A Model-Based Approach Supporting Abacavir/Dolutegravir/Lamivudine Fixed-Dose Combination Approval in Children Living with HIV-1.

In March 2022, the US Food and Drug Administration expanded indications of TRIUMEQ, a once-daily fixed-dose combination (FDC) containing abacavir (ABC), dolutegravir (DTG), and lamivudine (3TC) to include pediatric patients weighing at least 10 kg for the treatment of HIV-1. Prior to this extension, the ABC 600 mg/DTG 50 mg/3TC 300 mg FDC tablet was approved for use only in the adult/adolescent population, weighing ≥40 kg while each component of the FDC was approved for its use in pediatric patients at least 3 months and older. A new child-friendly formulation was developed as an FDC dispersible tablet (DT) of ABC 60 mg/DTG 5 mg/3TC 30 mg for pediatric patients with a body weight ≥ 6 kg. The present work demonstrates the utility of applying a model-informed drug development (MIDD) approach to expedite ABC/DTG/3TC FDC approval for pediatric patients (≥10 to <40 kg) based on data from the existing individual components and formulation bridging. Population pharmacokinetic models developed for pediatric participants across all three components of ABC/DTG/3TC FDC were employed for exposure prediction and incorporated relative bioavailability data. The predicted plasma exposures of ABC, DTG, and 3TC for FDC doses were consistent with those observed for the single entities in pediatric and adult studies. Thus, safety and efficacy observed in the individual component studies could be adequately extrapolated to the FDC that results in similar exposure. The current work demonstrates the significance of MIDD approaches in facilitating expedited access to child-friendly formulations in the HIV-1 therapeutic area.

Discovery of tertiary sulfonamides as potent liver X receptor antagonists.

Tertiary sulfonamides were identified in a HTS as dual liver X receptor (LXR, NR1H2, and NR1H3) ligands, and the binding affinity of the series was increased through iterative analogue synthesis. A ligand-bound cocrystal structure was determined which elucidated key interactions for high binding affinity. Further characterization of the tertiary sulfonamide series led to the identification of high affinity LXR antagonists. GSK2033 (17) is the first potent cell-active LXR antagonist described to date. 17 may be a useful chemical probe to explore the cell biology of this orphan nuclear receptor.

On the intractability of estrogen-related receptor alpha as a target for activation by small molecules.

The estrogen-related receptor alpha (ERRalpha) is a potential target for activation in the treatment of metabolic disease. To date, no small-molecule agonists of ERRalpha have been identified despite several high-throughput screening campaigns. We describe the synthesis and profiling of a small array of compounds designed on the basis of a previously reported agonist-bound crystal structure of the closely related receptor ERRgamma. The results suggest that ERRalpha may be intractable as a direct target for pharmacologic activation.

N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (SR141716A) interaction with LYS 3.28(192) is crucial for its inverse agonism at the cannabinoid CB1 receptor.

In superior cervical ganglion neurons, N-(piperidiny-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (SR141716A) competitively antagonizes the Ca(2+) current effect of the cannabinoid (CB) agonist (R)-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl)pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl]-1-naphthalenylmethanone (WIN55212-2), and behaves as an inverse agonist by producing opposite current effects when applied alone. In contrast, in neurons expressing CB1 with a K-->A mutation at residue 3.28(192) (i.e., K3.28A), SR141716A competitively antagonizes the effects of WIN55212-2, but behaves as a neutral antagonist by producing no current effects itself. Receptor modeling studies suggested that in the CB1 inactive (R) state, SR1417A16A stabilizes transmembrane helix 6 in its inactive conformation via aromatic stacking with F3.36/W6.48. In this binding site, SR141716A would exhibit higher affinity for CB1 R due to a hydrogen bond between the SR141716A C3 substituent and K3.28(192), a residue available to SR141716A only in R. To test this hypothesis, a "mutant thermodynamic cycle" was constructed that combined the evaluation of SR141716A affinity at WT CB1 and K3.28A with an evaluation of the wild-type CB1 and K3.28A affinities of an SR141716A analog, 5-(4-chlorophenyl)-3-[(E)-2-cyclohexylethenyl]-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole (VCHSR), that lacks hydrogen bonding potential at C3. Binding affinities suggested that K3.28 is involved in a strong interaction with SR141716A in WT CB1, but does not interact with VCHSR. Thermodynamic cycle calculations indicated that a direct interaction occurs between the C3 substituent of SR141716A and K3.28 in WT CB1. Consistent with these results, VCHSR acted as a neutral antagonist at WT CB1. These results support the hypothesis that hydrogen bonding of the SR141716A C3 substituent with K3.28 is responsible for its higher affinity for the inactive R state, leading to its inverse agonism.