3 Strategies to Combat Inferential Conservatism in Small Sample Sizes

Posted by Cytel

Jun 25, 2015 4:28:00 PM

When conducting a clinical trial with small or sparse data sets, statistical methods meant for large sample sizes may fail to obtain an accurate interpretation of data. This is where computationally challenging exact methods often come into play.

Exact methods, however, are inferentially conservative in the sense that due to small sample sizes, the actual Type 1 error rate is often smaller than the nominal (intended) rate [1]. There exists an array of strategies to combat this troublesome feature of exact tests, each of which varies along the parameter of computational complexity.

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Topics: Sample Size, Exact Inference, exact statistics, Small Sample Sparse Data


A Cautionary Tale about Composite Endpoint Construction: The ARISE Trial

Posted by Esha Senchaudhuri

Jun 18, 2015 5:38:45 PM

In August 2006 AstraZeneca completed the ARISE trial, which aimed to determine whether AGI-1067 was effective in reducing atherosclerosis in patients with acute coronary artery disease [1][2]. A double-blind, placebo controlled, Phase 3 trial, the primary efficacy endpoint was a composite endpoint which included major adverse cardiovascular events (MACE) like cardiovascular death, resuscitated cardiac arrest, non-fatal myocardial infarction and non-fatal stroke. However, it also included two less serious but more frequently observed events, namely hospitalization due to coronary revascularization and hospitalization due to unstable angina with evidence of ischemia [2]. 

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Topics: Cardiovascular, Composite Endpoints


Aligning Clinical Development & Regulatory Objectives for Cardiovascular Outcome Trials

Posted by Esha Senchaudhuri

Jun 11, 2015 5:21:09 PM

DIA_DC_Cyrus

When the FDA first began to require pharmaceuticals to perform cardiovascular outcome trials to establish the safety of certain new drugs, many worried that this new regulatory requirement would diminish investments in therapeutic areas like diabetes and obesity [1]. CVOTs are typically designed as massive time-to-event trials that need to enroll several thousands of patients to establish safety [2][3]. The sheer number of patients and size of the trial increases the time that it takes for these drugs to get to market.

So what is it the makes US and EU regulatory strategy different for diabetes and weightloss drugs, and how should this effect clinical development strategy?

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Topics: Cardiovascular, Clinical Development Strategy, Adaptive Clinical Trials


Building Teams to Handle Unexpected Regulatory Agency Requests

Posted by Esha Senchaudhuri

Jun 5, 2015 11:00:00 AM

Not long ago, one of our clients submitted Phase 2 and Phase 3 data for a new rare disease drug which had received priority review status. Following submission, regulators requested that our client also submit pooled data from its Phase 1 studies along with a safety analysis. This analysis had the potential to clinch NDA approval for the new product.

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Topics: Data Management, Clinical Research Services, Regulation, Phase 1


Patient Recruitment Feasibility: Would you bet $12 million dollars on it?

Posted by Charles Liu

Jun 4, 2015 3:11:26 PM

Two insightful papers from Applied Clinical Trials should be of interest to many clinical trial planners. The first by Kenneth Getz describes the problem of enrollment performance, while the second by Matthew Kibby proposes a potential solution.

The Facts

Getz reports a study providing recent estimates of industry-wide rates of enrollment delays [1]. In 2012, the Tufts Center for the Study of Drug Development (CSDD) requested data from 10 pharmaceutical companies and two CROs. The combined database covered nearly 16,000 investigative sites involved in 151 clinical trials from years 2008-2010. A few significant findings are worth highlighting:

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Topics: feasibility studies, patient enrollment, enforesys


How to Use Outsourcing to Reduce Clinical Development Risk

Posted by Esha Senchaudhuri

May 28, 2015 4:47:00 PM

Risks in drug development range from taking the wrong drugs forward to Phase 3 to investing in a drug development program at a time when regulatory standards are evolving, or competition is catching up with comparable products.

There is a particular source of risk, however, which deserves special attention. Currently, the pharmaceutical and biologics industry outsources approximately $25 billion dollars worth of clinical development projects. That is over a quarter of the $98 billion dollars currently devoted to clinical drug development.

This naturally raises several questions:

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Topics: Data Management, Clinical Research Services, outsourcing, Clinical Development Strategy


Seamless Adaptive Clinical Trials: Now that we get the statistics, what’s really at stake?

Posted by Esha Senchaudhuri

May 20, 2015 5:56:47 PM

Seamless adaptive clinical trials have gained popularity for reducing the projected time it takes to complete the process of drug development.  However, a study by Cuffe et al., shows that despite a tremendous amount of statistical knowledge about seamless trials, sponsors remain unsure about how to calculate the financial and operational costs of a seamless clinical development program [1]. This in turn results in many unnecessary risks and missed opportunities. This post offers advice on what you need to keep in mind in order to implement a successful seamless adaptive clinical study.

 

 

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Topics: Phase 1, Early Phase Trials, Clinical Development Strategy, Phase 3, Adaptive Clinical Trials, phase 2


Regulation and Reproducibility: Can You Reproduce Your Clinical Trial Results?

Posted by Esha Senchaudhuri

May 15, 2015 1:33:15 PM

Cytel Clinical Research Services

Imagine that it’s been three years since the completion of a trial, and that suddenly a regulatory body calls into question the findings:

  • Was a particular trial site operating properly?
  • Can you clarify an aspect of the results? 
  • Why did you make a particular decision at an interim look?

Suddenly, your somewhat old data needs to be able to reproduce your initial findings. In such a case, how long would it take you to satisfy the regulatory body?

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Topics: Data Management, Trial Quality, Trial Monitoring, FDA, ACES


‘A blend of courage and foolhardiness’: Marvin Zelen's 8 Predictions for the Future of Biostatistical Sciences

Posted by Esha Senchaudhuri

May 14, 2015 3:32:00 PM

Ten years ago, in May 2005, world-renowned biostatistician Marvin Zelen was asked to deliver a keynote address before the Eastern Mediterranean Region of the Biometric Society. His address, entitled ‘Biostatisticians, Biostatistical Science and the Future,’ [1] offered a reflection on the direction which the field at large would have to take, given the anticipated leaps in software and the rise of big data.

This included eight predictions on how short and longer term advances in technology would shape the field.

As we prepare to celebrate the annual Marvin Zelen Leadership Award in Statistical Science, this year awarded to Professor Nan Laird (Harvard University) [2] [3] we can take a moment to re-examine the predictions and insights of Cytel's beloved friend and Board Member. 

 


Where will the field of biostatistical sciences be ten years from now? Thirty years from now? How about one hundred years from now? It is perhaps a guessing game full of imprecise probabilities and chances for Bayesian updating.

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Topics: Movers & Shapers, Education, Marvin Zelen


New Articles on Adaptive Clinical Trials & Adaptive Financing

Posted by Esha Senchaudhuri

Apr 30, 2015 5:00:00 PM

Adaptive financing (not to be confused with adaptive licensing) explores how biotechs, pharmaceuticals and potential investors, can use adaptive designs for more strategic financial decision-making, as well as for efficient drug development.  

“For example,” writes Zoran Antonijevic, Senior Director at Cytel Consulting, “Reduction in costs and development time can be accomplished by combining stages of development, or by early stopping for efficacy or futility. Investment risks at late stage of development can be reduced by incorporating a sample size reassessment at an interim analysis, or simply by incorporating stopping rules for efficacy and/or futility."

Zoran has just edited a volume of Clinical Investigation featuring articles on the financial and developmental benefits of adaptive clinical trial design. The volume contains a broad spectrum of issues beginning with a couple of articles on adaptive financing by Tessella’s Tom Parke, and Christopher Weir of the Health Services Research Unit at the University of Edinburgh. 

The volume also stresses the pivotal nature of dose-finding for efficient development, with contributions on Phase 2 oncology trials from Anastasia Ivanova, Guochen Song, Olga Marchenko and Stergios Moschos; as well as Meinhard Kieser, Stefan Englert and Geraldine Rauch. Thomas Jaki also explains the use of multi-arm trials in treatment selection with a look at an Alzheimer’s case.

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Topics: Clinical Development Strategy, Adaptive Clinical Trials, Adaptive Finance


Dose-finding with Sequential Parallel Comparison Designs

Posted by Esha Senchaudhuri

Apr 23, 2015 3:53:00 PM

Last week the Cytel Blog discussed the benefits of using the Adaptive Maximizing Design [AM Design] for dose-finding trials involving clinical utility limiting therapies. However, there are other ways that a dose-finding trial can make use of frequent-adaptation maximizing designs. Here we look at what happens to early phase clinical development when an AM Design combines with another adaptive design that is slowly gaining popularity, namely the Sequential Parallel Comparison Design. 

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Topics: Cytel Consulting, Early Phase Trials, Clinical Development Strategy, Adaptive Clinical Trials, psychiatry and neuroscience


Adaptive SSR for Small Sample Sizes?

Posted by Esha Senchaudhuri

Apr 21, 2015 6:09:28 PM

“We shouldn’t use an adaptive design, our sample size is too small.”

Most clinical trial planners have heard this line of reasoning so often it has come to be taken as true. Never mind the fact that the first product to receive FDA approval using an adaptive sample size re-estimation design, was for a genetic condition affecting fewer than two thousand children worldwide [1].

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Topics: Clinical Research Services, Rare Disease, Clinical Development Strategy, Adaptive Clinical Trials


Phase 2 Designs for Clinical Utility Limiting Therapies

Posted by Esha Senchaudhuri

Apr 16, 2015 5:28:00 PM

When testing certain types of new drugs it is known in advance that the adverse side-effects of the medication will limit dose selection. For example, it is well-established that for many new pain medications, the side effects of nausea and vomiting will place constraints on the selection of higher dose levels.

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Topics: Dose-Finding, Adaptive Clinical Trials


New Cytel Whitepaper: Monte Carlo Simulations for Patient Recruitment

Posted by Cytel

Apr 13, 2015 11:23:00 AM

Cytel has published a new whitepaper on Monte Carlo Simulations for Patient Recruitment, which illustrates how a technique already popular within industrial and business environments is now changing the game of data-driven patient enrollment forecasting. 

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Topics: White Paper, Software Simulations, patient enrollment, Monte Carlo


Relative Clinical Efficiency and Phase 2 Biomarker Studies

Posted by Esha Senchaudhuri

Apr 9, 2015 11:37:00 AM

Last year. Nature Reviews Drug Discovery asked the FDA’s Tatiana Prowell (Hematology & Oncology Products Division) about the most common pitfalls confronting clinical trials in oncology. She cited the late stage evaluations of biomarkers as one of three critical issues leading to regulatory failure [1]. The primary lesson: those who want to test biomarkers need to start earlier.  

OncoMed’s Eric Holmgren recently expanded on the nature of the problem, at a Cytel and ASA sponsored symposium on Statistical Innovations in Clinical Development. According to Holgren, the use of biomarker testing during Phase 2 can satisfy many forward-looking objectives. The objectives to prioritize, however, should depend quite significantly on a clinical trial sponsor’s resource constraints and asset value, and in particular on pre-Phase 2 costs. He considers three scenarios to illustrate how the investment undertaken in pre-Phase 2 studies should shape the objectives of Phase 2.

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Topics: Oncology, Predictive Enrichment, Precision Medicine, Clinical Development Strategy, Statistical Innovations in Clinical Development


Monte Carlo Simulations II: Reassessing Strategic Options During an Interim Look

Posted by Esha Senchaudhuri

Apr 2, 2015 1:32:00 PM

 

Midway through a trial is a terrible time to realize that you need a new strategy to complete the study. Sadly, it is typically midway through a trial when drug supply, patient recruitment and budget all tend to deviate from the planned development path. Sometimes this is because the initial plan utilized idealized assumptions, (i.e. non-random patient enrollment), which failed to give the desired ballpark estimate of timelines and resource constraints. Other times, responding to unexpected operational or statistical challenges might have proven difficult due to inflexible trial designs [1].

Enforesys: Learn More We have spoken in some depth about how thorough planning and room for flexible decision-making can avoid some of these potential difficulties [1] [2] [3].  However, sometimes the specter of trial discontinuity arises anyway. Here is a scenario which recently confronted the Cytel Consulting Team.

 

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Topics: Clinical Development Strategy, patient enrollment, enforesys, Adaptive Clinical Trials


Leveraging the Flexibility of an Adaptive Clinical Trials: A Case Study

Posted by Esha Senchaudhuri

Mar 27, 2015 5:43:52 PM

We have often said that one of the greatest benefits of an adaptive clinical trial is the flexibility it affords for decision-making [1]. Often this flexibility is taken to mean that sponsors have some leeway to accommodate events - foreseen or unforeseen, challenging or advantageous - midway through a trial. However, when designing a trial, it is often possible to leverage this flexibility towards the sponsor's advantage. 

Recently, a client approached us, determined to select the best of eight candidate doses to move forward into a pivotal Phase 3 trial. Like many in their situation, our client worried that testing all eight doses would require unnecessary time and expense. However, given a variety of other constraints, a subpar Phase 3 dose was simply not an option.  

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Topics: Clinical Development Strategy, Adaptive Clinical Trials, Multi-Arm Studies


Statistical and Operational Challenges of the VALOR Trial: Mehta on the Promising Zone

Posted by Esha Senchaudhuri

Mar 26, 2015 4:00:00 PM

Last year Sunesis completed the VALOR trial, the first clinical study to make use of the groundbreaking promising zone design. The promising zone design implements an unblinded sample re-estimation after an interim look, but only if conditional power during the interim look falls within a designated promising zone. Although the VALOR trial did not confirm the efficacy of the new therapeutic, it provided the drug with the best possible chance to prove its efficacy.

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Topics: Promising Zone, Adaptive Clinical Trials, Statistical Innovations in Clinical Development


How Bayesian Strategies Can Expedite a Pediatric Clincial Trial Time by 20 - 40%

Posted by Esha Senchaudhuri

Mar 20, 2015 4:29:00 PM

Sometimes a new candidate drug for a pediatric study has already been tested on adults for safety and efficacy. We know that the drug is likely to work quite differently in children, but we do not know the degree to which the effects will be different. As a result, a conventional approach is to discard much of the information that has already gathered during studies of adults, and then to start from scratch with a pediatric trial.

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Topics: Bayesian Methods, Adaptive Clinical Trials, Pediatric


How to Plan Interim Looks in Adaptive Clinical Trials: 3 Strategies

Posted by Esha Senchaudhuri

Mar 19, 2015 5:26:00 PM

A well-timed interim analysis can generally supply added benefits to the operational and administrative aspects of a clinical trial. Particularly when clean data and safety adjudications provide information that is instrumental for stopping a trial early or informing sensitive interim decisions, the timing of an interim look may play a crucial role in leveraging all of the flexibility that a complex, adaptive design has to offer. 

 
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Topics: Interim Analyses, Cardiovascular, Cytel Events, Statistical Innovations in Clinical Development


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