Stratification of randomization is not required for a pre-specified subgroup analysis.

Published literature and regulatory agency guidance documents provide conflicting recommendations as to whether a pre-specified subgroup analysis also requires for its validity that the study employ randomization that is stratified on subgroup membership. This is an important issue, as subgroup analyses are often required to demonstrate efficacy in the development of drugs with a companion diagnostic. Here, it is shown, for typical randomization methods, that the fraction of patients in the subgroup given experimental treatment matches, on average, the target fraction in the entire study.

Tumor burden modeling versus progression-free survival for phase II decision making.

Randomized Phase II oncology trial endpoints for decision making include both progression-free survival (PFS) and change in tumor burden as measured by the sum of longest diameters (SLD) of the target lesions. In addition to observed SLD changes, tumor shrinkage and growth parameters can be estimated from the patient-specific SLD profile over time. The ability of these SLD analyses to identify an active drug is contrasted with that of a PFS analysis through the simulation of Phase II trials via resampling from each of 6 large, Phase II and III trials, 5 of which were positive and one negative.

Dynamic randomization and a randomization model for clinical trials data.

Randomization models are useful in supporting the validity of linear model analyses applied to data from a clinical trial that employed randomization via permuted blocks. Here, a randomization model for clinical trials data with arbitrary randomization methodology is developed, with treatment effect estimators and standard error estimators valid from a randomization perspective. A central limit theorem for the treatment effect estimator is also derived.

Inefficiency of randomization methods that balance on stratum margins and improvements with permuted blocks and a sequential method.

Stratified permuted blocks randomization is commonly applied in clinical trials, but other randomization methods that attempt to balance treatment counts marginally for the stratification variables are able to accommodate more stratification variables. When the analysis stratifies on the cells formed by crossing the stratification variables, these other randomization methods yield treatment effect estimates with larger variance than does stratified permuted blocks. When it is truly necessary to balance the randomization on many stratification variables, it is shown how this inefficiency can be improved by using a sequential randomization method where the first level balances on the crossing of the strata used in the analysis and further stratification variables fall lower in the sequential hierarchy.

Analysis of tumor burden versus progression-free survival for Phase II decision making.

Purpose: There have been recent recommendations to use percentage change in tumor burden (dTB) as a primary endpoint in randomized Phase II trials. We assessed whether dTB is better for the decision to start a Phase III trial than is progression-free survival (PFS).

Methods: We repeatedly sampled patients from six large randomized trials to obtain simulated Phase II trials.

Optimizing collection of adverse event data in cancer clinical trials supporting supplemental indications.

Purpose: Although much is known about the safety of an anticancer agent at the time of initial marketing approval, sponsors customarily collect comprehensive safety data for studies that support supplemental indications. This adds significant cost and complexity to the study but may not provide useful new information. The main purpose of this analysis was to assess the amount of safety and concomitant medication data collected to determine a more optimal approach in the collection of these data when used in support of supplemental applications.

Effectiveness of ipsapirone, a 5-HT-1A partial agonist, in major depressive disorder: support for the role of 5-HT-1A receptors in the mechanism of action of serotonergic antidepressants.

Desensitisation of serotonin 1A (5-HT-1A) receptors is a leading hypothesis for the mechanism of action of antidepressants which block serotonin reuptake. This hypothesis predicts that direct-acting 5-HT-1A agonists should also exhibit anti-depressant properties. Here we report the results of the first large-scale controlled study of the efficacy and tolerability of a 5-HT-1A agonist in outpatients with major depressive disorder (MDD).