- Source: Nemtabrutinib
Nemtabrutinib (MK-1026, formerly ARQ 531) is a small molecule drug that works as a reversible Bruton's tyrosine kinase (BTK) inhibitor; unlike other BTK inhibitors it also works against some mutated forms of BTK. Merck paid $2.7 billion to acquire the company ArQule and the drug, which is being investigated as a cancer treatment.