DCC-2036 (Rebastinib (DCC-2036)) is a conformational control Bcr-Abl inhibitor for Abl1(WT, IC50: 0.8 nM) and Abl1(T315I, IC50: 4 nM), also inhibits LYN, SRC, HCK, FGR, FLT3, KDR, and Tie-2, and low activity to c-Kit. Rebastinib aimed at the Angiopoietin2-Tie2 pathway.

Abl-1 (T315I):4 nM, Abl-1 (WT):0.8 nM

In a xenograft mouse model bearing Ba/F3-BCR-ABL1T315I leukemia cells, DCC-2036 (100 mg/kg/day, p.o.) significantly inhibits BCR-ABL1 signaling and notably prolongs the lifespan of the mice.

DCC-2036 exhibits antiproliferative activity against Ba/F3 cells expressing either wild-type or mutant BCR-ABL1, with IC50 values ranging from 2 to 150 nM. It also inhibits the proliferation of the Ph+ cell line K562 (IC50: 5.5 nM) and effectively induces apoptosis in Ba/F3 and K562 cells expressing BCR-ABL1. Notably, DCC-2036 selectively inhibits BCR-ABL positive cells by significantly suppressing CML cell lines compared to non-CML leukemia cell lines. It demonstrates potent non-ATP-competitive inhibition against unphosphorylated and phosphorylated ABL1 (IC50: 0.8/2 nM), unphosphorylated and phosphorylated mutant ABL1T315I (IC50: 1.4/5 nM), and the activation loop mutant ABL1H396P (IC50: 4 nM). Additionally, DCC-2036 inhibits SRC family kinases SRC/LYN/FGR/HCK and receptor TKs KDR/FLT3/TIE2 (IC50: 34/29/38/40/4/2/6 nM).

Assay of Abl1 kinase isoforms and determination of inhibitor potency: Activity of u-Abl1native is determined by following the production of ADP from the kinase reaction through coupling with the pyruvate kinase/lactate dehydrogenase system. In this assay, the oxidation of NADH (measured as a decreased A340 nM) is continuously monitored spectrophotometrically. The final reaction mixture (100 μL, in a 384-well Corning plate) is prepared as follows: An Abl1 kinase/coupled assay components mixture is prepared containing u-Abl1 kinase (1 nM), Abltide (EAIYAAPFAKKK, 0.2 mM), MgCl2 (9 mM), pyruvate kinase (~ 4 units), lactate dehydrogenase (~ 0.7 units), phosphoenol pyruvate (1 mM), and NADH (0.28 mM) in 90 mM Tris containing 0.1 % octyl-glucoside and 1 % DMSO, pH 7.5. Separately, an inhibitor mixture is prepared containing DCC-2036 serially diluted 3-fold in DMSO followed by dilution into buffer composed of 180 mM Tris, pH 7.5, containing MgCl2 (18 mM) and 0.2 % octyl-glucoside. Fifty μL of the inhibitor mixture is mixed with 50 μL of the above Abl1 kinase/coupled assay components mixture, which is then incubated at 30 °C for 2 hours before 2 μL of 25 mM ATP (500 μM, final) is added to start the reaction. The reaction is recorded every 2 minutes for 2.5 hours at 30 °C on a Polarstar Optima or Synergy2 plate reader. Reaction rate (slope) is calculated using the 1 to 2 hour time frame with reader's software. Percent inhibition is obtained by comparison of reaction rate with that of a DMSO control. IC50 values are calculated from a series of percent inhibition values determined at a range of inhibitor concentrations using GraphPad Prism. The kinase assay for Abl1T315I, p-Abl1native or Abl1H396P is assayed the same as above except that 2.2 nM Abl1T315I, 1 nM p-Abl1 native or 1.3 nM Abl1H396P is used. The above assay format is also used for kinases other than Abl1 with the exception of TIE2, for which a fluorescence polarization/Transcreener format is used.The assay conditions are the same as described above except that PolyE4Y (final 1 mg/mL) is used as the substrate and one hour preincubation is used.

Ba/F3 cells or primary Ph+ leukemia cells are plated in triplicate in 96-well plates containing test compounds. After 72 hours, viable cells are quantified by Resazurin or MTT assay. Cells are diluted in medium to be added to each well of a 96-well tissue culture-treated plate. All cells are incubated overnight and maintained in a humidified atmosphere at 37 °C and 5% CO2. Cells are treated the following day. Serum-free medium is used during treatment with DCC-2036. MTT is used to assess the viability of cells following treatment. Aliquots of 20 mL of stock MTT solution are added to each well containing 200 mL of medium (10% final solution) and incubated with the cells for 2 hours. Following incubation the medium is removed and 200 mL of dimethylsulfoxide added to solubilize the formazan crystals. The absorbance is read on the plate reader at 550 and 690 nm. A subtraction analysis of the dual wavelength is performed (D550 to D690) to increase accuracy of the measuremen(Only for Reference)