title: Synthesis and biological evaluation of novel 2,4-diaminoquinazoline derivatives as SMN2 promoter activators for the potential treatment of spinal muscular atrophy.
abstract: Proximal spinal muscular atrophy (SMA) is an autosomal recessive disorder characterized by death of motor neurons in the spinal cord that is caused by deletion and/or mutation of the survival motor neuron gene ( SMN1). Adjacent to SMN1 are a variable number of copies of the SMN2 gene. The two genes essentially differ by a single nucleotide, which causes the majority of the RNA transcripts from SMN2 to lack exon 7. Although both SMN1 and SMN2 encode the same Smn protein amino acid sequence, the loss of SMN1 and incorrect splicing of SMN2 have the consequence that Smn protein levels are insufficient for the survival of motor neurons. The therapeutic goal of our medicinal chemistry effort was to identify small-molecule activators of the SMN2 promoter that, by up-regulating gene transcription, would produce greater quantities of full-length Smn protein. Our initial medicinal chemistry effort explored a series of C5 substituted benzyl ether based 2,4-diaminoquinazoline derivatives that were found to be potent activators of the SMN2 promoter; however, inhibition of DHFR was shown to be an off-target activity that was linked to ATP depletion. We used a structure-guided approach to overcome DHFR inhibition while retaining SMN2 promoter activation. A lead compound 11a was identified as having high potency (EC50 = 4 nM) and 2.3-fold induction of the SMN2 promoter. Compound 11a possessed desirable pharmaceutical properties, including excellent brain exposure and long brain half-life following oral dosing to mice. The piperidine compound 11a up-regulated expression of the mouse SMN gene in NSC-34 cells, a mouse motor neuron hybrid cell line. In type 1 SMA patient fibroblasts, compound 11a induced Smn in a dose-dependent manner when analyzed by immunoblotting and increased the number of intranuclear particles called gems. The compound restored gems numbers in type I SMA patient fibroblasts to levels near unaffected genetic carriers of SMA.
authors.affiliation: deCODE Chemistry Inc, Woodridge, IL 60517, USA.
authors.forename: John
authors.initials: J
authors.lastname: Thurmond
authors.forename: Matthew E R
authors.initials: ME
authors.lastname: Butchbach
authors.forename: Marty
authors.initials: M
authors.lastname: Palomo
authors.forename: Brian
authors.initials: B
authors.lastname: Pease
authors.forename: Munagala
authors.initials: M
authors.lastname: Rao
authors.forename: Louis
authors.initials: L
authors.lastname: Bedell
authors.forename: Monica
authors.initials: M
authors.lastname: Keyvan
authors.forename: Grace
authors.initials: G
authors.lastname: Pai
authors.forename: Rama
authors.initials: R
authors.lastname: Mishra
authors.forename: Magnus
authors.initials: M
authors.lastname: Haraldsson
authors.forename: Thorkell
authors.initials: T
authors.lastname: Andresson
authors.forename: Gisli
authors.initials: G
authors.lastname: Bragason
authors.forename: Margret
authors.initials: M
authors.lastname: Thosteinsdottir
authors.forename: Jon Mar
authors.initials: JM
authors.lastname: Bjornsson
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Coovert
authors.forename: Arthur H M
authors.initials: AH
authors.lastname: Burghes
authors.forename: Mark E
authors.initials: ME
authors.lastname: Gurney
authors.forename: Jasbir
authors.initials: J
authors.lastname: Singh
mesh_terms: D000634:Aminoquinolines / Q000138:chemical synthesis* / Q000493:pharmacokinetics / Q000494:pharmacology; D000818:Animals; D001682:Biological Availability; D001812:Blood-Brain Barrier / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D005493:Folic Acid Antagonists / Q000138:chemical synthesis / Q000737:chemistry; D006579:Heterozygote; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D008968:Molecular Conformation; D009134:Muscular Atrophy, Spinal / Q000188:drug therapy*; D009419:Nerve Tissue Proteins / Q000235:genetics*; D010539:Permeability; D010880:Piperidines / Q000138:chemical synthesis* / Q000493:pharmacokinetics / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011799:Quinazolines / Q000138:chemical synthesis* / Q000493:pharmacokinetics / Q000494:pharmacology; D016601:RNA-Binding Proteins / Q000235:genetics*; D055532:SMN Complex Proteins; D014897:Spinal Muscular Atrophies of Childhood / Q000235:genetics / Q000473:pathology; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D055533:Survival of Motor Neuron 1 Protein; D055540:Survival of Motor Neuron 2 Protein; D013762:Tetrahydrofolate Dehydrogenase / Q000737:chemistry
chemical_list: C528496:(5-(1-(2-fluorobenzyl)piperidin-4-ylmethoxy))quinazoline-2,4-diamine; D000634:Aminoquinolines; D017362:Cyclic AMP Response Element-Binding Protein; D005493:Folic Acid Antagonists; D009419:Nerve Tissue Proteins; D010880:Piperidines; D011799:Quinazolines; D016601:RNA-Binding Proteins; D055532:SMN Complex Proteins; C526471:SMN1 protein, human; C526477:SMN2 protein, human; C526472:Smn1 protein, mouse; D055533:Survival of Motor Neuron 1 Protein; D055540:Survival of Motor Neuron 2 Protein; D013762:Tetrahydrofolate Dehydrogenase