Jeffrey M. Leiden
Analyst · ISI Group
Mark, it's Jeff Leiden. We've obviously had a number of questions on this and on the placebo group. And maybe let me take a step back, if you will, as I often do on this Phase II data, and tell you how we look at those data, which is we always look at the entirety of the results, and we try to look at it from every direction to see if we're seeing a consistency of the CF, we're seeing statistical significance. I guess when I look at this data, the thing that is very convincing to me is that when you start by looking at what we saw in the lab themselves, which was this additive effect of 661 on KALYDECO in exactly these cells, G551D, Delta 508, that again has translated into what we're seeing in the clinic. And obviously, now with 5, 6, 7 trials, relate that with the in vitro results, translates into in vivo results. Then we saw the on-effect when we added 661 to patients who were stable on KALYDECO and, honestly, with only 14 patients, surprisingly, we saw a statistically significant on-effect. And then, of course, the off-effect is important. So we removed the 661, left the patients on KALYDECO, and we saw a statistically significant decrease. And that pattern, I think in a Phase II trial, is always very important. And then, finally, correlated with sweat chloride, which always gives us confidence that what we're seeing is an on-mechanism effect. So when I look -- when I walk around the trial and look at it from all perspectives, I see a consistency of statistical significance and this nice correlation from in vitro to in vivo. I think that's what's really gives us the high level of confidence.