Amylyx Pharmaceuticals Inc

NASDAQ:AMLX

Earnings Call Analysis

Amylyx Reports Profitability and Growth Prospects

Amylyx Pharmaceuticals reported a successful year, marking their first full year of profitability with $49.3 million in net income. This stems from the demand for RELYVRIO, their ALS treatment, which has reached thousands of patients. The company highlighted their significant growth opportunities and a strong pipeline, with upcoming milestones in 2024. They are advancing programs such as the Phase III ORION trial in PSP and Phase II HELIOS trial in Wolfram syndrome, with results expected in the second half of the year. Amylyx is also looking forward to the PHOENIX trial's top-line data, which, if supportive, will further drive their growth.

A Year of Transformation and Profitability

For Amylyx Pharmaceuticals, 2023 marked a pivotal year as the company witnessed the first full year of commercial availability for its flagship product RELYVRIO, which generated substantial net revenue of $380.8 million. This achievement signified the company's remarkable transition to profitability, with RELYVRIO becoming the preferred ALS treatment for thousands in the U.S. and Canada. Reflecting this success, Amylyx's bottom line grew significantly, culminating in $49.3 million in net income for the year, alongside a strong balance sheet featuring $371.4 million in cash and short-term investments and an absence of debt.

Expansion Goals and Commercial Strategies

Driving growth, Amylyx sets its sights on broadening RELYVRIO's reach, aiming to have at least 10,000 U.S. patients undergo treatment simultaneously. This strategy includes enhancing physician engagement, raising awareness among neurologists, and promoting sustained treatment adherence. New leadership from Dan Monahan as General Manager and Head of U.S. Commercial underpins these initiatives, forecasting their fruition in 2024.

Forthcoming Clinical Data as a Catalyst

Investors are keenly anticipating the upcoming PHOENIX trial results for RELYVRIO, posited to be shared in Q2 of 2024 or earlier. These results could reinforce RELYVRIO's clinical efficacy and safety in a larger ALS cohort and potentially support approval in additional markets. Such positive outcomes could be game-changers, establishing RELYVRIO as the first therapeutics to demonstrate benefit in two distinct trials and enabling broader global reach.

Sustainable Financial Health

With a prudent cost structure in place, Amylyx's cost of goods sold remained within the expected range of 5% to 10%, even as it targets moderate increases in quarterly research and development as well as selling, general, and administrative expenses to support ongoing initiatives for growth.

Innovative Research and Diverse Pipeline

Amylyx not only concentrates on ALS therapy but also progresses with an impressive research portfolio. Projects include a Phase III trial for Progressive Supranuclear Palsy expected to yield results by 2025/2026, and a fully enrolled Phase II trial for Wolfram syndrome, with outcome details anticipated in the latter half of 2024. Additionally, Amylyx is advancing AMX0114, an antisense oligonucleotide aiming at Calpain-2 implicated in ALS, with clinical entry expected by year-end.

Enhanced Market Dynamics with Policy Changes

Policy changes such as the Medicare Part D benefit redesign are expected to favor patient economics, especially with the removal of co-pays during the catastrophic phase in 2025. Amylyx views these shifts positively for patients and is confident that its robust support programs will further mitigate any financial barriers to accessing RELYVRIO.

Earnings Call Transcript 2023-Q4

[Operator]

Good morning. My name is Jenny, and I will be your conference operator today. At this time, I would like to welcome everyone to the Amylyx Pharmaceuticals Fourth Quarter and Full Year 2023 Earnings Conference Call. [Operator Instructions] Please be advised that this call is being recorded at the company's request.I would now like to turn the call over to Lindsey Allen, Head, Investor Relations and Communications. Please proceed.

[Lindsey Allen, executive]

Good morning, and thank you for joining us today to discuss our fourth quarter and full year 2023 earnings.With me on the call are Josh Cohen and Justin Klee, our Co-CEOs; Jim Frates, our Chief Financial Officer; and Dr. Camille Bedrosian, our Chief Medical Officer.Before we begin, I would like to remind everyone that any statements we make or information presented on this call that are not historical facts are forward-looking statements that are made based on our current beliefs, plans and expectations and are made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. These statements include, but are not limited to: our expectations with respect to RELYVRIO, also known as ALBRIOZA or AMX0035; statements regarding our current and planned clinical trials and regulatory developments and the expected timing thereof; our business and marketing strategy and outlook; expectations regarding results of the Global Phase III PHOENIX trial of AMX0035 for the treatment of ALS and the impact of those results on the uptake of RELYVRIO or ALBRIOZA; the potential to expand global approvals for AMX0035 in ALS and other neurodegenerative diseases; and our expected financial performance.Actual events and results could differ materially from those expressed or implied by any forward-looking statements as a result of various risks, uncertainties and other factors, including those set forth in our most recent filings with the SEC and any other future filings that we may make with the SEC. You are cautioned not to place any undue reliance on these forward-looking statements, and Amylyx disclaims any obligation to update such statements unless required by law.Now I will turn the call over to Justin.

[Justin Klee, executive]

Thank you, Lindsey, and good morning.2023 was a transformational year for Amylyx. It was the first full year that our commercial product, RELYVRIO, also known as ALBRIOZA in Canada, was available for people living with ALS. The first full year of launch generated $380.8 million in net product revenue, including $108.4 million in the fourth quarter. We also made great progress on our global expansion, built a pipeline of potential medicines for neurodegenerative disease and transformed into a profitable company.We continue to have a steady number of new scripts being written in the quarter, and our discontinuation rates and net patients on RELYVRIO remained stable from the third quarter. Prescribing remains concentrated with roughly 80 prescribers, mostly at major ALS centers, still representing approximately half of all RELYVRIO prescriptions. We believe that we have significant room to grow with both the ALS specialists at these centers and the general neurologists.We are proud that 1 year into our launch, thousands of people with ALS in the U.S. and Canada are being treated with our therapy. We know there are tens and thousands more people to help. To reach them and achieve our goal of having at least 10,000 people on RELYVRIO in the U.S. at any point in time, we are focused on 3 key initiatives.First, expanding the use of RELYVRIO with physicians that specialize in ALS, who, as a group, care for about half of all people living with ALS. Second, increasing awareness of RELYVRIO among general neurologists and other physicians who care for the other half of all people living with ALS. And third, educating on the importance of sustained treatment with RELYVRIO, coupled with practical strategies to manage side effects.During Q4, we began rolling out these initiatives, and we expect the impact of these efforts will build throughout 2024. On that point, we recently onboarded Dan Monahan as the General Manager and Head of U.S. Commercial. Dan is an accomplished innovative leader with more than 20 years of experience across marketing, sales and market access covering numerous disease states, including his most recent position as VP of CNS Marketing and Portfolio Strategy at Otsuka. We are excited to have Dan leading our U.S. commercial organization and believe his leadership, approach and experience will help us with the goal of bringing the benefits of RELYVRIO to many more people.Of course, an important aspect of our launch will be our Phase III PHOENIX data. We are targeting top line data from PHOENIX during the second quarter of this year or before. We are thrilled to have Dr. Camille Bedrosian, our new Chief Medical Officer, joining us on the call today to discuss PHOENIX in more detail. Camille brings nearly 30 years of leadership in developing successful medicines for people living with rare diseases and facilitating global access to them. Her experience will be invaluable as we advance our mission.In addition to our focus on our U.S. launch, we remain committed to bringing the benefits of RELYVRIO to the more than 200,000 people living with ALS worldwide. While the vast majority of people taking RELYVRIO are in the U.S. and Canada, we have leveraged early access pathways in Europe and Israel in 2023, helping people gain access and generating revenue. We are making progress in Japan and have met with the Pharmaceuticals and Medical Devices Agency to discuss a potential regulatory path forward. We also continue to engage with key stakeholders around the world to identify other potential opportunities for pathways to access.Our long-term goal is to transform ALS from a disease for which symptom management is the standard of care to a disease that is treatable. RELYVRIO is an important tool in that transformation as it is the first and only therapy in ALS that has been shown to slow disease progression and help maintain functional independence in the same clinical trial and extend overall survival in a longer-term post-hoc analysis. We have made significant progress in our first full year launch. We look forward to continuing our work this year to reach the many more thousands of people living with ALS in the U.S., Canada and globally that could benefit from treatment.I will now turn the call over to Jim to discuss our financial results for the fourth quarter and full year 2023.

[James Frates, executive]

Thanks, Justin, and good morning.As mentioned, 2023 was a transformational year for Amylyx. We delivered a strong launch for people living with ALS, and we've become a profitable business. In addition, we're developing a significant pipeline of neurodegenerative disease and preparing for long-term growth.Now let me turn to the financial results for the quarter. Net product revenues were $108.4 million for the fourth quarter compared to net product revenue of $102.7 million for the third quarter of 2023, and $21.9 million for the fourth quarter of 2022. The increase from Q3 to Q4 was primarily driven by an increase in net product revenues in international markets, including revenues generated in Canada and through early access pathways in Europe. In the U.S., which represents the vast majority of our revenue, our net product revenue in Q4 were slightly ahead of our revenues in Q3.For the full year, net product revenues were $380.8 million. Gross to net adjustments were approximately 14% in the quarter and 12% for the full year, in line with our expected gross to net range. They were higher in Q4 as a greater proportion of our revenue came from outside the United States. Going forward, we continue to expect gross to net adjustments to be in the range of 12% to 15% until more significant revenues begin to accrue from outside the United States.Channel inventory levels at quarter end were as expected, with approximately 2 weeks of inventory in the channel at specialty pharmacies, similar to what we've seen in previous quarters.Cost of sales were $9.4 million for the quarter and $25.4 million for the full year, representing roughly 9% and 7% of net product revenues for the quarter and year, respectively, due to slightly higher write-offs in the quarter. We continue to expect COGS to be in the range of 5% to 10% of sales.In terms of free goods, roughly the same number of people in the United States received RELYVRIO for free in Q4 as they did in Q3 through either our interim access program or patient assistance program. Going forward, we expect free drug to remain in the range of 10% to 15% of total U.S. prescriptions.Research and development expenses were $44.9 million for the quarter and $128.2 million for the full year. The increase in the fourth quarter was primarily driven by increases in personnel expenses, our Global Phase III trial in PSP, which was initiated in December of 2023, the open-label extension of PHOENIX and spend related to the advancement of other programs in our portfolio. We expect quarterly R&D expenses to grow modestly quarter-by-quarter as we enroll patients in our ORION study and continue to build out our preclinical portfolio.Selling, general and administrative expenses, or SG&A, were $52.2 million for the quarter and $188.4 million for the full year. The increase was mainly driven by increases in personnel and marketing expenses. Again, we expect SG&A to grow modestly as we roll out additional growth initiatives for RELYVRIO in the United States and prepare for additional growth internationally, should the PHOENIX study be supportive.Our work this year led to a strong bottom line with $49.3 million in net income for the full year. This represents our first full year of profitability and is a testament to the demand that we see both near and long term for an efficacious treatment in ALS. Supported by our operating profits, we ended the year with a strong balance sheet. We had $371.4 million in cash and short-term investments and 0 debt.Finally, before I turn the call over to Camille, I'd like to take a moment to reflect on our first full year of launch. We're proud that RELYVRIO has already been prescribed to thousands of people with ALS in the United States and Canada, and our therapy is having a transformative effect on the way people with ALS are treated. We believe we have significant growth opportunities ahead of us as we work to bring our treatment to many more thousands of people. We're focused on delivering for people living with ALS, expanding the use of RELYVRIO in other neurodegenerative diseases and expanding our research into new mechanisms, even as we deliver on our bottom line. We're in a unique and exciting position as we enter 2024.I'll now turn the call over to Camille.

[Camille Bedrosian, executive]

Thanks, Jim, and I too wish you a good morning.I am pleased to have this opportunity to speak with all of you today. I joined Amylyx just a few months ago at an important inflection point of the company as we near anticipated top line data from the PHOENIX trial. The Amylyx team has made great strides in redefining how people with ALS are treated and in developing innovative therapeutic candidates for the treatment of neurodegenerative diseases more broadly.Prior to Amylyx, I was the Chief Medical Officer at Ultragenyx, Alexion and ARIAD. And now I'm excited to be a part of this mission-driven Amylyx team as we work to change the lives of people living with ALS and other neurodegenerative diseases.Many doctors consider ALS as one of the worst diagnoses possible to give a person. ALS is a disease of being locked in a body, relentlessly losing its ability to function independently, while also being conscious of what is going on. Every day, people living with ALS wake up in the morning and discover they will never again independently button their shirt, put in their contact lenses, brush their teeth or speak with their families. They lose the ability to eat, to hug a loved one and to walk. Knowing that the next loss is just around the corner, people living with ALS and their families live in a perpetual state of uncertainty and loss.We have shown the trajectory of ALS can be meaningfully changed. RELYVRIO is the first and only ALS therapy to help slow disease progression, maintain functional independence and extend overall survival in the same trial called CENTAUR. With CENTAUR, we completed a randomized placebo-controlled study that met its prespecified primary endpoint. This result led to regulatory approvals in the U.S. and Canada, publications in the New England Journal of Medicine, the Journal of Neurology, Neurosurgery and Psychiatry and several other peer-reviewed journals.The PHOENIX trial will provide additional efficacy and safety data in a larger population of people living with ALS and build on the robust and positive results observed in the CENTAUR trial. PHOENIX enrolled 664 people living with ALS and will evaluate function over 48 weeks using the same primary endpoint essential, the ALS Functional Rating Scale-Revised or ALSFRS-R, which is the gold standard measure of disability progression in ALS.Baseline characteristics show the population enrolled in PHOENIX has substantial overlap with CENTAUR, as was presented at ENCALS in July of 2023. The PHOENIX population is within 1 point of CENTAUR on the baseline ALSFRS-R score and within 1 month of CENTAUR on baseline time since symptom onset. PHOENIX has the potential to be the largest Phase III study in ALS to demonstrate a treatment benefit, which would make RELYVRIO the first and only therapy in ALS to generate positive data in 2 different trials. This would be an achievement never before seen in ALS, and we are enthusiastic about what supportive data from PHOENIX might mean for people living with this disease.Moving to our R&D pipeline. We are advancing several important programs and have a number of expected milestones coming up in 2024. We believe targeting neuronal death with RELYVRIO, also known as [ AMX0035 ], may have applicability across other neurodegenerative diseases. Our multinational Phase III ORION trial of AMX0035 in Progressive Supranuclear Palsy, or PSP, was initiated in December 2023, and we anticipate top line results in 2025 or 2026. We shared the scientific rationale on AMX0035 for the treatment of PSP in detail in a webinar posted on our website in July 2023.Turning now to our Phase II HELIOS trial of AMX0035 in Wolfram syndrome. The trial is now fully enrolled, and we expect to report results in the second half of this year. Wolfram syndrome is an ultra-rare genetic disease that leads to multisystem failure resulting in blindness, deafness, diabetes, ataxia, neurodegeneration and typically death by early adulthood. There are no approved therapies for Wolfram syndrome. Our R&D team has been collaborating with Washington University for many years to conduct research, which led to our decision to conduct the Phase II trial. We are looking forward to what the data from HELIOS would mean for people with Wolfram syndrome, a community where the unmet need is incredibly high.We are also advancing AMX0114, our antisense oligonucleotide candidate targeting Calpain-2 through IND-enabling studies and expect to enter the clinic by year-end. Calpain-2 is a critical effector of axonal degeneration, which is implicated in the pathogenesis of ALS.Again, I am very excited to be part of Amylyx and look forward to meeting many of you.I will now turn over the call to Josh.

[Joshua Cohen, executive]

Thanks, Camille.As we eagerly await the Phoenix top line results, we are developing updated clinician engagement and marketing program and believe supportive data would help in all aspects of our launch. And of course, our plan in the event of supportive data will be to reengage global regulatory agencies, including in Europe, in support of our goal to help more people access the benefits of RELYVRIO as quickly as possible.And to preempt a question that may be on many of your minds, there's no early look into the PHOENIX data, and we do not yet know the outcome of PHOENIX today. In addition, we are continually striving to transform and improve the way ALS is treated. And to this end, we are working to accelerate the time it takes to diagnose ALS.Current data suggests that diagnosis takes about a year from symptom onset and is not a straightforward path. Many people with ALS are misdiagnosed initially and see several specialists before they are accurately diagnosed with ALS; valuable time that could be spent on a therapy that slows neuronal death. To accomplish this, we are developing a novel biomarker panel to assist in diagnosing ALS earlier, and we intend to provide results from initial experimentation this year.Lastly, in addition to Camille and Dan, we are thrilled that Linda Arsenault recently joined us as our new Chief Human Resources Officer. She brings over 30 years of leadership and experience, including most recently from Sunovion, where she was the Chief Human Resources Officer. We are excited to welcome her to our team.In closing, we are proud of the achievements we made in 2023. We had a strong start to our launch of RELYVRIO and have reached many thousands of people living with ALS. In 2024, we are planning for PHOENIX top line data, anticipated during the second quarter or before, which we believe, if supportive, will be instrumental to our growth trajectory. We are a profitable company, which enables us to self-fund our R&D pipeline and evaluate RELYVRIO in other neurodegenerative diseases.We have a substantial opportunity ahead of us, both with our commercial launch in the U.S. and globally and with our pipeline. We are intently building a differentiated long-term franchise focused on developing and delivering innovative and impactful treatments for people living with neurodegenerative diseases around the world.Now, we'd be happy to take your questions. Operator, please open the call up to Q&A.

[Operator]

[Operator Instructions] Your first question is from Geoff Meacham from Bank of America.

[Chen Yang, analyst]

This is Charlie Yang on for Geoff. I guess for this year, given this Part D redesign, can you just talk about what's the potential growth projection for this coming year? And secondly, can you also tell us about what's the net patient adds for the fourth quarter compared to your prior quarter?

[Joshua Cohen, executive]

Yes. So maybe I'll start on the Part D benefit redesign and I could pass to Justin on the net patients as well. So the Part D benefit redesign, it kind of happens in 2 steps. There's some degree of the redesign that happened this year, and then it goes into a full implementation at the start of 2025. The big change this year is that the co-pay during the catastrophic phase of Part D is no longer in effect for patients. So I think we view that generally as positive for patients. But of course, we already have robust programs to provide financial assistance or free drug when necessary. So we don't think it's going to be a major impact on the business.I'll pass to Justin on net patients.

[Justin Klee, executive]

Yes. In our prepared remarks, we said net patients on therapy were stable to Q3, meaning it was approximately the same level as what we reported in the third quarter.

[Operator]

Your next question is from Neena Bitritto-Garg from Deutsche Bank Canada.

[Neena Bitritto-Garg, analyst]

So I was just wondering if you could talk a little bit more about some of the gross to net dynamics that impacted the numbers specifically in the U.S. I know you did take a gross price increase in the U.S. So just wondering if that was offset. And then if you could maybe explain a little bit more about the magnitude of the ex U.S. sales and how that compares to prior quarters and how we should think about that contribution moving forward.

[James Frates, executive]

Sure. Thanks, Neena. And I didn't realize you were part of Deutsche Bank Canada, but that's good. So yes, there really -- I mean, I think the gross to net, you see sort of typical fluctuations. And as I pointed out in the remarks, most of the change, sort of the upper-20 in Q4, really came from actually the European and Canadian revenue that we saw growing. So those have higher gross to nets than we do in the United States. And so in the United States, we did take a modest price increase. It was less than the inflation rate actually and really didn't impact gross to nets at all. So those remain stable, and we're not doing any contracting with insurers. That hasn't changed. And we think our access is actually really excellent in the U.S.So related to the European and Canadian sales, we announced our early access program in France in October. There are other managed access programs across Europe, some free, some paid. That's a far cry from, obviously, a full approval and the access that we want. But of course, post the successful PHOENIX, as Josh mentioned, we'll be back and looking for broader global approvals as quickly as is appropriate, should the data be supportive.But we did point out that the revenue in the United States was quite stable. It did grow slightly quarter-over-quarter, but the majority of our growth came from those programs ex U.S. And I think it does point to a global opportunity for us as we move forward, right? We retain rights around the world for this product. ALS is a disease that unfortunately strikes people equally in all regions of the world. And there's a major opportunity, as I think all of you know, in rare disease treatments for the global contribution to be quite significant over time. Obviously, we'll have to wait and see how PHOENIX goes, but I think it portends well for the future.

[Operator]

Your next question is from Corinne Jenkins from Goldman Sachs.

[Corinne Jenkins, analyst]

Maybe, for me, can you just provide an update on the duration of therapy you're seeing in the U.S. and talk to us about some of the specific strategies you're deploying to improve that duration of therapy? And then maybe as a follow-on, like, when do you expect those to potentially translate into real benefit as measured by revenue?

[Justin Klee, executive]

Yes, Corinne, thank you for the question. So our -- we've been reporting on our 6-month persistence rate and it's held steady. So in the U.S., we're still seeing approximately 60% of people still on RELYVRIO, 6 months after initiating treatment. And in Canada, that number is roughly 80% at 6 months. So I think the first thing is that we're taking learnings from Canada and applying those to the U.S. And I think what we found is that when you look doctor by doctor, some doctors have much, much higher persistence rates than others. And I think what we've learned from Canada as well as looking at those individual doctors, is that it comes down to education. If people know that this is -- they're being prescribed as treatment because it will slow down their ALS, it will keep them alive longer, then they're much more likely to stay on treatment. There are also very practical strategies for mitigating any potential side effects.Again, we're trying to transform ALS from a disease that has historically focused mostly on symptom management to one that focuses or we're trying to focus on intervention. And so part of that is, as things come up, how do we manage them. And there are very practical ways that we can do that. And so I think in terms of when that will translate to revenue, we, I think, made these recognitions recently. We've put many initiatives in place. We now have Dan Monahan leading our U.S. commercial efforts as well. So we expect all of these things to build throughout the year.

[Operator]

Your next question is from Michael DiFiore from Evercore ISI.

[Michael DiFiore, analyst]

Two for me. Number 1, how is the campaign of taking learning from Canada and applying it to U.S. prescribers? What's the reception been like so far? I realize it's pretty early. And my follow-up is, any thoughts or any color you could add on when you may lift the restriction on prescription reporting data? When might we expect that to happen?

[Justin Klee, executive]

Yes. Thank you and I'll certainly take the first one. So I agree, so it's early, but I think the learnings from Canada, the initiatives now that we're advancing in the U.S., we've had very positive feedback. I think again, if you try to think about what does it mean to transform a disease that historically is focused on symptom management because that's largely the tools that have been available, I think that, in short, it's education. So for example, saying that, well, this is not a cure, but it may slow down your ALS and keep you alive longer, that's a big deal. And that changes how one even talks about the disease, focusing on mitigation of any potential side effects. Again, in the past, if one has not had to manage side effects, then those things can be uncertain. But again, it just comes down to education. And I think that the doctors and nurses and therapists who care for people with ALS, I mean, first of all, they're just amazing people. And second, I think they're very, very excited at the opportunity to see this sort of transformation. But I think it's important that we and not just we, but all of our partners provide the right education on these things as well. So I would say that I think the reception has been excellent. As I was saying in the previous question, I think that the impact long-term on revenue, we'll see continue to build throughout the year.

[James Frates, executive]

Yes, Mike, and maybe I'll take the question on the access to the prescription data. I think from our read of the situation, it's not atypical to not have that data available in a rare disease indication. We don't have any plans to change it now. And I think we're really focused on making sure that we can deliver growth, particularly after PHOENIX and internationally. That's going to be where our focus remains.

[Operator]

Your next question is from Graig Suvannavejh from Mizuho.

[Graig Suvannavejh, analyst]

Two questions, if I could. One, any insights you could give into how things are progressing early in 2024, given like the changes that you're trying to make from a commercial perspective and whether there's any uptick versus the fourth quarter trends? And then secondly, I'm curious about this novel ALS biomarker panel that you're developing. Also there, could you provide some color on which exact -- or what types of biomarkers might be included in that panel, would be appreciated.

[Justin Klee, executive]

Yes. Thank you, Graig. So I would say, as I was saying in the previous remarks, I think with the initiatives we've seen, I think, a great reception from the community. And maybe break things out as I did in the opening remarks again into sort of 2 broad categories, I think first is physicians who specialize in ALS. And I think there, the educational opportunities, we've seen some people who have fundamentally changed their medical practice. Others have not. And so I think there, it's about educating on the benefits of RELYVRIO as well as tools -- practical tools to mitigate side effects. And then secondly, there's about half of people with ALS don't make it to a specialist or are not primarily cared for by a specialist. And for them -- for many of them, their knowledge and awareness of ALS is what they learned in medical school. I mean it's -- it might be 20, 25 years old. So they're very unaware of not just our treatment, but even the general advances that the field has made. So there, I think awareness is really key.And I would highlight as well that I think PHOENIX is a really great opportunity in both of those segments, both to increase confidence for the specialists and the potential benefits of RELYVRIO for their patients as well as the opportunity to increase awareness more generally in the medical community.And on the diagnostics side, I'll definitely pass to Josh.

[Joshua Cohen, executive]

Sure. So when we thought about the ALS diagnostic, I think the first thing to note is that when you think about the pathophysiology of ALS, you have the neurons that go from the brain to the spinal cord and then a second set of neurons that go from the spinal cord to the muscle that degenerate in massive quantity over the course of just 2 or more years. So it stands to reason that at least something must be released or measured or measurable when that process occurs. So we've collaborated with several experts in biomarkers and clinically in the ALS space. And what we can tell from looking is there has not really been a serious effort thus far in the field to try to develop a diagnostic in the space. There are many markers that seem to be up or down in ALS, but nobody's taken those together towards a kind of serious effort towards making diagnostics. So we're quite excited about that program. I think there's a lot of low-hanging fruit there, but we'll be reporting data on that later this year.

[Operator]

Your next question is from Marc Goodman from Leerink Partners.

[Madhumita Yennawar, analyst]

This is Madhu on the line for Marc. Are patients who are starting on RELYVRIO now earlier on in their disease or closer to diagnosis than earlier in the launch? And then secondly, what's your experience been outside of centers of excellence maybe in more community centers? Has engagement with the general neurologists there and patients been high? Or -- just curious on your experience there so far.

[Justin Klee, executive]

Yes. No, great questions. So I think, over time, naturally, I think we'll get people who are closer to diagnosis. I think at launch, we're looking at the prevalent population, whereas over time, the expectation is you get people closer and closer to diagnosis. And then I think that changes how you think about your education and persistence efforts as well. And then on the second question, the experience outside of the centers, yes. So I think our prescribing remains fairly concentrated still. So roughly 80 doctors account for about half of all prescriptions. And as you might imagine, those are -- the vast majority are ALS specialists. So I think some of our initiatives that we've just started kicking off, and we're very excited to have Dan lead as well, are to boost general awareness in the broader medical community. And so we'll continue to do those throughout 2024. And I think then we'll expect to see the prescriber base broaden throughout the year.But I think it's a really nice place to start from where we have people who have fundamentally changed their medical practice. These are the ALS specialists who see the most people with ALS. So I think it's a really nice foundation to have and then we can broaden out from there.

[Operator]

Your next question is from Joel Beatty from Baird.

[Unknown Analyst]

This is Ben on for Joel Beatty. Could you walk us through what the potential implications for RELYVRIO could be when the TUDCA-ALS trial results are announced?

[Joshua Cohen, executive]

Yes. So I think, first, it's really important to note that these are different products and different trials. So our drug, RELYVRIO, is a combination of sodium phenylbutyrate and taurursodiol and a proprietary co-formulation. So it is not the same product as TUDCA. And additionally, these are very different trials. PHOENIX and CENTAUR were trials designed with all the experts in the field, using some of the most state-of-the-art ways of running these trials in a controlled and rigorous way. I'd say, thus far, the TUDCA trial that's been run is quite different in design. It's a smaller trial, primarily with kind of an academic design tilt that was also run during the peak of COVID. So I think probably the broad strokes is, we don't really think they're comparable and that there will be read-through between the two. So we wouldn't draw those comparisons as that data comes.

[Justin Klee, executive]

And I would just reiterate, too, RELYVRIO is the only FDA-approved medication that was shown to slow ALS progression on the ALS Functional Rating Scale, extend overall survival in the same clinical trial and was published in the New England Journal of Medicine. So I think that's why, among the ALS specialists, we've seen such excitement. That's why FDA approved the medication.

[Operator]

Your next question is from Ananda Ghosh from H.C. Wainwright.

[Ananda Ghosh, analyst]

First of all, congratulations on reaching the milestone for completing the first year of the launch. It has been great seeing the story evolve from the inception. And being the last, maybe I have 2 questions. The first one is related to PHOENIX. On the PHOENIX side, the inclusion criteria mentions definite and clinically probable ALS patients. So my question is, how do one define clinically probable ALS patient? What was the rationale behind including that group of patient? And how does it change the way the data is analyzed?

[Joshua Cohen, executive]

Yes. So maybe first, I probably will try not to get too in the weeds, but first, in terms of the definition, so the El Escorial criteria of ALS defines many different potential groups, including suspected, possible or probable lab-supported, probable and definite. And the difference between those is essentially how many regions of the body are convincingly affected by ALS with possible being 1; probable lab supported being 1 plus different lab tests; probable -- clinically probable being 2; and definite being 3 or 4. The body is divided into 4 regions on the scale. What's been shown over time is that even people with possible ALS on this criteria have ALS, about 98% of them have ALS. So it's not like -- it's not actually a scale of certainty. It's much more a scale of diffusion, basically how far across the body ALS has progressed.When we did statistical modeling, going for the probable and definite patients does give you a more consistent and fast progression group, which is important, and that was one of the rationales for including them in the trial. But I think the most important thing when we compare CENTAUR and PHOENIX on the baseline characteristics is that, at baseline, the 2 populations look very similar. They're within 1 point on the baseline ALSFRS-R and within 1 month on the baseline time since symptom onset, which are 2 of the most important measures when we're thinking about how a cohort is likely to progress and to perform.

[Ananda Ghosh, analyst]

Got it. The second question is related to the rare disease. Yesterday, there was this public discussion on the biomarkers in the rare disease space, where Peter Marks, I think, was very positive about using biomarkers for accelerated approval pathway. Now, being in the company where you are looking at rare diseases like ALS, Wolfram syndrome and there was discussions on developing biomarker panels for ALS, is there a strategy to kind of develop very definitive biomarkers, like surrogate biomarkers that might help get to that accelerated approval pathway for other rare diseases in the pipeline such as Wolfram?

[Camille Bedrosian, executive]

Yes. Thank you. This is Camille. I appreciate the question. We actually are very heartened by Dr. Mark's comments around the possibility of using biomarkers for accelerated approval in rare disease. It will make a tremendous impact, giving the opportunity to treat individuals sooner, study the disease process and impact, in particular, neurodegenerative diseases where there is often a small window of opportunity and therefore, have drugs available to those individuals sooner. And we do see opportunities. You heard Josh mention the biomarker profile for diagnosis, which can be -- have an impact. And we're looking at Wolfram syndrome in similar ways as we consider with our initial trial, ways of learning about the clinical biology as well as potential biomarkers there. So stay tuned.

[Operator]

There are no further questions at this time. I will now turn the call back to Mr. Klee for the closing remarks.

[Justin Klee, executive]

Thank you, operator, and thank you all for joining us on our call today and for your support. We hope you have a great day.

[Operator]

Thank you. Ladies and gentlemen, the conference has now ended. Thank you all for joining. You may all disconnect.