Between-arm comparisons in randomized Phase II trials

Randomized phase II selection design with order constrained strata

The exploratory nature of phase II trials makes it quite common to include heterogeneous patient subgroups with different prognoses in the same trial. Incorporating such patient heterogeneity or stratification into statistical calculation for sample size can improve efficiency and reduce sample sizes in single-arm phase II trials with binary outcomes. However, such consideration is lacking in randomized phase II trials. In this paper, we propose methods that can utilize some natural order constraints that may exist in stratified population to gain statistical efficiency for randomized phase II designs. For thoroughness and simplicity, we focus on the randomized phase II selection designs in this paper, although our method can be easily generalized to the randomized phase II screening designs. We consider both binary and time-to-event outcomes in our development. Compared with methods that do not use order constraints, our method is shown to improve the probabilities of correct selection or reduce sample size in our simulation and real examples.

Lessons Learned from Phase II and Phase III Trials Investigating Therapeutic Agents for Cerebral Ischemia Associated with Aneurysmal Subarachnoid Hemorrhage

One of the challenges in bringing new therapeutic agents (since nimodipine) in for the treatment of cerebral ischemia associated with aneurysmal subarachnoid hemorrhage (aSAH) is the incongruence in therapeutic benefit observed between phase II and subsequent phase III clinical trials. Therefore, identifying areas for improvement in the methodology and interpretation of results is necessary to increase the value of phase II trials. We performed a systematic review of phase II trials that continued into phase III trials, evaluating a therapeutic agent for the treatment of cerebral ischemia associated with aSAH. We followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines for systematic reviews, and review was based on a peer-reviewed protocol (International Prospective Register of Systematic Reviews no. 222965). A total of nine phase III trials involving 7,088 patients were performed based on eight phase II trials involving 1558 patients. The following therapeutic agents were evaluated in the selected phase II and phase III trials: intravenous tirilazad, intravenous nicardipine, intravenous clazosentan, intravenous magnesium, oral statins, and intraventricular nimodipine. Shortcomings in several design elements of the phase II aSAH trials were identified that may explain the incongruence between phase II and phase III trial results. We suggest the consideration of the following strategies to improve phase II design: increased focus on the selection of surrogate markers of efficacy, selection of the optimal dose and timing of intervention, adjustment for exaggerated estimate of treatment effect in sample size calculations, use of prespecified go/no-go criteria using futility design, use of multicenter design, enrichment of the study population, use of concurrent control or placebo group, and use of innovative trial designs such as seamless phase II to III design. Modifying the design of phase II trials on the basis of lessons learned from previous phase II and phase III trial combinations is necessary to plan more effective phase III trials.

Optimal and ethical designs for hypothesis testing in multi-arm exponential trials

Multi-arm clinical trials are complex experiments which involve several objectives. The demand for unequal allocations in a multi-treatment context is growing and adaptive designs are being increasingly used in several areas of medical research. For uncensored and censored exponential responses, we propose a constrained optimization approach in order to derive the design maximizing the power of the multivariate test of homogeneity, under a suitable ethical constraint. In the absence of censoring, we obtain a very simple closed-form solution that dominates the balanced design in terms of power and ethics. Our suggestion can also accommodate delayed responses and staggered entries, and can be implemented via response adaptive rules. While other targets proposed in the literature could present an unethical behavior, the suggested optimal allocation is frequently unbalanced by assigning more patients to the best treatment, both in the absence and presence of censoring. We evaluate the operating characteristics of our proposal theoretically and by simulations, also redesigning a real lung cancer trial, showing that the constrained optimal target guarantees very good performances in terms of ethical demands, power and estimation precision. Therefore, it is a valid and useful tool in designing clinical trials, especially oncological trials and clinical experiments for grave and novel infectious diseases, where the ethical concern is of primary importance.

Inclusion of non-inferiority analysis in superiority-based clinical trials with single-arm, two-stage Simon's design

INTRODUCTION

Non-inferiority (NI) analysis is not usually considered in the early phases of clinical development. In some negative phase II trials, a post-hoc NI analysis justified additional phase III trials that were successful. However, the risk of false positive achievements was not controlled in these early phase analyses. We propose to preplan NI analyses in superiority-based Simon's two-stage designs to control type I and II error rates.

METHODS

Simulations have been proposed to assess the control of type I and II errors rates with this method. A total of 12,768 two-stage Simon's design trials were constructed based on different assumptions of rejection response probability, desired response probability, type I and II errors, and NI margins. P-value and type II error were calculated with stochastic ordering using Uniformly Minimum Variance Unbiased Estimator. Type I and II errors were simulated using the Monte Carlo method. The agreement between calculated and simulated values was analyzed with Bland-Altman plots.

RESULTS

We observed the same level of agreement between calculated and simulated type I and II errors from both two-stage Simon's superiority designs and designs in which NI analysis was allowed. Different examples has been proposed to explain the utility of this method.

CONCLUSION

Inclusion of NI analysis in superiority-based single-arm clinical trials may be useful for weighing additional factors such as safety, pharmacokinetics, pharmacodynamic, and biomarker data while assessing early efficacy. Implementation of this strategy can be achieved through simple adaptations to existing designs for one-arm phase II clinical trials.

A Three-Arm Randomised Controlled Trial of High- and Low-Intensity Implementation Strategies to Support Centre-Based Childcare Service Implementation of Nutrition Guidelines: 12-Month Follow-Up

The study aimed to compare the effectiveness of a suite of implementation strategies of varying intensities on centre-based childcare service implementation of nutrition guideline recommendations at 12-month follow-up. A six-month three-arm parallel group randomised controlled trial was undertaken with 69 services, randomised to one of three arms: high-intensity strategies (executive support; group face-to-face training; provision of resources; multiple rounds of audit and feedback; ongoing face-to-face and phone support); low-intensity strategies (group face-to-face training; provision of resources; single round of audit and feedback); or usual care control. Across all study arms, only three high-intensity services were compliant with overall nutrition guidelines. A significant group interaction was found between the three arms for compliance with individual food groups. Relative to control, a significantly greater proportion of low-intensity services were compliant with dairy, and a significantly greater proportion of high-intensity services were compliant with fruit, vegetables, dairy, breads and cereals, and discretionary foods. No significant differences between the high- and low-intensity for individual food group compliance were found. High-intensity implementation strategies may be effective in supporting childcare service implementation of individual food group recommendations. Further research is warranted to identify strategies effective in increasing overall nutrition compliance.

Exploratory trials in mental health: anything to learn from other disciplines?

OBJECTIVE

Confirmatory randomised controlled trials require solid justifications, especially with regard to whether the experimental intervention is promising. Such evidence is generated in exploratory trials. However, empirical evidence shows that the quality of such trials is still suboptimal. More generally, the development process of healthcare interventions and especially of drugs, remains inefficient. Over the past 10-20 years, a vast amount of methodological work has been published about exploratory trials. This overview introduces some of the concepts and recent developments in the field.

METHODS

A narrative approach was taken for this overview. This article focuses on study designs developed outside the mental health field to introduce concepts that might not be familiar to clinical researchers in psychiatry and psychology. Non-randomised and randomised exploratory trial designs are covered. The article ends with a brief discussion on pilot studies and their difference to exploratory studies.

RESULTS

Classical designs for exploratory trials such as Simon's two-stage design still have a role. However, randomised exploratory trials are probably more suitable for mental health interventions. Newer, more flexible designs such as multistage, multiarm trials or platform trials have the potential to improve the efficiency of exploratory and subsequently confirmatory experiments.

CONCLUSIONS

Although often not directly applicable, borrowing (study) design ideas from other medical disciplines has the potential to improve exploratory trials in the mental health field. At the same time, more explicit use of study designs specifically designed for exploratory trials will help to improve the transparency of such trials.

Screened selection design for randomised phase II oncology trials: an example in chronic lymphocytic leukaemia

BACKGROUND

As there are limited patients for chronic lymphocytic leukaemia trials, it is important that statistical methodologies in Phase II efficiently select regimens for subsequent evaluation in larger-scale Phase III trials.

METHODS

We propose the screened selection design (SSD), which is a practical multi-stage, randomised Phase II design for two experimental arms. Activity is first evaluated by applying Simon's two-stage design (1989) on each arm. If both are active, the play-the-winner selection strategy proposed by Simon, Wittes and Ellenberg (SWE) (1985) is applied to select the superior arm. A variant of the design, Modified SSD, also allows the arm with the higher response rates to be recommended only if its activity rate is greater by a clinically-relevant value. The operating characteristics are explored via a simulation study and compared to a Bayesian Selection approach.

RESULTS

Simulations showed that with the proposed SSD, it is possible to retain the sample size as required in SWE and obtain similar probabilities of selecting the correct superior arm of at least 90%; with the additional attractive benefit of reducing the probability of selecting ineffective arms. This approach is comparable to a Bayesian Selection Strategy. The Modified SSD performs substantially better than the other designs in selecting neither arm if the underlying rates for both arms are desirable but equivalent, allowing for other factors to be considered in the decision making process. Though its probability of correctly selecting a superior arm might be reduced, it still performs reasonably well. It also reduces the probability of selecting an inferior arm.

CONCLUSIONS

SSD provides an easy to implement randomised Phase II design that selects the most promising treatment that has shown sufficient evidence of activity, with available R codes to evaluate its operating characteristics.

Reporting of analyses from randomized controlled trials with multiple arms: a systematic review

BACKGROUND

Multiple-arm randomized trials can be more complex in their design, data analysis, and result reporting than two-arm trials. We conducted a systematic review to assess the reporting of analyses in reports of randomized controlled trials (RCTs) with multiple arms.

METHODS

The literature in the MEDLINE database was searched for reports of RCTs with multiple arms published in 2009 in the core clinical journals. Two reviewers extracted data using a standardized extraction form.

RESULTS

In total, 298 reports were identified. Descriptions of the baseline characteristics and outcomes per group were missing in 45 reports (15.1%) and 48 reports (16.1%), respectively. More than half of the articles (n = 171, 57.4%) reported that a planned global test comparison was used (that is, assessment of the global differences between all groups), but 67 (39.2%) of these 171 articles did not report details of the planned analysis. Of the 116 articles reporting a global comparison test, 12 (10.3%) did not report the analysis as planned. In all, 60% of publications (n = 180) described planned pairwise test comparisons (that is, assessment of the difference between two groups), but 20 of these 180 articles (11.1%) did not report the pairwise test comparisons. Of the 204 articles reporting pairwise test comparisons, the comparisons were not planned for 44 (21.6%) of them. Less than half the reports (n = 137; 46%) provided baseline and outcome data per arm and reported the analysis as planned.

CONCLUSIONS

Our findings highlight discrepancies between the planning and reporting of analyses in reports of multiple-arm trials.

Current issues in oncology drug development, with a focus on Phase II trials

In this commentary we discuss several challenges that are of current relevance to the design of clinical trials in oncology. We argue that the compartmentalization of trials into the three standard phases, with non overlapping aims, is not necessary and in fact may slow the clinical development of agents. Combined Phase I/II trials and/or Phase I trials that at minimum collect efficacy data and more optimally include a preliminary measure of efficacy in dosing determination should be more widely utilized. Similarly, we posit that randomized Phase II trials should be used more frequently, as opposed to the traditional historical single arm Phase II trial that usually does not have a valid comparison group. The use of non binary endpoints is a simple modification that can improve the efficiency of early phase trials. The heterogeneity in scientific goals and contexts in early phase oncology trials is considerable, and the potential to improve the design to match these goals is great. We review these and other issues in the context of 5 manuscripts related to Phase II trials published in this volume. Our overall premise is that the potential benefits associated with the oncology clinical trial community moving away from the one size fits all paradigm of trial design are great, and that more flexible and efficient designs tailored to match the goals of each study are currently available and being used successfully.