Utilization of treatment effect on a surrogate endpoint for planning a study to evaluate treatment effect on a final endpoint.

To design a phase III study with a final endpoint and calculate the required sample size for the desired probability of success, we need a good estimate of the treatment effect on the endpoint. It is prudent to fully utilize all available information including the historical and phase II information of the treatment as well as external data of the other treatments. It is not uncommon that a phase II study may use a surrogate endpoint as the primary endpoint and has no or limited data for the final endpoint. On the other hand, external information from the other studies for the other treatments on the surrogate and final endpoints may be available to establish a relationship between the treatment effects on the two endpoints. Through this relationship, making full use of the surrogate information may enhance the estimate of the treatment effect on the final endpoint. In this research, we propose a bivariate Bayesian analysis approach to comprehensively deal with the problem. A dynamic borrowing approach is considered to regulate the amount of historical data and surrogate information borrowing based on the level of consistency. A much simpler frequentist method is also discussed. Simulations are conducted to compare the performances of different approaches. An example is used to illustrate the applications of the methods.

Considerations for pediatric trial designs and analyses.

There are challenges in designing pediatric trials arising from special ethical issues and the relatively small accessible patient population. The application of conventional phase 3 trial designs to pediatrics is not realistic in some therapeutic areas. To address this issue, we propose various approaches for designing pediatric trials that incorporate data available from adult studies using James-Stein shrinkage estimation, empirical shrinkage estimation, and Bayesian methods. We also apply the concept of consistency used in multi-regional trials to pediatric trials. The performance of these methods is assessed through representative scenarios and an example using actual Type 2 diabetes mellitus (T2DM) trials.

Efficacy and safety of lixisenatide in elderly (≥65 years old) and very elderly (≥75 years old) patients with type 2 diabetes: an analysis from the GetGoal phase III programme.

BACKGROUND: The objective of this article is to evaluate the pharmacokinetics, efficacy and safety of lixisenatide (subcutaneous injection) in elderly (≥65 years old) and very elderly (≥75 years old) patients with type 2 diabetes mellitus. METHODS: We conducted a phase I, single-centre, open-label study to evaluate the safety and pharmacokinetics of a single lixisenatide 20 µg dose and a pooled analysis of six randomized, placebo-controlled, phase III studies (12-month or 24-month duration) that evaluated glycaemic parameters and safety in patients receiving lixisenatide 20 µg once daily or placebo. RESULTS: The pharmacokinetics study included 36 healthy subjects, including 18 elderly healthy subjects (≥65 years old) and 18 matched young healthy subjects (18-45 years old). The pooled analysis included 3188 patients, including 2565 patients <65 years old and 623 patients ≥65 years old (including 79 patients ≥75 years old). Mean exposure with lixisenatide 20 µg was ~30% higher in elderly than in young subjects, and the terminal half-life was prolonged by ~1.6 times. Maximum concentration (C(max)) and time to C(max) (t(max)) were comparable in both groups. Equal numbers of elderly and young subjects reported treatment-emergent adverse events, the majority of which were gastrointestinal disorders. In the pooled analysis, lixisenatide 20 µg once daily provided significant reductions in HbA1c versus placebo for all age groups. There was a similar incidence of treatment-emergent adverse events across all age groups (range: 69-73%). The incidence of symptomatic hypoglycaemia was generally comparable between lixisenatide-treated and placebo-treated patients. CONCLUSION: These data suggest that lixisenatide is effective and well tolerated in elderly and very elderly patients with type 2 diabetes mellitus.

Adaptive and repeated cumulative meta-analyses of safety data during a new drug development process.

During a new drug development process, it is desirable to timely detect potential safety signals. For this purpose, repeated meta-analyses may be performed sequentially on accumulating safety data. Moreover, if the amount of safety data from the originally planned program is not enough to ensure adequate power to test a specific hypothesis (e.g., the noninferiority hypothesis of an event of interest), the total sample size may be increased by adding new studies to the program. Without appropriate adjustment, it is well known that the type I error rate will be inflated because of repeated analyses and sample size adjustment. In this paper, we discuss potential issues associated with adaptive and repeated cumulative meta-analyses of safety data conducted during a drug development process. We consider both frequentist and Bayesian approaches. A new drug development example is used to demonstrate the application of the methods.

Considerations for design and data analysis of noninferiority/superiority cardiovascular trials.

The Food and Drug Administration (FDA) guidance for evaluating cardiovascular (CV) risk in new antidiabetic therapies to treat type 2 diabetes released in December 2008 recommends that sponsors conduct appropriate data analysis to rule out CV safety concerns for drugs treating type 2 diabetes. CV trials of antidiabetic drugs and drugs of other indications for chronic conditions are usually large-scale/long-term trials and can be designed as adaptive noninferiority/superiority trials. In these trials, treatment effect may not manifest immediately after patients take study medication and there will be a dilution in treatment effect after treatment discontinuation. These factors should be taken into account for more precise planning of study sample size and timeline. In this paper, we first derive closed-form formulas for the number of events and total exposure as functions of many other trial parameters. We then outline some considerations for the design of an adaptive noninferiority/superiority CV trial based on ideas of other authors. We also use an example to illustrate the application of the methods.

Long-term safety and, tolerability profiles and lipid-modifying efficacy of ezetimibe coadministered with ongoing simvastatin treatment: a multicenter, randomized, double-blind, placebo-controlled, 48-week extension study.

BACKGROUND: Ezetimibe (EZE) is a cholesterol-lowering drug that inhibits absorption of dietary and biliary cholesterol across the intestinal wall without affecting absorption of bile acids, fatty acids, fat-soluble vitamins, or triglycerides. It has a complementary mechanism of action to the statins, which inhibit cholesterol synthesis in the liver. Coadministration of EZE and statins provides inhibition of 2 sources of cholesterol, leading to greater reductions in low-density lipoprotein cholesterol (LDL-C) than with either agent alone. OBJECTIVES: This study evaluated the long-term safety and tolerability profiles and lipid-modifying efficacy of treatment with EZE 10 mg/d plus simvastatin (SIMVA) 10, 20, 40, or 80 mg/d for 48 weeks in patients with primary hypercholesterolemia. METHODS: This was an extension of a multicenter, double-blind, placebo (PBO)-controlled base study in which hypercholesterolemic patients were randomized to receive EZE 10 mg/d or PBO in addition to their current statin for 8 weeks. Patients who successfully completed the base study could enter the extension study if they were willing to switch from their current statin to an approximately equipotent dose of SIMVA for the 54-week study period. After a 6-week open-label SIMVA run-in phase, patients were rerandomized to receive EZE 10 mg/d or PBO in a 4:1 ratio, respectively, for 48 weeks. At each clinic visit, beginning at week 12, the dose of SIMVA was titrated upward until patients reached their National Cholesterol Education Program Adult Treatment Panel II LDL-C goal or the maximum SIMVA dose of 80 mg/d. Safety/tolerability and lipid efficacy parameters were assessed at 12-week intervals. RESULTS: Of 433 patients entering the extension study, 355 were randomized to receive EZE and 78 were randomized to receive PBO. Baseline demographic characteristics and lipid levels were similar between treatment groups. Overall, coadministration of EZE + SIMVA was well tolerated. There were no clinically meaningful differences between the EZE and PBO groups with regard to the incidence of treatment-related adverse events (AEs) (19% vs 17%, respectively), discontinuations due to AEs (7% vs 10%), serious AEs (12% vs 17%), consecutive elevations in liver function tests > or =3 times the upper limit of normal (ULN) (0.3% vs 0%), or elevations in creatine kinase > or =10 times the ULN (both, 0%). As in the base study, LDL-C levels were significantly lower with the addition of EZE to SIMVA compared with the addition of PBO (-24% vs 3%; P < 0.001). CONCLUSION: In these patients with primary hypercholesterolemia, EZE 10 mg/d added to ongoing SIMVA treatment for 48 weeks had a favorable safety and tolerability profile and was more efficacious than SIMVA monotherapy.

Treatment of high-risk patients with ezetimibe plus simvastatin co-administration versus simvastatin alone to attain National Cholesterol Education Program Adult Treatment Panel III low-density lipoprotein cholesterol goals.

This study assessed whether the co-administration of ezetimibe and simvastatin would be more effective than simvastatin monotherapy in allowing high-risk patients to achieve a low-density lipoprotein (LDL) cholesterol goal of <100 mg/dl. Men and women with LDL cholesterol >/=130 mg/dl and meeting National Cholesterol Education Program Adult Treatment Panel III criteria for coronary heart disease (CHD) or CHD risk equivalent were randomized to 1 of 4 daily treatments for 23 weeks: simvastatin 20 mg (n = 253), ezetimibe 10 mg plus simvastatin 10 mg (n = 251), ezetimibe 10 mg plus simvastatin 20 mg (n = 109), and ezetimibe 10 mg plus simvastatin 40 mg (n = 97). In all groups, patients not at goal had their simvastatin doses doubled at weeks 6, 12, and/or 18, up to a maximum of 80 mg. The primary efficacy objective was LDL cholesterol goal attainment (<100 mg/dl) after 5 weeks of treatment. Ezetimibe plus any dose of simvastatin produced greater reductions in LDL cholesterol and allowed more patients to achieve goal after 5 weeks (p <0.001) and at the end of the study (p <0.001) than simvastatin 20 mg alone. At 5 weeks, 75%, 83%, and 87% of patients receiving ezetimibe plus simvastatin 10, 20, and 40 mg had LDL cholesterol <100 mg/dl compared with 46% of patients receiving simvastatin 20 mg. In patients who started on ezetimibe plus simvastatin 10, 20 and 40 mg, 33%, 22%, and 12%, respectively, required simvastatin titration during the study compared with 68% of patients who started on simvastatin 20 mg. The corresponding median simvastatin doses used were 10, 20, 40, and 40 mg, respectively. Ezetimibe plus simvastatin was well tolerated, with an overall safety profile similar to that of simvastatin monotherapy. Thus, through the dual inhibition of cholesterol absorption and synthesis, ezetimibe plus simvastatin allowed more patients to reach LDL cholesterol <100 mg/dl at a lower simvastatin dose and with fewer dose titrations than simvastatin monotherapy.

Efficacy and safety of ezetimibe added to ongoing statin therapy for treatment of patients with primary hypercholesterolemia.

Ezetimibe is a lipid-lowering drug that inhibits the intestinal absorption of dietary and biliary cholesterol by blocking passage across the intestinal wall. The efficacy and safety of adding ezetimibe to ongoing statin therapy in patients with primary hypercholesterolemia was evaluated in a randomized, double-blind, placebo-controlled study. The study group included 769 adults (aged > or =18 years) with primary hypercholesterolemia who had not achieved National Cholesterol Education Program (NCEP) Adult Treatment Panel II goals with dietary alteration and statin monotherapy. Patients receiving a stable dose of a statin for > or =6 weeks were randomized to receive concurrent treatment with placebo (n = 390) or ezetimibe (n = 379), 10 mg/day, in addition to continuing their open-label statin for 8 weeks. The primary efficacy variable was the percent change in low-density lipoprotein (LDL) cholesterol from baseline with statin monotherapy to end point after intervention (secondary variables: high-density lipoprotein [HDL] cholesterol and triglycerides). Ongoing statin therapy plus ezetimibe led to changes of -25.1% for LDL cholesterol (HDL cholesterol +2.7%; triglycerides -14.0%) compared with LDL cholesterol -3.7% (p <0.001), HDL cholesterol +1.0% (p <0.05), and triglycerides -2.9% (p <0.001) for placebo added to ongoing statin therapy. Among patients not at LDL cholesterol goal at on-statin baseline, 71.5% receiving statin plus ezetimibe versus 18.9% receiving statin plus placebo reached goal at end point (odds ratio 23.7; p <0.001). The co-administration of statin and ezetimibe was generally well tolerated. Adding ezetimibe to ongoing statin therapy led to substantial additional reduction in LDL cholesterol levels, facilitating attainment of NCEP goals. Ezetimibe offers a new therapeutic option for patients receiving statins who require further reduction in LDL cholesterol.

Effects of simvastatin, an HMG-CoA reductase inhibitor, in patients with hypertriglyceridemia.

BACKGROUND: Patients with elevated levels of serum triglycerides (TG) often have other associated lipid abnormalities (e.g., low levels of high-density lipoprotein cholesterol [HDL-C]) and are at increased risk of developing coronary heart disease. Although the therapeutic benefits of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) in hypercholesterolemic patients have been well established, less is known about the effects of statins in patient populations with hypertriglyceridemia. HYPOTHESIS: The purpose of this study was to evaluate the lipoprotein-altering efficacy of simvastatin in hypertriglyceridemic patients. METHODS: This was a multicenter, randomized, double-blind, placebo-controlled study. In all, 195 patients with fasting serum triglyceride levels between 300 and 900 mg/dl received once daily doses of placebo or simvastatin 20, 40, or 80 mg for 6 weeks. RESULTS: Compared with placebo, simvastatin treatment across all doses resulted in significant reductions (p < 0.05 - < 0.001) in serum levels of triglycerides (-20 to -31% decrease) and TG-rich lipoprotein particles. Significant (p < 0.001) reductions were also seen in low-density lipoprotein cholesterol (-25 to -35%) and non-HDL-C (-26 to -40%). Levels of HDL-C were increased (7-11%) in the simvastatin groups compared with placebo (p < 0.05 - < 0.001). CONCLUSION: The results of this study demonstrate the beneficial effects of simvastatin in patients with hypertriglyceridemia.

Efficacy and safety of lovastatin therapy in adolescent girls with heterozygous familial hypercholesterolemia.

OBJECTIVE: The present study was designed to evaluate the lipid-altering efficacy, safety, and tolerability of lovastatin treatment in adolescent girls with heterozygous familial hypercholesterolemia. METHODS: A total of 54 postmenarchal girls, aged 10 to 17 years, were enrolled in a 24-week, double-blind, randomized, placebo-controlled study. After a 4-week diet/placebo run-in period, patients were randomized to 1 of 2 groups: (1) treatment with diet plus lovastatin 20 mg/day for 4 weeks, followed by diet plus lovastatin 40 mg/day for 20 weeks, or (2) diet plus placebo for 24 weeks. RESULTS: Baseline values of lipids, lipoproteins, and apolipoproteins (apo) were comparable between treatment groups. Lovastatin treatment was efficacious at reducing low-density lipoprotein cholesterol by 23% to 27%, total cholesterol by 17% to 22%, and apo B by 20% to 23% at weeks 4 and 24, respectively. Between-treatment group differences were not statistically significant for triglycerides, very-low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, or apo A-I. Lovastatin was generally safe and well tolerated. There were no clinically significant alterations in vital signs (blood pressure and pulse rate), anthropomorphic measurements (height, weight, and BMI), hormone levels (luteinizing hormone, follicle-stimulating hormone, dehydroepiandrosterone sulfate, estradiol, and cortisol), menstrual cycle length, or tests of liver and muscle function. CONCLUSIONS: Lovastatin offers an efficacious and well-tolerated treatment option for improving lipid profiles in adolescent girls with familial hypercholesterolemia.