Tanya Dorff: My pleasure.
Zachary Klaassen: So xaluritamig, it's a word full to say, but we've got some great data that sort of led to this trial in progress, this phase three trial. Just tell us the background of this agent.
Tanya Dorff: Xaluritamig, which was formerly known as AMG 509, is a T cell engager. So it's an immunotherapy and it binds to STEAP1. So STEAP1 is a cell surface antigen that's very commonly expressed in prostate cancer. And the phase one study of this T cell engager showed promising results in an unselected population. So there's no biomarker screening needed for application of this particular drug.
Zachary Klaassen: And those data I think a couple years ago now really impressive results that led to this. The phase three trial now. So this is now in combination with abiraterone. Maybe just tell us about the trial design for XALience.
Tanya Dorff: Yeah. So Meg went forward into two different phase three trials. The XALute trial which was in a post docetaxel PK setting. And that allowed physicians to choose on the control arm either cabazitaxel or an AR pathway inhibitor switch was a 2 to 1 randomization or the physician's choice. So that trial completed a cruel rapidly. I think people were really impressed by the phase one, the large phase one really encouraging response signals.
And then XALience was designed because many of us feel immunotherapy might have greater efficacy and even a lower toxicity burden earlier in the disease when the immune system is more intact, when the disease burden maybe not so heavy, when the maybe disease is less heterogeneous. Many, many reasons to think that it would make sense to move this earlier.
So XALience is a phase three with a 1 to 1 randomization of or the investigators choice, which in this case can be docetaxel or abiraterone. And I should mention that the salaried Meg is being partnered with abiraterone because of some promising data from the very large phase one that had various cohorts.
Zachary Klaassen: That's great. So what are we looking at in terms of primary and secondary outcomes for this phase three.
Tanya Dorff: So the primary endpoint is for with central review. Obviously always key secondary endpoints include overall survival and toxicity and such. But I think with the shifting landscape many trials these days look at four as the first signal.
Zachary Klaassen: Sure. You know the fun part about these conversations. We get to pontificate a little bit. So how far along are we in the trial accrual. And where do you see this. Maybe positioning itself in the sense that if this is a positive trial, where do you see this combo working.
Tanya Dorff: Well. So this is an international phase three. And it is accruing a little bit more robustly internationally than in the US. Some of our US sites that participated in earlier studies are still just getting up and running. So I anticipate accrual will pick up. But this is an agent that requires weekly dosing in that first step-up phase.
And then it's every two weeks dosing. So I think there can be those patients who are not quite ready for chemo and they're not quite ready for an immunotherapy that's that intensive either. So where it will ultimately find its home, I think we'll come down to how strikingly different or not different that efficacy signal comes through in the trials, because, you know, I anticipate toxicity would be similar.
Maybe it will be less in the pre-taxane cohort. But if efficacy is is really markedly superior, that would obviously inform our future application.
Zachary Klaassen: And it's such a busy disease space with. So we have so many options. So it'll be interesting to see what those results are and then positioning it in that landscape. So a great discussion. Congrats on the on the trial and progress. And we'll look forward to hearing more from XALience in the future.
Tanya Dorff: Yes. Thanks so much.