BACKGROUND: Patients with acute myeloid leukaemia (AML) positive for internal tandem duplication (ITD) mutations of FLT3 have poor outcomes. Quizartinib, an oral, highly potent, selective, type 2 FLT3 inhibitor, plus chemotherapy showed antitumour activity with an acceptable safety profile in patients with FLT3-ITD-positive newly diagnosed AML. The aim of the study was to compare the effect of quizartinib versus placebo on overall survival in patients with FLT3-ITD-positive newly diagnosed AML aged 18-75 years. METHODS: We conducted a randomised, double-blind, placebo-controlled, phase 3 trial comparing quizartinib and placebo in combination with chemotherapy in induction and consolidation, followed by quizartinib or placebo single-agent continuation, in patients with FLT3-ITD-positive newly diagnosed AML at 193 hospitals and clinics in 26 countries in Europe; North America; and Asia, Australia, and South America. Patients aged 18-75 years were eligible. Patients were randomly assigned (1:1) to the quizartinib group or the placebo group by an independent biostatistician through an interactive web and voice response system, stratified by region, age, and white blood cell count at diagnosis. Patients, investigators, funders, and contract research organisations were masked to treatments assigned. Induction therapy comprised a standard 7 + 3 induction regimen of cytarabine 100 mg/m2 per day (or 200 mg/m2 per day allowed if institutional or local standard) by continuous intravenous infusion from day 1 to day 7 and anthracycline (daunorubicin 60 mg/m2 per day or idarubicin 12 mg/m2 per day) by intravenous infusion on days 1, 2, and 3, then quizartinib 40 mg orally or placebo once per day, starting on day 8, for 14 days. Patients with complete remission or complete remission with incomplete neutrophil or platelet recovery received standard consolidation with high-dose cytarabine plus quizartinib (40 mg per day orally) or placebo, allogeneic haematopoietic cell transplantation (allo-HCT), or both as consolidation therapy, followed by continuation of single-agent quizartinib or placebo for up to 3 years. The primary outcome was overall survival, defined as time from randomisation until death from any cause and assessed in the intention-to-treat population. Safety was evaluated in all patients who received at least one dose of quizartinib or placebo. This study is registered with ClinicalTrials.gov (NCT02668653). FINDINGS: Between Sept 27, 2016, and Aug 14, 2019, 3468 patients with AML were screened and 539 patients (294 [55%] male patients and 245 [45%] female patients) with FLT3-ITD-positive AML were included and randomly assigned to the quizartinib group (n=268) or placebo group (n=271). 148 (55%) of 268 patients in the quizartinib group and 168 (62%) of 271 patients in the placebo group discontinued the study, primarily because of death (133 [90%] of 148 in the quizartinib group vs 158 [94%] of 168 in the placebo group) or withdrawal of consent (13 [9%] of 148 in the quizartinib group vs 9 [5%] of 168 in the placebo group). Median age was 56 years (range 20-75, IQR 46·0-65·0). At a median follow-up of 39·2 months (IQR 31·9-45·8), median overall survival was 31·9 months (95% CI 21·0-not estimable) for quizartinib versus 15·1 months (13·2-26·2) for placebo (hazard ratio 0·78, 95% CI 0·62-0·98, p=0·032). Similar proportions of patients in the quizartinib and placebo groups had at least one adverse event (264 [100%] of 265 in the quizartinib group and 265 [99%] of 268 in the placebo group) and one grade 3 or higher adverse event (244 [92%] of 265 in the quizartinib group and 240 [90%] of 268 in the placebo group). The most common grade 3 or 4 adverse events were febrile neutropenia, hypokalaemia, and pneumonia in both groups and neutropenia in the quizartinib group. INTERPRETATION: The addition of quizartinib to standard chemotherapy with or without allo-HCT, followed by continuation monotherapy for up to 3 years, resulted in improved overall survival in adults aged 18-75 years with FLT3-ITD-positive newly diagnosed AML. Based on the results from the QuANTUM-First trial, quizartinib provides a new, effective, and generally well tolerated treatment option for adult patients with FLT3-ITD-positive newly diagnosed AML. FUNDING: Daiichi Sankyo.

• MeSH
• akutní myeloidní leukemie * farmakoterapie   genetika   MeSH
• benzothiazoly * terapeutické užití   MeSH
• cytarabin MeSH
• dospělí MeSH
• dvojitá slepá metoda MeSH
• fenylmočovinové sloučeniny * terapeutické užití   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• protokoly protinádorové kombinované chemoterapie terapeutické užití   MeSH
• senioři MeSH
• tyrosinkinasa 3 podobná fms antagonisté a inhibitory   genetika   MeSH
• výsledek terapie MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• klinické zkoušky, fáze III MeSH
• práce podpořená grantem MeSH
• randomizované kontrolované studie MeSH

Vectorial proton transfer among carbonyl oxygen atoms was studied in two models of tripeptide via quantum chemical calculations using the hybrid B3LYP functional and the 6-31++G basis set. Two principal proton transfer pathways were found: a first path involving isomerization of the proton around the double bond of the carbonyl group, and a second based on the large conformational flexibility of the tripeptide model where all carbonyl oxygen atoms cooperate. The latter pathway has a rate-determining step energy barrier that is only around half of that for the first pathway. As conformational flexibility plays a crucial role in second pathway, the effect of attaching methyl groups to the alpha carbon atoms was studied. The results obtained are presented for all four possible stereochemical configurations.

• MeSH
• konformace proteinů MeSH
• molekulární modely MeSH
• ohebnost (fyzika) MeSH
• oligopeptidy chemie   MeSH
• protony MeSH
• stereoizomerie MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Haloalkane dehalogenases catalyze the hydrolysis of carbon-halogen bonds in various chlorinated, brominated and iodinated compounds. These enzymes have a conserved pair of halide-stabilizing residues that are important in substrate binding and stabilization of the transition state and the halide ion product via hydrogen bonding. In all previously known haloalkane dehalogenases, these residues are either a pair of tryptophans or a tryptophan-asparagine pair. The newly-isolated haloalkane dehalogenase DatA from Agrobacterium tumefaciens C58 (EC 3.8.1.5) possesses a unique halide-stabilizing tyrosine residue, Y109, in place of the conventional tryptophan. A variant of DatA with the Y109W mutation was created and the effects of this mutation on the structure and catalytic properties of the enzyme were studied using spectroscopy and pre-steady-state kinetic experiments. Quantum mechanical and molecular dynamics calculations were used to obtain a detailed analysis of the hydrogen-bonding patterns within the active sites of the wild-type and the mutant, as well as of the stabilization of the ligands as the reaction proceeds. Fluorescence quenching experiments suggested that replacing the tyrosine with tryptophan improves halide binding by 3.7-fold, presumably as a result of the introduction of an additional hydrogen bond. Kinetic analysis revealed that the mutation affected the substrate specificity of the enzyme and reduced its K(0.5) for selected halogenated substrates by a factor of 2-4, without impacting the rate-determining hydrolytic step. We conclude that DatA is the first natural haloalkane dehalogenase that stabilizes its substrate in the active site using only a single hydrogen bond, which is a new paradigm in catalysis by this enzyme family.

• MeSH
• Agrobacterium tumefaciens enzymologie   metabolismus   MeSH
• analýza hlavních komponent MeSH
• bakteriální proteiny chemie   genetika   metabolismus   MeSH
• biokatalýza MeSH
• halogenované uhlovodíky chemie   metabolismus   MeSH
• halogeny chemie   metabolismus   MeSH
• hydrolasy chemie   genetika   metabolismus   MeSH
• hydrolýza MeSH
• katalytická doména MeSH
• konformace proteinů MeSH
• kvantová teorie MeSH
• molekulární modely MeSH
• mutageneze cílená MeSH
• mutantní proteiny chemie   metabolismus   MeSH
• simulace molekulární dynamiky MeSH
• simulace molekulového dockingu MeSH
• stabilita enzymů MeSH
• substituce aminokyselin MeSH
• substrátová specifita MeSH
• tyrosin chemie   MeSH
• vodíková vazba MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• molekulární biologie MeSH
• proteiny MeSH
• Publikační typ
• monografie MeSH

• Konspekt
• Biochemie. Molekulární biologie. Biofyzika
• NLK Obory
• biochemie
• molekulární biologie, molekulární medicína