Dr. Chris Bowden
Management
A lot of interesting questions, Marc. It's not a co-primary endpoint. So, there are two primary endpoints. The trial is positive if it hits on either one. And we'll be disclosing the further details around the stats on the trial later in time, especially as we get them up and running. Your question around VOCs related to sort of what we would expect in terms of the numbers and how hydroxyurea will come into play there, I mean, I think that's one of the hardest things to predict in this disease and only rendered more challenging by virtue of the fact that you have now with crizanlizumab, at least in the U.S. and expanding in Europe, a drug that's effective in reducing the frequency of VOCs. So, that's going to be something that we need to follow. And so, one of the reasons why we designed the trial the way we did that it can be successful on the basis of either one of those readouts, a close to best case scenario, and we do have reason to believe that we could reduce VOCs. And I think that if you look at the history of trials and if you look at -- most recently, when you look at the voxelotor trial that clearly improves hemoglobin but wasn't able to demonstrate an improvement in the reduction in VOCs. There's clearly an unmet need there. And there's -- the other part of your question is, I think there's just a lot of heterogeneity in this disease. And that's one of the reasons why we've received a lot of feedback from both the EMA and the FDA in terms of pulling all this together. A trial design is a mix of many things. It's feedback from the authorities. It's talking to individuals with the disease, in this case, sickle cell, and they talk about issues with access. They talk about issues with trust of the medical community. When they talk about their symptoms, the one that really, really comes out is pain. And so, these are the types of things pulling all that together. And then, regulatory feedback is the mix of you should do this, you must do this. And so, then, as a company, you have to take some positions, especially when you're balancing EMA versus FDA because they don't obviously give -- usually, they give you for some degree of inconsistency in that feedback. And then, you have to look at what's happening from an operations and feasibility perspective. So, pulling all that together is -- it's fun, it's challenging, it's complex. And we've been working hard to come up with the plan that we have today, which we think balances all those factors and give us the best chance of having a positive trial that demonstrates clinical benefit for individuals with sickle cell disease.