Good day, ladies and gentlemen, and welcome to Acadia Pharmaceuticals' fourth quarter and full year 2021 financial results conference call. My name is Gigi, and I will be your coordinator for today. At this time, all participants are in listen-only mode. We will be facilitating a question and answer session toward the end of today's call. If at any time during the call you require assistance, please press star followed by zero, and the coordinator will be happy to assist you. I would now like to turn the presentation over to Mark Johnson, Vice President of Investor Relations at Acadia. Please proceed.
Thank you. Good afternoon, and thank you for joining us on today's call to discuss Acadia's fourth quarter and full year 2021 financial results. Joining me on the call today from Acadia are Steve Davis, our Chief Executive Officer, who will provide an overview of our 2021 financial performance, a review of our business, and our outlook for 2022. Following Steve, Mark Schneyer, our Chief Financial Officer, will then discuss our financial results and guidance. Also joining us today is Brendan Teehan, our Chief Operating Officer, Head of Commercial, will provide updates on our commercial initiatives. Dr. Serge Stankovic, our President, will then discuss our two new drug applications and our pipeline progress before turning it back to Steve for final remarks and opening up the call for your questions.
I would also like to point out that we're using supplement slides, which are available on the events and presentations section of our website. Before we proceed, I would first like to remind you that during our call today, we'll be making a number of forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements, including goals, expectations, plans, prospects, growth potential, timing of events or future results are based on current information, assumptions and expectations that are inherently subject to change and involve a number of risks and uncertainties that may cause actual results to differ materially. These factors and other risks associated with our business can be found in our filings made with the SEC. You are cautioned not to place undue reliance on these forward-looking statements which are made only as of today's date.
I'll now turn the call over to Steve.
Thank you, Mark. Good afternoon, everyone, and thank you for joining us today. Please turn to slide five. To deliver on our mission, we are focused on three strategic pillars. First, drive growth of NUPLAZID franchise, where we continue to perform at a high level. Second, advance our three late-stage opportunities by submitting applications for new approvals for pimavanserin in Alzheimer's disease psychosis, or ADP, and for trofinetide in Rett syndrome, and completing enrollment in our negative symptoms of schizophrenia program, also with pimavanserin. Third, develop the next wave of CNS breakthroughs with our early stage pipeline while continuing to pursue strategic business development opportunities. Starting on slide six, for the full year 2021, we achieved net sales of $484.1 million, which represents 10% year-over-year revenue growth.
During 2021, we grew both total prescriptions and market share as we continue to outperform the top neurology, Parkinson's, and long-term care drugs. We achieved this despite operating in a disproportionately affected Parkinson's disease market, where in-person Parkinson's patient visits remain down approximately 20% and occupancy rates in long-term care facilities remain down approximately 15% compared to pre-pandemic levels. Our strong performance during this time underscores our ability to grow the brand. As the pandemic conditions normalize and overall PD market dynamics improve, we are poised to accelerate this growth. As we look ahead in 2022, we expect to see improvement in the infection rates of COVID-19. More importantly, as it relates to the Parkinson's market, we'll be looking for a normalization of staffing turnover and reduction of staffing shortages in both the office space and long-term care settings.
We'll also be focused on the rate at which Parkinson's patients are seeing their physicians in person. As Mark will speak to in a minute, for the full year 2022, we expect net sales to be between $510 million and $560 million. What we achieve within this range will be a function of read-through from the pandemic conditions and our ability to continue to outperform the top neurology, Parkinson's and long-term care drugs. Now let's turn to our three late-stage opportunities on slide seven. We recently announced the resubmission of our sNDA for pimavanserin for the treatment of ADP. In addition, we look forward to submitting our NDA for trofinetide for the treatment of Rett syndrome around the middle of this year.
Our Alzheimer's disease psychosis resubmission provides additional analyses from two previously conducted clinical studies, HARMONY and Study 019, to support a proposed indication for the treatment of ADP and is intended to address issues raised in the FDA's complete response letter. As we've previously described, this resubmission gives the FDA an opportunity to fully review our new additional analyses, and through this process gives us an opportunity to make our case that pimavanserin should be the first drug approved for the treatment of ADP. An important contextual point is that in our studies with pimavanserin, we did not observe impairment of cognition or motor function compared to placebo, a very important consideration in this elderly and highly medically compromised population and a historical challenge in developing drugs to treat psychosis in Alzheimer's patients.
We expect this to be a Class Two resubmission, which would mean the FDA will be targeting a six-month review with an action date in the third quarter. Having recently submitted, we are not yet at the point where the FDA would assign an action date. We should reach that point soon, and we'll update you as soon as they do. Regarding our NDA for trofinetide, at the end of last year, we announced positive top-line results from our phase III LAVENDER study of trofinetide for the treatment of Rett syndrome. Our NDA submission will be based on the pivotal LAVENDER study and its co-primary endpoints. In preparing for our NDA submission, we scheduled two meetings with the FDA. We've already met with the FDA to review the overall content and format of the clinical data to be included in our NDA submission.
The second meeting, scheduled for March, will be dedicated to covering similar ground on CMC aspects of the submission. We are planning for an NDA submission around mid-year and expect a priority review with a PDUFA action date in the first quarter of 2023. Moving to our third late-stage opportunity. In our phase III negative symptoms of schizophrenia program, we have something that's very rare in this space, and that is a positive pivotal study, our ADVANCE-1 study. The negative symptoms that schizophrenia patients suffer from have proved to be the most difficult to treat. The symptoms, which generally revolve around the social withdrawal aspects of the disease versus the hallucinations and delusion symptoms, have been the largest unmet need in schizophrenia for multiple decades. Today, we still have no FDA-approved treatment for negative symptoms.
With one positive pivotal study complete, we're in the process of running a second pivotal study. This is our ADVANCE-2 study. ADVANCE-2 is designed to be virtually identical to our successful ADVANCE-1 study with an important difference. In ADVANCE-1, we observed that at the highest dose tested, 34 mg, the drug effect was markedly higher than the statistically significant and clinically meaningful results of the overall drug-treated group, which included lower doses as well. Therefore, in our ADVANCE-2 study, all patients are receiving the optimal 34 mg dose. Please turn to our pipeline chart on slide eight. Our third strategic pillar to grow our business is to develop the next wave of breakthroughs in our early-stage programs.
Our early-stage pipeline is highlighted by our ongoing phase II pain program, evaluating ACP-044 in two studies, one in acute and one in chronic models of pain, with data coming from both studies this year. We have additional earlier stage programs highlighted by collaborations with Vanderbilt University and Stoke Therapeutics, as well as early stage internal programs designed to leverage the learnings of pimavanserin to further our franchise and take advantage of indications we might never get to with pimavanserin. Finally, we look forward to continuing to evaluate and execute business development to grow our opportunity set in CNS, further leveraging our strong R&D and commercial capabilities. With that, I will now turn the mic over to Mark to discuss our financial performance and guidance.
Thank you, Steve. Today, I'll discuss our fourth quarter and full year 2021 results and our 2022 financial outlook. Please turn to slide 10. In the quarter, we recorded $130.8 million in net sales, an increase of approximately 8% compared to $121 million of net sales in Q4 of 2020. This was driven by strong performance of NUPLAZID across channels with year-over-year volume growth. As part of net sales, we observed a gross to net adjustment of 20.7%, which is up from 18.3% in the fourth quarter of last year. Moving down the P&L, GAAP R&D expenses increased to $67.1 million in the quarter compared to $62.1 million in the fourth quarter of 2020.
GAAP SG&A expenses decreased to $105.8 million in the quarter from $120.8 million in the fourth quarter of 2020, which included sales and marketing expenses related to the potential DRP launch. Please turn to slide 11. For the full year 2021, we recorded $484.1 million in net sales, an increase of 10% compared to $441.8 million of net sales in 2020. This was driven by 3% year-over-year volume growth. The gross to net adjustment for the full year was 19.1%. As a reminder, gross to net was higher in 2021 as we observed a higher percentage of 340B volume, though this remains a mid-single-digit percentage of our overall volume.
GAAP R&D expenses decreased to $239.4 million in 2021 from $319.1 million in 2020. This was primarily due to the typical ebbs and flows of clinical development and BD activity. For example, in 2020, we expensed in R&D a total of $62.8 million in upfront expenses related to the CerSci acquisition and Vanderbilt collaboration. GAAP SG&A expenses increased slightly to $396 million in 2021 from $388.7 million in 2020. We ended the year with $520.7 million in cash and investments on our balance sheet compared to $632 million at year-end 2020. Please turn to slide 12 for our 2022 financial guidance.
For the full year 2022, we are providing net sales guidance for NUPLAZID in Parkinson's disease psychosis of $510 million-$560 million. The midpoint of this range represents a similar level of demand for NUPLAZID as last year. The high end reflects an improvement in PD market dynamics with subsequent increased demand. The low end represents lower demand, similar to levels we experienced in the second half of 2021. Regarding gross to net, we are anticipating an increase to a range of 20%-22% in 2022 as a result of higher 340B volume mix. At the midpoint of the range, this would be an additional $13 million reduction to net sales year-over-year.
As a reminder, we expect gross net to be the highest in the first quarter due to the annual reset of the Donut Hole Manufacturer obligation for Medicare Part D patients. Note if pimavanserin is approved for the treatment of ADP this year, both our revenue and expense guidance ranges will need to be updated. On the expense side for 2022, we expect GAAP R&D expenses to be between $355 million and $375 million, including approximately $25 million in stock-based compensation expense. While our R&D range does not guide for incremental spend for business development transactions, it does include the $60 million related to the upfront expenses associated with the Stoke collaboration that we executed in January.
In addition, this year we will have additional costs associated with trofinetide, including manufacturing costs for commercial supply and a regulatory filing milestone payment to Neuren. We expect GAAP SG&A expense to be between $360 million and $380 million for the full year, including approximately $45 million in stock-based compensation. The midpoint of this range represents an approximate 7% reduction in spend as compared to 2021. There are a few puts and takes encompassed within the range that I'd like to provide further color on. First, we are making investments in preparing for the potential launch of trofinetide in Rett syndrome. Second, we are focused on continuing our relative commercial outperformance in 2022 for NUPLAZID in PDP, while efficiently managing our spend as a function of the PD market conditions related to the pandemic.
Third, as it relates to the potential launch of NUPLAZID for ADP, most of the pre-launch work was already completed in connection with DRP, so we don't need to make a lot of additional investments prior to the ADP action date. We expect our 2022 year-end cash balance to be approximately $355 million-$405 million based upon our expected range of operational cash flows. As we look ahead, under our current business plan, we expect to turn cash flow positive during 2023. This holds true whether or not pimavanserin for PDP and/or trofinetide for Rett syndrome are approved, but is subject to our standard caveats of future business development or if our pipeline experiences less than standard rates of attrition. I'll now turn it over to Brendan, who will discuss our PDP commercial performance and outlook for 2022.
Thank you, Mark. Please turn to slide 14. I am extremely proud of our team's performance in 2021, where we delivered another year of double-digit % revenue growth. Our results underscore our team's ability to adapt and find new ways to grow the brand, including our HCP and patient caregiver campaigns, which supported growth in the second half of the year and have positioned us well for continued growth in 2022. In 2021, we continued to outperform branded drugs in the space as NUPLAZID grew both total prescriptions and market share. In the office-based setting, NUPLAZID's current script levels are up 30% when compared to pre-pandemic levels. This continues to be nearly double the neurology segment branded average growth rate of 17%.
During the same time frame, the top 10 Parkinson's brands were down 7% and carbidopa/levodopa scripts were down 3% when under normal circumstances we would expect them to be up 3%-4%. This is particularly relevant because carbidopa and levodopa are essential PD motor medications. Let's turn to the long-term care setting. Here, carbidopa and levodopa remain even further down at 11%, a reflection of a significantly lower LTC occupancy rate. The top 15 LTC brands were even further suppressed, down an average of 24%. At the same time, NUPLAZID was actually up 4%. Most importantly, we continue to drive share growth in both the community and LTC settings for NUPLAZID.
This tells us that while patient dynamics may be temporarily suppressed, our messaging is resonating with our customers, leading to NUPLAZID being selected as the therapy of choice more often in appropriate PDP patients. We outperformed despite significantly fewer in-person PD patient visits with their physicians and significantly lower occupancy rates in long-term care facilities. As the graphs at the bottom of the slide indicate, these market dynamics continue to persist. In addition, throughout the pandemic, NUPLAZID has maintained very high refill rates, which point to a strong user experience and the fact that refills are not impacted by the same market dynamics. To grow meaningfully, we will need to continue to drive new patient starts, and those are most often diagnosed when patients have in-person physician visits or are admitted to a long-term care facility.
Most importantly, based on our market research and forecasts, we continue to see a significant opportunity to grow our brand for years to come. Beyond PDP, we have two near-term potential commercial opportunities. Let's start with NUPLAZID for the treatment of ADP on slide 15. As you know, we were previously preparing our commercial teams for a potential NUPLAZID label expansion for the treatment of dementia-related psychosis, of which 70% are ADP patients, and the market dynamics are very similar. While the ADP indication is much larger than PD psychosis, this indication will be a line extension of an established brand already on the market since 2016. For NUPLAZID, this means we will leverage and build upon our current commercial foundation and established infrastructure. For example, since its launch, NUPLAZID has generated significant brand awareness.
We have a well-established patient support service to help patients and caregivers start and stay on NUPLAZID and will expand that capability for ADP. NUPLAZID enjoys broad formulary access in PDP with a well-recognized value proposition, and we anticipate similar access dynamics for this line extension. Finally, we have strong and experienced field teams in both the community and LTC market segments. Now let's discuss the opportunity with trofinetide for the treatment of Rett syndrome. With strong positive phase III results in hand, we are now focused on preparing for a highly successful commercial launch. Today, we have developed partnerships with engaged and motivated patient advocacy groups within the Rett community and are working with the Rett Syndrome Centers of Excellence as we work to identify patients who can benefit from trofinetide at launch.
We are evaluating opportunities to increase education and genetic testing to further support patient identification, and we will leverage our existing sales force and infrastructure while investing appropriately in further dedicated customer-facing roles for trofinetide where necessary. In summary, we are executing on pre-launch preparedness for both opportunities and look forward to helping patients and caregivers alike. I would now like to turn it over to Serge to provide an R&D update.
Thank you, Brendan, and good afternoon, everyone. I would like to begin by taking a deeper dive on our two U.S. regulatory submissions this year. Please turn to slide 17 to discuss the recent resubmission of our sNDA for the treatment of Alzheimer's disease psychosis. We estimate that there are approximately 900,000 ADP patients currently treated in the United States, the vast majority of which are with off-label multi-receptor antipsychotics, which offer little to no proven efficacy and can accelerate cognitive decline and impact motor function. Today, there are no FDA-approved treatments for ADP. Our resubmission package focuses on additional efficacy analysis from two separate previously conducted placebo-controlled studies of pimavanserin that included ADP patients. In the HARMONY study, where we observed highly statistically significant and clinically meaningful results in the overall DRP population, we also observed a meaningful benefit in ADP, a pre-specified dementia subgroup.
As previously reported, the subgroups were not powered to show statistical significance. However, the additional analysis we've conducted show a consistency of effect that strongly support the meaningful benefit observed. Study 019 was designed and powered to evaluate pimavanserin in ADP patients and showed both statistically significant and clinically meaningful results demonstrating the benefit of pimavanserin in ADP. In our resubmission, we will include additional analyses which support the benefit observed and specifically address the issues the FDA laid out in the complete response letter. Given the high unmet need, the demonstration of benefit, and the lack of negative impact of cognition and motor function observed with pimavanserin compared to placebo, we strongly believe that pimavanserin should be approved for the treatment of ADP.
We would expect the FDA to notify us soon that this will be a class two resubmission, and as such, we expect an action date target in the third quarter. Let's turn to our trofinetide NDA starting on slide 18. Rett syndrome is a very serious and rare disorder for which we estimate there are between 6,000 and 9,000 patients in the United States, and for which there is no FDA-approved treatment. The core symptoms of Rett syndrome that significantly impact the daily life of patients include loss of ability to communicate, both verbally and non-verbally, gait abnormalities, and repetitive and relentless hand movements, motor and autonomic impact, and serious GI issues, especially constipation. Ultimately, Rett syndrome patients lose their ability to maintain independent functioning on a daily basis and require around-the-clock support. Our positive results from the pivotal LAVENDER study demonstrated efficacy across multiple core symptoms of Rett syndrome.
Trofinetide demonstrated statistically significant separation from placebo and meaningful benefit on the core primary endpoints, the Rett Syndrome Behavioral Questionnaire, a caregiver assessment tool, as well as the Clinical Global Impression of Improvement, a physician assessment tool. Importantly, trofinetide showed improvement across all eight domains of the RSBQ. In addition, the study achieved statistical significance versus placebo on its key secondary efficacy outcome, another caregiver assessment focused on the patient's ability to communicate. This has the potential to address a significant challenge for parents and their children, whose lack of ability to communicate fully interferes with many aspects of their daily living. Importantly, the efficacy results were consistent across all age groups and severity of disease.
Trofinetide has been granted Fast Track status, Orphan Drug Designation, and Rare Pediatric Disease Designation, which means it's eligible for priority review, and if approved, could be awarded a Rare Pediatric Disease Priority Review voucher. We recently met with the FDA to review the overall content and format of the clinical data to be included in our NDA submission. We have a dedicated CMC review meeting in March and plan to submit our NDA around mid-year. Now let's discuss our negative symptoms of schizophrenia program on slide 19. There are over 700,000 patients in the United States who are currently treated for schizophrenia, but still have persistent and potentially debilitating negative symptoms such as social withdrawal, lack of emotion, and blunted affect, among others, and for which there is no FDA-approved treatment.
As part of our ADVANCE program, we have one positive pivotal study already, ADVANCE-1, results for which were published last year in The Lancet Psychiatry. ADVANCE-1 served as a dose-finding study where we clearly observed the most robust results on the primary endpoint in patients receiving 34 milligrams of pimavanserin. Please recall this is the dose commercially available and recommended for PDP and showed the most robust results in ADP. We are now evaluating only the 34 mg dose of pimavanserin in our second pivotal study, ADVANCE-2. Building on the learnings of our two previous studies in schizophrenia, ADVANCE-2 is being conducted in non-U.S. clinical trial sites. Enrollment is going well and expected to complete by the end of this year, with top-line results available in 2023. Slide 20 highlights our early-stage pipeline opportunities.
For acute pain, we have an ongoing phase II study evaluating ACP-044 for the treatment of postoperative pain following bunionectomy surgery, and we expect results around the end of this quarter or early next quarter. For chronic pain, we have an ongoing phase II study evaluating ACP-044 for the treatment of pain associated with osteoarthritis that is expected to complete by the end of 2022. Our M1 PAM program that we licensed from Vanderbilt University has a lead compound, ACP-319, that is currently in phase I multiple ascending dose trial. Another exciting opportunity is our recently executed collaboration with Stoke Therapeutics to pursue multiple RNA-based treatments for severe and rare genetic neurodevelopmental diseases, including SYNGAP1 and Rett syndrome. Finally, we have multiple early-stage molecules which are focused on different targets, such as analog compounds, which build upon the learnings of pimavanserin.
With that, I'll turn it back to Steve for closing remarks.
Thank you, Serge. Please turn to slide 22. Today, we are executing on our promise to deliver NUPLAZID into patients with PDP while preparing for a potential second indication in ADP. In addition, in the middle of the year, we expect to submit a new drug application for trofinetide for the treatment of Rett syndrome. We continue to advance our third late-stage opportunity with expected enrollment completion of our pivotal phase III study in the negative symptoms of schizophrenia, with results expected in 2023. From our early stage pipeline, we have two ongoing phase II studies for ACP-044, with results expected this year. In closing, I would like to thank our employees for their accomplishments and their continued commitment and passion as we continue our mission to elevate life. I'll now open up the call for questions. Operator?
Ladies and gentlemen, if you wish to ask a question, please press star followed by one on your touch tone telephone. If your question has been answered or you wish to withdraw your question, press the pound key. Please limit yourself to one question. I repeat, please limit yourself to one question. Press star one to begin. Please stand by for your first question. Your first question comes from the line of Neena Bitritto-Garg from Citi. Your line is now open.
Hey, guys. Thanks for taking the question. I was just wondering if you could elaborate a little bit more on the SG&A guidance and what specifically you're kind of cutting back on there. I know you did have some commentary around kind of reprioritizing spend, but if you could talk a little bit more about that and then how we should assume the SG&A spend could ramp if pimavanserin is approved in PD. I know previously you were talking about maybe adding 250 reps. If that number has changed at all, it'd be great to know that too. Thanks.
Yeah. Thanks much for the question, Neena. Mark, you want to take these?
Sure. On the SG&A range, as we mentioned, we have a number of puts and takes, right? The investment in trofinetide. I know you asked a question about kind of PDP. I mean, we have a mixture of activities that support it. You know, we don't disclose exactly what we're spending on, but we are evaluating and focusing on the highest return investments.
Yes, kind of within this range, you know, depending upon how the market dynamics progress over the year, there could be a reduction in overall PDP commercial spend. As I mentioned in the prepared remarks, we from ADP standpoint, there is, you know, limited investment needed prior to our action date. I think we'll reserve kind of guidance for potential increases in expenses and revenue for ADP, as, you know, if we get a positive approval, and we'll reflect kind of later in the year, how to give guidance, as appropriate at that time.
Got it. Thank you.
Thank you. Our next question comes from the line of Tazeen Ahmad from Bank of America. Your line is now open.
Hi, guys. Good afternoon, and thanks for taking my question. Can I just ask about the upper end of guidance that you've provided for 2022 sales? What would you need to see in terms of the major driver to hit the upper end of guidance? Is it the ability to see more doctors in person, therefore leading to additional scripts? Or is it that, you know, for doctors already prescribing, you need them to prescribe to more patients than they do? Thanks.
Steve, I think you're on mute.
Sorry about that. Thank you. Let me answer at a very high level and then I'll turn it over to Mark. As we mentioned in our prepared remarks, the range of revenues that you see are really driven by two undercurrents. One is the pandemic conditions and how they normalize as we move through the year. The second is our ability to continue to outperform other drugs in the sector. We're very confident in the latter and our ability to do that in the investments that we're making on SG&A, and the revenues that we have in our forecast reflect that.
The level of normalization and the rate of normalization in the pandemic, what I mean by that is our ability as a society and particularly as it relates to the medical community and the Parkinson's community is something that we'll just have to continue to assess as we go forward. The precise timing of those things is less clear. Mark, I think Tazeen's specific questions were about things in particular that may drive that upper end of our guidance that would reflect an improvement in pandemic conditions. I'll let you add additional detail and color.
I think, you know, while we have, as always, a variety of assumptions that comprise our range, really the principal assumption underlying the range is what Steve reflected is really the underlying market dynamics. I think Steve explained it well, and it, you know, just at the higher end of the range, as I mentioned earlier, would reflect an improvement in market conditions from what we've seen, you know, last year and recently.
Okay. By market conditions, are you saying more interactions with physicians? Or-
I think it's staffing, right, at both in long-term care facilities and in office settings. More inpatient, in-person patient visits with their doctors and a continuation because we've seen improvement recently in our ability to visit physicians in person. Brendan, do you have anything else to add to that?
Brendan, I think you're on mute.
Sorry. Thanks. Yes. Tazeen, thanks for the question. I just wanted to add to that. Yeah. The biggest driver is patients returning for face-to-face visits increase in LTC census. Both of those are important market dynamics that as the pandemic abates, we'll have a better opportunity for new patient starts than we have today. You know, with that said, as Steve pointed out, we have grown market share throughout 2021, which suggests that our message is absolutely resonating. We are gaining more and more share of first-line setting patients. It's really the opportunity for those patients to show up in the office or for new residents to enter long-term care facilities.
Okay. That's helpful. Thank you.
Thank you. Our next question comes from the line of Cory Kasimov from JP Morgan. Your line is now open.
Hey, good afternoon, guys. Thanks for taking the question. I wonder if you have any insight from the agency yet as to whether or not you should expect an ad com for NUPLAZID in ADP. Is that something you would have been communicated to already, or would you expect to learn about that when you get the FDA response to your resubmission after, I think, 30 days? Just kind of taking a step back, would you look at the opportunity to go in front of an FDA advisory committee as a favorable development for you? Thank you.
Yeah. Thanks so much for the question, Cory. Serge, you want to take that? Serge, you're on mute.
Yes, Cory. Thanks for the question. In respect to the advisory committee, this is a decision for the FDA, and-
You know, at this time, it's really difficult for us to speculate on whether or not they would request it. It's unlikely, I would say, that we will learn about that in the 30-day communication when the FDA response following our submission. You know, we would anticipate, considering the six-month review cycle, that fairly soon we should learn about that. You know, all I can say is in regard to advisory committee, we will be ready to make our case to the FDA advisors as well. We look for every opportunity to make the case of the efficacy and safety of pimavanserin in treatment of Alzheimer's disease psychosis.
You know, we'll just wait for the ultimate decision of FDA in regard to whether or not they will move toward the advisory committee.
Okay. Thank you.
Thank you. Our next question comes from the line of Ritu Baral from Cowen. Your line is now open.
Hi, guys. Thanks for taking the question. It's on trofinetide for Rett. Have you guys discussed functional unblinding analyses as part of the FDA meeting that you had on the data, or was it submitted as part of the statistical analysis plan? Further, can you just go through what the gating items are aside from that PMC meeting for that submission? Thanks.
Thanks for the question, Ritu. Serge?
Yes, thanks, Ritu. As a part of our briefing documents for the meetings, we have submitted a detailed information on the results from our pivotal trial and from the results of the trial. A complete and full both efficacy and safety information was available to the FDA in preparation for the meeting. To your question, whether this potential functional unblinding was discussed, the answer is no. That question was not raised in the meetings and contacts that we had with the FDA, so we did not discuss that at all.
Was that analysis-
Serge, do you wanna just recap the analyses that we've done on that point?
Oh, yeah.
Sorry, Ritu.
Go ahead.
I'm sorry, you were both speaking, so.
Yeah, maybe you could just give a very high-level recap of the analysis that we've done on that point.
Oh, yes. I mean, you know, we did a very detailed analysis both evaluating the efficacy data for patients with and without diarrhea on either of the co-primary outcome measures. We also looked at the scatter plots. We looked at the responder analysis. We did look. We did perform a very detailed analysis and all of them point in the same consistent conclusion that there is no indication of any bias in terms of the assessment of efficacy in regard to diarrhea as a adverse event. As I said, that question was not raised, and there was no discussion on that question at all in the meetings.
Got it. Were those analyses, Serge, pre-specified and submitted as part of the statistical analysis plan?
Those analyses will be part of our submission, well, NDA submission. Obviously, statistical analysis plan is always submitted prior to unblinding the data. These analyses were not part of the statistical analysis plan because there wasn't any information or basis on which you could anticipate those analyses.
Got it. Thank you.
Thank you. Our next question comes from the line of Jeff Hung from Morgan Stanley. Your line is now open.
Hey, thanks for taking the question. For your collaboration with Stoke and Rett, can you just remind us of how that may be differentiated from trofinetide and how different might the patient population be than those that you could treat with trofinetide?
Sure. Serge, you wanna take that question?
Yes. The Stoke technology addresses about one-third of the patient that display genetic hypomorphism. That's not the entirety of the population, but rather, as I said, about 35% to potentially 40% of the overall population of the patients. The difference in technology is that, based on this intervention, the increase in the protein is actually on the gene that is not performing sub-optimally. From that perspective, it's a completely different approach than what in general is approached with trofinetide.
I think maybe just to add a couple of annotations there. One is, with trofinetide, we have rights to North America, and then Stoke collaboration, our rights are worldwide, in that program. The short version is, with the approach that we're taking in collaboration with Stoke, there's a greater potential for disease modification. Potential for an even greater or more profound effect, with that type of approach. We think that program is a very nice complement to the franchise that we're building around trofinetide.
Thank you.
Thank you. Our next question comes from the line of Marc Goodman from SVB Leerink. Your line is now open.
Yes, Serge, I was wondering if you could talk about 044 and the upcoming data in acute pain. What are we gonna see? Kind of, what's the bar for you to move forward and get excited about the product? Then just talk about whether the mechanism works both in acute and chronic in the same way, such that the first study would give us a good sense of, you know, how the second study is gonna report out later this year. Thanks.
Yes. Thanks, Marc. This is, you know, the bunionectomy study is a first phase II study evaluating ACP-044 for treatment of postoperative pain following bunionectomy. It's an acute model. The study, just as a reminder, is a randomized double-blind, placebo-controlled, enrolled about 240 patients. It's appropriately powered. The objective of this study is really to evaluate safety and efficacy of ACP-044 in the targeted patient population and to evaluate efficacy in compared to placebo in pain control in analgesia. From that perspective, we would consider success of the study if we have statistically significant separation from placebo in terms of the pain control and have acceptable safety and tolerability profile for the drug.
Related to your question, we are doing the chronic model osteoarthritis study. That study will take a little longer to complete, so results will be sometime next year. You know, obviously, the mechanism per se, theoretically, but also on the basis of the preclinical animal models, the molecule was active both in acute and chronic models of pain. From that perspective, our anticipation would be that success in one model should indicate potential success in the other model. However, I will remind everybody, the pain studies are notoriously sensitive to placebo response. They are difficult to conduct.
From that perspective, I think that read-through is not automatic, and we should be always very careful in interpreting and translating the results of one model into another model.
Thank you. Our next question comes from the line of Jay Olson from Oppenheimer. Your line is now open.
Oh, hey, this is Matt on for Jay. Thanks for taking our questions. The first question we had was just on your M1 PAM program, just in terms of data timelines. As a corollary, if you would ever plan or imagine doing a combination trial of your M1 PAM with pimavanserin, if you could imagine any combination synergies there, that would be interesting to hear about. Also in terms of what indications could make sense. Then separately, we were just curious about any physician feedback you might have gotten so far after the phase III LAVENDER results for trofinetide, and how you're currently thinking about the market opportunity in terms of driving diagnosis rates. That would be really helpful. Thank you.
Okay. We've got a few questions in there.
Sorry, my watch is talking to me. I'll start with an answer on the combination, then I'll turn it over to Serge for f urther color on the M1 PAM program and then Brendan on trofinetide. Regarding the combination, I'll just simply say for competitive reasons, we don't talk a lot about opportunities we're interested in terms of additional things we're doing that are early in the pipeline, or things that we might have an interest in pursuing. I'll just simply say that you know, the potential applications for 319 we find very interesting, and there are things that we've learned through the development and commercialization of pimavanserin that we think give us insights to further leverage with new molecules, including combinations going forward.
Serge, you wanna speak more to 319, and then Brendan, you wanna take the trofinetide question?
Yeah. Just as a reminder, Matt, our ACP-319 M1 PAM program is for the potential treatment of cognition, cognitive impairment in Alzheimer's disease and negative symptoms in cognitive impairment in schizophrenia. As we announced, we initiated multiple ascending dose phase I study last year. It's currently ongoing. It's a multiphase study, and we look forward to providing additional updates later this year on the study. Even in this early development phase I studies, we will be evaluating target engagement to try to better understand whether, where are the benefits and what may be the potential for our further development. But as I said, we look forward to updating you later this year on the progress with the 319.
Just not to forget, to address your question on the feedback that we are receiving on the results of the LAVENDER study. I can say that we are quite pleased with the level of enthusiasm and excitement that we are seeing with treating physicians and experts out there in regard to the data. I mean, you know, it's to some extent understandable considering that so far there haven't been successful late-stage programs in Rett syndrome for treatment of symptoms of Rett syndrome. From that perspective, there is quite a bit excitement not only in the medical community, in the scientific community, but also in the parents and caregivers and community.
Bottom line, we are very enthusiastic to see the level of excitement and enthusiasm across and look forward to the NDA and approval.
Thanks, Serge. I just wanna echo Serge's comments. The Rett treatment community has given us very encouraging feedback on what they've seen of the LAVENDER results. To address your question specifically, Matt, around Rett diagnoses, as with a number of rare pediatric diseases, the pursuit of a diagnosis has increased pretty dramatically over time. There is already a high diagnosis rate for Rett, so we have access to databases that will show us physicians and numbers of patients that they have that are already diagnosed with Rett.
There's also been a significant increase in genetic testing in recent years, and we as an organization will work diligently and are pursuing a number of avenues to educate on MECP2 testing and then looking at potential partnerships to have confirmatory MECP2 testing for suspect Rett patients post-launch.
Okay. Got it. Extremely helpful. Appreciate all the info.
Sure.
Thank you. Our next question comes from the line of Ami Fadia from Needham. Your line is now open.
Hi. Thanks for taking my question. I had two questions. Firstly, just with regards to the PDP indication for NUPLAZID, has something changed structurally with regards to the market, because of which, you know, we may not see a recovery in patient inflow or, patients being admitted to long-term care, for quite some time? Can you sort of comment on that? Just separately on the ADP indication, should you get approval, can you talk to the market opportunity there and your expectation for, you know, being able to tap into that market relative to PDP? Thanks.
Brendan, you wanna start? I'll add color. I think you're on mute, Brendan.
My apologies. Ami, thank you so much for both questions. In PDP, no. I don't think that there's anything fundamentally restructured around PDP as a market. With the abating Omicron trends, we would expect that in-person PDP patient visits will improve.
We've already seen from some of our top physicians that type of dynamic has taken place. Patients that we're not seeing in December, they are beginning to see more readily in the first quarter. I think there are pandemic-related headwinds that as those abate will improve for us. Similarly, in long-term care, as you had suggested, the census rate has been suppressed. As Steve spoke to staffing challenges in long-term care facilities, again, in this environment, we're seeing selective improvements where staffing is improving. When staffing improves, new residents become potentially available to us. Again, I would call these temporal types of changes for us to adapt to in the near term, but we are hopeful that as pandemic conditions abate, so will these begin to return as well.
Your second question was around ADP. This is a tremendous opportunity for us. It has about seven times the number of addressable patients that we have in PDP. We've quoted a number of about 900,000 patients treated today. This is a line extension for an already existing and very well-known brand in NUPLAZID launched back in 2016. The core reasons to treat are very similar as they are for PDP, and there's an overlap in the types of treaters that are addressing ADP that also have treated PDP. We will expand obviously to address a broader audience of psychiatrists and psych-like PCPs that will also address ADP. This is an opportunity for us to be first to market by a significant margin with a product that would be the first to treat ADP.
I just add one quick thought to Brendan's point on PDP. The question was, do we see any evidence of a structural change in the market? As Brendan mentioned, the impact that we're seeing, the principal leading indicator, it's multifaceted, but the principal leading indicator is not infection rates, but it's staffing. It's staffing both in long-term care as well as an office-based setting, both shortage of staffing as well as significant staffing turnover. In addition to, particularly in long-term care, where occupancy rates are just down, the staffing turnover both have an impact on new patient starts. In all other aspects of the franchise, we continue to see very solid results.
Our refill rates have not wavered, so we continue to see very high refill rates. Our conversion rates, when scripts are written, quite frankly, climbed during this time frame. But the impact of the pandemic, particularly as it relates to staffing rates and as it relates to Parkinson's patients seeing their physician in person, have more of an impact on starting new patients. That's why we say as we see conditions normalize and those dynamics shift, we'll see an increased opportunity to start new patients. As Brendan mentioned, we've continued to grow share during this time frame. As these conditions normalize, we expect that there'll be a significant lift there for growth rates.
If I could just sort of follow up. I mean, it seems that you've assumed a comparable volume to last in your guidance at the midpoint of your guidance. Is that sort of conservative? As you see the trends evolve, you know, you would sort of review that. Is that how I should think about it? Or is there something else you're seeing, you know, which has sort of guided you to think about a or because of which you are sort of giving a guidance range where it's sort of a flat volume versus last year?
Mark, do you want to respond to that?
Yeah. Just to clarify, I guess the midpoint of the range is similar volume growth to last year, not flat volume over last year. There is underlying growth, just not, you know, as high as we've seen in the past. That is, you know, as we live through, you know, still living through the pandemic. Then the higher end of the range is coming out of the pandemic and getting back towards, you know, higher growth, and hopefully over the long term, that trajectory and above. I think that's kind of where we stand now. I wouldn't, you know, I would just say, listen, we're, you know, it's in the third year of the pandemic. I think we're getting better at forecasting. I wouldn't use the word conservative.
I would just say we have confidence in the range. We still are living in the pandemic, so that is influencing this range. We hope and expect to exit that, you know, in the near term, and then continue on with investment and growth in the brand.
Mark spoke to the midpoint of the range and the upper end. Just for the sake of completeness, of course, when we provide a guidance range, we model a number of scenarios. At the low end of the range, we're reflecting the recognition that it's possible that we're gonna have another variant besides Omicron or what would be Omicron two. There are other things that we just can't predict today that could impact us. At the lower end of the range, you do see flat volume there. That's not our expectation. Our expectation is as infection rates subside, most importantly, as staffing stabilizes, as Parkinson's patients get more comfortable coming to see their physicians in person that will get lift from that.
The timing of those changes and the magnitude of them directly correlate to the scenarios that we've modeled.
That's very helpful. Thank you.
Ladies and gentlemen, if you wish to ask a question, please press star followed by one on your touchtone telephone. If your question has been answered or you wish to withdraw your question, press the pound key. Please limit yourself to one question. I repeat, please limit yourself to one question. Our next question comes from the line of Paul Matteis from Stifel. Your line is now open.
Hey, thanks for taking our question. This is Alex on for Paul. Just one question on the ADVANCE-2 study. I was wondering if you could comment on impacts from sites in Ukraine and Russia as it relates to, you know, data integrity as well as potential timing of the study. Thanks.
Sure. Serge, you wanna take that?
Yeah. Let me just remind you first that ADVANCE-2 is a multinational study, and it's being conducted in 12 countries across multiple regions, Western Europe, Eastern Europe, and South America. So from the perspective of impact of the current geopolitical situation in Russia and Ukraine, I think that although there will be some impact locally, we certainly expect that considering the setup of the study, that no single country or geography would have a prevailing impact on the overall recruitment or conduct of the study. You know, when in regard to the data, we have through the COVID pandemic made a number of adaptations in terms of the remote data collection and interruptions in the programs.
We have in place mechanisms to deal with this sort of situation as well. Having said all of this, I do also wanna express a grave concern for the Ukrainian people and, you know, the suffering that they are going through with this unprovoked attack. I wish that the situation obviously gets resolved as fast as possible to the constructive resolution for Ukraine. I will say as far as our trial is going, we do not expect a dramatic impact.
Thank you. Our next question comes from the line of Gregory Renza from RBC Capital Markets. Your line is now open.
Hey, good evening, Steve and team. Thanks for the update, and thanks for taking my question. Maybe just a quick one, Steve, just in the event that I missed it. I'm just curious if you could comment just a bit about what you're seeing in this current quarter with nearly two months down, just as far as that recovery is concerned. While I certainly appreciate the general comments on the full year, I'm just interested in some of your thoughts on that recovery and some of those market dynamics for NUPLAZID in PDP as we've come out of the gate, not just with 2021, but entering January and also entering February to that extent. Thank you very much.
Yeah. Thanks much, Greg. I just need to start by saying, you know, we don't guide quarter to quarter, and the guidance we gave for the year today reflects very up-to-date information in terms of what we're seeing in the marketplace. The thing that I would like to stress is the factors that we believe are responsible for us outperforming basket of top neurology, top Parkinson's, top LTC drugs continue to be very much at play. We're continuing to see strong performance on those elements. We're continuing to see very strong performance in terms of our refill rates, our conversion rates, et cetera.
As we move forward in the year, we're at a point right now where we're just now kinda coming out as a society, it appears, of the Omicron wave. We don't know what the impact will be from reduction of mask requirements and just the way we behave as a society. But I would just simply say that as it relates to our business and specifically around PDP, we've tried to cover the range of outcomes for the year, and everything we've seen right up to today is consistent with the scenarios or reflected in the scenarios that we've run.
Again, the two underlying currents, undercurrents that will determine where we fall in this range are both our ability to continue to outperform drugs in the sector. We're highly confident of that. Then just precisely the precise timing magnitude of normalization of pandemic. For that, I think that we're as well informed as anyone can be, particularly as it relates to the impacts on the Parkinson's community, but we do need a little bit of time to see this play out through the year.
Great. Thanks for the color.
Thank you. We have time for one last question. Our next question goes to the line of Jason Butler from JMP Securities. Your line is now open.
Hi. Thanks for taking the question. Just wondering if you can speak to the commercial prep work you'll be doing in Rett this year. Obviously, assume the infrastructure build-out will mainly be, you know, towards the end of the year into next. But from a medical education perspective, just can you walk us through the work you're gonna be doing to get the market ready for the drug? Thanks.
Sure. Brendan, you wanna start? Brendan, I think you're on mute.
My humble apologies. Jason, thanks again for the question. Yes, obviously, we're very excited about the trofinetide opportunity, and we have been preparing even as the LAVENDER study was ongoing in phase III for a favorable result. The initial work, obviously we wanna work with the payer community to make sure that they're aware of the burden of illness, understand the unmet medical need and the size of the patient population, roughly 6,000-9,000 patients. We also have developed over time strong relationships with the foundations that support patients, caregivers, and the healthcare community, which has helped us to understand where we're gonna find our Rett patients and the volumes of patients that we're going to want to support.
Broadly, another area that we'll focus on are our white glove support services to be prepared by the time of launch, to support families, not only getting started on trofinetide, but to have a successful clinical experience, all of the support that they need from a clinical perspective, as well as prior authorization, assistance with co-pay, and so on. Those are probably the principal areas where we'll focus as they relate to the product. For the disease state, obviously this is a tightly knit community. There's a high level of awareness of Rett syndrome. We will work with the community to make sure that, where necessary confirmatory, MECP2 tests will also be available for suspected patients with Rett, at any of their HCPs.
Great. Thank you.
Thank you. Mr. Davis, please proceed to closing remarks.
Thank you, operator, and thanks to each of you for joining today. We appreciate your time and attention and support, and look forward to updating you as we go forward.
Thank you for your participation in today's conference call. This concludes the presentation. You may now disconnect. Good day.