CA-125 KELIM as a Potential Complementary Tool for Predicting Veliparib Benefit: An Exploratory Analysis From the VELIA/GOG-3005 Study.

PURPOSE: In VELIA trial, veliparib combined with carboplatin-paclitaxel, followed by maintenance (veliparib-throughout) was associated with improved progression-free survival (PFS) compared with carboplatin-paclitaxel alone in patients with high-grade ovarian carcinomas. We explored the prognostic value of the modeled cancer antigen (CA)-125 elimination rate constant K (KELIM), which is known to be an indicator of the intrinsic tumor chemosensitivity (the faster the rate of CA-125 decline, the higher the KELIM and the higher the chemosensitivity), and its association with benefit from veliparib. PATIENTS AND METHODS: Individual KELIM values were estimated from longitudinal CA-125 kinetics. Patients were categorized as having favorable (≥ median) or unfavorable (< median) KELIM. The prognostic value of KELIM for veliparib-related PFS benefit was explored in cohorts treated with primary or interval debulking surgery, according to the surgery completeness, the disease progression risk group, and the homologous recombination (HR) status (BRCA mutation, HR deficiency [HRD], or HR proficiency [HRP]). RESULTS: The data from 854 of 1,140 enrolled patients were analyzed (primary debulking surgery, n = 700; interval debulking surgery, n = 154). Increasing KELIM values were associated with higher benefit from veliparib in HRD cancer, as were decreasing KELIM values in HRP cancer. The highest PFS benefit from veliparib was observed in patients with both favorable KELIM and BRCA mutation (hazard ratio, 0.28; 95% CI, 0.13 to 0.61) or BRCA wild-type HRD cancer (hazard ratio, 0.43; 95% CI, 0.26 to 0.70), consistent with the association between poly (adenosine diphosphate-ribose) polymerase inhibitor efficacy and platinum sensitivity. In contrast, seventy-four percent of patients with a BRCA mutation and unfavorable KELIM progressed within 18 months while on veliparib. The patients with HRP cancer and unfavorable KELIM might have benefited from the veliparib chemosensitizing effect. CONCLUSION: In addition to HRD/BRCA status, the tumor primary chemosensitivity observed during the first-line chemotherapy might be another complementary determinant of poly (adenosine diphosphate-ribose) polymerase inhibitor efficacy.

Drug response hysteresis in the concentration-QTc analysis of early clinical trials.

According to the International Conference on Harmonisation E14 Q&As R3, concentration-QTc analysis can serve as an alternative to the by-time-point analysis or intersection-union test as the primary basis for decisions to classify the QTc risk of a drug. In a recent scientific white paper on concentration-QTc analysis, a pre-specified linear mixed effect model was suggested to study a QTc prolongation effect. The model assumes a direct time-concordant relationship (direct effect) between QTc interval and drug-concentrations. In the case of lagged drug QTc effects, also called 'hysteresis', a linear direct effect model may yield a biased QTc estimate. In this work, we estimate the bias of QTc effects via simulations when hysteresis is not accounted for in the linear mixed effect model analysis. Simulations are performed to compare different methods of identifying hysteresis when two physiologically plausible QT drug mechanisms are considered. The focus of this paper is to provide hysteresis identification methods and assess the influence of hysteresis in estimating the QT prolongation for most commonly observed QT-Concentration profiles.

Global Analysis of Models for Predicting Human Absorption: QSAR, In Vitro, and Preclinical Models.

Models intended to predict intestinal absorption are an essential part of the drug development process. Although many models exist for capturing intestinal absorption, many questions still exist around the applicability of these models to drug types like "beyond rule of 5" (bRo5) and low absorption compounds. This presents a challenge as current models have not been rigorously tested to understand intestinal absorption. Here, we assembled a large, structurally diverse dataset of ∼1000 compounds with known in vitro, preclinical, and human permeability and/or absorption data. In silico (quantitative structure-activity relationship), in vitro (Caco-2), and in vivo (rat) models were statistically evaluated for predictive performance against this human intestinal absorption dataset. We expect this evaluation to serve as a resource for DMPK scientists and medicinal/computational chemists to increase their understanding of permeability and absorption model utility and applications for academia and industry.

Use of Early Clinical Trial Data to Support Thorough QT Study Waiver for Upadacitinib and Utility of Food Effect to Demonstrate ECG Assay Sensitivity.

Exposure-response analyses of QT data from early-stage clinical studies represent a valuable tool to assess the QT prolongation potential for drugs in development in lieu of standalone thorough QT (TQT) studies. However, demonstrating adequate electrocardiogram assay sensitivity can be challenging in the absence of a positive pharmacological control. Upadacitinib is a Janus kinase 1 inhibitor currently being evaluated in phase III rheumatoid arthritis trials. Exposure-response analyses to evaluate the QT prolongation potential for upadacitinib from phase I trials and the utility of the effect of food on QTcF to demonstrate ECG assay sensitivity are presented. The analyses demonstrated no effect of upadacitinib on QT interval and confirmed the sensitivity of the ECG assay to detect the small QT shortening effect caused by food. Lack of bias from manual ECG adjudication was also demonstrated. These analyses supported requesting a waiver for the regulatory requirement for a dedicated thorough QT study for upadacitinib.

Application of Exposure-Response Analyses to Establish the Pharmacodynamic Similarity of a Once-Daily Regimen to an Approved Twice-Daily Dosing Regimen for the Treatment of HCV Infection.

The triple direct-acting antiviral (3-DAA) regimen (two co-formulated tablets of ombitasvir/paritaprevir/ritonavir once daily and one tablet of dasabuvir twice daily) for patients with hepatitis C virus (HCV) genotype 1 infection has been reformulated for once-daily administration containing all three active DAAs (3QD regimen). Two bioequivalence studies compared the 3-DAA and 3QD regimens. In study 1, fed, single-, and multiple-dose crossover comparisons revealed exposures for drug components that were slightly outside the bioequivalence criteria, i.e., 21 to 29% lower dasabuvir C trough, paritaprevir C max, and ritonavir C max. In study 2, fed and fasted single-dose crossover comparisons demonstrated a large impact of food on exposures, confirming the product's labeling requirement for administration only with food, and revealed a lack of bioequivalence under fasting conditions. Exposure-response analyses using efficacy data from phase 2/3 studies of the 3-DAA regimen demonstrated that the lower dasabuvir C trough for the 3QD regimen (under fed condition) would have minimal impact on sustained virologic response at week 12 post-treatment (SVR12). Thus, the pharmacodynamic similarity between the regimens was established and the analyses provided the basis for regulatory approval of the 3QD regimen to treat patients with chronic HCV genotype 1 infection.

Pharmacokinetic and exposure-response analyses of leuprolide following administration of leuprolide acetate 3-month depot formulations to children with central precocious puberty.

BACKGROUND AND OBJECTIVE: A pharmacokinetic substudy was conducted within a phase 3 clinical trial that evaluated the efficacy and safety of two leuprolide acetate 3-month depot formulations in children with central precocious puberty (CPP), where the pharmacokinetics of leuprolide and the exposure-response relationship between leuprolide concentration and the probability of luteinizing hormone (LH) suppression were assessed. METHODS: Children diagnosed with CPP (N = 42 in each dosing cohort), who were treatment naïve or previously treated, received a total of two intramuscular injections of either leuprolide acetate depot 11.25 or 30 mg formulations administered 3 months apart. Serial blood samples were collected for leuprolide concentration determination in a subset of subjects (N = 24 in each cohort). One-way analysis of covariance was used to assess dose proportionality. The probability of LH suppression (peak-stimulated LH concentrations <4 mIU/mL) exposure-response relationship was modelled using repeated measures logistic regression. The predicted probability of LH suppression and the corresponding 95 % confidence interval at the mean leuprolide concentration of each dose group and at each time of measurement were computed. RESULTS: Mean leuprolide concentrations between weeks 4 and 12 for 11.25 and 30 mg doses were relatively constant and dose proportional, with no accumulation of leuprolide upon repeated administration. Body weight and age were not found to be significant covariates on leuprolide pharmacokinetics. Higher leuprolide concentrations were associated with higher probability of LH suppression and both doses provided LH suppression levels <4 mIU/mL. CONCLUSION: Leuprolide pharmacokinetics were characterized for 11.25 and 30 mg 3-month depot injections. An exposure-response model was developed to link leuprolide concentrations and probability of peak-stimulated LH suppression.

Results of a phase I, open-label, randomized, crossover study evaluating the effects of linifanib on QTc intervals in patients with solid tumors.

PURPOSE: Linifanib is a selective inhibitor of the vascular endothelial growth factor and platelet-derived growth factor family of tyrosine kinase inhibitors. The purpose of this high-precision QT study was to evaluate the effects of linifanib on cardiac repolarization in patients with advanced metastatic tumors. METHODS: Enrolled patients (n = 24) had measurable disease refractory to standard therapies, ECOG performance status of 0-1, and adequate organ function. Patients were randomized in a 2-sequence, 2-period crossover design. Serial ECG measurements and pharmacokinetic samples were collected for each crossover period. An intersection-union test was performed for time-matched baseline-adjusted QTcF intervals. An exposure-response analysis was explored to correlate the plasma concentration and QTcF. RESULTS: The maximum 95 % upper confidence bound for the baseline-adjusted QTcF was 4.3 ms at hour 3 at the maximum tolerated linifanib dose of 0.25 mg/kg. Linifanib did not meet the regulatory threshold (10 ms) for QT prolongation. Exposure-response modeling showed that the QTcF change was not significant at the maximum plasma concentration. CONCLUSIONS: Linifanib does not significantly affect cardiac repolarization in patients with advanced solid tumors.

Crossover versus parallel designs: dose-escalation design comparisons for first-in-human studies.

We study the statistical efficiency for rising-dose designs in the context of first-in-human studies. Specifically, we identify a class of crossover designs that are appealing in terms of both subject safety and statistical efficiency and, for a three-period, two-panel design in such a class, we compare its A-efficiency relative to the corresponding parallel designs and optimal/efficient crossover designs, respectively, under various plausible models. In the meantime, we also evaluate the impact of inclusion of baseline measurements as a covariate in the statistical analysis, for both crossover and parallel studies.

The joint modeling of drug and positive control effects to estimate sample size and power in crossover "thorough" QT/QTc studies.

We present analytical results for computing the power and sample size in a thorough QT/QTc study with a four-period crossover design in which the treatments are placebo, positive control, supratherapeutic dose of investigational drug, and therapeutic dose of investigational drug. An assessment of noninferiority of the supratherapeutic dose to placebo is performed by the intersection-union test and assay sensitivity is tested (union-intersection test) at prespecified time points using positive control within the framework of a linear mixed-effects analysis. The power and sample size estimates are obtained using the joint distribution of statistics to test noninferiority of the supratherapeutic dose to placebo and to test assay sensitivity using positive control.

Population analyses of efficacy and safety of ABT-594 in subjects with diabetic peripheral neuropathic pain.

ABT-594, a neuronal nicotinic acetylcholine receptor ligand, is 30- to 100-fold more potent than morphine in animal models of nociceptive and neuropathic pain. Efficacy and safety of ABT-594 in subjects with painful diabetic polyneuropathy was evaluated in a phase 2 study. The objective of this work was to use a nonlinear mixed effects model-based approach for characterizing the relationship between dose and response (efficacy and safety) of ABT-594. Subjects (N = 266) were randomized into four groups in a double-blind, placebo-controlled, 7-week study to receive twice daily regimens of placebo or 150, 225, and 300 µg of ABT-594. The primary efficacy variable, pain score (11-point Likert scale), was assessed on five occasions. The probability of change from baseline pain score of ≥1, ≥2, and ≥3 was modeled using cumulative logistic regression with dose and days of treatment as explanatory variables. The incidence of five most frequently occurring adverse events (AEs) was modeled using linear logistic regression. ABT-594 ED(50) values (improvement in 50% of subjects) for improvement in pain scores of ≥1, ≥2, and ≥3 were 50, 215, and 340 µg, respectively, for the average number of days (33) on treatment. The rank order of ED(50) values for AEs was nausea, vomiting, dizziness, headache, and abnormal dreams; nicotine users were less sensitive to AEs. Population pharmacodynamic models developed to characterize the improvement in pain score and incidence of adverse events indicate an approximately twofold separation between the ED(50) values for efficacy and AEs.

Sample size and power estimation in "thorough" QT/QTc studies with parallel group design.

We developed analytical results for computing the power in a thorough QT/QTc study with a four-group parallel design in which the treatments are placebo, positive control, supratherapeutic dose of investigational drug, and therapeutic dose of investigational drug. An assessment of non-inferiority of the supratherapeutic dose to placebo is performed by the intersection-union test within the framework of a linear mixed effects analysis with baseline covariate. The power estimates obtained using analytical results and from the simulation study were presented and they are quite close and hence the analytical results could be used for computing power and sample size in the planning stage of a thorough QT/QTc study.

Exposure-response modeling approach for assessing QT effect in "thorough" QT/QTc studies.

We assess the QT effect using an exposure-response model in a "thorough QT/QTc study" with a four-period crossover design in which the treatments are placebo, positive control, higher dose of investigational drug, and therapeutic dose of investigational drug. In the study, QTc interval values and the drug concentrations are obtained for several specified times during treatment. This approach to the assessment of non-inferiority of the higher dose to placebo is an alternative strategy suggested in ICH-E14 guideline (Section 2.2.5) to the intersection-union test.

Randomized, placebo-controlled, double-blind, parallel design trial of the efficacy and safety of Zestra in women with mixed desire/interest/arousal/orgasm disorders.

Over 256 women, age 21 to 65, with acquired mixed female sexual disorders participated in a 16-week randomized, placebo-controlled, double-blind study of Zestra, a topical botanical preparation. Routine outcome instruments measured efficacy and safety. Zestra was well tolerated. The only significant safety finding was mild-to-moderate genital burning seen only in Zestra-treated subjects (14.6%). Zestra provided significant desire, arousal, and treatment satisfaction benefits for a broadly generalized group of women with sexual difficulties.

ABT-335, the choline salt of fenofibric acid, does not have a clinically significant pharmacokinetic interaction with rosuvastatin in humans.

ABT-335 is the choline salt of fenofibric acid under clinical development as a combination therapy with rosuvastatin for the management of dyslipidemia. ABT-335 and rosuvastatin have different mechanisms of actions and exert complementary pharmacodynamic effects on lipids. The current study assessed the pharmacokinetic interaction between the 2 drugs following a multiple-dose, open-label, 3-period, randomized, crossover design. Eighteen healthy men and women received 40 mg rosuvastatin alone, 135 mg ABT-335 alone, and the 2 drugs in combination once daily for 10 days. Blood samples were collected prior to dosing on multiple days and up to 120 hours after day 10 dosing for the measurements of fenofibric acid and rosuvastatin plasma concentrations. Coadministering 40 mg rosuvastatin had no significant effect on the steady-state Cmax, Cmin, or AUC24 of fenofibric acid (P > .05). Coadministering ABT-335 had no significant effect on the steady-state Cmin or AUC24 of rosuvastatin (P > .05) but increased Cmax by 20% (90% confidence interval: 12%-28%). All 3 regimens were generally well tolerated with no clinically significant changes in clinical laboratory values, vital signs, or electrocardiograms during the study. Results from this study demonstrate no clinically significant pharmacokinetic interaction between ABT-335 at the full clinical dose and rosuvastatin at the highest approved dose.

Atrasentan, an endothelin-receptor antagonist for refractory adenocarcinomas: safety and pharmacokinetics.

PURPOSE: Endothelin receptors, particularly the ET(A) receptor, have been shown to participate in the pathophysiology of prostate and other cancers. Atrasentan, an endothelin antagonist, binds selectively to the ET(A) receptor. This study evaluated the safety, pharmacokinetics, and maximum-tolerated dose of atrasentan in cancer patients. PATIENTS AND METHODS: Patients who were 18 years or older and had histologically confirmed adenocarcinoma refractory to therapy enrolled in this 28-day, open-label, phase I study. Enrollment was planned for cohorts of three patients at doses escalating from 10 to 140 mg/d. When any patient had dose-limiting toxicity, that cohort was expanded. The primary outcome variable was safety; secondary outcome variables were pharmacokinetics, tumor response, and pain relief. RESULTS: Thirty-one cancer patients (14 prostate) were treated at daily atrasentan doses of 10, 20, 30, 45, 60, and 75 mg (n = 3 to 8 per cohort). The most common adverse events, such as rhinitis, headache, asthenia, and peripheral edema, were reversible on drug discontinuation and responded to symptom-specific treatment. Reversible hemodilution was apparent in laboratory findings and weight gain. Clinically significant headache was the dose-limiting adverse event; the maximum-tolerated dose was 60 mg/d. Pharmacokinetics were dose-proportional across the 10- to 75-mg dose range. Atrasentan was rapidly absorbed; the time to maximum observed concentration was approximately 1.5 hours. The terminal elimination half-life was approximately 24 hours, and steady-state plasma concentrations were achieved within 7 days. Decreases in prostate-specific antigen and pain relief were noted in a patient subset. CONCLUSION: Adverse events were consistent with atrasentan's pharmacologic vasodilatory effect. Linear, dose-proportional pharmacokinetics suggest that atrasentan can be easily and consistently dosed.