Adaptive designs in clinical trials: why use them, and how to run and report them

Review article: Primer for clinical researchers on innovative trial designs for emergency medicine

Randomised trials have long been recognised as the gold standard research tool for evidence-based medicine. The past decade has seen the emergence of several innovative trial designs that are revolutionising how trials are conducted. These innovative designs enable more efficient, pragmatic trials that can address complex research questions which were previously not possible. In this paper, we provide an overview of the key innovative designs that are likely to be useful in the emergency medicine context, namely cluster crossover and stepped wedge designs, sequential multiple assignment randomised trial (SMART) designs, and platform trials. We describe the main features of each design, outline their pros and cons, and describe when they may or may not be useful. We also provide examples of these innovative designs in contexts that are relevant to emergency medicine.

Past, present, and future of Phase 3 vaccine trial design: rethinking statistics for the 21st century

Vaccines are crucial for protecting health globally; however, their widespread use relies on rigorous clinical development programmes. This includes Phase 3 randomized controlled trials (RCTs) to confirm their safety, immunogenicity, and efficacy. Traditionally, such trials used fixed designs with predetermined assumptions, lacking the flexibility to change during the trial or stop early due to overwhelming evidence of either efficacy or futility. Modern vaccine trials benefit from innovative approaches like adaptive designs, allowing for planned trial adaptations based on accumulating data. Here, we provide an overview of the evolution of Phase 3 vaccine trial design and statistical analysis methods from traditional to more innovative contemporary methods. This includes adaptive trial designs, which offer ethical advantages and enable early termination if indicated; Bayesian methods, which combine prior knowledge and observed trial data to increase efficiency and enhance result interpretation; modern statistical analysis methods, which enable more accurate and precise inferences; the estimand framework, which ensures the primary question of interest is addressed in a trial; novel approaches using machine learning methods to assess heterogeneity of treatment effects; and statistical advances in safety analysis to evaluate reactogenicity and clinical adverse events. We conclude with insights into the future direction of vaccine trials, aiming to inform clinicians and researchers about conventional and novel RCT design and analysis approaches to facilitate the conduct of efficient, timely trials.

Recruiting Young People for Digital Mental Health Research: Lessons From an AI-Driven Adaptive Trial

BACKGROUND

With increasing adoption of remote clinical trials in digital mental health, identifying cost-effective and time-efficient recruitment methodologies is crucial for the success of such trials. Evidence on whether web-based recruitment methods are more effective than traditional methods such as newspapers, media, or flyers is inconsistent. Here we present insights from our experience recruiting tertiary education students for a digital mental health artificial intelligence-driven adaptive trial-Vibe Up.

OBJECTIVE

We evaluated the effectiveness of recruitment via Facebook and Instagram compared to traditional methods for a treatment trial and compared different recruitment methods' retention rates. With recruitment coinciding with COVID-19 lockdowns across Australia, we also compared the cost-effectiveness of social media recruitment during and after lockdowns.

METHODS

Recruitment was completed for 2 pilot trials and 6 minitrials from June 2021 to May 2022. To recruit participants, paid social media advertising on Facebook and Instagram was used, alongside mailing lists of university networks and student organizations or services, media releases, announcements during classes and events, study posters or flyers on university campuses, and health professional networks. Recruitment data, including engagement metrics collected by Meta (Facebook and Instagram), advertising costs, and Qualtrics data on recruitment methods and survey completion rates, were analyzed using RStudio with R (version 3.6.3; R Foundation for Statistical Computing).

RESULTS

In total, 1314 eligible participants (aged 22.79, SD 4.71 years; 1079, 82.1% female) were recruited to 2 pilot trials and 6 minitrials. The vast majority were recruited via Facebook and Instagram advertising (n=1203; 92%). Pairwise comparisons revealed that the lead institution's website was more effective in recruiting eligible participants than Facebook (z=3.47; P=.003) and Instagram (z=4.23; P<.001). No differences were found between recruitment methods in retaining participants at baseline, at midpoint, and at study completion. Wilcoxon tests found significant differences between lockdown (pilot 1 and pilot 2) and postlockdown (minitrials 1-6) on costs incurred per link click (lockdown: median Aus $0.35 [US $0.22], IQR Aus $0.27-$0.47 [US $0.17-$0.29]; postlockdown: median Aus $1.00 [US $0.62], IQR Aus $0.70-$1.47 [US $0.44-$0.92]; W=9087; P<.001) and the amount spent per hour to reach the target sample size (lockdown: median Aus $4.75 [US $2.95], IQR Aus $1.94-6.34 [US $1.22-$3.97]; postlockdown: median Aus $13.29 [US $8.26], IQR Aus $4.70-25.31 [US $2.95-$15.87]; W=16044; P<.001).

CONCLUSIONS

Social media advertising via Facebook and Instagram was the most successful strategy for recruiting distressed tertiary students into this artificial intelligence-driven adaptive trial, providing evidence for the use of this recruitment method for this type of trial in digital mental health research. No recruitment method stood out in terms of participant retention. Perhaps a reflection of the added distress experienced by young people, social media recruitment during the COVID-19 lockdown period was more cost-effective.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12621001092886; https://tinyurl.com/39f2pdmd; Australian New Zealand Clinical Trials Registry ACTRN12621001223820; https://tinyurl.com/bdhkvucv.

AI as an intervention: improving clinical outcomes relies on a causal approach to AI development and validation

The primary practice of healthcare artificial intelligence (AI) starts with model development, often using state-of-the-art AI, retrospectively evaluated using metrics lifted from the AI literature like AUROC and DICE score. However, good performance on these metrics may not translate to improved clinical outcomes. Instead, we argue for a better development pipeline constructed by working backward from the end goal of positively impacting clinically relevant outcomes using AI, leading to considerations of causality in model development and validation, and subsequently a better development pipeline. Healthcare AI should be "actionable," and the change in actions induced by AI should improve outcomes. Quantifying the effect of changes in actions on outcomes is causal inference. The development, evaluation, and validation of healthcare AI should therefore account for the causal effect of intervening with the AI on clinically relevant outcomes. Using a causal lens, we make recommendations for key stakeholders at various stages of the healthcare AI pipeline. Our recommendations aim to increase the positive impact of AI on clinical outcomes.

Targeting common disease pathomechanisms to treat amyotrophic lateral sclerosis

The motor neuron disease amyotrophic lateral sclerosis (ALS) is a devastating condition with limited treatment options. The past few years have witnessed a ramping up of translational ALS research, offering the prospect of disease-modifying therapies. Although breakthroughs using gene-targeted approaches have shown potential to treat patients with specific disease-causing mutations, the applicability of such therapies remains restricted to a minority of individuals. Therapies targeting more general mechanisms that underlie motor neuron pathology in ALS are therefore of considerable interest. ALS pathology is associated with disruption to a complex array of key cellular pathways, including RNA processing, proteostasis, metabolism and inflammation. This Review details attempts to restore cellular homeostasis by targeting these pathways in order to develop effective, broadly-applicable ALS therapeutics.

Comparing the Use of Acupuncture as Adjunct Therapy to Usual Pain Control for Patients Presenting With Chronic Pain Exacerbations

The aim of the Research to Practice column is to enhance the research critique abilities of both advanced practice registered nurses and emergency nurses, while also aiding in the translation of research findings into clinical practice. Each column focuses on a specific topic and research study. In this article, we used a scenario of chronic pain exacerbation to explore the study by Eucker et al., titled "An Adaptive Pragmatic Randomized Controlled Trial of Emergency Department Acupuncture for Acute Musculoskeletal Pain Management".

The future of clinical trials of gut microbiome therapeutics in cirrhosis

The last two decades have witnessed an explosion of microbiome research, including in hepatology, with studies demonstrating altered microbial composition in liver disease. More recently, efforts have been made to understand the association of microbiome features with clinical outcomes and to develop therapeutics targeting the microbiome. While microbiome therapeutics hold much promise, their unique features pose certain challenges for the design and conduct of clinical trials. Herein, we will briefly review indications for microbiome therapeutics in cirrhosis, currently available microbiome therapeutics, and the biological pathways targeted by these therapies. We will then focus on the best practices and important considerations for clinical trials of gut microbiome therapeutics in cirrhosis.

Novel trial designs: Master protocol trials

Conventional trial designs are resource and time-intensive. To accelerate the process of testing new interventions, we now have several novel research trial designs. This article focuses on master protocol trials, which allow several therapies to be tested within a single larger trial.

CONSORT-DEFINE explanation and elaboration: recommendations for enhancing reporting quality and impact of early phase dose-finding clinical trials

Early phase dose-finding (EPDF) trials are key in the development of novel therapies, with their findings directly informing subsequent clinical development phases and providing valuable insights for reverse translation. Comprehensive and transparent reporting of these studies is critical for their accurate and critical interpretation, which may improve and expedite therapeutic development. However, quality of reporting of design characteristics and results from EPDF trials is often variable and incomplete. The international consensus-based CONSORT-DEFINE (Consolidated Standards for Reporting Trials Dose-finding Extension) statement, an extension of the CONSORT statement for randomised trials, was developed to improve the reporting of EPDF trials. The CONSORT-DEFINE statement introduced 21 new items and modified 19 existing CONSORT items.This CONSORT-DEFINE Explanation and Elaboration (E&E) document provides important information to enhance understanding and facilitate the implementation of the CONSORT-DEFINE checklist. For each new or modified checklist item, we provide a detailed description and its rationale with supporting evidence, and present examples from EPDF trial reports published in peer-reviewed scientific journals. When reporting the results of EPDF trials, authors are encouraged to consult the CONSORT-DEFINE E&E document, together with the CONSORT and CONSORT-DEFINE statement papers, and adhere to their recommendations. Widespread adoption of the CONSORT-DEFINE statement is likely to enhance the reporting quality of EPDF trials, thus facilitating the peer review of such studies and their appraisal by researchers, regulators, ethics committee members, and funders.

Funding

This work is a further extension of the CONSORT-DEFINE study, which was funded by the UK Medical Research Council (MRC)-National Institute for Health and Care Research (NIHR) Methodology Research Programme (MR/T044934/1). The Clinical Trials and Statistics Unit at The Institute of Cancer Research (ICR-CTSU) receives programmatic infrastructure funding from Cancer Research UK (C1491/A25351; CTUQQR-Dec 22/100 004), which has contributed to accelerating the advancement and successful completion of this work.

Methodological review to develop a list of bias items for adaptive clinical trials: Protocol and rationale

BACKGROUND

Randomized-clinical trials (RCTs) are the gold-standard for comparing health care interventions, but can be limited by early termination, feasibility issues, and prolonged time to trial reporting. Adaptive clinical trials (ACTs), which are defined by pre-planned modifications and analyses that occur after starting patient recruitment, are gaining popularity as they can streamline trial design and time to reporting. As adaptive methodologies continue to be adopted by researchers, it will be critical to develop a risk of bias tool that evaluates the unique methodological features of ACTs so that their quality can be improved and standardized for the future. In our proposed methodological review, we will develop a list of risk of bias items and concepts, so that a risk of bias tool specific to ACTs can be developed.

METHODS AND ANALYSIS

We will perform a systematic database search to capture studies that have proposed or reviewed items pertaining to methodological risk, bias, and/or quality in ACTs. We will perform a comprehensive search of citation databases, such as Ovid MEDLINE, EMBASE, CENTRAL, the Cochrane library, and Web of Science, in addition to multiple grey literature sources to capture published and unpublished literature related to studies evaluating the methodological quality of ACTs. We will also search methodological registries for any risk of bias tools for ACTs. All screening and review stages will be performed in duplicate with a third senior author serving as arbitrator for any discrepancies. For all studies of methodological quality and risk of bias, we will extract all pertinent bias items, concepts, and/or tools. We will combine conceptually similar items in a descriptive manner and classify them as referring to bias or to other aspects of methodological quality, such as reporting. We will plan to generate pertinent risk of bias items to generate a candidate tool that will undergo further refinement, testing, and validation in future development stages.

ETHICS AND DISSEMINATION

This review does not require ethics approval as human subjects are not involved. As mentioned previously, this study is the first step in developing a tool to evaluate the risk of bias and methodological quality of ACTs. The findings of this review will inform a Delphi study and the development of a risk of bias tool for ACTs. We plan on publishing this review in a peer-reviewed journal and to present these findings at international scientific conferences.

Effectiveness of behavior change techniques in eHealth-based cardiac rehabilitation in patients with coronary artery disease: A systematic review: Effective behavior change techniques in eHealth CR

Background

Participation in cardiac rehabilitation (CR) reduces risk of cardiovascular mortality, improves functional capacity and enhances quality of life in patients with coronary artery disease (CAD). eHealth-based CR can increase participation rates, but research into effective components is necessary. The objective of this systematic review was to identify effective behavior change techniques (BCTs) used in eHealth-based CR interventions.

Methods

A search of four databases (CINAHL, PubMed, PsychINFO, and MEDLINE) was conducted until January 10, 2023. Randomized controlled trials investigating eHealth-based interventions for patients with CAD were included. Risk of bias was assessed using the Effective Public Healthcare Practice Project tool. BCTs were coded following the Behavior Change Taxonomy. A best-evidence synthesis was conducted to determine the effectiveness of BCTs, with ratings ranging from A (strong evidence indicating either a positive effect (+) or no effect (-)) to D (no data collected).

Results

A total of 88 studies (25,007 participants) met the eligibility criteria. The interventions in these studies used 31 different BCTs. The most common BCTs were instructions on how to perform the behavior (k = 86), social support (k = 69) and and information about health consequences (k = 56). The evidence for action planning was rated as A+ for medication adherence and diet. Conversely, for systematically decreasing the number of prompts/cues sent during an intervention, the evidence was rated as A- for physical activity, medication adherence and smoking cessation. The evidence for feedback on behavior was rated as A+ for medication adherence and A- for smoking cessation.

Conclusions

Action planning is effective as a BCT in eHealth-based CR, whereas reducing prompts/cues is not. Feedback on behavior may, depending on the behavior targeted, exert both positive and no effect, suggesting that BCT-behavior matching is important to optimize effectiveness of eHealth-based CR.

Booster-free anti-retroviral therapy for persons living with HIV and multidrug resistance (B-Free): protocol for a multicentre, multistage, randomised, controlled, non-inferiority trial

INTRODUCTION

Anti-retroviral therapy (ART) simplification strategies are needed for treatment-experienced people with HIV (PWH) and multidrug-resistant viruses. These individuals are commonly treated with boosted ART regimens and are thereby at risk for harmful drug-drug interactions (DDI). In this trial, we aim to assess the efficacy of the combination doravirine, dolutegravir and lamivudine (DOR/DTG/3TC) among people with a history of virological failure who receive boosted ART.

METHODS AND ANALYSIS

B-Free is a multistage, randomised, multicentre, open-label, non-inferiority trial, embedded within the Swiss HIV Cohort Study and conducted in collaboration with cohorts of PWH in the Netherlands and France. Cohort participants with a history of ART change due to virologic failure and who maintain HIV virologic suppression with an ART regimen consisting of a pharmacological booster and at least two drugs from classes other than nucleoside reverse transcriptase inhibitors are included. Patients with major drug resistance mutations against DTG or DOR and individuals with chronic hepatitis B virus infection are not eligible for the study. Individuals are randomised 1:1 to either receiving co-formulated DTG/3TC and DOR once daily or continuing their boosted ART regimen. The primary outcome is the proportion of individuals lacking virologic control (HIV-RNA ≥50 cp/mL) at 48 weeks, according to the Food and Drug Administration snapshot algorithm. Changes in DDI burden (assessed using a DDI score), treatment satisfaction (assessed using the HIV Treatment Satisfaction Questionnaire), quality of life and mental health represent key secondary outcomes. Additional secondary outcomes include the proportion of individuals developing new resistance-associated mutations and changes in quality of life and mental health. In a qualitative substudy, we will conduct semistructured interviews with a subset of participants to assess their expectations and experiences towards HIV treatment and clinical research in general. Enrolling 210 individuals will provide 80% power to demonstrate non-inferiority, defined as less than 8% absolute increase in loss of viral suppression in individuals randomised to DOR/DTG/3TC (one-sided type I error rate of 0.025).

ETHICS AND DISSEMINATION

The study was approved by the competent ethics committees (reference number BASEC 2023-01060) and the regulatory authority Swissmedic (reference number 701655) in Switzerland before the enrolment of the first participant. Approval by the European Medicines Agency and local ethical committees in the Netherlands and France will be obtained prior to including participants in these countries. Participant's written informed consent is obtained by the investigators before enrolment. The results of all major B-Free study outcomes will be submitted to peer-reviewed journals that enable Open Access publication.

TRIAL REGISTRATION NUMBER

Swiss National Clinical Trials Portal (SNCTP000005686, registered on 06 November 2023) and Clinicaltrials.gov (NCT06037564, registered on 07 September 2023).

Economic Considerations in Designs and Modifications of Multiarm, Multistage Adaptive and Adaptive Platform Randomized Controlled Trials: A Systematic Literature Review

OBJECTIVES

There is uncertainty around whether, and under what circumstances, there is value in embedding economic considerations into multiarm, multistage (MAMS) adaptive, and adaptive platform trial designs. This systematic review was conducted to assess the analytical methods and factors that are considered when incorporating health economic analyses when designing and modifying MAMS adaptive and adaptive platform trials.

METHODS

The review searched for health economic analyses, including planned analyses, of interventions assessed through MAMS adaptive, and adaptive platform trials. The search for articles was conducted in EMBASE, MEDLINE, Web of Science, Scopus, and ClinicalTrials.gov electronic databases from their inception to 7 August 2023. The screening for articles was conducted by 2 blinded reviewers who followed a predetermined screening process. A narrative synthesis was conducted on the methods used in the analysis and how the results informed the trial designs and modifications.

RESULTS

The review included 17 articles, of which 4 were the results of economic evaluations, whereas 13 were economic evaluation protocols. No trial was reported using pretrial economic evaluations to inform the trial designs. In 14 articles, it was possible to estimate the costs and benefits of the interventions at the interim analysis stages. There were only 5 interim cost-effectiveness analyses, and 3 of these had informed decisions to drop or maintain trial arms.

CONCLUSIONS

Health economics is being embedded in some MAMS adaptive and adaptive platform trials to inform trial modifications. Nevertheless, the use of economic evidence is limited, both by design and circumstance, despite its potential importance in adopting decisions.

The Great Controversy of Obstructive Sleep Apnea Treatment for Cardiovascular Risk Benefit: Advancing the Science Through Expert Consensus. An Official American Thoracic Society Workshop Report

The prevalence of obstructive sleep apnea (OSA) is on the rise, driven by various factors including more sensitive diagnostic criteria, increased awareness, enhanced technology through at-home testing enabling easy and cost-effective diagnosis, and a growing incidence of comorbid conditions such as obesity. Treating symptomatic patients with OSA syndrome to enhance quality of life remains a cornerstone approach. However, there is a lack of consensus regarding treatment to improve cardiovascular disease (CVD) outcomes, particularly in light of overall negative results from several randomized controlled trials (RCT) indicating no benefit of positive airway pressure (PAP) therapy on primary and secondary CVD events. These RCTs were limited by suboptimal PAP adherence, use of composite CVD outcomes, and limited diversity and generalizability to Sleep Clinic patients. As such, this workshop assembled clinical experts, as well as researchers in basic and translational science, epidemiology, clinical trials, and population health to discuss the current state, and future research directions to guide personalized therapeutic strategies and future research directions in OSA. There was overall consensus among workshop participants that OSA represents a heterogeneous disease with variable endotypes and phenotypes, and heterogeneous responses to treatment. Future research should prioritize employing multi-modal therapeutic approaches within innovative and adaptive trial designs, focusing on specific subgroups of OSA patients hypothesized to benefit from a CVD perspective. Future work should also be inclusive of diverse populations and consider the life-course of OSA to better comprehend treatment strategies that can address the disproportionate impact of OSA on racially minoritized groups. Further, a more holistic approach to sleep must be adopted to include broader assessments of symptoms, sleep duration, and comorbid sleep and circadian disorders. Finally, it is imperative to establish a sleep research consortium dedicated to collecting raw data and biospecimens categorized by OSA subtypes. This will facilitate mechanistic determinations, foster collaborative research, and help bolster the pipeline of early-career researchers.

A seamless Phase I/II platform design with a time-to-event efficacy endpoint for potential COVID-19 therapies

In the search for effective treatments for COVID-19, the initial emphasis has been on re-purposed treatments. To maximize the chances of finding successful treatments, novel treatments that have been developed for this disease in particular, are needed. In this article, we describe and evaluate the statistical design of the AGILE platform, an adaptive randomized seamless Phase I/II trial platform that seeks to quickly establish a safe range of doses and investigates treatments for potential efficacy. The bespoke Bayesian design (i) utilizes randomization during dose-finding, (ii) shares control arm information across the platform, and (iii) uses a time-to-event endpoint with a formal testing structure and error control for evaluation of potential efficacy. Both single-agent and combination treatments are considered. We find that the design can identify potential treatments that are safe and efficacious reliably with small to moderate sample sizes.

Interpreting modern randomized controlled trials of medical therapy in inflammatory bowel disease

Treatment options for the medical management of inflammatory bowel disease (IBD) have expanded substantially over the past decade. Multiple classes of advanced therapies, including both monoclonal antibodies and novel oral small molecules, are now available for the treatment of moderately-to-severely active Crohn's disease and ulcerative colitis, highlighted by the approvals of the first IL23p19 antagonists, selective Janus kinase inhibitors and sphingosine-1-phosphate receptor modulators. These advances have been accompanied by the identification of novel targets and the rapid growth in both the number and size of IBD clinical trials. Over a dozen landmark randomized controlled trials (RCTs) have been completed in the past 5 years, including the first head-to-head biologic trials, the first combination biologic studies, and multiple phase III registrational trials of novel compounds with new co-primary and composite end points that will change the treatment landscape for years to come. Importantly, the methodology of RCTs in IBD has evolved substantially, with new trial designs, evaluation of unique patient populations, and different types of efficacy and safety end points being key innovations. In this Review, we provide a comprehensive evaluation of how modern RCTs of IBD medical therapies have evolved and the implications for their appraisal that will help guide the application of these data to clinical practice.

Adaptive Clinical Trials in Stroke

Designing a clinical trial to evaluate the efficacy of an intervention is often complicated by uncertainty over aspects of the study population, potential treatment effects, most relevant outcomes, dropouts, and other factors. However, once participants begin to be enrolled and partial trial data become available, this level of uncertainty is reduced. Adaptive clinical trials are designed to take advantage of the accumulating data during the conduct of a trial to make changes according to prespecified decision rules to increase the likelihood of success or statistical efficiency. Common adaptive rules address early stopping for benefit or futility, sample size reestimation, adding or dropping treatment arms or altering randomization ratios, and changing the eligibility criteria to focus on responder patient subgroups. Adaptive clinical trials are gaining popularity for clinical stroke research. We provide an overview of the methods, practical considerations, challenges and limitations, and potential future role of adaptive clinical trials in advancing knowledge and practice in stroke.

The ESMO Tumour-Agnostic Classifier and Screener (ETAC-S): a tool for assessing tumour-agnostic potential of molecularly guided therapies and for steering drug development

BACKGROUND

Advances in precision oncology led to approval of tumour-agnostic molecularly guided treatment options (MGTOs). The minimum requirements for claiming tumour-agnostic potential remain elusive.

METHODS

The European Society for Medical Oncology (ESMO) Precision Medicine Working Group (PMWG) coordinated a project to optimise tumour-agnostic drug development. International experts examined and summarised the publicly available data used for regulatory assessment of the tumour-agnostic indications approved by the US Food and Drug Administration and/or the European Medicines Agency as of December 2023. Different scenarios of minimum objective response rate (ORR), number of tumour types investigated, and number of evaluable patients per tumour type were assessed for developing a screening tool for tumour-agnostic potential. This tool was tested using the tumour-agnostic indications approved during the first half of 2024. A taxonomy for MGTOs and a framework for tumour-agnostic drug development were conceptualised.

RESULTS

Each tumour-agnostic indication had data establishing objective response in at least one out of five patients (ORR ≥ 20%) in two-thirds (≥4) of the investigated tumour types, with at least five evaluable patients in each tumour type. These minimum requirements were met by tested indications and may serve as a screening tool for tumour-agnostic potential, requiring further validation. We propose a conceptual taxonomy classifying MGTOs based on the therapeutic effect obtained by targeting a driver molecular aberration across tumours and its modulation by tumour-specific biology: tumour-agnostic, tumour-modulated, or tumour-restricted. The presence of biology-informed mechanistic rationale, early regulatory advice, and adequate trial design demonstrating signs of biology-driven tumour-agnostic activity, followed by confirmatory evidence, should be the principles for tumour-agnostic drug development.

CONCLUSION

The ESMO Tumour-Agnostic Classifier (ETAC) focuses on the interplay of targeted driver molecular aberration and tumour-specific biology modulating the therapeutic effect of MGTOs. We propose minimum requirements to screen for tumour-agnostic potential (ETAC-S) as part of tumour-agnostic drug development. Definition of ETAC cut-offs is warranted.

Adaptive enrichment trial designs using joint modelling of longitudinal and time-to-event data

Adaptive enrichment allows for pre-defined patient subgroups of interest to be investigated throughout the course of a clinical trial. These designs have gained attention in recent years because of their potential to shorten the trial's duration and identify effective therapies tailored to specific patient groups. We describe enrichment trials which consider long-term time-to-event outcomes but also incorporate additional short-term information from routinely collected longitudinal biomarkers. These methods are suitable for use in the setting where the trajectory of the biomarker may differ between subgroups and it is believed that the long-term endpoint is influenced by treatment, subgroup and biomarker. Methods are most promising when the majority of patients have biomarker measurements for at least two time points. We implement joint modelling of longitudinal and time-to-event data to define subgroup selection and stopping criteria and we show that the familywise error rate is protected in the strong sense. To assess the results, we perform a simulation study and find that, compared to the study where longitudinal biomarker observations are ignored, incorporating biomarker information leads to increases in power and the (sub)population which truly benefits from the experimental treatment being enriched with higher probability at the interim analysis. The investigations are motivated by a trial for the treatment of metastatic breast cancer and the parameter values for the simulation study are informed using real-world data where repeated circulating tumour DNA measurements and HER2 statuses are available for each patient and are used as our longitudinal data and subgroup identifiers, respectively.

Enhancing DHA supplementation adherence: A Bayesian approach with finite mixture models and irregular interim schedules in adaptive trial designs

Docosahexaenoic acid (DHA) supplementation has proven beneficial in reducing preterm births. However, the challenge lies in addressing nonadherence to prescribed supplementation regimens-a hurdle that significantly impacts clinical trial outcomes. Conventional methods of adherence estimation, such as pill counts and questionnaires, usually fall short when estimating adherence within a specific dosage group. Thus, we propose a Bayesian finite mixture model to estimate adherence among women with low baseline red blood cell phospholipid DHA levels (<6%) receiving higher DHA doses. In our model, adherence is defined as the proportion of participants classified into one of the two distinct components in a normal mixture distribution. Subsequently, based on the estimands from the adherence model, we introduce a novel Bayesian adaptive trial design. Unlike conventional adaptive trials that employ regularly spaced interim schedules, the novelty of our proposed trial design lies in its adaptability to adherence percentages across the treatment arm through irregular interims. The irregular interims in the proposed trial are based on the effect size estimation informed by the finite mixture model. In summary, this study presents innovative methods for leveraging the capabilities of Bayesian finite mixture models in adherence analysis and the design of adaptive clinical trials.

Heart Failure Drug Development Over the Eras: From the Heart Failure Collaboratory

Over the past decade, the field of heart failure (HF) has witnessed remarkable progress in drug development, resulting in the approval of numerous groundbreaking drugs by the U.S. Food and Drug Administration. To address some of these challenges, the U.S. Food and Drug Administration has issued guidance documents that have been critical in contemporary HF drug development; however, there are still many challenges in need of investigation. This paper leverages efforts of the Heart Failure Collaboratory and the scientific community to discuss the critical need for innovative trial designs, important concepts in clinical trials in the modern era, and the utilization of big data to accelerate HF drug development. At this inflection point in HF drug development, it is imperative that, as a global scientific community, we foster increased collaboration among researchers, clinicians, patients, and regulatory bodies. Only through such unified efforts can we navigate the complexities of HF, accelerate the development process, and ultimately deliver effective therapies that transform patient outcomes.

Screen Failures in Clinical Trials in Retina

PURPOSE

Disparities in clinical trials are a major problem because of significant underrepresentation of certain gender, racial, and ethnic groups. Several factors including stringent eligibility criteria and recruitment strategies hinder our understanding of retinal disease. Thus, we aimed to study the various reasons of screen failures and specific patient and study characteristics among screen failures.

DESIGN

This is a cross-sectional retrospective study.

METHODS

Screening data of 87 trials from 6 centers were analyzed. Study characteristics (disease studied, phase of trial, and route of drug administration) and patient demographics (age, gender, race, ethnicity, and employment status) were compared among different causes of screen failures. Screen failures were broadly classified into 6 categories: exclusion because of vision-based criteria, exclusion because of imaging findings, exclusion because of other factors, patient-related criteria, physician-related criteria, and miscellaneous. Descriptive statistics, Pearson chi-square test, and analysis of variance were used for statistical analysis.

MAIN OUTCOME MEASURES

Prevalence of various reasons for screen failures in multiple trials and its trend among different study and patient characteristics.

RESULTS

Among 87 trials and 962 patients, 465 (48.2%) patients were successfully randomized and 497 (51.8%) patients were classified as screen failures. The trials were conducted for various retinal diseases. Mean age was 76.50 ± 10.45 years and 59.4% were females. Predominantly White patients (93.4%) and unemployed/retired patients (66.6%) were screened. Of the 497 screen failures, most were because of patients not meeting inclusion criteria of imaging findings (n = 221 [44.5%]) followed by inclusion of vision-based criteria (n = 73 [14.7%]), exclusion because of other factors (n = 75 [15.1%]), patient-related (n = 34 [6.8%]), physician-related (n = 28 [5.6%]), and miscellaneous reasons (n = 39 [7.8%]). Reason for screen failure was not available for 27 (5.4%) patients. A higher proportion of patients screened for surgical trials (15%) declined to participate in the study compared with noninvasive trials involving topical drugs and photobiomodulation (0%) (P = 0.02).

CONCLUSIONS

Patients not meeting the imaging and vision-cased criteria were the most common reasons for screen failures. White patients and unemployed patients predominantly participated in clinical trials. Patients are more inclined to continue participation in noninvasive clinical trials compared with surgical trials. Better recruitment strategies and careful consideration of study criteria can aid in decreasing the rate of screen failures.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references in the Footnotes and Disclosures at the end of this article.

Next-gen spinal cord injury clinical trials: lessons learned and opportunities for future success

Despite promising basic science discoveries and a surge in clinical trials, the quest for effective treatments that restore neurological function after spinal cord injury lags on. While "failed" in a conventional sense, emerging solutions to longstanding challenges represent promising steps towards a future with effective interventions. In this personal view, we highlight clinical trials implementing new solutions and their impact on the field. Our perspective is that, ultimately, the integration of shared knowledge, adaptive designs, and a deeper understanding of the intricacies of spinal cord injury holds promise of unlocking of major breakthroughs, leading to improved outcomes for people with spinal cord injury.

Adaptive Trials in Stroke: Current Use and Future Directions

Inclusion of adaptive design features in a clinical trial provides preplanned flexibility to dynamically modify a trial during its conduct while preserving validity and integrity. Adaptive trials are needed to accelerate the conduct of more efficient, informative, and ethical clinical research in the field of neurology. Stroke is a natural candidate for adoption of these innovative approaches to trial design. This Research Methods in Neurology article is informed by a scoping review that identified 45 completed or ongoing adaptive clinical trials in stroke that were appraised: 15 trials had published results with or without a published protocol and 30 ongoing trials (14 trials had a published protocol, and 16 trials were registered only). Interventions spanned acute (n = 28), rehabilitation (n = 8), prevention (n = 8), and rehabilitation and prevention (n = 1). A subsample of these trials was selected to illustrate the utility of adaptive design features and discuss why each adaptive feature was incorporated in the design to best achieve the aim; whether each individual feature was used and whether it resulted in expected efficiencies; and any learnings during preparation, conduct, or reporting. We then discuss the operational, ethical, and regulatory considerations that warrant careful consideration during adaptive trial planning and reflect on the workforce readiness to deliver adaptive trials in practice. We conclude that adaptive trials can be designed, funded, conducted, and published for a wide range of research questions and offer future directions to support adoption of adaptive trial designs in stroke and neurologic research more broadly.

Adaptive designs in clinical trials: a systematic review-part I

BACKGROUND

Adaptive designs (ADs) are intended to make clinical trials more flexible, offering efficiency and potentially cost-saving benefits. Despite a large number of statistical methods in the literature on different adaptations to trials, the characteristics, advantages and limitations of such designs remain unfamiliar to large parts of the clinical and research community. This systematic review provides an overview of the use of ADs in published clinical trials (Part I). A follow-up (Part II) will compare the application of AD in trials in adult and pediatric studies, to provide real-world examples and recommendations for the child health community.

METHODS

Published studies from 2010 to April 2020 were searched in the following databases: MEDLINE (Ovid), Embase (Ovid), and International Pharmaceutical Abstracts (Ovid). Clinical trial protocols, reports, and a secondary analyses using AD were included. We excluded trial registrations and interventions other than drugs or vaccines to align with regulatory guidance. Data from the published literature on study characteristics, types of adaptations, statistical analysis, stopping boundaries, logistical challenges, operational considerations and ethical considerations were extracted and summarized herein.

RESULTS

Out of 23,886 retrieved studies, 317 publications of adaptive trials, 267 (84.2%) trial reports, and 50 (15.8%) study protocols), were included. The most frequent disease was oncology (168/317, 53%). Most trials included only adult participants (265, 83.9%),16 trials (5.4%) were limited to only children and 28 (8.9%) were for both children and adults, 8 trials did not report the ages of the included populations. Some studies reported using more than one adaptation (there were 390 reported adaptations in 317 clinical trial reports). Most trials were early in drug development (phase I, II (276/317, 87%). Dose-finding designs were used in the highest proportion of the included trials (121/317, 38.2 %). Adaptive randomization (53/317, 16.7%), with drop-the-losers (or pick-the-winner) designs specifically reported in 29 trials (9.1%) and seamless phase 2-3 design was reported in 27 trials (8.5%). Continual reassessment methods (60/317, 18.9%) and group sequential design (47/317, 14.8%) were also reported. Approximately two-thirds of trials used frequentist statistical methods (203/309, 64%), while Bayesian methods were reported in 24% (75/309) of included trials.

CONCLUSION

This review provides a comprehensive report of methodological features in adaptive clinical trials reported between 2010 and 2020. Adaptation details were not uniformly reported, creating limitations in interpretation and generalizability. Nevertheless, implementation of existing reporting guidelines on ADs and the development of novel educational strategies that address the scientific, operational challenges and ethical considerations can help in the clinical trial community to decide on when and how to implement ADs in clinical trials. STUDY PROTOCOL REGISTRATION: https://doi.org/10.1186/s13063-018-2934-7 .

Pulmonary hypertension associated with left heart disease

Left heart disease (LHD) is the most common cause of pulmonary hypertension (PH), which may be classified further as isolated post-capillary (ipcPH) or combined post- and pre-capillary PH (cpcPH). The 7th World Symposium on Pulmonary Hypertension PH-LHD task force reviewed newly reported randomised clinical trials and contemplated novel opportunities for improving outcome. Results from major randomised clinical trials reinforced prior recommendations against the use of pulmonary arterial hypertension therapy in PH-LHD outside of clinical trials, and suggested possible harm. Greater focus on phenotyping was viewed as one general strategy by which to ultimately improve clinical outcomes. This is potentially achievable by individualising ipcPH versus cpcPH diagnosis for patients with pulmonary arterial wedge pressure within a diagnostic grey zone (12-18 mmHg), and through a newly developed PH-LHD staging system. In this model, PH accompanies LHD across four stages (A=at risk, B=structural heart disease, C=symptomatic heart disease, D=advanced), with each stage characterised by progression in clinical characteristics, haemodynamics and potential therapeutic strategies. Along these lines, the task force proposed disaggregating PH-LHD to emphasise specific subtypes for which PH prevalence, pathophysiology and treatment are unique. This includes re-interpreting mitral and aortic valve stenosis through a contemporary lens, and focusing on PH within the hypertrophic cardiomyopathy and amyloid cardiomyopathy clinical spectra. Furthermore, appreciating LHD in the profile of PH patients with chronic lung disease and chronic thromboembolic pulmonary disease is essential. However, engaging LHD patients in clinical research more broadly is likely to require novel methodologies such as pragmatic trials and may benefit from next-generation analytics to interpret results.

Clinical trial design, end-points, and emerging therapies in pulmonary arterial hypertension

Clinical trials in pulmonary arterial hypertension (PAH) have led to the approval of several effective treatments that improve symptoms, exercise capacity and clinical outcomes. In phase 3 clinical trials, primary end-points must reflect how a patient "feels, functions or survives". In a rare disease like PAH, with an ever-growing number of treatment options and numerous candidate therapies being studied, future clinical trials are now faced with challenges related to sample size requirements, efficiency and demonstration of incremental benefit on traditional end-points in patients receiving background therapy with multiple drugs. Novel clinical trial end-points, innovative trial designs and statistical approaches and new technologies may be potential solutions to tackle the challenges facing future PAH trials, but these must be acceptable to patients and regulatory bodies while preserving methodological rigour. In this World Symposium on Pulmonary Hypertension task force article, we address emerging trial end-points and designs, biomarkers and surrogate end-point validation, the concept of disease modification, challenges and opportunities to address diversity and representativeness, and the use of new technologies such as artificial intelligence in PAH clinical trials.

Reporting and communication of sample size calculations in adaptive clinical trials: a review of trial protocols and grant applications

BACKGROUND

An adaptive design allows modifying the design based on accumulated data while maintaining trial validity and integrity. The final sample size may be unknown when designing an adaptive trial. It is therefore important to consider what sample size is used in the planning of the study and how that is communicated to add transparency to the understanding of the trial design and facilitate robust planning. In this paper, we reviewed trial protocols and grant applications on the sample size reporting for randomised adaptive trials.

METHOD

We searched protocols of randomised trials with comparative objectives on ClinicalTrials.gov (01/01/2010 to 31/12/2022). Contemporary eligible grant applications accessed from UK publicly funded researchers were also included. Suitable records of adaptive designs were reviewed, and key information was extracted and descriptively analysed.

RESULTS

We identified 439 records, and 265 trials were eligible. Of these, 164 (61.9%) and 101 (38.1%) were sponsored by industry and public sectors, respectively, with 169 (63.8%) of all trials using a group sequential design although trial adaptations used were diverse. The maximum and minimum sample sizes were the most reported or directly inferred (n = 199, 75.1%). The sample size assuming no adaptation would be triggered was usually set as the estimated target sample size in the protocol. However, of the 152 completed trials, 15 (9.9%) and 33 (21.7%) had their sample size increased or reduced triggered by trial adaptations, respectively. The sample size calculation process was generally well reported in most cases (n = 216, 81.5%); however, the justification for the sample size calculation parameters was missing in 116 (43.8%) trials. Less than half gave sufficient information on the study design operating characteristics (n = 119, 44.9%).

CONCLUSION

Although the reporting of sample sizes varied, the maximum and minimum sample sizes were usually reported. Most of the trials were planned for estimated enrolment assuming no adaptation would be triggered. This is despite the fact a third of reported trials changed their sample size. The sample size calculation was generally well reported, but the justification of sample size calculation parameters and the reporting of the statistical behaviour of the adaptive design could still be improved.

Sample size recalculation in three-stage clinical trials and its evaluation

BACKGROUND

In clinical trials, the determination of an adequate sample size is a challenging task, mainly due to the uncertainty about the value of the effect size and nuisance parameters. One method to deal with this uncertainty is a sample size recalculation. Thereby, an interim analysis is performed based on which the sample size for the remaining trial is adapted. With few exceptions, previous literature has only examined the potential of recalculation in two-stage trials.

METHODS

In our research, we address sample size recalculation in three-stage trials, i.e. trials with two pre-planned interim analyses. We show how recalculation rules from two-stage trials can be modified to be applicable to three-stage trials. We also illustrate how a performance measure, recently suggested for two-stage trial recalculation (the conditional performance score) can be applied to evaluate recalculation rules in three-stage trials, and we describe performance evaluation in those trials from the global point of view. To assess the potential of recalculation in three-stage trials, we compare, in a simulation study, two-stage group sequential designs with three-stage group sequential designs as well as multiple three-stage designs with recalculation.

RESULTS

While we observe a notable favorable effect in terms of power and expected sample size by using three-stage designs compared to two-stage designs, the benefits of recalculation rules appear less clear and are dependent on the performance measures applied.

CONCLUSIONS

Sample size recalculation is also applicable in three-stage designs. However, the extent to which recalculation brings benefits depends on which trial characteristics are most important to the applicants.

Perioperative platform for muscle-invasive bladder cancer trials: designs and endpoints

PURPOSE OF REVIEW

This review explores the design and endpoints of perioperative platforms in clinical trials for muscle-invasive bladder cancer (MIBC).

RECENT FINDINGS

The choice of clinical trial design in perioperative platforms for MIBC must align with specific research objectives to ensure robust and meaningful outcomes. Novel designs in perioperative platforms for MIBC integrate bladder-sparing approaches. Primary endpoints such as pathological complete response and disease-free survival are highlighted for their role in expediting trial results in perioperative setting. Incorporating patient-reported outcomes is important to inform healthcare decision makers about the outcomes most meaningful to patients. Given the growing body of evidence, potential biomarkers, predictive and prognostic tools should be considered and implemented when designing trials in perioperative platforms for MIBC.

SUMMARY

Effective perioperative platforms for MIBC trials are critical in enhancing patient outcomes. The careful selection and standardization of study designs and endpoints in the perioperative platform are essential for the successful implementation of new therapies and the advancement of personalized treatment approaches in MIBC.

Strategic Developments in Polymer-Functionalized Liposomes for Targeted Colon Cancer Therapy: An Updated Review of Clinical Trial Data and Future Horizons

Liposomes, made up of phospholipid bilayers, are efficient nanocarriers for drug delivery because they can encapsulate both hydrophilic and lipophilic drugs. Conventional cancer treatments sometimes involve considerable toxicities and adverse drug reactions (ADRs), which limits their clinical value. Despite liposomes' promise in addressing these concerns, clinical trials have revealed significant limitations, including stability, targeted distribution, and scaling challenges. Recent clinical trials have focused on enhancing liposome formulations to increase therapeutic efficacy while minimizing negative effects. Notably, the approval of liposomal medications like Doxil demonstrates their potential in cancer treatment. However, the intricacy of liposome preparation and the requirement for comprehensive regulatory approval remain substantial impediments. Current clinical trial updates show continued efforts to improve liposome stability, targeting mechanisms, and payload capacity in order to address these issues. The future of liposomal drug delivery in cancer therapy depends on addressing these challenges in order to provide patients with more effective and safer treatment alternatives.

Acute severe ulcerative colitis trials: the past, the present and the future

Acute severe ulcerative colitis (ASUC), characterised by bloody diarrhoea and systemic inflammation, is associated with a significant risk of colectomy and a small risk of mortality. The landmark trial of cortisone in 1955 was pivotal for two reasons: first, for establishing the efficacy of a drug that remains a first-line therapy today and, second, for producing the first set of disease severity criteria and clinical trial endpoints that shaped the subsequent ASUC trial landscape. Trials in the 1990s and at the turn of the millennium established the efficacy of infliximab and ciclosporin, but since then, there has been little progress in drug development for this high-risk population. This systematic review evaluates all interventional randomised controlled trials (RCTs) conducted in patients hospitalised with severe UC. It provides an overview of the efficacy of treatments from past to present and assesses the evolution of trial characteristics with respect to study populations, eligibility criteria and study designs over time. This review details ongoing RCTs in this field and provides a perspective on the challenges for future clinical trial programmes and how these can be overcome to help deliver novel ASUC therapies.

Therapeutic use of the humanoid robot, Telenoid, with older adults: A critical interpretive synthesis review

This review sought to critically evaluate the use of the teleoperated humanoid robotic communications device, Telenoid, for therapeutic purposes with older adults, and identify and highlight key considerations for future research and clinical practice within gerontechnology. A critical interpretive synthesis was conducted, with nine electronic databases and online sources searched using the keyword "Telenoid." Studies were included in the review if they were: written in English; reported primary research; employed a qualitative, quantitative, or mixed-method design; and described or measured effects, experiences, or perceptions of using Telenoid for therapeutic purposes with older adults. Critical engagement with the studies identified key themes, as well as opportunities to advance future research. Ten studies involving Telenoid were identified, with eight focused on older adults living with dementia. Study findings centered around two themes: effects (including positive effects and negative reactions), and challenges and considerations (including technical issues, operator training, acceptability, and dosage). Although several issues currently challenge the use of Telenoid, available studies show some therapeutic potential of using Telenoid with older adults, including those living with dementia, particularly for communication and mood. Higher-quality studies are required to advance understanding, and considerations for the field are outlined to aid development.

A Systematic Review of Adaptive Seamless Clinical Trials for Late-Phase Oncology Development

INTRODUCTION

Although oncology has seen large scientific and clinical advances over the last decade, it also has one of the lowest success rates for novel agents across therapeutic areas. Adaptive clinical trial design has been a popular option for increasing clinical trial efficiency and the chances of trial success. Seamless clinical trial design are studies in which two or more clinical trial phases are combined into a single study with a pre-specified transition between stages. This integration of phases may enhance efficiency.

METHODS

To understand the precedent for the use of seamless designs, this working group was formed to conduct a comprehensive literature search on seamless clinical trials conducted with confirmatory intent in oncology. Trial design features were extracted into a database and analyzed with descriptive statistics.

RESULTS

A literature search identified 68 clinical trials meeting inclusion and exclusion criteria. The most common design feature was a gate on treatment efficacy, where the trial would only proceed to the second stage if sufficient efficacy was observed in the first. The next most common feature was a selection of a dose or treatment regimen. Inferentially and operationally seamless designs were approximately equally represented.

DISCUSSION

Key statistical considerations for seamless phase II/III designs include optimizing design choices by evaluating and comparing operating characteristics across design alternatives as well as showing control of overall Type I error rates. Executing the transition between phases should be evaluated for issues related to accrual, drug production, and procedures to maintain trial integrity.

CONCLUSIONS

While there are unique statistical, regulatory, and operational considerations for seamless designs they are also uniquely suited to many development settings. These include, for example, addressing dose selection under FDA's Project Optimus and addressing the growing use of biomarkers and personalized medicine approaches in cancer treatment.

Adaptive designs in dermatology clinical trials: Current status and future perspectives

Current drug development strategies present many challenges that can impede drug approval by regulatory agencies. Alternative study models, such as adaptive trial designs, have recently sparked interest, as they provide a flexible and more efficient approach in conducting clinical trials. Adaptive trial designs offer several potential benefits over traditional randomized controlled trials, which include decrease in costs, reduced clinical development time and limiting exposure of patients to potentially ineffective treatments allowing completion of studies with fewer patients. This article explores the current use of adaptive trial designs in non-oncologic skin diseases and highlights the most common types of adaptive designs used in the field. We also review the operational challenges and statistical considerations associated with such designs and propose clinical development strategies to successfully implement adaptive designs. The article also proposes instances where adaptive trial designs are particularly beneficial, and other situations where they may not be very useful.

Recommendations for clinical trial design in acute kidney injury from the 31st acute disease quality initiative consensus conference. A consensus statement

PURPOSE

Novel interventions for the prevention or treatment of acute kidney injury (AKI) are currently lacking. To facilitate the evaluation and adoption of new treatments, the use of the most appropriate design and endpoints for clinical trials in AKI is critical and yet there is little consensus regarding these issues. We aimed to develop recommendations on endpoints and trial design for studies of AKI prevention and treatment interventions based on existing data and expert consensus.

METHODS

At the 31st Acute Disease Quality Initiative (ADQI) meeting, international experts in critical care, nephrology, involving adults and pediatrics, biostatistics and people with lived experience (PWLE) were assembled. We focused on four main areas: (1) patient enrichment strategies, (2) prevention and attenuation studies, (3) treatment studies, and (4) innovative trial designs of studies other than traditional (parallel arm or cluster) randomized controlled trials. Using a modified Delphi process, recommendations and consensus statements were developed based on existing data, with > 90% agreement among panel members required for final adoption.

RESULTS

The panel developed 12 consensus statements for clinical trial endpoints, application of enrichment strategies where appropriate, and inclusion of PWLE to inform trial designs. Innovative trial designs were also considered.

CONCLUSION

The current lack of specific therapy for prevention or treatment of AKI demands refinement of future clinical trial design. Here we report the consensus findings of the 31st ADQI group meeting which has attempted to address these issues including the use of predictive and prognostic enrichment strategies to enable appropriate patient selection.

Analysis of Nonconcurrent Controls in Adaptive Platform Trials: Separating Randomized and Nonrandomized Information

Adaptive platform trials allow treatments to be added or dropped during the study, meaning that the control arm may be active for longer than the experimental arms. This leads to nonconcurrent controls, which provide nonrandomized information that may increase efficiency but may introduce bias from temporal confounding and other factors. Various methods have been proposed to control confounding from nonconcurrent controls, based on adjusting for time period. We demonstrate that time adjustment is insufficient to prevent bias in some circumstances where nonconcurrent controls are present in adaptive platform trials, and we propose a more general analytical framework that accounts for nonconcurrent controls in such circumstances. We begin by defining nonconcurrent controls using the concept of a concurrently randomized cohort, which is a subgroup of participants all subject to the same randomized design. We then use cohort adjustment rather than time adjustment. Due to flexibilities in platform trials, more than one randomized design may be in force at any time, meaning that cohort-adjusted and time-adjusted analyses may be quite different. Using simulation studies, we demonstrate that time-adjusted analyses may be biased while cohort-adjusted analyses remove this bias. We also demonstrate that the cohort-adjusted analysis may be interpreted as a synthesis of randomized and indirect comparisons analogous to mixed treatment comparisons in network meta-analysis. This allows the use of network meta-analysis methodology to separate the randomized and nonrandomized components and to assess their consistency. Whenever nonconcurrent controls are used in platform trials, the separate randomized and indirect contributions to the treatment effect should be presented.

If it walks like a duck…: Monitored Emergency Use of Unregistered and Experimental Interventions (MEURI) is research

Monitored Emergency Use of Unregistered and Experimental Interventions (MEURI) is an ethical framework developed by the WHO for using unproven interventions in public health emergencies outside the context of medical research. It is mainly intended for use when medical research would be impracticable, but there is still a need to systematically gather data about unproven interventions. As such, it is designed as something of a middle ground between clinical and research ethical frameworks.However, I argue that MEURI does not truly lie at the intersection of clinical care and research. Due to its intent, structure and oversight requirements, it takes on most of the crucial features of research, to the point that it is best understood as a form of research. As a result, cases where MEURI could practicably be applied should instead make use of existing research frameworks. For those circumstances where research is truly impracticable, a more straightforward oversight system than MEURI is needed. While existing practices of compassionate use have some applicability, proposals to make use of clinical ethics committees to oversee unproven interventions may help achieve the right balance in acting in a patient's best interests when the relevant evidence base is weak.

The impact of heterogeneity on the analysis of platform trials with normally distributed outcomes

BACKGROUND

A platform trial approach allows adding arms to on-going trials to speed up intervention discovery programs. A control arm remains open for recruitment in a platform trial while intervention arms may be added after the onset of the study and could be terminated early for efficacy and/or futility when early stopping is allowed. The topic of utilising non-concurrent control data in the analysis of platform trials has been explored and discussed extensively. A less familiar issue is the presence of heterogeneity, which may exist for example due to modification of enrolment criteria and recruitment strategy.

METHOD

We conduct a simulation study to explore the impact of heterogeneity on the analysis of a two-stage platform trial design. We consider heterogeneity in treatment effects and heteroscedasticity in outcome data across stages for a normally distributed endpoint. We examine the performance of some hypothesis testing procedures and modelling strategies. The use of non-concurrent control data is also considered accordingly. Alongside standard regression analysis, we examine the performance of a novel method that was known as the pairwise trials analysis. It is similar to a network meta-analysis approach but adjusts for treatment comparisons instead of individual studies using fixed effects.

RESULTS

Several testing strategies with concurrent control data seem to control the type I error rate at the required level when there is heteroscedasticity in outcome data across stages and/or a random cohort effect. The main parameter of treatment effects in some analysis models correspond to overall treatment effects weighted by stage wise sample sizes; while others correspond to the effect observed within a single stage. The characteristics of the estimates are not affected significantly by the presence of a random cohort effect and/ or heteroscedasticity.

CONCLUSION

In view of heterogeneity in treatment effect across stages, the specification of null hypotheses in platform trials may need to be more subtle. We suggest employing testing procedure of adaptive design as opposed to testing the statistics from regression models; comparing the estimates from the pairwise trials analysis method and the regression model with interaction terms may indicate if heterogeneity is negligible.

Bayesian sequential monitoring strategies for trials of digestive cancer therapeutics

BACKGROUND

New therapeutics in oncology have presented challenges to existing paradigms and trial designs in all phases of drug development. As a motivating example, we considered an ongoing phase II trial planned to evaluate the combination of a MET inhibitor and an anti-PD-L1 immunotherapy to treat advanced oesogastric carcinoma. The objective of the paper was to exemplify the planning of an adaptive phase II trial with novel anti-cancer agents, including prolonged observation windows and joint sequential evaluation of efficacy and toxicity.

METHODS

We considered various candidate designs and computed decision rules assuming correlations between efficacy and toxicity. Simulations were conducted to evaluate the operating characteristics of all designs.

RESULTS

Design approaches allowing continuous accrual, such as the time-to-event Bayesian Optimal Phase II design (TOP), showed good operating characteristics while ensuring a reduced trial duration. All designs were sensitive to the specification of the correlation between efficacy and toxicity during planning, but TOP can take that correlation into account more easily.

CONCLUSIONS

While specifying design working hypotheses requires caution, Bayesian approaches such as the TOP design had desirable operating characteristics and allowed incorporating concomittant information, such as toxicity data from concomitant observations in another relevant patient population (e.g., defined by mutational status).

The performance of a Bayesian value-based sequential clinical trial design in the presence of an equivocal cost-effectiveness signal: evidence from the HERO trial

BACKGROUND

There is increasing interest in the capacity of adaptive designs to improve the efficiency of clinical trials. However, relatively little work has investigated how economic considerations - including the costs of the trial - might inform the design and conduct of adaptive clinical trials.

METHODS

We apply a recently published Bayesian model of a value-based sequential clinical trial to data from the 'Hydroxychloroquine Effectiveness in Reducing symptoms of hand Osteoarthritis' (HERO) trial. Using parameters estimated from the trial data, including the cost of running the trial, and using multiple imputation to estimate the accumulating cost-effectiveness signal in the presence of missing data, we assess when the trial would have stopped had the value-based model been used. We used re-sampling methods to compare the design's operating characteristics with those of a conventional fixed length design.

RESULTS

In contrast to the findings of the only other published retrospective application of this model, the equivocal nature of the cost-effectiveness signal from the HERO trial means that the design would have stopped the trial close to, or at, its maximum planned sample size, with limited additional value delivered via savings in research expenditure.

CONCLUSION

Evidence from the two retrospective applications of this design suggests that, when the cost-effectiveness signal in a clinical trial is unambiguous, the Bayesian value-adaptive design can stop the trial before it reaches its maximum sample size, potentially saving research costs when compared with the alternative fixed sample size design. However, when the cost-effectiveness signal is equivocal, the design is expected to run to, or close to, the maximum sample size and deliver limited savings in research costs.