Protein kinases including mitogen-activated protein kinase (MAPK) govern fundamental cellular signaling network such as proliferation, differentiation, and survival. Overactivated kinases caused by mutations result in various diseases such as cancer and small molecule kinase inhibitors have been discovered for targeted therapy. Chronic myelogenous leukemia is a myeloproliferative disorder characterized at the molecular level by the expression of Bcr-Abl, a 210 kD fusion protein with deregulated tyrosine kinase activity. In an effort to find new pharmacological modalities to overcome resistance to ATP-binding-site inhibitors of Bcr–Abl, GNF-2 and GNF-5 were identified as selective allosteric Bcr–Abl inhibitors. Using solution NMR, X-ray crystallography, mutagenesis, it has been revealed that GNF-2 binds to the myristate-binding site of Abl, leading to changes in the structural dynamics of the ATP-binding site. GNF-5, an analogue of GNF-2 with improved pharmacokinetic properties, when used in combination with the ATP-competitive inhibitors imatinib or nilotinib, suppressed the emergence of resistance mutations in vitro, displayed additive inhibitory activity in biochemical and cellular assays against T315I mutant human Bcr–Abl and displayed in vivo efficacy against this recalcitrant mutant in a murine bone-marrow transplantation model. These results show that therapeutically relevant inhibition of Bcr–Abl activity can be achieved with inhibitors that bind to the myristate-binding site and that combining allosteric and ATP-competitive inhibitors can overcome resistance to either agent alone. We have published GNF-7, a multi-targeted kinase inhibitor, as a potent T315I-Bcr-Abl kinase inhibitor. Most recently, we found that GNF-7 potently and selectively inhibits mtNRAS-dependent cells in pre-clinical models of AML (acute myelogenous leukemia). Mechanistic analysis revealed that its effects were mediated through combined inhibition of ACK1 and MAP4K2 (GCK).
Aberrant RET kinase signaling plays critical roles in several human cancers such as thyroid carcinoma. The gatekeeper mutants (V804L or V804M) of RET are resistant to currently approved RET inhibitors such as cabozantinib and vandetanib. We, for the first time, identified a highly selective and extremely potent RET inhibitor, YHJ6097 rationally designed. YHJ6097 inhibits strongly RET gatekeeper mutants and other clinically relevant RET mutants as well as wt-RET.