyl are optionally substituted with 1, 2 or 3 F;
• Rb is each independently selected from F, Cl, Br, I, OH and NH2;
• Rc is each independently selected from 4- to 8-membered heterocycloalkyl, wherein the 4- to 8-membered heterocycloalkyl is optionally substituted with 1, 2 or 3 R;
• Rd is each independently selected from F, Cl, Br, I, OH, NH2 and CN;
• R is each independently selected from H, F, Cl, Br, OH, CN, C1-3 alkyl, C1-3 alkoxy and —C1-3 alkyl-O—C(═O)—C1-3 alkylamino;
• provided that when R1 is naphthyl, the naphthyl is optionally substituted with F, Cl, Br, OH, NH2, CF3, CH2CH3 and —C≡CH, and R5, R6 and R7 are each independently H.