Conjugates of cereblon binding compounds and G12C mutant KRAS, HRAS or NRAS protein modulating compounds and methods of use thereof

A conjugate having the formula (I):

• or a pharmaceutically acceptable salt or stereoisomer thereof, wherein:
• X has the following structure:
• wherein:
• J is H or oxo;
• and
• is a bond to Y;
• Y is direct bond or a linker;
• B4 is N, CH or C—CN;
• R1 is aryl or heteroaryl;
• R3a is H or C1-C6 alkyl;
• and
• R4a is H or C1-C6 alkyl;
• wherein aryl and heteroaryl are optionally substituted with or one or more substituents selected from the group consisting of hydroxy, halo C1-C12 alkyl, C1-C12 haloalkyl, C1-C6 alkoxy and C3-C8 cycloalkyl.