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      Critical concepts in adaptive clinical trials

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          Abstract

          Adaptive clinical trials are an innovative trial design aimed at reducing resources, decreasing time to completion and number of patients exposed to inferior interventions, and improving the likelihood of detecting treatment effects. The last decade has seen an increasing use of adaptive designs, particularly in drug development. They frequently differ importantly from conventional clinical trials as they allow modifications to key trial design components during the trial, as data is being collected, using preplanned decision rules. Adaptive designs have increased likelihood of complexity and also potential bias, so it is important to understand the common types of adaptive designs. Many clinicians and investigators may be unfamiliar with the design considerations for adaptive designs. Given their complexities, adaptive trials require an understanding of design features and sources of bias. Herein, we introduce some common adaptive design elements and biases and specifically address response adaptive randomization, sample size reassessment, Bayesian methods for adaptive trials, seamless trials, and adaptive enrichment using real examples.

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          The BATTLE trial: personalizing therapy for lung cancer.

          The Biomarker-integrated Approaches of Targeted Therapy for Lung Cancer Elimination (BATTLE) trial represents the first completed prospective, biopsy-mandated, biomarker-based, adaptively randomized study in 255 pretreated lung cancer patients. Following an initial equal randomization period, chemorefractory non-small cell lung cancer (NSCLC) patients were adaptively randomized to erlotinib, vandetanib, erlotinib plus bexarotene, or sorafenib, based on relevant molecular biomarkers analyzed in fresh core needle biopsy specimens. Overall results include a 46% 8-week disease control rate (primary end point), confirm prespecified hypotheses, and show an impressive benefit from sorafenib among mutant-KRAS patients. BATTLE establishes the feasibility of a new paradigm for a personalized approach to lung cancer clinical trials. The BATTLE study is the first completed prospective, adaptively randomized study in heavily pretreated NSCLC patients that mandated tumor profiling with "real-time" biopsies, taking a substantial step toward realizing personalized lung cancer therapy by integrating real-time molecular laboratory findings in delineating specific patient populations for individualized treatment.
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            Safety and efficacy of minimally invasive surgery plus recombinant tissue plasminogen activator in intracerebral haemorrhage evacuation (MISTIE): a randomised, phase 2 trial

            SUMMARY Background Craniotomy, when evaluated in trials, does not improve outcome after intracerebral haemorrhage (ICH). Whether minimally invasive catheter evacuation followed by thrombolysis is safe and can achieve a good functional outcome by removing clot is unknown. We investigated safety and efficacy of alteplase with minimally invasive surgery (MIS) in patients with intracerebral haemorrhage. Methods MISTIE was an international, randomized, open-label study and was done in 26 hospitals in the USA, Canada, the UK, and Germany. Patients (aged 18–80 years), with non-traumatic (spontaneous) ICH ≥20 mL were randomly allocated, centrally, to medical care or image-guided MIS plus rt-PA (0.3 mg or 1.0 mg every 8 hours for up to 9 doses) to remove clot using surgical aspiration followed with alteplase clot irrigation. The primary efficacy outcome was the adjusted dichotomized modified Rankin Scale (mRS) 0–3 vs 4–6 assessed at day 180 after symptom onset. Analysis was by intention to treat. (ClinicalTrials.gov number NCT00224770). Findings Between February 2, 2006 and April 8, 2013, 96 subjects were randomized and completed follow-up: 54 received treatment and 42 medical care. Primary safety outcomes: mortality, symptomatic bleeding, brain infections, as well as withdrawal of care, did not differ between groups. Asymptomatic hemorrhages were more common in the surgical group (3 (7%) vs. 12 (22%) p= 0.05) producing a difference of 15.1% (95% CI: 1.5% to 28.6%). The estimated absolute benefit, i.e., the unadjusted difference in observed proportions of all subjects with mRS 0–3 (33% vs 21%) at 180 days comparing MISPA vs. medical control, is 0.109 [95%CI: −0.088, 0.294; p=0.26], and is 0.162 [95%CI: 0.003, 0.323; p=0.05] after adjustment for potential imbalances in baseline severity between study arms (primary efficacy outcome). Interpretation MIS+rt-PA appears safe with an apparent advantage of better functional outcome at 180 days. Increased asymptomatic bleeding is a major cautionary finding. The MISTIE trial results, if replicable, could produce a meaningful functional benefit adding surgical management as a therapeutic strategy for ICH. Funding National Institute of Neurologic Disorders and Stroke, Genentech, and Codman.
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              Twenty‐five years of confirmatory adaptive designs: opportunities and pitfalls

              ‘Multistage testing with adaptive designs’ was the title of an article by Peter Bauer that appeared 1989 in the German journal Biometrie und Informatik in Medizin und Biologie. The journal does not exist anymore but the methodology found widespread interest in the scientific community over the past 25 years. The use of such multistage adaptive designs raised many controversial discussions from the beginning on, especially after the publication by Bauer and Köhne 1994 in Biometrics: Broad enthusiasm about potential applications of such designs faced critical positions regarding their statistical efficiency. Despite, or possibly because of, this controversy, the methodology and its areas of applications grew steadily over the years, with significant contributions from statisticians working in academia, industry and agencies around the world. In the meantime, such type of adaptive designs have become the subject of two major regulatory guidance documents in the US and Europe and the field is still evolving. Developments are particularly noteworthy in the most important applications of adaptive designs, including sample size reassessment, treatment selection procedures, and population enrichment designs. In this article, we summarize the developments over the past 25 years from different perspectives. We provide a historical overview of the early days, review the key methodological concepts and summarize regulatory and industry perspectives on such designs. Then, we illustrate the application of adaptive designs with three case studies, including unblinded sample size reassessment, adaptive treatment selection, and adaptive endpoint selection. We also discuss the availability of software for evaluating and performing such designs. We conclude with a critical review of how expectations from the beginning were fulfilled, and – if not – discuss potential reasons why this did not happen. © 2015 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd.
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                Author and article information

                Journal
                Clin Epidemiol
                Clin Epidemiol
                Clinical Epidemiology
                Clinical Epidemiology
                Dove Medical Press
                1179-1349
                2018
                23 March 2018
                : 10
                : 343-351
                Affiliations
                [1 ]Department of Medicine, University of British Columbia, Vancouver, BC, Canada
                [2 ]Department of Health Research Methods, Evidence, and Impact (HEI), McMaster University, Hamilton, ON, Canada
                [3 ]The Bill and Melinda Gates Foundation, Seattle, WA, USA
                Author notes
                Correspondence: Edward J Mills, Department of Health Research Methods, Evidence, and Impact (HEI), McMaster University, 1280 Main Street W, Hamilton, L8S 4L8 ON, Canada, Tel +1 604 294 3823, Fax +1 604 806 9044, Email millsej@ 123456mcmaster.ca
                Article
                clep-10-343
                10.2147/CLEP.S156708
                5868584
                29606891
                a50a8b06-cfee-44be-abf2-91875ecb1ad4
                © 2018 Park et al. This work is published and licensed by Dove Medical Press Limited

                The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License ( http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed.

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                Public health
                adaptive designs,response adaptive randomization,sample size reassessment,bayesian adaptive trials,seamless trials,adaptive enrichment

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