Clinical Trial Simulation to Inform Phase 2: Comparison of Concentrated vs. Distributed First-in-Patient Study Designs in Psoriasis.

Clinical trial simulation (CTS) and model-based meta-analysis (MBMA) can increase our understanding of small, first-in-patient (FIP) trial design performance to inform Phase 2 decision making. In this work, we compared dose-ranging designs vs. designs testing only placebo and the maximum dose for early decision making in psoriasis. Based on MBMA of monoclonal antibodies in the psoriasis space, a threshold of greater than a 50 percentage point improvement over placebo effect at the highest feasible drug dose was required for the advancement in psoriasis. Studies testing only placebo and the maximum dose made the correct advancement decision marginally more often than dose-ranging designs in the majority of the cases. However, dose-ranging studies in FIP trials offer important design advantages in the form of dose-response (D-R) information to inform Phase 2 dose selection. CTS can increase the efficiency and quality of drug development decision making by studying the limitations and benefits of study designs prospectively.CPT: Pharmacometrics & Systems Pharmacology (2013) 2, e58; doi:10.1038/psp.2013.32; published online 24 July 2013.

Magnesium sulphate for prevention of eclampsia: are intramuscular and intravenous regimens equivalent? A population pharmacokinetic study.

OBJECTIVE: To compare magnesium sulphate concentrations achieved by intramuscular and intravenous regimens used for the prevention of eclampsia. SETTING: Low-resource obstetric hospitals in Nagpur and Vellore, India. POPULATION: Pregnant women at risk for eclampsia due to hypertensive disease. METHODS: A pharmacokinetic study was performed as part of a randomised trial that enrolled 300 women comparing intramuscular and intravenous maintenance regimens of magnesium dosing. Data from 258 enrolled women were analysed in the pharmacokinetic study. A single sample was drawn per woman with the expectation of using samples in a pooled data analysis. MAIN OUTCOME MEASURES: Pharmacokinetic parameters of magnesium distribution and clearance. RESULTS: Magnesium clearance was estimated to be 48.1 dl/hour, volume of distribution to be 156 dl and intramuscular bioavailability to be 86.2%. The intramuscular regimen produced higher initial serum concentrations, consistent with a substantially larger loading dose. At steady state, magnesium concentrations in the intramuscular and intravenous groups were comparable. With either regimen, a substantial number of women would be expected to have serum concentrations lower than those generally held to be therapeutic. CONCLUSIONS: Clinical implications were that a larger loading dose for the intravenous regimen should be considered; where feasible, individualised dosing of magnesium sulphate would reduce the variability in serum concentrations and might result in more women with clinically effective magnesium concentrations; and lower dose magnesium sulphate regimens should be considered with caution.

OS034. Magnesium sulfate for prevention of eclampsia: Are intramuscularand intravenous regimens equivalent?

INTRODUCTION: Magnesium sulfate is the agent of choice for the treatment and prevention of eclampsia. Optimal loading and maintenance dosing has not been determined. OBJECTIVES: To compare the pharmacokinetic parameters if IM vs. IV magnesium sulfate. METHODS: A pharmacokinetic study was performed as part of a randomized trial that enrolled 300 women comparing IM and IV regimens of magnesium dosing in two low resource sites in India. Data from 258 enrolled women were analyzed in the pharmacokinetic study. Due to infrastructure available at the sites, a single sample was drawn per subject with the expectation of utilizing samples in a pooled data analysis. RESULTS: Magnesium clearance was estimated via pharmacokinetic modeling to be 48.1dL/h, volume of distribution 156dL and IM bioavailability 86.2%. The IM regimen produced higher initial serum concentrations, consistent with a substantially larger loading dose. At steady state, Mg concentrations in the IM and IV Groups were comparable. With either regimen, a substantial number of subjects would be expected to have serum concentrations lower than those generally expected to be therapeutic. CONCLUSION: A larger loading dose for the IV regimen should be considered. Where feasible, individualized higher doses of magnesium sulfate would yield a greater number of treated women with clinically effective magnesium concentrations.

A dose-response meta-analysis for quantifying relative efficacy of biologics in rheumatoid arthritis.

We present a dose-response meta-analysis to quantify relative efficacy of biologic disease-modifying antirheumatic drugs (DMARDs) in patients with rheumatoid arthritis (RA). There is a strong rationale for this analysis because, although multiple biologics are available, information on head-to-head comparisons is limited. Data on the percentage of patients attaining American College of Rheumatology (ACR) 20, 50, and 70 responses were extracted from 50 randomized controlled trials representing 21,500 patients, five mechanisms of action, and nine biologics. The analysis showed that all tumor necrosis factor inhibitors (anti-TNFs) share the same dose-response relationship for ACR 20, 50, and 70, differing only in potency. Yet there are significant differences in efficacy among the anti-TNFs due to differences in the clinical dose ranges available. At the suggested starting dose, golimumab was the least efficacious, followed by infliximab, adalimumab, etanercept, and certolizumab. Significant differences in the dose-response relationship were found between anti-TNFs and other biologics, resulting in differences in efficacy and differential impact of dose titration.

Personalized dosing of cyclophosphamide in the total body irradiation-cyclophosphamide conditioning regimen: a phase II trial in patients with hematologic malignancy.

This study investigates the efficacy and safety of personalized cyclophosphamide (CY) dosing in 50 patients receiving CY along with total body irradiation (TBI). Participants received CY 45 mg/kg with subsequent therapeutic drug monitoring using Bayesian parameter estimation to personalize the second CY dose to a target area under the curve (AUC) for carboxyethylphosphoramide mustard (CEPM) (a reporter molecule for CY-derived toxins) and for hydroxycyclophosphamide (to ensure engraftment). The mean second CY dose was 66 mg/kg; the total dose ranged from 45 to 145 mg/kg. After completion of this phase II study, we compared participants' clinical outcomes with those of concurrent controls (n = 100) who received TBI along with standard CY doses of 120 mg/kg. Patients receiving personalized CY dosing had significantly lower postconditioning peak total serum bilirubin (P = 0.03); a 38% reduction in the hazard of acute kidney injury (AKI) (P = 0.03); and nonrelapse and overall survival rates similar to those in the controls (P = 0.70 and 0.63, respectively) despite the lower doses of CY administered to most of the patients in the personalized dosage group.

Radiation therapy in the treatment of pituitary adenomas.

Seventy-eight patients with pituitary adenomas were seen in the Department of Radiation Oncology at Hahnemann University between 1961 and 1986. Most were treated with megavoltage photons with or without prior surgery. In this group, 68 patients were followed: 39 were treated with radiation therapy (RT) alone, and 29 were treated with a combination of surgery and RT (S/RT). Patients were followed for 2 to 20 years. Of 68 patients, (97%) experienced complete response to treatment; 86% of the RT patients remained free of disease at 5 and 10 years. In the S/RT group, 100% and 94% remained free of disease at 5 and 10 years, respectively. Total disease-free survivals at 5 and 10 years were, respectively, 91% and 89%. The majority of the failures occurring in the RT group were with growth hormone-secreting tumors and Cushing's disease. Of the 7 patients that failed or recurred (time to recurrence: 1-16 years posttreatment), 6 have been followed: 4 were treated with surgery, 1 with RT, and 1 with S/RT. All 6 have remained free of disease since salvage, with 2- to 14-year follow-up periods. Serious morbidity and mortality have been reported previously with bitemporal field radiation using kilovoltage and low megavoltage RT. However, there was no temporal lobe necrosis or death in any of the patients in this study.

Ameloblastoma of the jaw. Treatment with radiation therapy and a case report.

Ameloblastoma of the jaw is an aggressive benign tumor of epithelial origin that has generally been treated surgically even for metastases. This article is a review of the literature and a report of a previously unpublished case. Despite earlier reports, it is suggested that the available data clearly indicate that it is a radiosensitive tumor. In this report, specific recommendations for radiation therapy are outlined, and guidelines for treatment planning, radiation dosage, and fractionation expected outcome and follow-up are given.