Nemtabrutinib

Nemtabrutinib (MK-1026, formerly ARQ 531) is a small molecule drug is a Bruton's tyrosine kinase (BTK) inhibitor; unlike first generation BTK inhibitors it does not bind covalently|Covalent bond]], and inhibits the ATP binding site of BTK, and was designed to inhibit Src family kinases and kinases related to ERK signalling, along with BTK.^[1]

Nemtabrutinib

Clinical data
Other names	MK-1026; ARQ 531
Legal status
Legal status	Investigational
Identifiers
CAS Number	2095393-15-8
PubChem CID	129045720
UNII	JTZ51LIXN4
Chemical and physical data
Formula	C25H23ClN4O4
Molar mass	478.93 g·mol−1

Merck paid $2.7 billion to acquire the company ArQule and the drug, which at the time had just completed a Phase I clinical trial as a treatment for B-cell cancers.^[2] As of December 2024 Merck had started Phase III trials in chronic lymphocytic leukaemia and other blood cancers, and had finished a Phase I trial for kidney disease.^[3][4]