Biogen Inc. and C4 Therapeutics Inc. have disclosed proteolysis targeting chimera (PROTAC) compounds comprising a degradation signaling moiety such as E3 ubiquitin ligase-binding moiety covalently linked to a Bruton tyrosine kinase (BTK)-targeting moiety through a linker reported to be useful for the treatment of leukemia and lymphoma, multiple sclerosis, atopic dermatitis, rheumatoid arthritis and systemic lupus erythematosus.