The Cytel blog keeps you up to speed with the latest developments in biostatistics and clinical biometrics.
A 2018 publication in the Biometrical Journal by Cytel’s Cyrus Mehta, Lingyun Liu and Sam Hsiao, ‘Optimal Promising Zone Designs’ (1) marks a new milestone for adaptive sample size re-estimation. Inspired by insights from the team's work with a number of Cytel's strategic consulting clients, it presents an easy to implement and new iteration of the popular promising zone design. The basic principle? That any investment of sample size at an interim analysis should be contingent on a minimal acceptable return on the investment. This return is expressed in terms of guaranteed conditional power, By identifying a minimum rate of return upfront, the new design offers greater efficiency to clinical trial planners. Importantly, the design concept is both easy to communicate, and easily understood among statistical and clinical stakeholders alike.
In this blog, Cytel Co-Founder and Fellow of the American Statistical Association, Cyrus Mehta shares his insights with us on the goals and key takeaways of the publication, and how it adds to the growing toolkit of intuitive adaptive designs available to drug developers today. We also share full access to the publication itself.
The ASA Biopharmaceutical Section Regulatory-Industry Statistics Workshop is sponsored by the ASA Biopharmaceutical Section in cooperation with the FDA Statistical Association. Each year 800 statistical practitioners come together to absorb new information on statistical practices in all areas regulated by the FDA.
Cytel was honored to be involved in the workshop program, and our subject matter experts added value to the conference by sharing their academic and regulatory experiences.
Don’t worry if you missed the event!
In this blog, we share the full slide set slide from Cytel contributions at the ASA Biopharmaceutical Section Regulatory Industry Statistics Workshop.
Following the recent publication of their review article Adaptive Designs for Clinical Trials in the New England Journal of Medicine, co-authors Cyrus Mehta ( President and Co-Founder of Cytel, and Adjunct Professor of Biostatistics at Harvard University) and Deepak L. Bhatt M.D C M.P.H. (Executive Director of Interventional Cardiovascular Programs, Brigham and Women’s Hospital Heart and Vascular Center) were invited to participate in a live video discussion with the journal.
Why You Should Not Power for Superiority Upfront: Promising Zone Clinical Trials with "Adaptive Switch"
Powering a trial for superiority can be financially risky. In some instances it may also prove unnecessary.
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.
Cardiovascular outcome trials (CVOTs) have earned the reputation of being the untamable behemoths of the clinical world. Needless to say these trials are long and require extremely large sample-sizes. The Contrave LIGHT study required 8900 patients. The SAVOR TIMI trial enrolled 16,492 patients. Even the EXAMINE trial, which benefited from a promising zone design, required 650 patients.
However, since the explosive controversy over the FDA’s conditional approval of anti-obesity drug Contrave four years ago, there is much we have learned about how to make these trials shorter while also diminishing the financial risks of investing in them. For example, one of our clients managed to shorten the expected study length of an a CVOT by two years using a four point MACE Assessment (see below).
In this post, we explore some of the lessons we have learned when designing these large-scale clinical trials.
When designing clinical trials, many trial designers are advised to keep the trial simple. Prima facie, the keep it simple principle seems like sound advice. There are various logistical uncertainties that arise when implementing a clinical trial, and the more simple a trial – so conventional wisdom says – the easier it is to respond to these uncertainties.
According to Zoran Antonijevic, a Senior Director at Cytel Consulting, there is reason to doubt such conventional wisdom. After all, flexibility is hardly a virtue of a traditional trial design. Simple designs may seem to make it easier to monitor data and report results. However, a flexible design can better address remaining uncertainties in product development. These uncertainties are related to treatment effect, dose selection, or a sub-population that would experience the best benefit/risk from the treatment.
FDA-Industry Session on Cardiovascular Outcome Trials: Mehta on EXAMINE Trial’s Promising Zone Design
The FDA requires sponsors of new antidiabetic drugs to conduct cardiovascular outcome trials (CVOTs). CVOTs demonstrate that new therapies do not place unacceptable cardiovascular risk on patients suffering from Type 2 diabetes. The average CVOT requires about 5000 patients and takes an average of 5 years to complete. However, a recent white paper by the Cardiac Safety Research Consortium outlines a variety of methods to decrease sample size and study duration, by employing group sequential and adaptive CVOT designs.
As more clinical trials make use of adaptive designs, investors have come to realize that high quality trial designs can result in significant improvements to a trial’s financial risk profile. Regardless of a trial’s eventual success or failure, a well-constructed design provides a drug with the highest possible probability of success while mitigating financial risk.