Long-term efficacy and safety of migalastat treatment in Fabry disease: 30-month results from the open-label extension of the randomized, phase 3 ATTRACT study

Results from the 18-month randomized treatment period of the phase 3 ATTRACT study demonstrated the efficacy and safety of oral migalastat compared with enzyme replacement therapy (ERT) in patients with Fabry disease who previously received ERT. Here, we report data from the subsequent 12-month, migalastat-only, open-label extension (OLE) period. ATTRACT (Study AT1001–012; NCT01218659) was a randomized, open-label, active-controlled study in patients aged 16–74 years with Fabry disease, an amenable GLA variant, and an estimated glomerular filtration rate (eGFR) ≥30 mL/min/1.73 m2. During the OLE, patients who received migalastat 150 mg every other day (QOD) during the randomized period continued receiving migalastat (Group 1 [MM]); patients who received ERT every other week discontinued ERT and started migalastat treatment (Group 2 [EM]). Outcome measures included eGFR, left ventricular mass index (LVMi), composite clinical outcome (renal, cardiac or cerebrovascular events), and safety. Forty-six patients who completed the randomized treatment period continued into the OLE (Group 1 [MM], n = 31; Group 2 [EM], n = 15). eGFR remained stable in both treatment groups. LVMi decreased from baseline at month 30 in Group 1 (MM) in patients with left ventricular hypertrophy at baseline. Only 10% of patients experienced a new composite clinical event with migalastat treatment during the OLE. No new safety concerns were reported. In conclusion, in patients with Fabry disease and amenable GLA variants, migalastat 150 mg QOD was well tolerated and demonstrated durable, long-term stability of renal function and reduction in LVMi

Safety and efficacy of alternative alglucosidase alfa regimens in Pompe disease

AbstractEmerging phenotypes in long-term survivors with Pompe disease on standard enzyme replacement therapy (ERT) (alglucosidase alfa 20 mg/kg/2 weeks) can include patients with worsening motor function. Whether higher doses of ERT improve skeletal function in these patients has not been systematically studied. This exploratory, randomized, open-label, 52-week study examined the safety and efficacy of 2 ERT regimens of alglucosidase alfa (20 mg/kg/week or 40 mg/kg/2 weeks) in 13 patients with Pompe disease and clinical decline or a lack of improvement on standard ERT: late-onset (n = 4), infantile-onset (n = 9). Cross-reactive immunologic material assay-negative patients were excluded. Eleven of 13 patients completed the study. Trends for improvement were seen in total gross motor function, but not mobility; however, 6 (late-onset, 2; infantile-onset, 4) of 11 patients (55%) who met the entry criteria of motor decline (late-onset, 4; infantile-onset, 7) showed improvement in motor and/or mobility skills. No between-regimen differences in efficacy emerged. Two case studies highlight the benefits of increased ERT dose in patients with Pompe disease experiencing clinical decline. Both alternative regimens were generally well tolerated. This study was limited by the small sample size, which is not uncommon for small clinical studies of rare diseases. Additionally, the study did not include direct assessment of muscle pathology, which may have identified potential causes of decreased response to ERT. Results were inconclusive but suggest that increased ERT dose may be beneficial in some patients with Pompe disease experiencing motor decline. Controlled studies are needed to clarify the benefits and risks of this strategy

Solvent-Induced Reversal of Activities between Two Closely Related Heterogeneous Catalysts in the Aldol Reaction

The relative rates of the aldol reaction catalyzed by supported primary and secondary amines can be inverted by 2 orders of magnitude, depending on the use of hexane or water as a solvent. Our analyses suggest that this dramatic shift in the catalytic behavior of the supported amines does not involve differences in reaction mechanism, but is caused by activation of imine to enamine equilibria and stabilization of iminium species. The effects of solvent polarity and acidity were found to be important to the performance of the catalytic reaction. This study highlights the critical role of solvent in multicomponent heterogeneous catalytic processes

Computational Treatment of Metalloproteins

Metalloproteins present a considerable challenge for modeling, especially when the starting point is far from thermodynamic equilibrium. Examples include formidable problems such as metalloprotein folding and structure prediction upon metal addition, removal, or even just replacement; metalloenzyme design, where stabilization of a transition state of the catalyzed reaction in the specific binding pocket around the metal needs to be achieved; docking to metal-containing sites and design of metalloenzyme inhibitors. Even more conservative computations, such as elucidations of the mechanisms and energetics of the reaction catalyzed by natural metalloenzymes, are often nontrivial. The reason is the vast span of time and length scales over which these proteins operate, and thus the resultant difficulties in estimating their energies and free energies. It is required to perform extensive sampling, properly treat the electronic structure of the bound metal or metals, and seamlessly merge the required techniques to assess energies and entropies, or their changes, for the entire system. Additionally, the machinery needs to be computationally affordable. Although a great advancement has been made over the years, including some of the seminal works resulting in the 2013 Nobel Prize in chemistry, many aforementioned exciting applications remain far from reach. We review the methodology on the forefront of the field, including several promising methods developed in our lab that bring us closer to the desired modern goals. We further highlight their performance by a few examples of applications

The mechanism of the Pd-catalyzed formation of coumarins: a theoretical study.

The mechanism of the formation of coumarins via the Pd-catalyzed intramolecular hydroarylation of the C-C triple bond is elucidated computationally, in corroboration with experimental data. It is shown that the reaction follows the concerted metalation-deprotonation (CMD) mechanism. The typically suspected mechanisms of ambiphilic metal ligand activation (AMLA), electrophilic aromatic substitution (EAS), and oxidative addition (OA) are suggested to be non-competitive, based on predicted conformations and energetics. Two forms of the Pd catalysts are used: Pd(OAc)2, and Pd(TFA)2. The predicted activation free energy barrier for the TFA-based catalyst is lower, both in the gas phase and in the CH2Cl2 solvent, in agreement with the experimental observations. Adding electron-withdrawing groups to the catalyst assists the first and rate-limiting step of the reaction, the deprotonation of the aromatic ring, as understood through charge analysis

The mechanism of the Pd-catalyzed formation of coumarins: a theoretical study.

The mechanism of the formation of coumarins via the Pd-catalyzed intramolecular hydroarylation of the C-C triple bond is elucidated computationally, in corroboration with experimental data. It is shown that the reaction follows the concerted metalation-deprotonation (CMD) mechanism. The typically suspected mechanisms of ambiphilic metal ligand activation (AMLA), electrophilic aromatic substitution (EAS), and oxidative addition (OA) are suggested to be non-competitive, based on predicted conformations and energetics. Two forms of the Pd catalysts are used: Pd(OAc)2, and Pd(TFA)2. The predicted activation free energy barrier for the TFA-based catalyst is lower, both in the gas phase and in the CH2Cl2 solvent, in agreement with the experimental observations. Adding electron-withdrawing groups to the catalyst assists the first and rate-limiting step of the reaction, the deprotonation of the aromatic ring, as understood through charge analysis

Incorporating a completely renormalized coupled cluster approach into a composite method for thermodynamic properties and reaction paths

The correlation consistent composite approach (ccCA), using the S4 complete basis set two-point extrapolation scheme (ccCA-S4), has been modified to incorporate the left-eigenstate completely renormalized coupled cluster method, including singles, doubles, and non-iterative triples (CR-CC(2,3)) as the highest level component. The new ccCA-CC(2,3) method predicts thermodynamic properties with an accuracy that is similar to that of the original ccCA-S4 method. At the same time, the inclusion of the single-reference CR-CC(2,3) approach provides a ccCA scheme that can correctly treat reaction pathways that contain certain classes of multi-reference species such as diradicals, which would normally need to be treated by more computationally demanding multi-reference methods. The new ccCA-CC(2,3) method produces a mean absolute deviation of 1.7 kcal/mol for predicted heats of formation at 298 K, based on calibration with the G2/97 set of 148 molecules, which is comparable to that of 1.0 kcal/mol obtained using the ccCA-S4 method, while significantly improving the performance of the ccCA-S4 approach in calculations involving more demanding radical and diradical species. Both the ccCA-CC(2,3) and ccCA-S4 composite methods are used to characterize the conrotatory and disrotatory isomerization pathways of bicyclo[1.1.0]butane to trans-1,3-butadiene, for which conventional coupled cluster methods, such as the CCSD(T) approach used in the ccCA-S4 model and, in consequence, the ccCA-S4 method itself might fail by incorrectly placing the disrotatory pathway below the conrotatory one. The ccCA-CC(2,3) scheme provides correct pathway ordering while providing an accurate description of the activation and reaction energies characterizing the lowest-energy conrotatory pathway. The ccCA-CC(2,3) method is thus a viable method for the analyses of reaction mechanisms that have significant multi-reference character, and presents a generally less computationally intensive alternative to true multi-reference methods, with computer costs and ease of use that are similar to those that characterize the more established, CCSD(T)-based, ccCA-S4 methodology

Cu,Zn-superoxide dismutase without Zn is folded but catalytically inactive

Amyotrophic lateral sclerosis has been linked to the gain of aberrant function of superoxide dismutase, Cu,Zn-SOD1 upon protein misfolding. The mechanism of SOD1 misfolding is thought to involve mutations leading to the loss of Zn, followed by protein unfolding and aggregation. We show that the removal of Zn from SOD1 may not lead to an immediate unfolding but immediately deactivates the enzyme through a combination of subtle structural and electronic effects. Using quantum mechanics/discrete molecular dynamics, we showed that both Zn-less wild-type (WT)-SOD1 and its D124N mutant that does not bind Zn have at least metastable folded states. In those states, the reduction potential of Cu increases, leading to the presence of detectable amounts of Cu(I) instead of Cu(II) in the active site, as confirmed experimentally. The Cu(I) protein cannot participate in the catalytic Cu(I)-Cu(II) cycle. However, even without the full reduction to Cu(I), the Cu site in the Zn-less variants of SOD1 is shown to be catalytically incompetent: unable to bind superoxide in a way comparable to the WT-SOD1. The changes are more radical and different in the D124N Zn-less mutant than in the Zn-less WT-SOD1, suggesting D124N being perhaps not the most adequate model for Zn-less SOD1. Overall, Zn in SOD1 appears to be influencing the Cu site directly by adjusting its reduction potential and geometry. Thus, the role of Zn in SOD1 is not just structural, as was previously thought; it is a vital part of the catalytic machinery

Incorporating a completely renormalized coupled cluster approach into a composite method for thermodynamic properties and reaction paths

The correlation consistent composite approach (ccCA), using the S4 complete basis set two-point extrapolation scheme (ccCA-S4), has been modified to incorporate the left-eigenstate completely renormalized coupled cluster method, including singles, doubles, and non-iterative triples (CR-CC(2,3)) as the highest level component. The new ccCA-CC(2,3) method predicts thermodynamic properties with an accuracy that is similar to that of the original ccCA-S4 method. At the same time, the inclusion of the single-reference CR-CC(2,3) approach provides a ccCA scheme that can correctly treat reaction pathways that contain certain classes of multi-reference species such as diradicals, which would normally need to be treated by more computationally demanding multi-reference methods. The new ccCA-CC(2,3) method produces a mean absolute deviation of 1.7 kcal/mol for predicted heats of formation at 298 K, based on calibration with the G2/97 set of 148 molecules, which is comparable to that of 1.0 kcal/mol obtained using the ccCA-S4 method, while significantly improving the performance of the ccCA-S4 approach in calculations involving more demanding radical and diradical species. Both the ccCA-CC(2,3) and ccCA-S4 composite methods are used to characterize the conrotatory and disrotatory isomerization pathways of bicyclo[1.1.0]butane to trans-1,3-butadiene, for which conventional coupled cluster methods, such as the CCSD(T) approach used in the ccCA-S4 model and, in consequence, the ccCA-S4 method itself might fail by incorrectly placing the disrotatory pathway below the conrotatory one. The ccCA-CC(2,3) scheme provides correct pathway ordering while providing an accurate description of the activation and reaction energies characterizing the lowest-energy conrotatory pathway. The ccCA-CC(2,3) method is thus a viable method for the analyses of reaction mechanisms that have significant multi-reference character, and presents a generally less computationally intensive alternative to true multi-reference methods, with computer costs and ease of use that are similar to those that characterize the more established, CCSD(T)-based, ccCA-S4 methodology. © 2012 American Institute of Physics