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1.
Am J Clin Dermatol ; 2024 May 02.
Article in English | MEDLINE | ID: mdl-38698175

ABSTRACT

BACKGROUND: Atopic dermatitis (AD), a highly pruritic, inflammatory skin disease, affects approximately 7% of adolescents globally. A topical formulation of ruxolitinib, a Janus kinase (JAK) 1/JAK2 inhibitor, demonstrated safety and efficacy among adolescents/adults in two phase 3 studies (TRuE-AD1/TRuE-AD2). OBJECTIVE: To describe safety and efficacy of 1.5% ruxolitinib cream versus vehicle and long-term disease control of ruxolitinib cream among adolescents aged 12-17 years from pooled phase 3 study data. METHODS: Patients [≥ 12 years old with AD for ≥ 2 years, Investigator's Global Assessment score (IGA) 2/3, and 3-20% affected body surface area (BSA) at baseline] were randomized 2:2:1 to ruxolitinib cream (0.75%/1.5%) or vehicle for 8 weeks of continuous use followed by a long-term safety (LTS) period up to 52 weeks with as-needed use. Patients originally applying vehicle were rerandomized 1:1 to 0.75%/1.5% ruxolitinib cream. Efficacy measures at week 8 included IGA treatment success (IGA-TS; i.e., score of 0/1 with ≥ 2 grade improvement from baseline), ≥ 75% improvement in Eczema Area and Severity Index (EASI-75), and ≥ 4-point improvement in itch numerical rating scale (NRS4). Measures of disease control during the LTS period included IGA score of 0 (clear) or 1 (almost clear) and percentage affected BSA. Safety was assessed throughout the study. RESULTS: Of 1249 randomized patients, 245 (19.6%) were aged 12-17 years. Of these, 45 patients were randomized to vehicle and 92 patients to 1.5% ruxolitinib cream. A total of 104/137 (75.9%) patients continued on 1.5% ruxolitinib cream in the LTS period [82/92 (89.1%) continued on 1.5% ruxolitinib cream; 22/45 (48.9%) patients on vehicle were reassigned to 1.5% ruxolitinib cream], and 83/104 (79.8%) of these patients completed the LTS period. At week 8, substantially more patients who applied 1.5% ruxolitinib cream versus vehicle achieved IGA-TS (50.6% versus 14.0%), EASI-75 (60.9% versus 34.9%), and NRS4 (52.1% versus 17.4%; P = 0.009). The mean (SD) reduction in itch NRS scores was significantly greater in patients applying 1.5% ruxolitinib cream versus vehicle from day 2 [- 0.9 (1.9) versus -0.2 (1.4); P = 0.03]. During the LTS period, mean (SD) trough steady-state ruxolitinib plasma concentrations at weeks 12/52 were 27.2 (55.7)/15.5 (31.5) nM. The percentage of patients achieving IGA score of 0 or 1 was sustained or further increased with 1.5% ruxolitinib cream; mean affected BSA was generally low (< 3%; i.e., mild disease). Through 52 weeks, application site reactions occurred in 1.8% of adolescent patients applying 1.5% ruxolitinib cream at any time; no patients had serious adverse events. There were no serious infections, malignancies, major adverse cardiovascular events, or thromboembolic events. CONCLUSIONS: Meaningful anti-inflammatory and antipruritic effects were demonstrated with 1.5% ruxolitinib cream in the subset of adolescent patients with AD, comparable with those observed in the overall study population; long-term, as-needed use maintained disease control and was well tolerated. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov identifiers NCT03745638 (registered 19 November 2018) and NCT03745651 (registered 19 November 2018).

2.
J Dermatolog Treat ; 35(1): 2310633, 2024 Dec.
Article in English | MEDLINE | ID: mdl-38297490

ABSTRACT

Purpose: Ruxolitinib (selective Janus kinase [JAK] 1 and JAK2 inhibitor) cream demonstrated efficacy and safety in patients with atopic dermatitis (AD) in the phase 3 TRuE-AD studies. In TRuE-AD1/TRuE-AD2 (NCT03745638/NCT03745651), adults and adolescents with mild to moderate AD were randomized to apply twice-daily ruxolitinib cream or vehicle for eight weeks. Here, we evaluated the efficacy and tolerability of ruxolitinib cream by anatomic region, focusing on head/neck (HN) lesions that are typically difficult to manage and disproportionately affect quality of life (QoL).Materials and methods: Eczema Area and Severity Index (EASI) responses in anatomic regions were evaluated in the pooled population (N = 1208) and among patients with baseline HN involvement (n = 663). Itch, Investigator's Global Assessment (IGA), QoL, and application site tolerability were also assessed.Results: By Week 2 (earliest assessment), ruxolitinib cream application resulted in significant improvements across all EASI anatomic region subscores and AD signs versus vehicle, with further improvements through Week 8. Significantly more patients with HN involvement who applied ruxolitinib cream versus vehicle achieved clinically meaningful improvements in itch, IGA, and QoL. Application site reactions with ruxolitinib cream were infrequent (<3%), including in patients with HN involvement.Conclusions: These results support the use of ruxolitinib cream for AD treatment across all anatomic regions, including HN.


Subject(s)
Dermatitis, Atopic , Nitriles , Pyrazoles , Pyrimidines , Adolescent , Adult , Humans , Dermatitis, Atopic/pathology , Double-Blind Method , Emollients , Immunoglobulin A , Pruritus/drug therapy , Pruritus/etiology , Quality of Life , Severity of Illness Index , Treatment Outcome , Clinical Trials, Phase III as Topic , Randomized Controlled Trials as Topic
3.
J Dermatol ; 50(12): 1523-1530, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37830436

ABSTRACT

Ruxolitinib cream is a topical formulation of ruxolitinib, a selective inhibitor of Janus kinase (JAK) 1 and JAK2. In two phase 3 studies in adults and adolescents (aged ≥12 years) with atopic dermatitis (AD; TRuE-AD1/TRuE-AD2), significantly more patients who applied ruxolitinib cream versus vehicle cream achieved Investigator's Global Assessment treatment success (IGA-TS; IGA score of 0/1 with ≥2-point improvement from baseline) at week 8 (primary endpoint). This post hoc analysis evaluated the efficacy, safety, and disease control of ruxolitinib cream in patients with AD who did not achieve IGA-TS at week 8. Patients in TRuE-AD1/TRuE-AD2 (N = 1249) were randomized 2:2:1 to apply twice-daily 0.75% ruxolitinib cream, 1.5% ruxolitinib cream, or vehicle cream for 8 weeks followed by a long-term safety period in which patients applied ruxolitinib cream as needed. In this pooled analysis, clinically meaningful response thresholds included ≥50% improvement in the Eczema Area and Severity Index, ≥2-point reduction in the Itch Numerical Rating Scale, ≥4-point improvement in the Dermatology Life Quality Index (DLQI) or ≥6-point improvement in Children's DLQI, and ≥1-point reduction in IGA from baseline. Among patients who did not achieve IGA-TS at week 8 (n = 584), significantly more patients who applied either strength ruxolitinib cream versus vehicle achieved each response threshold at week 8. A response in ≥1 clinically meaningful endpoint was achieved in significantly more patients who applied ruxolitinib cream (93.4%/90.9% for 0.75%/1.5% ruxolitinib cream, respectively) versus vehicle (69.0%, both P < 0.0001). Progressive improvements in disease control were observed, with many patients achieving IGA-TS by week 52 (55.2%/56.3% for 0.75%/1.5% ruxolitinib cream, respectively). Ruxolitinib cream was well tolerated during the 52-week study in this patient population. Taken together, these results demonstrate that most patients with AD who did not achieve IGA-TS at week 8 have clinically meaningful responses to ruxolitinib cream, and continued therapy beyond 8 weeks could result in additional benefit.


Subject(s)
Dermatitis, Atopic , Child , Humans , Adult , Adolescent , Dermatitis, Atopic/drug therapy , Double-Blind Method , Pyrimidines/therapeutic use , Treatment Outcome , Emollients/therapeutic use , Immunoglobulin A , Severity of Illness Index
4.
J Am Acad Dermatol ; 88(5): 1008-1016, 2023 05.
Article in English | MEDLINE | ID: mdl-36574595

ABSTRACT

BACKGROUND: Ruxolitinib cream demonstrated safety and efficacy over 8 weeks in 2 double-blind phase 3 atopic dermatitis studies (NCT03745638/NCT03745651). OBJECTIVE: To evaluate long-term safety (LTS) and disease control with ruxolitinib cream. METHODS: Patients initially randomized to twice-daily 0.75%/1.5% ruxolitinib cream maintained their regimen during the 44-week LTS period (as-needed treatment). Patients on vehicle were rerandomized (1:1) at week 8 to either ruxolitinib cream strength. Safety and disease control (Investigator's Global Assessment score 0/1 and affected body surface area) were assessed. RESULTS: Over 52 weeks, adverse events were reported in 67.4%/62.6%/53.5%/57.6% of patients in 0.75%/1.5% ruxolitinib cream/vehicle to 0.75% ruxolitinib cream/vehicle to 1.5% ruxolitinib cream groups (n = 426/446/101/99). Most common adverse events were upper respiratory tract infection (10.3%/11.4%/5.9%/7.1%) and nasopharyngitis (8.9%/9.9%/7.9%/14.1%). Most adverse events were considered unrelated to treatment. Application site reactions were infrequent (3.8%/1.8%/1.0%/1.0%). Disease control was achieved throughout the LTS; 74.1% to 77.8% of patients had Investigator's Global Assessment 0/1 at week 52, and mean affected body surface area was low (1.4%-1.8%). LIMITATIONS: LTS had no control treatment. CONCLUSION: During 44 weeks of as-needed treatment, ruxolitinib cream demonstrated effective disease control and tolerability; low ruxolitinib plasma concentrations alongside safety findings reflecting known risk factors suggest physiologically meaningful systemic Janus kinase inhibition is highly unlikely.


Subject(s)
Dermatitis, Atopic , Humans , Dermatitis, Atopic/drug therapy , Double-Blind Method , Emollients , Nitriles , Pyrimidines/adverse effects , Severity of Illness Index , Treatment Outcome
7.
Drug Des Devel Ther ; 14: 1177-1189, 2020.
Article in English | MEDLINE | ID: mdl-32256049

ABSTRACT

PURPOSE: Camrelizumab inhibits PD-1 in non-clinical models and showed typical non-clinical pharmacokinetic (PK) and safety profiles for an IgG4 monoclonal antibody. We report results from the First-in-Human Phase 1 trial of camrelizumab in Australian population. METHODS: Camrelizumab was administered to patients with advanced solid tumors who had failed standard therapies. In the dose-escalation phase (n=23), camrelizumab was administered intravenously at 1 mg/kg, 3 mg/kg, 6 mg/kg, and 10 mg/kg every 2 weeks. In dose expansion (n=26), camrelizumab was given at 200 mg or 600 mg every 4 weeks. RESULTS: Two dose-limiting toxicities were observed during dose escalation: transaminase elevation and diarrhea (both grade 3). Overall, treatment-related adverse events were consistent with the expected toxicity profile of immune checkpoint inhibition, with the striking exception of the dose-related development of angiomatous skin lesions characterized as reactive cutaneous capillary endothelial proliferation. The PK profile showed a dose-progressive increase in half-life from 3 days at 1 mg/kg to 7 days at 10 mg/kg. Moreover, receptor occupancy assays showed a PD-1 occupancy of >50% in most patients out to 28 days post-dose. The objective response rate was 15.2% (95% CI 6.3-28.9). CONCLUSION: Camrelizumab has manageable toxicity and encouraging preliminary antitumor activity in advanced solid tumors in Australia. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02492789.


Subject(s)
Antibodies, Monoclonal, Humanized/therapeutic use , Antineoplastic Agents/therapeutic use , Biliary Tract Neoplasms/drug therapy , Endometrial Neoplasms/drug therapy , Thymus Neoplasms/drug therapy , Adult , Aged , Aged, 80 and over , Antibodies, Monoclonal, Humanized/administration & dosage , Antibodies, Monoclonal, Humanized/adverse effects , Antineoplastic Agents/administration & dosage , Antineoplastic Agents/adverse effects , Australia , Dose-Response Relationship, Drug , Female , Humans , Injections, Intravenous , Male , Maximum Tolerated Dose , Middle Aged
8.
Clin Cancer Res ; 23(10): 2405-2413, 2017 May 15.
Article in English | MEDLINE | ID: mdl-27821605

ABSTRACT

Purpose: This phase I/II single-arm study evaluated the safety, pharmacokinetics, pharmacodynamics, and activity of foretinib, an oral multikinase inhibitor of MET, ROS, RON, AXL, TIE-2, and VEGFR2, in the first-line setting in advanced hepatocellular carcinoma patients.Experimental Design: In the phase I part, advanced hepatocellular carcinoma patients were dose escalated on foretinib (30-60 mg) every day using the standard 3+3 design. Once the maximum tolerated dose (MTD) was determined, an additional 32 patients were dosed at the MTD in the phase II expansion cohort for assessment of efficacy and safety. Exploratory analyses were conducted to assess potential biomarkers that might correlate with clinical efficacy and survival.Results: The MTD of foretinib was established as 30 mg every day. The most frequent adverse events were hypertension, decreased appetite, ascites, and pyrexia. When dosed at 30 mg every day in the first-line setting, foretinib demonstrated promising antitumor activity. According to the modified mRECIST, the objective response rate was 22.9%, the disease stabilization rate 82.9%, and the median duration of response 7.6 months. The median time to progression was 4.2 months and the median overall survival (OS) was 15.7 months. Fifteen candidate biomarkers whose levels in the circulation were significantly altered in response to foretinib treatment were elucidated. Multivariate analyses identified IL6 and IL8 as independent predictors of OS.Conclusions: Foretinib demonstrated promising antitumor activity and good tolerability in the first-line setting in Asian advanced hepatocellular carcinoma patients. Baseline plasma levels of IL6 or IL8 might predict the response to foretinib. Clin Cancer Res; 23(10); 2405-13. ©2016 AACR.


Subject(s)
Anilides/administration & dosage , Carcinoma, Hepatocellular/drug therapy , Interleukin-6/blood , Interleukin-8/blood , Liver Neoplasms/drug therapy , Quinolines/administration & dosage , Adult , Aged , Anilides/pharmacokinetics , Biomarkers, Pharmacological/blood , Carcinoma, Hepatocellular/blood , Carcinoma, Hepatocellular/pathology , Female , Humans , Liver Neoplasms/blood , Liver Neoplasms/pathology , Male , Maximum Tolerated Dose , Middle Aged , Protein-Tyrosine Kinases/antagonists & inhibitors , Proto-Oncogene Proteins/antagonists & inhibitors , Proto-Oncogene Proteins c-met/antagonists & inhibitors , Quinolines/pharmacokinetics , Receptor Protein-Tyrosine Kinases/antagonists & inhibitors , Receptor, TIE-2/antagonists & inhibitors , Vascular Endothelial Growth Factor Receptor-2/antagonists & inhibitors , Axl Receptor Tyrosine Kinase
9.
J Clin Pharmacol ; 55(10): 1184-92, 2015 Oct.
Article in English | MEDLINE | ID: mdl-25998042

ABSTRACT

Foretinib is a multikinase inhibitor that inhibits multiple receptor tyrosine kinases, including MET and VEGFR, with the potential for treatment of solid tumors. Hepatocellular carcinoma (HCC) pathogenesis is associated with overexpression of MET, and physiologic changes in the livers of HCC patients may decrease CYP3A isozyme-mediated metabolism of foretinib. A population pharmacokinetic model of foretinib was developed to explore the effect of tumor type, formulation, and other covariates. Data from 1 HCC study in Asia and 3 non-HCC studies in the United States with varying foretinib regimens and formulations were used for analysis. A 2-compartment model with a linear first-order absorption and elimination and lag time in absorption adequately described foretinib pharmacokinetics in 132 advanced non-HCC and HCC patients and identified an effect of formulations on bioavailability. The bisphosphate salt capsules and freebase tablets had a relative bioavailability 37% and 20% higher, respectively, than the solution formulation. HCC patients had ≈19.6% lower mean clearance (70.14 L/h), ≈16% lower mean volume of distribution (1725.6 L), and higher dose-normalized exposure compared with non-HCC patients. This could be a result of differences in metabolism in HCC patients, body weight, or activity of CYP3A isozymes between Asian and Western cancer patients.


Subject(s)
Anilides/pharmacokinetics , Antineoplastic Agents/pharmacokinetics , Carcinoma, Hepatocellular/metabolism , Liver Neoplasms/metabolism , Models, Biological , Protein Kinase Inhibitors/pharmacokinetics , Quinolines/pharmacokinetics , Adult , Aged , Aged, 80 and over , Anilides/blood , Antineoplastic Agents/blood , Cross-Over Studies , Female , Humans , Male , Middle Aged , Protein Kinase Inhibitors/blood , Quinolines/blood , Young Adult
10.
PLoS One ; 8(3): e54014, 2013.
Article in English | MEDLINE | ID: mdl-23516391

ABSTRACT

PURPOSE: The receptors for hepatocyte and vascular endothelial cell growth factors (MET and VEGFR2, respectively) are critical oncogenic mediators in gastric adenocarcinoma. The purpose is to examine the safety and efficacy of foretinib, an oral multikinase inhibitor targeting MET, RON, AXL, TIE-2, and VEGFR2 receptors, for the treatment of metastatic gastric adenocarcinoma. PATIENTS AND METHODS: Foretinib safety and tolerability, and objective response rate (ORR) were evaluated in patients using intermittent (240 mg/day, for 5 days every 2 weeks) or daily (80 mg/day) dosing schedules. Thirty evaluable patients were required to achieve alpha = 0.10 and beta = 0.2 to test the alternative hypothesis that single-agent foretinib would result in an ORR of ≥ 25%. Up to 10 additional patients could be enrolled to ensure at least eight with MET amplification. Correlative studies included tumor MET amplification, MET signaling, pharmacokinetics and plasma biomarkers of foretinib activity. RESULTS: From March 2007 until October 2009, 74 patients were enrolled; 74% male; median age, 61 years (range, 25-88); 93% had received prior therapy. Best response was stable disease (SD) in 10 (23%) patients receiving intermittent dosing and five (20%) receiving daily dosing; SD duration was 1.9-7.2 months (median 3.2 months). Of 67 patients with tumor samples, 3 had MET amplification, one of whom had SD. Treatment-related adverse events occurred in 91% of patients. Rates of hypertension (35% vs. 15%) and elevated aspartate aminotransferase (23% vs. 8%) were higher with intermittent dosing. In both patients with high baseline tumor phospho-MET (pMET), the pMET:total MET protein ratio decreased with foretinib treatment. CONCLUSION: These results indicate that few gastric carcinomas are driven solely by MET and VEGFR2, and underscore the diverse molecular oncogenesis of this disease. Despite evidence of MET inhibition by foretinib, single-agent foretinib lacked efficacy in unselected patients with metastatic gastric cancer.


Subject(s)
Anilides/therapeutic use , Antineoplastic Agents/therapeutic use , Quinolines/therapeutic use , Stomach Neoplasms/drug therapy , Stomach Neoplasms/pathology , Adult , Aged , Aged, 80 and over , Anilides/pharmacology , Animals , Antineoplastic Agents/pharmacology , Female , Humans , Male , Mice , Middle Aged , Neoplasm Metastasis , Proto-Oncogene Proteins c-met/antagonists & inhibitors , Quinolines/pharmacology , Treatment Outcome , Vascular Endothelial Growth Factor Receptor-2/antagonists & inhibitors , Xenograft Model Antitumor Assays
11.
Invest New Drugs ; 31(2): 417-24, 2013 Apr.
Article in English | MEDLINE | ID: mdl-22918720

ABSTRACT

BACKGROUND: Foretinib is a small-molecule, oral multikinase inhibitor primarily targeting the mesenchymal epithelial transition (MET) factor receptor, and the vascular endothelial growth factor receptor 2. We conducted a phase II study to evaluate the single-agent activity and tolerability of foretinib in patients with recurrent/metastatic squamous cell carcinoma of the head and neck (SCCHN). METHODS: An open-label, single-arm, multicenter trial employing a Simon 2-stage design was conducted with a total of 41 patients planned for the study. One or more responses in the first 14 patients were required in order to progress to the second stage. Foretinib was administered as 240 mg orally for 5 consecutive days of a 14-day treatment cycle (5/9 schedule) to patients with recurrent and/or metastatic SCCHN. RESULTS: Fourteen patients were enrolled. The study did not meet criteria for continuing to the second stage. A maximum of 30 cycles were administered (median = 4.0). Fifty percent of patients (7/14) showed stable disease (SD), 43% of patients (6/14) experienced tumor shrinkage and two patients had prolonged disease stabilization for ≥13 months. The most common adverse events were fatigue, constipation and hypertension, which were manageable with additional medication or adjustments to the dosing schedule. CONCLUSION: Foretinib 240 mg on a 5/9 schedule was generally well tolerated. SD was the best-observed outcome, with minor tumor shrinkage detected in nearly half of all patients. The efficacy results, prolonged disease stabilization and tolerable side-effect profile, support further investigation, possibly in combination with other targeted agents or cytotoxic chemotherapy for SCCHN.


Subject(s)
Anilides/therapeutic use , Bone Neoplasms/drug therapy , Carcinoma, Squamous Cell/drug therapy , Head and Neck Neoplasms/drug therapy , Liver Neoplasms/drug therapy , Lung Neoplasms/drug therapy , Neoplasm Recurrence, Local/drug therapy , Quinolines/therapeutic use , Aged , Aged, 80 and over , Anilides/pharmacokinetics , Bone Neoplasms/mortality , Bone Neoplasms/secondary , Carcinoma, Squamous Cell/mortality , Carcinoma, Squamous Cell/secondary , Dose-Response Relationship, Drug , Female , Follow-Up Studies , Head and Neck Neoplasms/mortality , Head and Neck Neoplasms/pathology , Humans , Liver Neoplasms/mortality , Liver Neoplasms/secondary , Lung Neoplasms/mortality , Lung Neoplasms/secondary , Lymphatic Metastasis , Male , Maximum Tolerated Dose , Middle Aged , Neoplasm Recurrence, Local/mortality , Neoplasm Recurrence, Local/secondary , Neoplasm Staging , Prognosis , Quinolines/pharmacokinetics , Survival Rate , Tissue Distribution , Vascular Endothelial Growth Factor Receptor-2/antagonists & inhibitors
12.
Tuberculosis (Edinb) ; 84(6): 353-60, 2004.
Article in English | MEDLINE | ID: mdl-15525558

ABSTRACT

Tuberculosis remains a global health problem, and programs dedicated to discovery of novel compounds against Mycobacterium tuberculosis require robust assays for high-throughput screening of chemical and natural product libraries. Enzymes involved in the biosynthesis of mycolic acids, vital components of the mycobacterial cell wall, have received much attention as potential drug targets. KasA and KasB, examples of the beta-ketoacyl-acyl carrier protein synthase I/II (KASI/II) class of condensing enzymes of the M. tuberculosis fatty acid synthase II system have been the focus of several studies designed to biochemically characterize these enzymes. Whilst robust methods have been developed for FabH-like proteins, fast and sensitive assays for high-throughput screening of KASI/II enzymes have not been available. Here we report the development of a direct scintillation proximity assay (SPA) for the KASI/II enzymes, KasA and KasB. The SPA was more sensitive than existing assays, as shown by its ability to measure activity using less enzyme than other assay formats, and the SPA was validated using the known KAS inhibitor thiolactomycin. In addition, the KasA and KasB SPA was adapted for use with Staphylococcus aureus FabF to show the versatility of this assay format to KAS enzymes from other pathogenic organisms.


Subject(s)
3-Oxoacyl-(Acyl-Carrier-Protein) Synthase/metabolism , Mycobacterium tuberculosis/enzymology , Mycolic Acids/metabolism , Oxidoreductases/metabolism , Anti-Bacterial Agents/pharmacology , Chemistry Techniques, Analytical/methods , Dimethyl Sulfoxide/pharmacology , Enoyl-(Acyl-Carrier Protein) Reductase (NADPH, B-Specific) , Enzyme Inhibitors/pharmacology , Mycobacterium tuberculosis/drug effects , Staphylococcus aureus , Thiophenes/pharmacology , Time Factors
13.
J Biol Chem ; 279(43): 44883-8, 2004 Oct 22.
Article in English | MEDLINE | ID: mdl-15292254

ABSTRACT

3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) synthase, a member of the family of acyl-condensing enzymes, catalyzes the first committed step in the mevalonate pathway and is a potential target for novel antibiotics and cholesterol-lowering agents. The Staphylococcus aureus mvaS gene product (43.2 kDa) was overexpressed in Escherichia coli, purified to homogeneity, and shown biochemically to be an HMG-CoA synthase. The crystal structure of the full-length enzyme was determined at 2.0-A resolution, representing the first structure of an HMG-CoA synthase from any organism. HMG-CoA synthase forms a homodimer. The monomer, however, contains an important core structure of two similar alpha/beta motifs, a fold that is completely conserved among acyl-condensing enzymes. This common fold provides a scaffold for a catalytic triad made up of Cys, His, and Asn required by these enzymes. In addition, a crystal structure of HMG-CoA synthase with acetoacetyl-CoA was determined at 2.5-A resolution. Together, these structures provide the structural basis for an understanding of the mechanism of HMG-CoA synthase.


Subject(s)
Hydroxymethylglutaryl-CoA Synthase/chemistry , Staphylococcus aureus/enzymology , Amino Acid Motifs , Amino Acid Sequence , Asparagine/chemistry , Binding Sites , Catalysis , Cholesterol/metabolism , Cloning, Molecular , Crystallography, X-Ray , Cysteine/chemistry , Dimerization , Escherichia coli/metabolism , Histidine/chemistry , Hydroxymethylglutaryl-CoA Synthase/genetics , Kinetics , Models, Chemical , Models, Molecular , Molecular Sequence Data , Protein Conformation , Sequence Homology, Amino Acid
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