Tessa Romero — Analyst, JPMorgan
Hi, Catherine and team. Thanks so much for taking our questions this evening. Liz, actually a question for you. Thinking through the outcome of the phase II RADIANT trial, how should we think about scenarios around effect size here around your primary endpoint of the SAPS H&D? How should we think about the lower bounds of what could still have a path forward into phase III? Put another way, how much room do you think you have in your data to be able to execute on a phase III plan that is de-risked enough in ADP? Thank you.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
It's a great question, Tess, and obviously one we've been giving a great deal of thought to, of what would be really phase III-enabling data. I'll make a few comments there. First off, as I'm sure everyone on this call knows by now, we are 80% powered for a moderate effect size, 0.4 effect size on our SAPS H&D. There is probably a little bit of flexibility around that in terms of what would still be a supportable and phase III progressable asset. There is a lower level beyond which you start worrying about whether you'd be able to replicate the effect. I think we've got a ways there. In general, we're going to be looking certainly at the impact on SAPS at H&D, but that's not going to be the only thing we're going to look for at an effect size perspective.
We're going to look at responder analyses on SAPS H&D. There are a number of other endpoints that we're considering as well. Broadly speaking, we're looking to see that we've got something that we think continues to align with what we think would be a meaningful drug in this space. That's something that's going to be easy for patients to take, something they can take once a day with or without food, something that has evidence of efficacy, a supportive safety profile, and some of the stuff we won't definitively answer in phase II, of course. We are going to want to feel good about the fact that we don't have negative cognitive impact or negative impact on motor, things like that.
There's a number of different considerations we're going to be looking at, but that hopefully gives you a little bit of a flavor for the thinking.
Thanks, Tessa.
Tessa Romero — Analyst, JPMorgan
Thanks.
Ritu Baral — Analyst, TD Cowen
Hi. Thanks, guys. Two questions. One is actually a follow-up to Tess's and specifically, Liz, around the CGI-S. We had previously talked about how you intended to anchor the SAPS H&D to the CGI-S. Can you talk to what the MCID for CGI-S is, and if you're going to release that data, and if there's going to be sort of a correlative analysis with the top-line data with your data announcement? Second, could you speak a little more to some of the presentations that our team saw at IRSF around from the Delphi consensus? They talked a fair bit about improved tolerability. I believe it's an independent group, but improved tolerability with DAYBUE STIX and improved DAYBUE tolerability with new titration regimens and how what they presented at IRSF is making an impact on DAYBUE commercially. Thanks.
Elizabeth Thompson — PhD, EVP, and Head of Research and Development, ACADIA Pharmaceuticals
I'll take a shot at the first part, certainly, and then probably we'll do some tag teaming on the second. With respect to some of the
CGI-S and how we may use that. First and foremost, this is our key secondary endpoint. I will say, I guess I should start with level setting with expectations around what's actually going to be put out at the time that we do our initial press release. I think it's probably best to think in terms of what's going to be there for sure is going to be our primary efficacy endpoint and a comment on safety. Additional information, we're going to determine whether that is necessary and helpful at that time, and some things we will certainly wait for future medical meetings. I would not anticipate that you're going to see any kind of correlation analyses between CGI-S and SAPS H&D.
I think when I referred to the anchoring before, what I was talking about is in the context of an eventual dossier to support the applicability of an endpoint for regulatory purposes. We do anticipate we would need to have a full dossier explaining the behavior of the instrument, the appropriateness of it, et cetera. That is one path that we could take to help support that, is through an anchoring with the CGI-S. Generally speaking, it is considered that a change on CGI-S or CGI-I, that those in and of themselves are clinically meaningful, and so that's helpful as you're trying to define meaningful change on another instrument. I think that covered everything around the CGI-S. With respect to some of the presentations at IRSF, taking the tolerability with titration piece first.
What I will say is some of the information that we have from LOTUS has suggested over time that there, in patients who titrate, that you certainly don't see onset of diarrhea with the same kind of rate. That can give an opportunity for patients and families to get accustomed to the drug in context of many other tools that are in the toolbox. Things that we have encouraged physicians to make more use of is use of fiber, adequate water intake, making sure that they are discontinuing the antidiarrheals, et cetera. There are a number of different tools that can help from a tolerability perspective. I guess, Tom, I'll let you comment on how that is impacting physician use.
Thomas Garner — Chief Commercial Officer, ACADIA Pharmaceuticals
Just a couple of things I would say. First off, in terms of the Delphi consensus reaches that you mentioned, yes, we did present a number of papers at IRSF. As a reminder, the Delphi consensus was actually conducted prior to the launch of STIX. All of the information that you were seeing there relates to the oral solution. As it relates to STIX and the real experience that we're seeing, what we would say is, at the moment, it seems to be on par with what we've seen historically with oral solution in terms of tolerability. Obviously, we're learning more as we go, and this has only been the first full quarter where it's been in the hands of patients and caregivers beyond COEs.
What I would say is we've been very encouraged by the early start that we've made with STIX and have been pleased with the momentum that we're seeing across both COEs and non-COEs as we've moved into the community.
Ashwani Verma — Analyst, UBS
Great. Thanks for taking our question. I've got two on ADP as well. Maybe since in the phase II, the effect size that you're shooting for, the 0.4 that you mentioned about the powering. Just help us understand, the prior Study 019, I think, from data that had shown a 0.32, that was using a different NPI-NH scale. In RADIANT, you are using SAPS H&D, so is that effectively comparable or not, the effect sizes? Then secondly, saw that you started the phase III screening and enrolling the patients already, but we are waiting the data from phase II. If you're having to dose patients in the phase III before we get the phase II data, which dose would you be inclined to? Thanks.
Elizabeth Thompson — PhD, EVP, and Head of Research and Development, ACADIA Pharmaceuticals
I'll just keep going. With ADP, just to ground a little bit in the pimavanserin data. Study 019 was the phase II study of pimavanserin in ADP. It was, as you rightly note, using a different endpoint. There are other differences from a population perspective. In our current study, we are, of course, requiring biomarker confirmation, though I will say on balance, we expect that most patients who were in the 019 study probably would have been biomarker positive as they were fairly advanced in their disease course. We don't actually have biomarkers to be able to confirm that. Probably another important thing to keep in mind is one of the things that we have seen in the dataset is that there does appear to be a more significant impact in patients with greater baseline psychosis.
In the RADIANT trial, we are looking to move that patient population on balance to a somewhat more severe psychosis population than was in Study 019. With that context, yes, the phase II of pimavanserin did have an effect size of about 0.32. We did power for remlifanserin for 0.4 for a couple of reasons. One, of course, is the endpoint where we've changed to something that we think is more sensitive to change, but also the fact that we have enriched for that more severe psychosis population, which if you look in Study 019, actually, if you look in the severe psychosis population, your effect size goes up to more like 0.6.
We think that 0.4 is a defensible and appropriate powering assumption, and we think that if we meet that or in that vicinity, what we have is an agent that potentially could be meaningful for patients. I think the second piece was about phase III. Yes, the design of our study is operationally seamless. What that does mean is that once enrollment completed in the phase II portion, which we did announce recently, sites were able to start screening and then enrolling for the phase III portion. Right now, our phase IIIs are designed very similarly to the phase II study. The fact that these are statistically separate does mean we have the opportunity to analyze those data, which we are going to do in the September to October timeframe and share those data, but also make modifications to the phase III as needed.
Right now, we are enrolling for both dosing arms, so there would be placebo 30 and 60. There is a possible future where one of those dosing arms doesn't need to be taken forward, for now, we are continuing on with that.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
Thanks, Liz. It's going to be the Liz show today. The next question will be-
Marc Goodman — Analyst, Leerink Partners
Yes. Now that it looks like DAYBUE Europe is going to happen, can you help quantify that opportunity for us? You mentioned Germany in the fourth quarter. What other countries are you expecting to launch? Just give us a sense of how fast you think that ramp can be. Thank you.
Thomas Garner — Chief Commercial Officer, ACADIA Pharmaceuticals
Sure. I'll take that one, Marc. Thanks for the question. First off, goes without saying that we are very pleased that we've been able to turn around a negative opinion into a positive outcome for patients in Europe. As I mentioned in the preparatory remarks, the team are geared up and ready to go. We anticipate EC decision by the end of Q3, as Liz mentioned, the team is going to be pretty quickly ready to go thereafter. Germany will be the launch market as we get out the gates, you would then follow the normal cadence that you'd expect to see in terms of other early launch markets in the EU, which tends to be Nordics and then others that we're working through. Austria tends to be pretty quickly after Germany at the same time.
In terms of the commercial opportunity, I go back to what we've shared previously, which is, as you look at the $700 million guidance for 2028, we estimate somewhere less than 50% of that number to come from Europe. As you think about cadence for the launch, it will be somewhat gradual through the end of Q4 as the patients who are receiving free drug today in Germany transition to paid treatment, and then you'll see it consistently come online through next year. More information to come, but we're excited by the opportunity. I think as you think about the three pillars of growth for DAYBUE into the future, international expansion in Europe is certainly one, and we're really looking forward to pulling that through.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
Just to sort of put a nail on that, Mark, as you know, it takes years for countries to come online in Europe, so we will continue to follow the path that Tom's laid out. Also in the meantime, where we can supply physician demand through our named patient programs, we will be honoring that as well. Both of those things will be happening depending on the country and what's going on and what the legal system allows. Just to continue that.
Marc Goodman — Analyst, Leerink Partners
Thanks.
Tazeen Ahmad — Analyst, Bank of America
Hi. Good afternoon. Thanks for taking my questions. To clarify, do you expect the discontinuation rate to change with the STIX formulation? Secondly, on pricing in Europe for DAYBUE, on average, what % discount do you think you'll have to take in the major European countries over time? Thanks.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
Thanks, Tazeen. I'll let Tom talk about Stix and the discontinuation rate.
Thomas Garner — Chief Commercial Officer, ACADIA Pharmaceuticals
Sure. I think as we've been monitoring this Stix performance out of the gate, to date, as I mentioned earlier on, from the early data that we're seeing, it seems to be performing fairly similarly to what we have seen with the oral solution historically. Obviously, what's been very different though with the Stix launch is that we are now able to reengage patients who had previously discontinued the oral solution now that we have the new therapy. It's clear that patients and caregivers in particular, are willing to come back to DAYBUE given the efficacy that the brand offers. We're continuing to monitor closely. What I would say overall as you think about discontinuation rates, although we don't talk about them publicly so much as we did before, is they are largely in line with what we've shared in prior quarters.
They remain under double digits. It remains very consistent. As we see more patients move to the Stix therapy, and we're seeing that adoption happen somewhat quicker than we anticipated, we'll be sharing additional information on that.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
In terms of pricing in Europe, I think for now we're not guiding or giving any indication to prices in Europe. We will keep you updated as we move through those discussions with the individual national reimbursement authorities, starting with Germany. As you know, free pricing in Germany is for the first six months, and after that we'll start our negotiation. It won't be until the middle of next year that we start talking about that.
Yigal Nochomovitz — Analyst, Citigroup
Hi. Great. Thank you. Actually, just one more on pricing. You just mentioned the free pricing for the first six months. After that, what happens? Is there an accrual period where you estimate the expected negotiated price and then once you get that price, then you move to the set price? With regard, again, back to the ADP readout, I'm wondering if you could just speak to the statistical test. I know I think for the prior study for pimavanserin ADP
It was a t-test, but there was also in the PDP trial, you used MMRM. I'm just wondering if you could speak to those details. Thank you.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
I'll get Tom to talk about the analog discussion, and then Liz can move on.
Thomas Garner — Chief Commercial Officer, ACADIA Pharmaceuticals
Yeah. Thanks for the question, Yigal. Regarding Germany, as soon as we have the approval, obviously, we'll be launching in Germany, as we said. During that free pricing period, essentially per the legislation that exists in Germany, we have the ability to price as we wish. At the same point, we will be working with AMNOG directly because we'll have submitted our pricing reimbursement dossier, and that actually begins the process of negotiating what the price then becomes post that six-month free pricing period. At which point, that becomes the price that's recognized on a GTN basis. Essentially, for that first six months, we recognize the revenue at full price, whatever it may be set at. Post that six-month moratorium, that's when we start recognizing a different price from the publicly available price that you would see.
Elizabeth Thompson — PhD, EVP, and Head of Research and Development, ACADIA Pharmaceuticals
We haven't talked a lot about the statistical considerations in terms of the phase II study, but what I can say is that it is an MMRM analysis, and we are controlling for multiplicity, as you would anticipate with a pre-specified hierarchy.
Yigal Nochomovitz — Analyst, Citigroup
Got it. Thank you.
Malcolm Hoffman — Analyst, BMO Capital Markets
Hi. Thanks for taking our question, and congrats on the quarter. I was wondering if you could provide any color on whether you have seen a normalization of typical refill rates for NUPLAZID. I know you had mentioned new patient starts are really strong, just wanted to get a sense whether recurring scripts are back on track. For remlifanserin, can you comment on whether you have had to correct for any rater drift throughout the study? I know maintaining the consistency of the rating throughout the trial is pretty critical here. Thanks.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
We'll get Tom to start on NUPLAZID.
Thomas Garner — Chief Commercial Officer, ACADIA Pharmaceuticals
Sure. Yes, NUPLAZID referral and restart rates are exactly where we expected them to be. In fact, if we look at Q2 of 2026 versus Q2 of 2025 in historical years, there's actually been a particularly good rebound versus prior years. I think the phenomenon that we saw in Q1 of this year clearly does seem to have been a one-off. Obviously, we'll be monitoring very closely as we end 2026. Everything, as it relates to demand and pull-through and patients returning, is exactly where we anticipated it to be.
Elizabeth Thompson — PhD, EVP, and Head of Research and Development, ACADIA Pharmaceuticals
As far as commenting on rater evaluation, potential for rater drift, et cetera. We have tried to be mindful of that. We have a rigorous process, well, back in the day, for our site and our rater selection, including proven experience in these kinds of trials and psychosis assessments. We have extensive training, calibration exercises, and some standardized scoring protocols. Probably most relevant to your question, we are on an ongoing basis looking at blinded data and having sort of booster training of raters based on review of blinded data on an as-needed basis.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
Thanks for the question, Malcolm.
Speaker — Analyst, Morgan Stanley
Good afternoon, Catherine and team. Thanks for taking my question. Hope everyone's well. On DAYBUE STIX, clearly an acceleration there, can you quantify how much of the recent demand reflects entirely new patients versus improved compliance, persistence, or conversion from the oral formulation? Where do you estimate the current treated patient population penetration stands in the U.S. and how much untreated or underdiagnosed opportunity remains? Thank you.
Thomas Garner — Chief Commercial Officer, ACADIA Pharmaceuticals
Hi, Sean. It's Tom. Thank you for the question. Let me just provide a little more color on the dynamics that we saw in the quarter. If you look at our overall mix in the quarter, both across STIX and the oral solution. Around 60% of our referrals were coming from naive patients, 40% were returning patients. As we think about, again, future growth potential for the brand, obviously naive will remain a focus. I think with STIX, we now have this additional opportunity to engage patients who had previously just discontinued. When we look at STIX in isolation, it's interesting there that we saw 55% of our existing patients were switching from oral solution, 45% were either new or returning. That gives you a little more flavor. We've also been particularly encouraged by just the momentum that we've seen through the quarter.
If we take June in isolation and we look across the entire business, 60% of all of our referrals in June alone was the Stix formulation. I think that that gives you a very clear direction of travel as we think about just the uptake of Stix, the positive reaction that we've seen from both the clinical community and the patient community. We had a very strong IRSF meeting, and I think the momentum that we're building gives us a real sense of confidence that we can finish this year strong and really build further as we think about 2027.
Speaker — Analyst, Morgan Stanley
Thank you, Tom. Much appreciated.
Thomas Garner — Chief Commercial Officer, ACADIA Pharmaceuticals
Thank you.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
Next question.
Speaker — Analyst, RBC Capital Markets
Hi, team. This is Kevin on for Brian. Thank you for taking our questions. Maybe just one on the DAYBUE opportunity in Japan. Can you remind us maybe what the phase III trial design is there, and what efficacy endpoints those regulators might require? Then just what the addressable Rett syndrome population is in Japan. Thank you.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
We'll start with the addressable, then we'll move to Liz just to give her an opportunity to take a breath. Japan, we're looking to commercialize after we get our registrational study completed, which Liz can give you details on. The epidemiology of Rett around the world is similar. It's one in 10 to one in 15,000 live female births. We believe there's around 1,000 patients in Japan who have Rett syndrome. Various different sources give slightly different numbers, but it's around that. We're looking forward to our phase III trial, which Liz can give you a little bit of a description on.
Elizabeth Thompson — PhD, EVP, and Head of Research and Development, ACADIA Pharmaceuticals
It is a bit atypical as phase IIIs go. I think it's important to think of this in context of through discussions with PMDA. The primary support for an eventual indication, should we get there, is going to be our LAVENDER data. The phase III study that we're running in Japan is primarily to give some experience in Japanese patients. It is a very small trial. Think on the order of 20-ish patients. There is a placebo control, but obviously it is in a very small number. Again, we're looking at week 12 endpoints. We are looking at the same kinds of endpoints that we looked at in the trofinetide global program. Here, though, it is CGI-I as the primary with RSBQ as a key secondary endpoint. Again, the intent here is more to get experience in the Japanese population.
There's no expectation that we would be able to hit a P value, for example, with this kind of trial. It will give us some sense of how the drug behaves there, and we think will be hopefully supportive for what is primarily going to be a LAVENDER-based package.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
Liz?
Speaker — Analyst, RBC Capital Markets
Thank you very much.
Sumant Kulkarni — Analyst, Canaccord Genuity
Good afternoon. Thanks for taking our questions. I have two, one on remlifanserin and one on peak sales potential. It looks like Bristol's enrollment for ADEPT of KarXT ADP is going somewhat slower than that company initially expected. Given your experience with the ongoing ADP trial, do you think that pace is something specific to their program, or does it have wider implications for other ADP programs, including yours?
Elizabeth Thompson — PhD, EVP, and Head of Research and Development, ACADIA Pharmaceuticals
Probably should be careful on how much I'm speculating on somebody else's program. I guess what I'd comment on there is essentially we took a while in enrollment because we were looking to make sure we were enrolling the right patient population. I think that anybody who is considering trials in this space should be thoughtful about how they are enrolling their patient population and ensuring that they have the patients enrolled that they're looking to. One of our versions there, of course, is the biomarker confirmation, but overall, we are being careful in that.
Sumant Kulkarni — Analyst, Canaccord Genuity
Got it. Given where you are today with your solid performance in NUPLAZID, and you have now European approval for DAYBUE, do you have anything to add relative to your earlier $1.7 billion in peak global net sales in 2028 for those products?
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
I think we're talking about our confidence now of hitting those numbers as we move through the end of this year and we look at the continued uptake of DAYBUE STIX and we see how NUPLAZID ends the year. We will revisit that at that time. For right now, both for the $1 billion on NUPLAZID and the $700 million on DAYBUE, we are confident that we will achieve those numbers during 2028.
Sumant Kulkarni — Analyst, Canaccord Genuity
Thank you.
Rudy Li — Analyst, Wolfe Research
Hey, thanks for taking my question and congrats on a strong quarter for DAYBUE. Maybe just a quick follow-up to the patient dynamic for the STIX formulation. Can you maybe talk about the trend moving into July and August across different patient segments? Another question based on your recent market research and physician feedback, how should we think about the market dynamic for Rett syndrome with potential gene therapies in the coming years? Thank you.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
Yeah. I'm going to ask Tom to talk about July and August then talk about our view on gene therapy.
Thomas Garner — Chief Commercial Officer, ACADIA Pharmaceuticals
Yeah. A few things I would say, and thanks for the question, is as you look at the momentum that we saw during Q2, as I mentioned, 60% of our prescriptions at the end of June were already for STIX. We are really now beginning to focus our team's efforts beyond the COEs as we think about pushing STIX more broadly. We feel pretty confident that the momentum that we saw during Q2 is going to continue into Q3. Early signs are indicating that way. In addition to all of the additional programs that we have outside of the U.S. for inbound requests from inpatient sales as well. I think as you take that together, this gives us confidence in the guidance that we shared.
Obviously, we have lifted both the bottom and the top as we think about the end of this year. We feel good about where we're situated as we think about the remaining five months of 2026.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
In terms of gene therapy, just as a top line, we don't see any impact to our commercial forecast either in the short or long term with the potential introduction of a gene therapy. While we welcome any new option for patients with Rett syndrome, we believe that DAYBUE will remain the standard of care for patients with Rett syndrome, both in the U.S. and globally. Tom, I don't know if you want to talk any more about that.
Thomas Garner — Chief Commercial Officer, ACADIA Pharmaceuticals
I think obviously we're watching with a keen interest these first-generation gene therapies. I think there's optimism amongst certain patient types and certain members of the treating community. Again, we believe in the foundational standard of care that DAYBUE offers, obviously, it can be used either pre or post gene therapy. We think that that inherent flexibility and the fact that you can use DAYBUE, it's completely reversible. We know the profile of the treatment very closely, that DAYBUE will remain an important treatment for Rett syndrome moving forward. I think the advent of DAYBUE STIX, I suggest makes us even more confident in that fact.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
Thank you for the question.
David Huang — Analyst, Deutsche Bank
Hi there. Thanks for taking my questions and congrats on the quarter. I want to ask about the development of remlifanserin in ADP versus Lewy body. Is there any reason to think that probability of success would be different between those two indications? Then on the commercial side, I know you've talked about the $4 billion peak sales number there for remlifanserin across indications. Directionally, how should we think about how that might break out between ADP and Lewy body?
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
All right. I'll let Liz start on that one. I'll come up behind.
Elizabeth Thompson — PhD, EVP, and Head of Research and Development, ACADIA Pharmaceuticals
Yeah. I was so busy writing things down, I may have missed the second half of the question. Broadly speaking, we are enthused about both the possibility in Alzheimer's as well as in Lewy body. These are both areas with tremendous unmet need and really nothing available for these patients. In broad terms, I don't think we see the probability as wildly different across the two. We have more data in Alzheimer's with pimavanserin, certainly, but the data that we do have in Lewy body, though in a smaller number of patients, is pretty striking in its magnitude. We're looking forward to the first readout coming September to October, while we haven't disclosed the Lewy body readout, we are looking forward to that in the future as well.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
I think in terms of the commercial opportunity we've described before, and so have many others, the size of these markets, which are both considerable in the U.S. and beyond. I think in terms of how we see the $4 billion split out, I would say it's roughly 60% ADP, 40% Lewy body. Obviously, that highly depends on the data, the competitive frame, and who else is also on the market at the same time. I would say we're roughly around 60/40, but that will evolve as we get there. Let's cross the data threshold first. With that, we'll take the next question.
Speaker — Analyst, Baird
Hi, everyone. Thanks for taking my questions. This is Chris on for Jack. Just turning back to DAYBUE. Regarding the Stix uptake, I heard you just mention that 45% of Stix users were either new or returning. Can you provide what percentage of that 45% were new? Are you seeing higher rates of uptake in a certain patient demographic, age, for example? If so, do you see that changing over time? Thank you.
Thomas Garner — Chief Commercial Officer, ACADIA Pharmaceuticals
Yeah. As you think about the 45% that I mentioned, if you zoom in on Stix, it is roughly 60% were new, 40% were returning that we saw in the quarter. Again, as we go further into community, we anticipate that those dynamics may shift. It's notable that we actually saw a very significant shift in Q2 to community prescriptions versus what we saw in Q1, which you'd expect because obviously that's when we were actually talking to Stix more broadly beyond just the Centers of Excellence. In terms of returning patients, we are seeing a very diverse mix. One of the things that has been different to what we had assumed before we launched is that it would primarily be patients who had discontinued due to formulation concerns that would return to the brand.
We're actually seeing that a far broader group of patients are willing to return, which again, I think just talks to the community's interest in trying DAYBUE again based upon the efficacy that they know that patients can see with this treatment. I think the new formulation will potentially give us an avenue to unlock that opportunity further.
Ananda Ghosh — Analyst, H.C. Wainwright
Thanks, guys, congrats on the quarter. I have two questions on ADP. The first one is, where do enrolled patients of RADIANT sit compared to prior trials as mentioned, like the Ballard et al paper, what instrument was chosen on that criteria? The second follow-up question is, we noted that Study 019 was using NPI-NH both for screening as well as on the endpoint determination. The RADIANT, I think, the screening tool is different than the endpoint, what's the rationale behind that?
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
Ananda, the first part of your question was a little bit unclear. Maybe we'll get to start the Study 019 response, then you can re-ask it so that we can answer the right question.
Elizabeth Thompson — PhD, EVP, and Head of Research and Development, ACADIA Pharmaceuticals
Sure. What I'll say is on the screening criteria that we used, let me phrase this carefully. When we are considering patients that we're including in the analysis, we're taking into account both the NPI-NH values as well as the SAPS H&D values in terms of who qualifies for the primary analysis. We are actually including a component of the endpoint as well as another criterion. Again, the goal here is to edge up that overall population level psychosis severity, because we do think that slightly more severe patient population does seem to have a greater effect size that's shown.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
I think the first part of the question was around enrolled patients, perhaps you could just ask it again so we can understand it properly.
Ananda Ghosh — Analyst, H.C. Wainwright
Yeah. No, that was helpful. I think this answers a part of that question. My question was, given that one of the ideas from the Study 019 was that you need to have much more severe patients. Given the baseline of RADIANT, where do they sit with respect to the overall Study 019 population? That was the question.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
Got it.
Elizabeth Thompson — PhD, EVP, and Head of Research and Development, ACADIA Pharmaceuticals
We're not at this point disclosing what baseline characteristics of the population look like. What I can say is we did have enrollment criteria that should be consistent with edging up that overall population level severity. We're not currently disclosing what the actual baseline values are.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
Thanks for the question, Ananda.
Uy Ear — Analyst, Mizuho
Hey, guys. Congrats on the quarter, and thanks for taking our question. Just going back to the RADIANT study, I was wondering if you can provide a little more color in terms of the number of patients enrolled and whether all the patients have been dosed and what are the gating factors, I guess, to getting the data in September versus October. My second question is, are you able to share for which program the milestone payment in R&D was shifted to 2027? Thanks.
Elizabeth Thompson — PhD, EVP, and Head of Research and Development, ACADIA Pharmaceuticals
Sure. Again, hopefully I got all my notes down here. In terms of complete enrollment in the RADIANT program and in particular in the phase II portion of it, that was 363 patients that were enrolled. The main gating factor between September and October is going to be the 30-day safety follow-up if patients don't roll over. The study is still ongoing. Everybody has gotten past randomization, but there are still patients on study. I cannot answer today whether all patients are going to go into the open label extension or whether we may need that 30-day follow-up, which would move us out later. In terms of the milestone question. Sorry.
As we've been progressing ACP-711 forward, one of the things that we've been pleased, actually, is from a non-clinical perspective, we found that we both have the ability from a tox perspective and also the potential benefit of higher dosing. Accordingly, we added in some additional higher dosing that we're going to be exploring in phase I before we go into phase II. That did shift out our timing a little bit such that the milestone's not going to hit this year. I do look forward to updating more with some specifics around timelines and study impact as we get through that phase I dosing. We wanted to reflect reality of when we thought milestone would hit.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
That's great. Thanks, Liz.
Speaker — Analyst, Stifel
Hey, how's it going? Thanks so much for taking our questions. This is Julian on for Paul. In thinking about DAYBUE STIX with the reversal of the CHMP opinion, you sort of set this 15% threshold for contribution. Just thinking about the peak opportunity, I guess, is that a reasonable sort of benchmark, or do you have any analogs that you can point to in the rare disease space that can sort of set expectations to what contribution ex U.S. that DAYBUE could potentially have to your franchise? One quick question also on remlifanserin. There have been some studies published out there from independent authors that suggest that pimavanserin unapproved doses can get to 90% receptor occupancy after only a couple of weeks of dosing.
I guess just with the improvements to your molecule, what do you think is it fair to expect that it's going to be driving greater efficacy due to receptor occupancy, or is it going to be elucidating an effect due to the improvements you made to the clinical trial? Thank you.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
Thanks, Julian. I'll just make a quick comment around the peak opportunity for DAYBUE outside the U.S. As we've talked about already, we've guided to $700 million in 2028. That is definitely not the peak opportunity that we see. That is the 2028 number, just to be clear about that. Right now we're talking about around 15% of those sales to be from outside the U.S. That is obviously highly dependent on the reimbursement decisions that we get as we move through the reimbursement discussions that we've already sort of talked about. I would say that's an average analog for other rare disease opportunities. As we progress through the reimbursement discussions and we get those decisions and we get the first view of prices in the EU, we will be better able to articulate what percentage of our 2028 sales as well as further future peak opportunities would be.
I think for right now, that's a fairly normal analog for rare disease. As rare disease is very heterogeneous, there is really not a normal analog. It's one that we are sticking with for right now, and we will update you as we go through. I'm now going to hand the other question back to Liz.
Elizabeth Thompson — PhD, EVP, and Head of Research and Development, ACADIA Pharmaceuticals
Yeah. Briefly, I suspect that the data that you're referring to is in young, healthy volunteers, because that's where most of the receptor occupancy information is. I'll say that is true that we get to near full receptor occupancy, even with pimavanserin at marketed doses. It is our expectation and belief that in elderly and diseased patients, this is a bit of a different animal, and higher levels are going to be necessary to get to the same receptor occupancy. To sort of support this, I would point again to the exposure response analyses that we've done out of prior datasets in both Alzheimer's and Lewy Body that do suggest that levels that are higher than what you can get to with a marketed dose of pimavanserin on average do seem to be associated with higher efficacy.
Again, I think that that is a strong reason to believe there's the potential for greater efficacy. I will say that even if the degree of efficacy we saw with remlifanserin winds up being more similar to what we've seen with pimavanserin, we're structuring our programs in such a way by being focused on the individual diseases and properly powered, such that I think that we have an increased likelihood of technical and regulatory success, even if the effect were to be similar to the pimavanserin in terms of its scope.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
Thanks, Liz.
Catherine Owen Adams — CEO, ACADIA Pharmaceuticals
We'd just like to thank you all for your questions and continued support of ACADIA and look forward to reporting on our next quarter, where we will have an exciting set of results for remlifanserin. Thank you all for your attention today.