Monica Simeoni

Modeling of human tumor xenografts and dose rationale in oncology

Xenograft models are commonly used in oncology drug development. Although there are discussions about their ability to generate meaningful data for the translation from animal to humans, it appears that better data quality and better design of the preclinical experiments, together with appropriate data analysis approaches could make these data more informative for clinical development. An approach based on mathematical modeling is necessary to derive experiment-independent parameters which can be linked with clinically relevant endpoints. Moreover, the inclusion of biomarkers as predictors of efficacy is a key step towards a more general mechanism-based strategy.

Safety, Pharmacokinetics, and Pharmacodynamics of Escalating Repeat Doses of GSK249320 in Patients With Stroke

Background and Purpose— Restorative therapies have the potential to improve function and reduce disability after stroke with a wide therapeutic window. The current study evaluated GSK249320, a monoclonal antibody that blocks the axon outgrowth inhibition molecule myelin-associated glycoprotein and also protects oligodendrocytes. Methods— Patients with mild-moderate stroke were randomized to intravenous GSK249320 (1, 5, or 15 mg/kg per infusion, in escalating cohorts of 8–9 subjects) versus placebo (n=17). Infusion 1 was 24 to 72 hours after stroke; infusion 2 was 9±1 days later. The primary objective evaluated safety and tolerability, and the secondary objectives evaluated immunogenicity, pharmacokinetics, biomarkers, neurophysiology, and motor function. Results— Baseline (n=42) characteristics were similar across treatment groups. No safety concerns were found based on adverse events, examination, vital signs, ECG, nerve conduction tests, brain imaging, motor function testing, and laboratory studies. Two of the 25 subjects dosed with GSK249320 developed transient antidrug antibodies after infusion 1. The pharmacokinetics profile was as expected for an IgG1 type monoclonal antibody. Serum levels of the biomarker S100&bgr; did not differ between groups. Global outcome measures were similar across groups. Modality-specific end points could be consistently measured in the first few days after stroke, and one of these, gait velocity, demonstrated a trend toward improvement with GSK249320 compared with placebo. Conclusions— GSK249320 was generally well tolerated. No major safety issues were identified in this first study of a monoclonal antibody to modulate the neurobiology of brain repair after stroke. Future studies might explore the efficacy of GSK249320 as a restorative therapy for stroke. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique Identifier: NCT00833989.

Modulation of β-amyloid by a single dose of GSK933776 in patients with mild Alzheimer’s disease: a phase I study

IntroductionIn this study, we evaluated the safety and pharmacodynamic effects of the Fc-inactivated anti-β-amyloid (anti-Aβ) monoclonal antibody GSK933776 in patients with mild Alzheimer’s disease and mild cognitive impairment. Aβ and tau levels were investigated in cerebrospinal fluid (CSF), and the relationship between Aβ levels and Aβ modulation in plasma was explored. The feasibility of a continuous sampling method using a lumbar catheter was assessed.MethodsThis trial was a phase I, open-label, uncontrolled, single-dose, exploratory experimental medicine study of intravenous GSK933776 at doses of 1 mg/kg, 3 mg/kg or 6 mg/kg (n = 6/group). The time course of plasma and CSF concentrations of GSK933776 and Aβ was assessed. Sample size was based on feasibility, and no formal statistical analyses were performed.ResultsFollowing administration of GSK933776 at doses of 1 mg/kg, 3 mg/kg and 6 mg/kg, there were decreases from baseline in CSF Aβ1–42 (from 0 to 12 hours) by 22.8 pg/ml (6.2%), 43.5 pg/ml (9.2%) and 60.5 pg/ml (12.5%), respectively. Plasma concentrations of total Aβ18–35 and Aβ4228–42 increased immediately after infusion and CSF tau concentration increased slightly, but did not significantly change, following administration of all doses of GSK933776. Pharmacokinetics confirmed the presence of GSK933776 in the CSF, which exhibited a dose–response relationship. One patient underwent minor surgery without sequelae following a ruptured lumbar catheter.ConclusionGSK933776 demonstrated pharmacological activity and target engagement in CSF and plasma, and the continuous sampling method via a catheter successfully assessed the Aβ changes following single-dose administration of GSK933776.Trial registrationClinicalTrials.gov Identifier: NCT01424436. Registered 4 August 2011

First Administration of the Fc-Attenuated Anti-β Amyloid Antibody GSK933776 to Patients with Mild Alzheimer's Disease: A Randomized, Placebo-Controlled Study

Objective To assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of the Fc-inactivated anti-β amyloid (Aβ) monoclonal antibody (mAb) GSK933776 in patients with mild Alzheimer’s disease (AD) or mild cognitive impairment (MCI). Methods This was a two-part, single blind, placebo-controlled, first-time-in-human (FTIH) study of single (n = 18) and repeat dose (n = 32) intravenous GSK933776 0.001–6 mg/kg (ClinicalTrials.gov: NCT00459550). Additional safety data from an open-label, uncontrolled, single dose study of intravenous GSK933776 1–6 mg/kg (n = 18) are included (ClinicalTrials.gov: NCT01424436). Results There were no cases of amyloid-related imaging abnormalities-edema (ARIA-E) or –hemorrhage (ARIA-H) after GSK933776 administration in both studies. Three patients across the two studies developed anti-GSK933776 antibodies. Plasma GSK933776 half-life (t1/2) was 10–15 days after repeat dosing. After each of three administrations of GSK933776, plasma levels of total Aβ42 and Aβ increased whereas plasma levels of free Aβ decreased dose dependently; no changes were observed for placebo. For total Aβ42 the peak:trough ratio was ≤2 at doses ≥3 mg/kg; for total Aβ the ratio was ≤2 at 6 mg/kg. CSF concentrations of Aβ showed increases from baseline to week 12 for Aβ X–38 (week 12:baseline ratio: 1.65; 95%CI: 1.38, 1.93) and Aβ X–42 (week 12:baseline ratio: 1.18; 95%CI: 1.06, 1.30) for values pooled across doses. Conclusion In this FTIH study the Fc-inactivated anti-Aβ mAb GSK933776 engaged its target in plasma and CSF without causing brain ARIA-E/H in patients with mild AD or MCI. Trial Registration ClinicalTrials.gov NCT00459550

Modeling Alzheimer's disease progression using the disease system analysis approach

A novel mechanistic model based on a disease system analysis paradigm was developed to explore the role of homeostatic mechanisms involved in Alzheimers disease (AD) progression. We used longitudinal AD Assessment Scale‐cognitive subscale (ADAS‐cog) scores from 926 subjects with AD on stable acetylcholinesterase inhibitor therapy randomized to placebo treatment in two 54‐week clinical trials. Alternative mechanistic models were evaluated by assuming that the rate of change of ADAS‐cog over time was jointly regulated by a process characterizing the deterioration of ADAS‐cog and by a process associated with a compensatory regulatory response. The model based on a time‐varying deterioration rate of ADAS‐cog performed better than the model based on a time‐varying homeostatic control. The covariate analysis indicated that baseline Mini‐Mental State Examination score, education, age, and apolipoprotein ε4 genotype had a significant effect on the level and shape of the trajectories of the mean model predicted ADAS‐cog change from baseline.

Proof-of-Concept Randomized Trial of the Monoclonal Antibody GSK249320 Versus Placebo in Stroke Patients

Background and Purpose— One class of poststroke restorative therapy focuses on promoting axon outgrowth by blocking myelin-based inhibitory proteins such as myelin-associated glycoprotein. The purpose of the current study was to extend preclinical and clinical findings of GSK249320, a humanized monoclonal antibody to myelin-associated glycoprotein with disabled Fc region, to explore effects on motor outcomes poststroke. Methods— In this phase IIb double-blind, randomized, placebo-controlled study, patients at 30 centers with ischemic stroke 24 to 72 hours prior and gait deficits were randomized to 2 IV infusions of GSK249320 or placebo. Primary outcome measure was change in gait velocity from baseline to day 90. Results— A total of 134 subjects were randomized between May 2013 and July 2014. The 2 groups were overall well matched at baseline. The study was stopped at the prespecified interim analysis because the treatment difference met the predefined futility criteria cutoff; change in gait velocity to day 90 was 0.55±0.46 (mean±SD) in the GSK249320 group and 0.56±0.50 for placebo. Secondary end points including upper extremity function were concordant. The 2 IV infusions of GSK249320 were well tolerated. No neutralizing antibodies to GSK249320 were detected. Conclusions— GSK249320, within 72 hours of stroke, demonstrated no improvement on gait velocity compared with placebo. Possible reasons include challenges translating findings into humans and no direct evidence that the therapy reached the biological target. The antibody was well tolerated and showed low immunogenicity, findings potentially useful to future studies aiming to use a monoclonal antibody to modify activity in specific biological pathways to improve recovery from stroke. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT01808261.

Randomized clinical study of safety, pharmacokinetics, and pharmacodynamics of RIPK1 inhibitor GSK2982772 in healthy volunteers

GSK2982772 is a highly selective inhibitor of receptor‐interacting protein kinase 1 (RIPK1) being developed to treat chronic inflammatory diseases. This first‐in‐human study evaluated safety, tolerability, pharmacokinetics (PK), and exploratory pharmacodynamics (PD) of GSK2982772 administered orally to healthy male volunteers. This was a Phase I, randomized, placebo‐controlled, double‐blind study. In Part A, subjects received single ascending doses of GSK2982772 (0.1‐120 mg) or placebo in a crossover design during each of 4 treatment periods. In Part B, subjects received repeat doses of GSK2982772 (20 mg once daily [QD] to up to 120 mg twice daily [BID]) or placebo for 14 days. Part C was an open‐label relative bioavailability study comparing 20‐mg tablets vs capsules. Safety, tolerability, pharmacokinetics (PK), RIPK1 target engagement (TE), and pharmacodynamics (PD) were assessed. The most common adverse events (AEs) were contact dermatitis and headache. Most AEs were mild in intensity, and there were no deaths or serious AEs. The PK of GSK2982772 was approximately linear over the dose range studied (up to 120 mg BID). There was no evidence of drug accumulation upon repeat dosing. Greater than 90% RIPK1 TE was achieved over a 24‐hour period for the 60‐mg and 120‐mg BID dosing regimens. Single and repeat doses of GSK2982772 were safe and well tolerated. PK profiles showed dose linearity. The high levels of RIPK1 TE support progression into Phase II clinical trials for further clinical development.

Tumor Growth Modelling for Drug Development

The development of a drug is a long and increasingly expensive process. Mathematical models have become fundamental tools for the most efficient use of resources in pharmaceutical research, driving the design of more informative studies and therefore reducing the number of animals or patients evaluated. Models provided with some mechanistic ground allow discriminating drug-related parameters from system-related parameters, which is a fundamental requirement for predicting the effect of a new treatment in different studies and settings. A tumor growth inhibition model of this kind, which describes the effect of oncology agents in xenograft mice, has been developed. The model returns a measure of drug potency and allows the calculation of the minimal concentration needed to stop the tumor growth. The model has been extended to different scenarios, like combination therapy. Even more importantly, it has been possible to determine a relationship between the drug potency parameters estimated in animals and efficacious clinical exposures in oncology patients, further supporting the robustness of the model in guiding the decision making during the drug development process.