ABSTRACT
A high-throughput screen against Aurora A kinase revealed several promising submicromolar pyrimidine-aniline leads. The bioactive conformation found by docking these leads into the Aurora A ATP-binding site had a semicircular shape. Macrocycle formation was proposed to achieve novelty and selectivity via ring-closing metathesis of a diene precursor. The nature of the optimal linker and its size was directed by docking. In a kinase panel screen, selected macrocycles were active on other kinase targets, mainly FLT3, JAK2, and CDKs. These compounds then became leads in a CDK/FLT3/JAK2 inhibitor project. Macrocycles with a basic nitrogen in the linker form a salt bridge with Asp86 in CDK2 and Asp698 in FLT3. Interaction with this residue explains the observed selectivity. The Asp86 residue is conserved in most CDKs, resulting in potent pan-CDK inhibition by these compounds. Optimized macrocycles generally have good DMPK properties, and are efficacious in mouse models of cancer. Compound 5 (SB1317/TG02), a pan-CDK/FLT3/JAK2 inhibitor, was selected for preclinical development, and is now in phase 1 clinical trials.
Subject(s)
Cyclin-Dependent Kinases/antagonists & inhibitors , Drug Design , Heterocyclic Compounds, 4 or More Rings/pharmacology , Janus Kinase 2/antagonists & inhibitors , Nitrogen/chemistry , Protein Kinase Inhibitors/pharmacology , fms-Like Tyrosine Kinase 3/antagonists & inhibitors , Adenosine Triphosphate/metabolism , Animals , Binding Sites , Cyclin-Dependent Kinases/metabolism , Heterocyclic Compounds, 4 or More Rings/chemistry , High-Throughput Screening Assays , Humans , Inhibitory Concentration 50 , Janus Kinase 2/metabolism , Macrocyclic Compounds/chemistry , Macrocyclic Compounds/pharmacology , Mice , Models, Molecular , Protein Kinase Inhibitors/chemistry , Structure-Activity Relationship , fms-Like Tyrosine Kinase 3/metabolismABSTRACT
Herein, we describe the design, synthesis, and SAR of a series of unique small molecule macrocycles that show spectrum selective kinase inhibition of CDKs, JAK2, and FLT3. The most promising leads were assessed in vitro for their inhibition of cancer cell proliferation, solubility, CYP450 inhibition, and microsomal stability. This screening cascade revealed 26 h as a preferred compound with target IC(50) of 13, 73, and 56 nM for CDK2, JAK2 and FLT3, respectively. Pharmacokinetic (PK) studies of 26 h in preclinical species showed good oral exposures. Oral efficacy was observed in colon (HCT-116) and lymphoma (Ramos) xenograft studies, in line with the observed PK/PD correlation. 26h (SB1317/TG02) was progressed into development in 2010 and is currently undergoing phase 1 clinical trials in advanced leukemias and multiple myeloma.
Subject(s)
Antineoplastic Agents/chemical synthesis , Cyclin-Dependent Kinases/antagonists & inhibitors , Heterocyclic Compounds, 4 or More Rings/chemical synthesis , Janus Kinase 3/antagonists & inhibitors , fms-Like Tyrosine Kinase 3/antagonists & inhibitors , Administration, Oral , Animals , Antineoplastic Agents/pharmacokinetics , Antineoplastic Agents/pharmacology , Cell Line, Tumor , Cell Proliferation/drug effects , Computer Simulation , Dogs , Drug Screening Assays, Antitumor , Female , Heterocyclic Compounds, 4 or More Rings/pharmacokinetics , Heterocyclic Compounds, 4 or More Rings/pharmacology , Humans , Male , Mice , Mice, Inbred BALB C , Mice, Nude , Microsomes, Liver/metabolism , Models, Molecular , Neoplasm Transplantation , Rats , Stereoisomerism , Structure-Activity Relationship , Transplantation, HeterologousABSTRACT
Discovery of the activating mutation V617F in Janus Kinase 2 (JAK2(V617F)), a tyrosine kinase critically involved in receptor signaling, recently ignited interest in JAK2 inhibitor therapy as a treatment for myelofibrosis (MF). Herein, we describe the design and synthesis of a series of small molecule 4-aryl-2-aminopyrimidine macrocycles and their biological evaluation against the JAK family of kinase enzymes and FLT3. The most promising leads were assessed for their in vitro ADME properties culminating in the discovery of 21c, a potent JAK2 (IC(50) = 23 and 19 nM for JAK2(WT) and JAK2(V617F), respectively) and FLT3 (IC(50) = 22 nM) inhibitor with selectivity against JAK1 and JAK3 (IC(50) = 1280 and 520 nM, respectively). Further profiling of 21c in preclinical species and mouse xenograft and allograft models is described. Compound 21c (SB1518) was selected as a development candidate and progressed into clinical trials where it is currently in phase 2 for MF and lymphoma.
Subject(s)
Antineoplastic Agents/chemical synthesis , Bridged-Ring Compounds/chemical synthesis , Janus Kinase 2/antagonists & inhibitors , Lymphoma/drug therapy , Primary Myelofibrosis/drug therapy , Pyrimidines/chemical synthesis , fms-Like Tyrosine Kinase 3/antagonists & inhibitors , Adenosine Triphosphate/chemistry , Animals , Antineoplastic Agents/pharmacokinetics , Antineoplastic Agents/pharmacology , Binding Sites , Bridged-Ring Compounds/pharmacokinetics , Bridged-Ring Compounds/pharmacology , Cell Line, Tumor , Dogs , Drug Screening Assays, Antitumor , Humans , In Vitro Techniques , Mice , Mice, Nude , Microsomes, Liver/metabolism , Models, Molecular , Neoplasm Transplantation , Pyrimidines/pharmacokinetics , Pyrimidines/pharmacology , Rats , Solubility , Transplantation, Heterologous , Transplantation, HomologousABSTRACT
A series of alkenyl indazoles were synthesized and evaluated in Aurora kinase enzyme assays. Several promising leads were optimized for selectivity towards Aurora B. Excellent binding affinity and good selectivity were achieved with optimized compounds in isolated Aurora subfamily assays.
