Jeff Ludwig
Analyst · Bank of America. Please proceed with your question.
Yes, happy to. Thanks for the question. Appreciate it. Obviously, we think dose escalation is really important to the adoption of neratinib and the risk-benefit profile. Dose escalation has been very well received. Our teams talk about it consistently. It's been added to our package insert. It's been added to NCCN guidelines for both early stage and metastatic. And we actually see very good discussions and support around dose escalation from our leading breast KOLs. So the question you're asking is, hey, why aren't we at, say, 100% adoption on the graph that we're showing. And let me just give you some more color around that as we think about physicians who do adopt and those that don't adopt. There is certainly a group of physicians largely in a metastatic setting that believe you should start with full dose. They want to get full dose immediately upon treatment initiation. So there's a subset that will likely not going to start with a reduced dose. Number two, we do have some physicians in the community that have dealt with neratinib for a long time that do not have challenges managing diarrhea, and they've got their own way of dealing with it. And so they start with full dose and if they have a challenge, they dose reduce. The third situation is we believe the numbers that I'm showing you, although that methodology is very consistent, it really undercalls the complete adoption of dose escalation. We pull that data from our SP channel, which, as I mentioned before, is about 80% of our business, so it's a very good surrogate. We do not have visibility into the SD channel. And so for example, if a patient starts in the SD portion of the business, it's not uncommon for them to fill one time in the SD channel and then move over to the SP channel for their second and subsequent fields. In that example, if the patient starts in dose escalation in the SD when they come over to the SP, it's likely they'll come at full dose, and we'll pick that up as a full dose start, even though they started on a low dose. So these numbers, we believe, are very conservative. And quite honestly, I'm very happy with the overall trend. I would guess that the max that we'd ever see, I'm estimating might be 70%, 75%, that would be almost full adoption. So hopefully, that helps and add a little more color.