What are the types of clinical trials? Dr. Ruben Mesa explains the differences and discusses what patients should expect with each type.
Dr. Ruben Mesa is an international expert in the research and care of patients with myeloproliferative neoplasms (MPNs). He serves as executive director of UT Health San Antonio MD Anderson Cancer Center in San Antonio, Texas. More about this expert, here.
You touched upon the various types of clinical trials and I would like to look at each one of them individually. So, let’s start with the double-blind clinical trial. What is that?
What that refers to is that neither the patient nor the physician knows which of the two comparator arms of the trial are more that a patient receives. So, with a trial, let’s say that there’s more than one way that someone can be treated. Let’s say arm A is drug X, and arm B is drug X plus drug Y, where drug Y is the experimental drug, and drug X is our standard of care. The reason they are double-blinded is that if the physician or the patient know exactly which arm they’re on, that might have an influence in terms of the physician assessing the response of the patient, the patient filling out questionnaires regarding response in symptoms.
It’s natural for us if we’re on a drug to say, “Oh, wow, you know, I automatically feel better. I’m excited about being on this,” and lead to what we call a bit of a placebo effect. Where there have been studies in the past where someone got a placebo but believed they were already feeling better even though nothing different had occurred. So, that they had somewhat kind of convinced themselves they were going to be doing better. So, the intent is, again, just to get the most objective set of response both from the physician and from the patient.
What is a randomized clinical trial?
A randomized trial means that when there is more than one arm, which treatment that a patient receives is random, is not chosen by the physician. Why that is the case is, again, we truly want to see which approach is better.
If the physician got to choose, they may inadvertently put all the sicker patients on one arm, or put all the less sick patients on one arm. In either case, it would make the value of the clinical trial less.
The value of the clinical trial, the entire reason we do them, is to try to, in the best way that we can, figure out which approach was better, whether that’s a treatment for your MPN, whether that’s figuring out whether a COVID vaccine helps to prevent to COVID, whether it’s figuring out whether a cholesterol lowering medicine is a good medicine to be on. Regardless of the reason, we want to know, is it the right way to go?
Because after that, there will be a lot of people who receive that treatment.
And finally, what is a controlled clinical trial?
A controlled clinical trial is, again – is following these same pieces where it has a comparator, where that comparator arm is sometimes also called the control, meaning that’s kind of the baseline – and, again, you’re looking to see, does that make a difference a baseline. So, let me use an MPN analogy. When ruxolitinib or Jakafi was first tested, there were no approved drugs for myelofibrosis.
So, how that worked – it was a controlled study. There was randomized placebo control. Half the group got ruxolitinib, half got placebo. After 24 weeks, people could then go on to get the ruxolitinib.
So, everyone eventually got the ruxolitinib. But, for those 24 weeks, we were able to compare what did the standard of care, which was really nothing, against ruxolitinib and saw a dramatic benefit. Now, the newer trials, now that ruxolitinib (Jakafi) is approved, ruxolitinib has been the control.
So, when there was a ruxolitinib and momelotinib trial to see if momelotinib was an effective drug, it was compared against ruxolitinib. Now, it was blinded, so that you didn’t know which of the two that you were on, but people were getting an active control. So, that is an active-controlled trial versus a placebo-controlled trial where the comparator is placebo.
What is an observational study, and how does that differ from the other clinical trials?
An observational study, as the name might suggest, is, again, where you’re observing a group of individuals, whether they start on a treatment, whether you’re trying to see how the disease behaves over a period of time.
But what it typically does not do is that you are intervening in a very specific sort of way where you are again changing how people otherwise would have been treated.