Dr Jonathan Silverberg: Trial Washout Periods Are Methodologically Necessary

April 23, 2021

Washout periods are necessary to flush out any lingering effects of drugs that patients are taking before a study, explained Jonathan Silverberg, MD, PhD, MPH, associate professor of dermatology, George Washington University School of Medicine and Health Sciences.

Washout periods are necessary to flush out any lingering effects of drugs that patients are taking before a study, especially for those with known safety concerns, noted Jonathan Silverberg, MD, PhD, MPH, associate professor of dermatology, George Washington University School of Medicine and Health Sciences.

Silverberg is an author of the poster, “Efficacy of Ruxolitinib Cream Among Patients With Atopic Dermatitis Based on Previous Medication History: Pooled Results From Two Phase 3 Studies,” which is being presented at this year’s American Academy of Dermatology Virtual Meeting Experience.

Transcript

How will the washout periods in the TRuE-AD1 and TRuE-AD2 trials inform knowledge of atopic dermatitis?

The washout periods that are used in clinical trials are not necessarily always real world, but they're necessary from a methodologic rigor standpoint. Because what happens is, if you have a patient who's using variable quantities of topical corticosteroids or calcineurin inhibitors—doesn't make a difference which treatment—if they're using something which is already known to be effective or potentially even to have its own safety concerns, and they're using that running into the study, the big challenge is it's almost impossible to know how well the investigational drug is working. So you use that washout period so that any lingering effects of those initial drugs, like the corticosteroids, are flushed out the system.

Now, that's important for a few different reasons. But perhaps more than anything is when you look at the efficacy of ruxolitinib, one of the remarkable findings that was observed was that as early as 12 hours, there was already statistically significant improvements in terms of certain end points. So if you don't do that washout period, you can't see that, right? You don't know why you're seeing those signals. Is it simply because the patient is using their old medication and there's an imbalance there, or is it truly because of the investigational product? But because we have that kind of rigorous washout period, you really get to understand with more clarity and cleanliness the efficacy of your drug.

But in the real world, if we were switching therapies, I wouldn't tell a patient washout for a week. I would just say, “Okay, you failed topical corticosteroids. Tonight, switch over to ruxolitinib,” for example. But it is necessary, from a methodological standpoint.