Dr. Dan Skovronsky
Analyst · Evercore. Please go ahead.
Great, thanks. Umer, for your first question on IADRS and its correlation with CDR. Look, when we think about an endpoint for any clinical trial, there's really two things that make an endpoint, a good endpoint. One is the statistical validation behind it. So in other words, is it reliable across different patients across different time points, across different trials, we put together a lot of data that support that. Second, is it meaningful for patients? And in this course - case, of course, we believe that that's inherently true. This is a composite of two things that are widely used, both thought to be important and meaningful ADAS-Cog and activities of daily living, obviously, activities of daily living inherently meaningful for patients. Now, why do we pick IADRS versus CDR to be the primary outcome of the study? That should be obvious, it's because we believe that IADRS would be more sensitive for measuring decline and therefore more sensitive for measuring a drug effect. That's based on all of that statistical validation data that we did. If ADAS and some of the boxes were perfectly well correlated then ADAS couldn't be better, couldn't be more powerful. And yet, I'm telling you that our assumption going into this trial was that it would be. So of course, different outcomes will have some correlation, but they won't be perfectly correlated. Based on what we saw in this trial, I think we haven't changed our thinking on outcomes, and we still think ADAS is a very valid and important outcome for Alzheimer's trials. Of course, that's a discussion to be had with regulators in the scientific community. With the zagotenemab, this is our anti-tau antibody. Just as donanemab was a different type of anti-amyloid beta based on its specificity for plaque, zagotenemab is a different kind of anti-tau antibody. It's highly specific for aggregated tau. Now, we think that's particularly important in the case of tau because there's a lot of soluble monomeric tau, and tau antibodies, like any other antibody, not much of it gets in the brain. So if you have a lot of monomer and a little bit of antibody, it could sop up all of your antibody and not have left to go after what we think is the more important species, aggregated tau. So, we'll have to wait and see. Of course, this is a field that is younger than anti-amyloid therapies, but we've taken a lot of things we learned from anti-amyloid, applied them to anti-tau, and we're quite looking forward to getting that data later this year.