Compound 22b represents a novel chemical scaffold class for receptor-interacting protein kinase 1 (RIPK1) inhibitors [1
]. It has shown anti-metastasis activity in the experimental B16 melanoma lung metastasis model. The molecular mechanism underlying this effect is identified as inhibition of tumour-dependent RIPK1-induced programmed necrosis (necroptosis) of vascular endothelial cells, which facilitates tumour cell extravasation and metastasis. Compound 22b is a type II kinase inhibitor that interacts with the inactive conformation (DFG-out) of the RIPK1 kinase domain.