Asciminib (ABL001)

ABL001 is a potent, selective BCR-ABL inhibitor that maintains activity across most mutations, including T315I, with a distinct, allosteric mechanism of action^[1]. ABL001 binds at a regulatory site typically occupied by a myristoyl group in wild-type ABL and inhibits ABL kinase activity through a mechanism distinct from catalytic site inhibitors^[2]. It binds to a pocket on the BCR-ABL kinase domain that is normally occupied by the myristoylated N-terminus of ABL1. Upon fusion with BCR, this myristoylated N-terminus that serves to autoregulate ABL1 activity is lost. ABL001 functionally mimics the role of the myristoylated N-terminus by occupying its vacant binding site and restores the negative regulation of the kinase activity. ABL001 selectively inhibits the growth of chronic myelogenous leukemia (CML) and Ph+ ALL cells with potencies ranging from 1-10 nM range while BCR-ABL-negative cell lines remained unaffected at concentrations 1000-fold higher^[1]. NMR and biophysical studies confirm that ABL001 binds potently (dissociation constant (Kd) = 0.5-0.8 nM) and selectively to the myristoyl pocket of ABL1 and induces the inactive C-terminal helix conformation. ABL001 lacks activity against more than 60 kinases, including SRC and is similarly inactive against G-protein-coupled receptors, ion channels, nuclear receptors and transporters. Thus, ABL001 has high selectivity^[3].

KCL-22 cells are treated across a range of concentrations of ABL001 for 1 hour. Cells are harvested, protein lysates generated and analyzed with Western Blots.

In the KCL-22 mouse xenograft model, ABL001 displays potent anti-tumor activity with complete tumor regression observed and a clear dose-dependent correlation with pSTAT5 inhibition^[1]. ABL001 has moderate oral absorption, volume of distribution and half-life across all species. It as a single agent induces clinical anti-tumour activity and is well tolerated to date in a heavily pre-treated subgroup of patients with chronic myelogenous leukemia. As for the pharmacokinetics, pharmacodynamics and efficacy of ABL001, The CL (clearance) are 12, 16 and 6 mL/min/kg in mice, rats and dogs after a sigle iv dose of 1mg/kg, 2mg/kg and 1mg/kg, respectively. In mouse and dog, the T_1/2term are 1.1 and 3.7 h after a single i.v. dose at 1 mg/kg. In Rat, theT_1/2term is 2.7 h after a single i.v. dose at 2 mg/kg. The oral bioavailability of ABL001 in mouse and rat are 35% and 27% respectively when dosed at 30 mg/kg p.o. While in dogs the oral BA of ABL001 is 111% (15 mg/kg, p.o)^[3].