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Muscle contraction is driven by the molecular machinery of the sarcomere. As phosphorylation is a critical regulator of muscle function, the identification of regulatory kinases is important for understanding sarcomere biology. Pathogenic variants in alpha kinase 3 (ALPK3) cause cardiomyopathy and musculoskeletal disease, but little is known about this atypical kinase. Here we show that ALPK3 is an essential component of the M-band of the sarcomere and define the ALPK3-dependent phosphoproteome. ALPK3 deficiency impaired contractility both in human cardiac organoids and in the hearts of mice harboring a pathogenic truncating Alpk3 variant. ALPK3-dependent phosphopeptides were enriched for sarcomeric components of the M-band and the ubiquitin-binding protein sequestosome-1 (SQSTM1) (also known as p62). Analysis of the ALPK3 interactome confirmed binding to M-band proteins including SQSTM1. In human pluripotent stem cell-derived cardiomyocytes modeling cardiomyopathic ALPK3 mutations, sarcomeric organization and M-band localization of SQSTM1 were abnormal suggesting that this mechanism may underly disease pathogenesis.

Aripiprazole lauroxil (AL), a long-acting injectable antipsychotic for the treatment of schizophrenia, requires 21 days of oral aripiprazole supplementation upon initiation (21-day initiation regimen). An alternative 1-day initiation regimen utilizing a nano-crystalline milled dispersion of AL (ALNCD) plus a single 30 mg oral aripiprazole dose achieved aripiprazole concentrations associated with therapeutic doses of aripiprazole in the same time frame as the 21-day initiation regimen when starting AL (441 or 882 mg). A population pharmacokinetic (PopPK) model was developed to describe aripiprazole pharmacokinetics following administration of ALNCD, AL and oral aripiprazole, and evaluate dosing scenarios likely to be encountered in clinical practice. In total, 12,768 plasma aripiprazole concentrations from 343 patients (from 4 clinical studies) were included in the PopPK analysis and used to construct the model. Concomitant administration of the 1-day initiation regimen with all approved AL dosing regimens (441, 662, or 882 mg monthly, 882 mg every 6 weeks, or 1064 mg every 2 months) is predicted to achieve aripiprazole concentrations associated with therapeutic doses of AL using the 21-day initiation regimen within 4 days, maintaining these concentrations until the next AL dose. Administration of the first AL injection 10 days after the 1-day initiation regimen resulted in median aripiprazole concentrations just before the second dose of AL ≥ 77% of that when coadministered on the same day. Coadministration of AL with a single ALNCD injection was predicted to be effective in rapidly re-establishing concentrations associated with therapeutic doses of AL following dose delay. Model-based simulations demonstrate that the 1-day initiation regimen is suitable for starting treatment with all AL doses, allowing a window of ≤ 10 days between initiation and AL administration. ALNCD may also be used to re-establish concentrations associated with therapeutic doses of AL in conjunction with a delayed AL dose.

Background Aripiprazole lauroxil (AL) is a long-acting injectable medication approved for the treatment of schizophrenia. Current AL regimens are 441 mg, 662 mg, and 882 mg administered monthly (every 4 weeks [q4wk]), or 882 mg administered every 6 weeks (q6wk). Objective We examined the feasibility of a 2-month (every 8 weeks [q8wk]) dosing interval of AL in a phase I open-label pharmacokinetic study investigating AL 1064 mg administered q8wk for 24 weeks, followed by 20 weeks of safety and pharmacokinetic measurements (ClinicalTrials.gov ID: NCT02320032). Second, a population pharmacokinetic model (referred to as the 2MPopPK model) was generated using data collected from the present trial, as well as data obtained from earlier studies. Methods The phase I study included patients with schizophrenia or schizoaffective disorder maintained on an oral antipsychotic (n = 140) who were assigned to one of three groups: AL 441 mg q4wk, AL 882 mg q6wk, or AL 1064 mg q8wk, with a total of seven, five, or four injections administered, respectively. No oral aripiprazole lead-in supplementation was administered and patients continued on maintenance oral antipsychotics. Pharmacokinetic samples were collected at various time points during the 24-week study period and the 20-week follow-up period. Plasma concentrations obtained from the phase I study were analyzed using non-compartmental methods. Additionally, the data were combined with data collected from prior studies to develop the 2MPopPK model. Results Following the final injection of AL in the phase I study, maximum aripiprazole concentrations were achieved 24.4–35.2 days after the last dose and persisted for the duration of the study. The mean C avg,ss values were 125.8 ng/ml, 131.1 ng/ml, and 140.7 ng/ml for the 441 mg q4wk, 882 mg q6wk, and 1064 mg q8wk doses, respectively. The mean elimination half-life of aripiprazole following the last dose was 53.9 days for the 1064 mg dose, 55.1 days for the 882 mg dose, and 57.2 days for the 441 mg dose. The 2MPopPK dataset included 14,524 aripiprazole concentrations from 700 patients with schizophrenia. The duration of absorption of aripiprazole was estimated as 43 days (95% confidence interval [CI] 42–45 days), which was preceded by a 3.2-day lag time (95% CI 3.0–3.5 days) for a total duration of input into the systemic circulation of 46 days following intramuscular administration of AL. Multiple-dose simulations showed that the 1064 mg q8wk regimen provides aripiprazole concentrations within the concentration range associated with 441 mg and 882 mg q4wk doses previously demonstrated to be efficacious in a phase III study. Conclusion These data from the phase I study and the 2MPopPK model support the suitability of using the AL 1064 mg dose as a 2-month (q8wk) dose interval option for the treatment of schizophrenia. Electronic supplementary material The online version of this article (doi:10.1007/s40263-017-0447-7) contains supplementary material, which is available to authorized users.

Structural and functional changes following infarction in a human heart can be modelled with human cardiac organoids set in a hypoxic gradient and stimulated with the neurotransmitter noradrenaline.

Congenital heart defects can be caused by mutations in genes that guide cardiac lineage formation. Here, we show deletion of NKX2-5, a critical component of the cardiac gene regulatory network, in human embryonic stem cells (hESCs), results in impaired cardiomyogenesis, failure to activate VCAM1 and to downregulate the progenitor marker PDGFRα. Furthermore, NKX2-5 null cardiomyocytes have abnormal physiology, with asynchronous contractions and altered action potentials. Molecular profiling and genetic rescue experiments demonstrate that the bHLH protein HEY2 is a key mediator of NKX2-5 function during human cardiomyogenesis. These findings identify HEY2 as a novel component of the NKX2-5 cardiac transcriptional network, providing tangible evidence that hESC models can decipher the complex pathways that regulate early stage human heart development. These data provide a human context for the evaluation of pathogenic mutations in congenital heart disease., A gene regulatory network, including the transcription factor Nkx2-5, regulates cardiac development. Here, the authors show that on deletion of NKX2-5 from human embryonic stem cells, there is impaired cardiomyogenesis and changes in action potentials, and that this is regulated via HEY2.