Voxelotor's Potential as Treatment for Sickle Cell Disease

Neil B. Minkoff, MD: Why don’t we use that as a springboard to try to say, what is the future going to bring? Because you mentioned that hopefully we’ll soon have a full toolbox. There are a few different molecules that are coming down the pipeline. Could you give us an overview of some of those leading ones in the pipeline? And then we can have a conversation about how we think that’s going to affect the treatment of the patient and then the payer market behind it.

Ahmar U. Zaidi, MD: Absolutely. I guess we can start with voxelotor. Voxelotor, as we discussed earlier, has a landmark mechanism. With the sickle erythrocytes, you have the polymer forming, the polymerization of sickle hemoglobin. And voxelotor is being called a polymerization inhibitor. And the way that it does that is by stabilizing hemoglobin in the oxygenated state, of course remembering that hemoglobin has to be deoxygenated for it to polymerize. And the phase 3 study was recently published in the New England Journal of Medicine. It was a multicenter phase 3 placebo-controlled, randomized-controlled trial. It was a safety/efficacy trial that looked at 2 dosing ranges, 1500 mg and 900 mg. This is an oral medication that’s taken once daily, with a primary endpoint that was quite innovative that looked at an increase in hemoglobin of 1 g and what percentage of the patient population enrolled achieved it.

The age range in this study was 12 to 65 years old. And actually the results were quite promising. They showed that out of just under 300 patients that they enrolled, of which about two-thirds were on hydroxyurea, about half of them achieved a hemoglobin response at the high dose levels, which was very statistically significant compared to the placebo group. And they looked at how hemoglobin changed basically from initiation of study to week 24, so the delta of where the patients ended up. They also looked at markers of hemolysis to ensure that there was an effect on decrease in hemolysis in these patients. And they were able to show, as their secondary endpoints, some reduction in things like bilirubin and markers of hemolysis.

Neil B. Minkoff, MD: Based on the administration and the frequency, how do you think that would affect patient practice?

Ahmar U. Zaidi, MD: It’s amazing to be able to have a medication that will be once a day and oral. It’s always tough with medication. Adherence is always going to be an issue, and we have to start becoming innovative as providers on how we are going to push the button on adherence. It’s really beyond making the patient take the medication in the clinic. It’s hard for us to stay on top of that, but we just have to become innovative in our methods.

Neil B. Minkoff, MD: Where would you see using this in your practice?

Ahmar U. Zaidi, MD: For me, the idea of potentially having a medication that can increase hemoglobin by at least a gram in most of my patients and potentially reduce their risk of progression to multi-organ failure, a drug that promises organ preservation and a potentially decreased risk of stroke, it seems like a foregone conclusion that I’m going to want as many patients as possible on this medication.