Synthesis of SMT022357 enantiomers and in vivo evaluation in a Duchenne muscular dystrophy mouse model.

Following on from ezutromid, the first-in-class benzoxazole utrophin modulator that progressed to Phase 2 clinical trials for the treatment of Duchenne muscular dystrophy, a new chemotype was designed to optimise its physicochemical and ADME profile. Herein we report the synthesis of SMT022357, a second generation utrophin modulator preclinical candidate, and an asymmetric synthesis of its constituent enantiomers. The pharmacological properties of both enantiomers were evaluated in vitro and in vivo. No significant difference in the activity or efficacy was observed between the two enantiomers; activity was found to be comparable to the racemic mixture.

Discovery and SAR of 2-arylbenzotriazoles and 2-arylindazoles as potential treatments for Duchenne muscular dystrophy.

Families of 2-arylbenzotriazoles and 2-arylindazoles that show positive effects in screens predictive of endogenous utrophin upregulation have been identified. Synthesis and structure-activity relationships are described leading to compounds with attractive in vitro profiles.

Isolation, Structural Identification, Synthesis, and Pharmacological Profiling of 1,2-trans-Dihydro-1,2-diol Metabolites of the Utrophin Modulator Ezutromid.

5-(Ethylsulfonyl)-2-(naphthalen-2-yl)benzo[d]oxazole (ezutromid, 1) is a first-in-class utrophin modulator that has been evaluated in a phase 2 clinical study for the treatment of Duchenne muscular dystrophy (DMD). Ezutromid was found to undergo hepatic oxidation of its 2-naphthyl substituent to produce two regioisomeric 1,2-dihydronaphthalene-1,2-diols, DHD1 and DHD3, as the major metabolites after oral administration in humans and rodents. In many patients, plasma levels of the DHD metabolites were found to exceed those of ezutromid. Herein, we describe the structural elucidation of the main metabolites of ezutromid, the regio- and relative stereochemical assignments of DHD1 and DHD3, their de novo chemical synthesis, and their production in systems in vitro. We further elucidate the likely metabolic pathway and CYP isoforms responsible for DHD1 and DHD3 production and characterize their physicochemical, ADME, and pharmacological properties and their preliminary toxicological profiles.

2-Arylbenzo[d]oxazole Phosphinate Esters as Second-Generation Modulators of Utrophin for the Treatment of Duchenne Muscular Dystrophy.

Utrophin modulation is a promising therapeutic strategy for Duchenne muscular dystrophy (DMD), which should be applicable to all patient populations. Following on from ezutromid, the first-generation utrophin modulator, we describe the development of a second generation of utrophin modulators, based on the bioisosteric replacement of the sulfone group with a phosphinate ester and substitution of the metabolically labile naphthalene with a haloaryl substituent. The improved physicochemical and absorption, distribution, metabolism, and excretion (ADME) properties, further reflected in the enhanced pharmacokinetic profile of the most advanced compounds, 30 and 27, led to significantly better in vivo exposure compared to ezutromid and alleviation of the dystrophic phenotype in mdx mice. While 30 was found to have dose-limiting hepatotoxicity, 27 and its enantiomers exhibited limited off-target effects, resulting in a safe profile and highlighting their potential utility as next-generation utrophin modulators suitable for progression toward a future DMD therapy.

Daily treatment with SMTC1100, a novel small molecule utrophin upregulator, dramatically reduces the dystrophic symptoms in the mdx mouse.

BACKGROUND: Duchenne muscular dystrophy (DMD) is a lethal, progressive muscle wasting disease caused by a loss of sarcolemmal bound dystrophin, which results in the death of the muscle fibers leading to the gradual depletion of skeletal muscle. There is significant evidence demonstrating that increasing levels of the dystrophin-related protein, utrophin, in mouse models results in sarcolemmal bound utrophin and prevents the muscular dystrophy pathology. The aim of this work was to develop a small molecule which increases the levels of utrophin in muscle and thus has therapeutic potential. METHODOLOGY AND PRINCIPAL FINDINGS: We describe the in vivo activity of SMT C1100; the first orally bioavailable small molecule utrophin upregulator. Once-a-day daily-dosing with SMT C1100 reduces a number of the pathological effects of dystrophin deficiency. Treatment results in reduced pathology, better muscle physiology leading to an increase in overall strength, and an ability to resist fatigue after forced exercise; a surrogate for the six minute walk test currently recommended as the pivotal outcome measure in human trials for DMD. CONCLUSIONS AND SIGNIFICANCE: This study demonstrates proof-of-principle for the use of in vitro screening methods in allowing identification of pharmacological agents for utrophin transcriptional upregulation. The best compound identified, SMT C1100, demonstrated significant disease modifying effects in DMD models. Our data warrant the full evaluation of this compound in clinical trials in DMD patients.

Discovery of 2-arylbenzoxazoles as upregulators of utrophin production for the treatment of Duchenne muscular dystrophy.

A series of novel 2-arylbenzoxazoles that upregulate the production of utrophin in murine H2K cells, as assessed using a luciferase reporter linked assay, have been identified. This compound class appears to hold considerable promise as a potential treatment for Duchenne muscular dystrophy. Following the delineation of structure-activity relationships in the series, a number of potent upregulators were identified, and preliminary ADME evaluation is described. These studies have resulted in the identification of 1, a compound that has been progressed to clinical trials.