Aptose Biosciences Inc. (NASDAQ:APTO) Q4 2022 Earnings Call Transcript

Joe Pantginis: No, it does. And I guess maybe just a little on the — for the listeners and everyone and investors in general, benchmarking, you would look at from an efficacy standpoint,

William Rice: Yeah. So Ref, do you want to put that in context relative to the ADMIRAL trial? And Joe, thanks for the questions.

Rafael Bejar: Yeah, exactly. I think that that’s the way you need to view it is, what population are we treating and what expectations might they have from alternatives if Tustin wasn’t available. And remember, these are patients who, if they have FLT3 mutated and have seen FLT3 inhibitors, they’ve likely been through at least two lines of prior therapy. So they’re coming to us third line or beyond. In the second line setting, with the study at the early — at the interim analysis for gilteritinib, the CR/CRh rate was 21%. Now, later, that matured, especially with the inclusion of patients whose best response was measured after transplant. But at the point of that interim analysis that led to the approval of the drug, that was 21% in second line in patients, largely naive of other therapies.

So we would argue that a meaningful number in the third line setting would be significantly less than that. Perhaps, as low as half of that, or somewhere between half to that range, given that the alternatives for those patients at that point are going to be even less effective than they might have been in the second line setting as they were in the Admiral study where the chemotherapy response rate for CR was about 11%. So, that’s the ballpark that we’re working with and what we come down with, with the FDA, I think, we’ll then shape the scope of the study, the size, and so on and that’s the discussion we’re going to have.

Joe Pantginis: Great. Yeah, but the bar is fairly low for that patient population, as you said. Many of them will have already failed, other FLT3 inhibitor, venetoclax and more and more patients that are coming along now, especially in the US are having our much more experience with prior drug therapy. And so these patients are very difficult to treat. So we think the bar will not be exceptionally high but we also believe we can achieve it.

Operator: Our next question comes from the line of Edward Tenthoff with Piper Sandler. Your line is opus.

Edward Tenthoff: Great. Thank you very much and congrats on all the progress. It’s going to be an exciting year. I think most of the questions on 235 or 539 were asked, but I wanted to ask on lock’s sort of higher level how this fits into the treatment para or how this treats into your development plans. And specifically, what are expectations here? Is this a drug that you would consider partnering? Does it ultimately have comparability, maybe even with 539? Thanks very much.

William Rice: Hey, thanks Ted, for the questions. Yeah, we don’t get that many questions on Lux anymore but we’re still excited by the drug. Now that we have our new formulation, and especially as we go up to that next higher dose level, that’s the plan now, and we hope we get higher exposure as we go into that. But in terms of what we would like to do with this molecule, first of all, I must say that Tuspetinib is our top priority among everything and it has to be because it is delivering, it’s more advanced, it’s delivering, but Lux, as we move forward, we’d love to see that we’re getting the exposure that we want, and that the pill burden is also much less cost of goods, much less. If we continue to see activity in AML, we have done studies where we’ve put Tus and Lux together, and they are not antagonistic.