Phase IIa Proof-of-Concept Evaluation of the Antiviral Efficacy, Safety, Tolerability, and Pharmacokinetics of the Next-Generation Maturation Inhibitor GSK3640254.

BACKGROUND: GSK3640254 (GSK'254) is a next-generation human immunodeficiency virus type 1 (HIV-1) maturation inhibitor with pharmacokinetics (PK) supporting once-daily therapy. METHODS: This phase IIa double-blind (sponsor-unblinded), randomized, placebo-controlled, adaptive study evaluated antiviral effect, safety, tolerability, and PK of once-daily GSK'254 monotherapy administered with food (moderate-fat meal) in HIV-1-positive, treatment-naive adults. In part 1, participants received GSK'254 10 or 200 mg for 10 days. In part 2, participants received GSK'254 40, 80, or 140 mg for 7 days, modified from 10 days by a protocol amendment to decrease potential for resistance-associated mutations (RAMs). The primary endpoint was maximum change from baseline in HIV-1 RNA. RESULTS: Maximum changes in HIV-1 RNA of -0.4, -1.2, -1.0, -1.5, and -2.0 log10 occurred with GSK'254 10, 40, 80, 140, and 200 mg, respectively. Regardless of dosing duration, doses ≥40 mg resulted in ≥1-log10 declines in HIV-1 RNA. Plasma PK was generally dose proportional to 140 mg but non-proportional between 140 and 200 mg. Four participants in the 200-mg group developed RAMs on day 11 in part 1, 1 with phenotypic resistance. No RAMs occurred in part 2. Adverse events (AEs) were reported by 22 (65%) participants; headache was the most common (n = 4). Two non-drug-related serious AEs occurred. All AEs were of mild-to-moderate intensity, except for 2 grade 3 non-drug-related AEs in 1 participant. CONCLUSIONS: This monotherapy study established a dose-antiviral response relationship for GSK'254. No safety or tolerability concerns were noted. These results supported dose selection for the ongoing phase IIb study (ClinicalTrials.gov: NCT04493216). CLINICAL TRIALS REGISTRATION: NCT03784079.

Bioequivalence and Food Effect Assessment of 2 Fixed-Dose Combination Formulations of Dolutegravir and Lamivudine.

This single-dose study evaluated the bioequivalence, food effect, and safety of 2 experimental, 2-drug, fixed-dose formulations of 50 mg dolutegravir and 300 mg lamivudine (formulation AH and formulation AK) as compared with coadministration of single-entity tablets of 50 mg dolutegravir and 300 mg lamivudine (reference). In fasted subjects, formulation AH lamivudine exposure was similar to the reference; however, dolutegravir exposure was consistently higher in formulation AH, with area under the concentration-time curve (AUC) and maximum concentration (Cmax ) approximately 27% to 28% greater than reference. Formulation AK met bioequivalence standards to the reference for dolutegravir (AUC0-∞ and Cmax ) and lamivudine (AUC0-∞ and AUC0-t ) exposure; however, dolutegravir AUC0-t and lamivudine Cmax were approximately 16% and 32% higher than the reference, respectively. A high-fat meal increased dolutegravir AUC and Cmax by up to 33% and 21%, respectively, and decreased lamivudine Cmax by approximately 30%. Both test and reference formulations were well tolerated. The results support further development of formulation AK as a novel, 2-drug, fixed-dose combination tablet treatment for patients with HIV.

Population Pharmacokinetics and Pharmacodynamics Modelling of Dilmapimod in Severe Trauma Subjects at Risk for Acute Respiratory Distress Syndrome.

INTRODUCTION: Dilmapimod is a potent p38 mitogen-activated protein kinase (MAPK) inhibitor and was investigated in a study (NCT00996840) for its anti-inflammatory effect in non-head injury trauma patients at risk for developing acute respiratory distress syndrome (ARDS). The purpose of this paper is to present the details of the development of a population pharmacokinetic (PK) model, an empirical population placebo response model, and the exploration of a PK/pharmacodynamic (PD) model of dilmapimod. METHODS: A population PK model was developed to characterise the PK profile of dilmapimod in this patient population; the potential effect of available covariates on the PK of dilmapimod was evaluated. An empirical population placebo response model was conducted, and a population PK/PD model was explored to evaluate the relationship between dilmapimod concentration and C-reactive protein (CRP) (a systemic biomarker of p38 inhibition). All analyses were performed using NONMEM software. RESULTS: Following intravenous dosing, dilmapimod was quickly distributed to peripheral compartments and then slowly eliminated. The plasma concentration of dilmapimod was adequately described by a three-compartment model. It increased approximately proportionally to the increase in dose. The population clearance (CL) parameter value was 35.87 L/h, and the steady-state volume of distribution (Vss) [sum of the volume of distribution of the central compartment (Vc) and of the peripheral compartments V2 and V3] was 160 L. The effect of body mass index (BMI) on CL and inter-compartment clearance (Q2) was found statistically significant, with an increase in BMI of 1 kg/m2 resulting in a 1.79 L/h and 0.52 L/h increase in CL and Q2, respectively. The CRP profile post injury was adequately described by an indirect response model, with a sharp increase in the CRP levels following injury, followed by them slowly diminishing. Data exploration indicated potential drug effects of dilmapimod on inhibiting the production of CRP levels; however, the current small dataset did not show a statistically significant improvement in the PK/PD modelling. CONCLUSION: The population PK modelling adequately evaluated the dilmapimod plasma concentration-time profiles in severe trauma subjects at risk for ARDS, and BMI was found to be a significant covariate in the PK model. An indirect response model was adequate to describe the production and degradation of CRP levels in these subjects.

Pharmacometrics-guided drug development of antihyperhidrosis agents.

The objective of the present work was to use modeling and simulation to inform trial design of a proof-of-concept study for agents used in the treatment of hyperhidrosis. Data were available from 36 subjects who received the vehicle, 2% or 4% topical glycopyrrolate wipes daily for 4 weeks, with response (hyperhidrosis disease severity scale [HDSS] and sweat production [SP]) measured weekly. The HDSS and SP time courses were best described using a longitudinal model with maximum response achieved by 1 week. Glycopyrrolate 4% had a higher HDSS responder rate than 2% (50% vs 33%) and placebo (0%) at week 1. Mean change from baseline (mg/5 min [SD]) in SP at week 1 was -90 (220), -185 (214), and -271 (265) for placebo, 2%, and 4% glycopyrrolate, respectively. Subjects with higher baseline SP had higher sweat reduction from baseline. Virtual clinical trials were simulated and analyzed using conventional (at the end of the study) versus model-based methods to determine sample size for achieving 80% power to identify a dose-response relationship. Twenty-seven subjects compared with at least 120 subjects would be needed using model-based and conventional methods, respectively. Thus, the model-based method using longitudinal data required fewer subjects than the conventional single-point method.

Abl N-terminal cap stabilization of SH3 domain dynamics.

Crystal structures and other biochemical data indicate that the N-terminal cap (NCap) region of the Abelson tyrosine kinase (c-Abl) is important for maintaining the downregulated conformation of the kinase domain. The exact contributions that the NCap makes in stabilizing the various intramolecular interactions within c-Abl are less clear. While the NCap appears to be important for locking the SH3 and SH2 domains to the back of the kinase domain, there may be other more subtle elements of regulation. Hydrogen exchange (HX) and mass spectrometry (MS) were used to determine if the NCap contributes to intramolecular interactions involving the Abl SH3 domain. Under physiological conditions, the Abl SH3 domain underwent partial unfolding and its unfolding half-life was slowed during binding to the SH2 kinase linker, providing a unique assay for testing NCap-induced stabilization of the SH3 domain in various constructs. The results showed that the NCap stabilizes the dynamics of the SH3 domain in certain constructs but does not increase the relative affinity of the SH3 domain for the native SH2 kinase linker. The stabilization effect was absent in constructs of just the NCap and SH3 but was obvious when the SH2 domain and the SH2 kinase linker were present. These results suggest that interactions between the NCap and the SH3 domain can contribute to c-Abl stabilization in constructs that contain at least the SH2 domain, an effect that may partially compensate for the absence of the negative regulatory C-terminal tail found in the related Src family of kinases.

SRC family kinase activity is required for murine embryonic stem cell growth and differentiation.

Self-renewal and differentiation of embryonic stem (ES) cells are regulated by cytokines and growth factors through tyrosine kinase-dependent signaling pathways. In murine ES cells, signals for self-renewal are generated by the leukemia inhibitory factor (LIF). LIF and other growth factors are linked to the activation of the Src family of cytoplasmic protein-tyrosine kinases (SFKs), which consists of eight members having shared structural architecture. In this article, we show that murine ES cells express seven SFKs, three of which (Hck, Src, and Fyn) exhibit constitutive activity in self-renewing ES cells. Differentiation of ES cells to embryoid bodies was associated with rapid transcriptional silencing of Hck and Lck and with the loss of the corresponding kinase proteins. The expression of other family members remained relatively constant, although some loss of Fgr and Lyn proteins was observed during differentiation. Like ES cells, embryoid bodies maintained constitutive Src and Fyn kinase activity. Partial inhibition of endogenous SFK activity with the ATP-competitive inhibitors 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine or Src kinase inhibitor-1 induced differentiation of ES cells in the presence of LIF. In contrast, suppression of all SFK activity with higher concentrations of these inhibitors, or with the more potent compound A-419259 (Bioorg Med Chem Lett 12:1683-1686, 2002) blocked differentiation in response to LIF withdrawal. It is surprising that these inhibitor-treated cells remained pluripotent despite the absence of LIF. Our results implicate individual members of the Src kinase family in distinct ES cell renewal and differentiation pathways and show that small-molecule SFK inhibitors can control ES cell fate.

Small molecule modulators of endogenous and co-chaperone-stimulated Hsp70 ATPase activity.

The molecular chaperone and cytoprotective activities of the Hsp70 and Hsp40 chaperones represent therapeutic targets for human diseases such as cancer and those that arise from defects in protein folding; however, very few Hsp70 and no Hsp40 modulators have been described. Using an assay for ATP hydrolysis, we identified and screened small molecules with structural similarity to 15-deoxyspergualin and NSC 630668-R/1 for their effects on endogenous and Hsp40-stimulated Hsp70 ATPase activity. Several of these compounds modulated Hsp70 ATPase activity, consistent with the action of NSC 630668-R/1 observed previously (Fewell, S. W., Day, B. W., and Brodsky, J. L. (2001) J. Biol. Chem. 276, 910-914). In contrast, three compounds inhibited the ability of Hsp40 to stimulate Hsp70 ATPase activity but did not affect the endogenous activity of Hsp70. Two of these agents also compromised the Hsp70/Hsp40-mediated post-translational translocation of a secreted pre-protein in vitro. Together, these data indicate the potential for continued screening of small molecule Hsp70 effectors and that specific modulators of Hsp70-Hsp40 interaction can be obtained, potentially for future therapeutic use.

The FEAR Before MEN: networks of mitotic exit.

Variations in the normal regulation of the mitotic cell cycle can lead to such global cellular changes as differential development or malignant transformation. Studies on the control of mitosis are particularly important to discover the details of the basic mechanisms responsible for normal cell division, as well as to learn about strategies employed by cancerous cells to indefinitely proliferate. The past years have brought noteworthy progress in elucidating the molecular pathways that regulate crucial events during mitosis such as: chromosome condensation, formation of the mitotic spindle, chromosome segregation, cytokinesis, and disassembly of the mitotic spindle.